1

42
nd
NATIONAL SCIENCE OLYMPIAD: 9 March 2006
QUESTIONS AND SOLUTIONS: BIOLOGY

1. A bacterial cell reproduces by
mitosis at intervals of 20 seconds.
Starting with a single bacterium in a
dish, how many bacterial cells would
be in the dish after one minute?

A. 16
B. 4
C. 8
D. 6

Answer: C
There are sixty seconds in a minute. In
twenty seconds, there will be two bacterial
cells. These will each divide in another
twenty seconds to give 4 bacterial cells.
After another twenty seconds, each of these
will have divided once to give a total of 8
cells. The simple mathematical sequence for
this twenty second replication is thus
2
n
: n = 0, 1, 2,

2. Forensic investigators would best
make meaning out of the following

A. Finger prints
B. Blood pathogens
C. Sweat
D. Scratch marks


Answer: A (Encyclopaedia Britannica)
A fingerprint is an impression made by the
papillary ridges on the ends of the fingers
and thumbs. Fingerprints afford an infallible
means of personal identification, because
the ridge arrangement on every finger of
every human being is unique and does not
alter with growth or age. Fingerprints serve
to reveal an individual's true identity despite
personal denial, assumed names, or
changes in personal appearance resulting
from age, disease, plastic surgery, or
accident. The practice of utilizing fingerprints
as a means of identification, referred to as
dactyloscopy, is an indispensable aid to
modern law enforcement. Each ridge of the
epidermis (outer skin) is dotted with sweat
pores for its entire length and is anchored to
the dermis (inner skin) by a double row of
peg-like protuberances, or papillae. Injuries
such as superficial burns, abrasions, or cuts
do not affect the ridge structure or alter the
dermal papillae, and the original pattern is
duplicated in any new skin that grows. An
injury that destroys the dermal papillae,
however, will permanently obliterate the
ridges. Any ridged area of the hand or foot
may be used as identification. However,
finger impressions are preferred to those
from other parts of the body because they
can be taken with a minimum of time and
effort, and the ridges in such impressions
form patterns (distinctive outlines or shapes)
that can be readily sorted into groups for
ease in filing.

2

Fingerprint patterns. From top left to bottom right:
loop, double loop, central pocket loop, plain
whorl, plain arch, and tented arch.

3. Which one of the following diseases
is transmitted by an invertebrate
vector?

A. Tuberculosis
B. Malaria
C. Measles
D. Rabies

Answer: B (Encyclopaedia Britannica)
Tuberculosis is an infectious disease that is
caused by the tubercle bacillus,
Mycobacterium tuberculosis. In most forms
of the disease, the bacillus spreads slowly
and widely in the lungs, causing the
formation of hard nodules (tubercles) or
large, cheese-like masses that break down
the respiratory tissues and form cavities in
the lungs. Blood vessels also can be eroded
by the advancing disease, causing the
infected person to cough up bright red
blood. The tubercle bacillus is a small, rod-
shaped bacterium that is extremely hardy; it
can survive for months in a state of dryness
and can also resist the action of mild
disinfectants. Infection spreads primarily by
the respiratory route directly from an
infected person who discharges live bacilli
into the air. Minute droplets ejected by
sneezing, coughing, and even talking can
contain hundreds of tubercle bacilli that may
be inhaled by a healthy person. There the
bacilli become trapped in the tissues of the
body, are surrounded by immune cells, and
finally are sealed up in hard, nodular
tubercles. A tubercle usually consists of a
centre of dead cells and tissues, cheese-like
(caseous) in appearance, in which can be
found many bacilli. This centre is
surrounded by radially arranged phagocytic
(scavenger) cells and a periphery containing
connective tissue cells. The tubercle thus
forms as a result of the body's defensive
reaction to the bacilli. Individual tubercles
are microscopic in size, but most of the
visible manifestations of tuberculosis, from
barely visible nodules to large tuberculous
masses, are conglomerations of tubercles.
In otherwise healthy children and adults, the
primary infection often heals without causing
symptoms. The bacilli are quickly
sequestered in the tissues, and the infected
person acquires a lifelong immunity to the
disease. A skin test taken at any later time
may reveal the earlier infection and the
immunity, and a small scar in the lung may
be visible by X-ray. In this condition,
sometimes called latent tuberculosis, the
affected person is not contagious. In some
cases, however, sometimes after periods of
time that can reach 40 years or more, the
original tubercles break down, releasing
viable bacilli into the bloodstream. From the
blood the bacilli create new tissue infections
3
elsewhere in the body, most commonly in
the upper portion of one or both lungs. This
causes a condition known as pulmonary
tuberculosis, a highly infectious stage of the
disease. In some cases the infection may
break into the pleural space between the
lung and the chest wall, causing a pleural
effusion, or collection of fluid outside the
lung. Particularly among infants, the elderly,
and immuno-compromised adults (organ
transplant recipients or AIDS patients, for
example), the primary infection may spread
through the body, causing miliary
tuberculosis, a highly fatal form if not
adequately treated. In fact, once the bacilli
enter the bloodstream, they can travel to
almost any organ of the body, including the
lymph nodes, bones and joints, skin,
intestines, genital organs, kidneys, and
bladder. An infection of the meninges that
cover the brain causes tuberculous
meningitis; before the advent of specific
drugs, this disease was always fatal, though
most affected people now recover.
Malaria is a serious, relapsing infection in
humans, characterized by periodic attacks of
chills and fever, anemia, splenomegaly
(enlargement of the spleen), and often fatal
complications. It is caused by one-celled
parasites of the genus Plasmodium that are
transmitted to humans by the bite of
Anopheles mosquitoes. Malaria can occur in
temperate regions, but it is most common in
the tropics and subtropics. In many parts of
sub-Saharan Africa, entire populations are
infected more or less constantly. Malaria is
also common in Central America, the
northern half of South America, and in South
and Southeast Asia. The disease also
occurs in countries bordering on the
Mediterranean, in the Middle East, and in
East Asia. In Europe, North America, and
the developed countries of East Asia,
malaria is still encountered in travelers
arriving or returning from affected tropical
zones. Annual cases of malaria worldwide
are estimated at 250 million, with more than
one million deaths resultingmost of them
young children in Africa. Malaria is actually
four diseases caused by four related
protozoan (single-celled) parasites:
Plasmodium falciparum, P. vivax, P. ovale,
and P. malariae. The most common is P.
vivax; the deadliest is P. falciparum. The
parasites are spread by the bite of infected
female Anopheles mosquitoes, which feed
on human blood in order to nourish their
own eggs. While taking its meal (usually
between dusk and dawn), an infected
mosquito injects immature forms of the
parasite, called sporozoites, into the
person's bloodstream. The sporozoites are
carried by the blood to the liver, where they
mature into forms known as schizonts. Over
the next one to two weeks each schizont
multiplies into thousands of other forms
known as merozoites. The merozoites break
out of the liver and reenter the bloodstream,
where they invade red blood cells, grow and
divide further, and destroy the blood cells in
the process. The interval between invasion
of a blood cell and rupture of that cell by the
next generation of merozoites is about 48
hours for P. falciparum, P. vivax, and P.
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ovale; in P. malariae the cycle is 72 hours
long. Most merozoites reproduce
asexuallythat is, by making identical
copies of themselves rather than by mixing
the genetic material of their parents. A few,
however, develop into a sexual stage known
as a gametocyte. These will mate only when
they enter the gut of another mosquito that
bites the infected person. Mating between
gametocytes produces embroyonic forms
called ookinetes; these embed themselves
in the mosquito's gut, where they mature
after 9 to 14 days into oocysts, which in turn
break open and release thousands of
sporozoites that migrate to the insect's
salivary glands, ready to infect the next
person in the cycle. Typically, victims who
are bitten by malaria-carrying mosquitoes
experience no symptoms until 10 to 28 days
after infection. The first clinical signs may be
any combination of chills, fever, headache,
muscle ache, nausea, vomiting, diarrhea,
and abdominal cramps. Chills and fever
occur in periodic attacks; these last 4 to 10
hours and consist first of a stage of shaking
and chills, then a stage of fever and severe
headache, and finally a stage of profuse
sweating during which the temperature
drops back to normal. Between attacks the
temperature may be normal or below
normal. The classic attack cycles, recurring
at intervals of 48 hours (in so-called tertian
malaria) or 72 hours (quartan malaria),
coincide with the synchronized release of
each new generation of merozoites into the
bloodstream. Often, however, a victim may
be infected with different species of
parasites at the same time or may have
different generations of the same species
being released out of synchronyin which
case the classic two- or three-day pattern
may be replaced by more frequent rigours of
chills, fever, and sweating. The parasites
continue to multiply until the body's immune
system suppresses the infectionunless the
victim is treated with appropriate drugs or
dies in the interim. Besides attacks, persons
with malaria commonly have anemia (owing
to the destruction of red blood cells by the
parasites), enlargement of the spleen (the
organ responsible for ridding the body of
degenerate red blood cells), and general
weakness and debility. Infections due to P.
falciparum are by far the most dangerous.
Victims of this malignant tertian form of the
disease may deteriorate rapidly from mild
symptoms to coma and death unless they
are diagnosed and treated promptly and
properly. The greater virulence of P.
falciparum is associated with its tendency to
infect a large proportion of the red blood
cells; patients infected with that species will
exhibit ten times the number of parasites per
cubic millimetre of blood than patients
infected with the other three malaria
species. In addition, red blood cells infected
with P. falciparum have a special tendency
to adhere to the walls of the tiniest blood
vessels, or capillaries. This results in
obstruction of the blood flow in various
organs, but the consequences are gravest
when capillaries in the brain are affected, as
they often are. It is this latter complication
known as cerebral malaria and manifested
5
by confusion, convulsions, and comathat
frequently kills victims of P. falciparum
malaria. Several strains of P. falciparum
have developed that are resistant to some of
the drugs used to treat or prevent malaria.
Also called rubeola, measles is a
contagious viral disease marked by fever,
cough, conjunctivitis, and a characteristic
rash. Measles is commonest in children but
may appear in older persons who have
escaped it earlier in life. Infants are immune
up to four or five months of age if the mother
has had the disease. Immunity to measles
following an attack is usually lifelong.
Measles is so highly communicable that the
slightest contact with an active case may
infect a susceptible person. After an
incubation period of about 10 days, the
patient develops fever, redness and
watering of the eyes, profuse nasal
discharge, and congestion of the mucous
membranes of the nose and throat
symptoms often mistaken for those of a
severe cold. This period of invasion lasts for
48 to 96 hours. The fever increases with
appearance of a blotchy rash, and the
temperature may rise as high as 40 C
(about 105 F) when the rash reaches its
maximum. Twenty-four to 36 hours before
the rash develops, there appear in the
mucous membranes of the mouth typical
maculae, called Koplik spotsbluish-white
specks surrounded by bright red areas
about
1
/
32
inch (0.75 mm) in diameter. After
a day or two the rash becomes a deeper red
and gradually fades, the temperature drops
rapidly, and the catarrhal symptoms
disappear. No drug is effective against
measles; the only treatment required is
control of fever, rest in bed, protection of the
eyes, care of the bowels, and sometimes
steam inhalations to relieve irritation of the
bronchial tree. When no complications
occur, the illness lasts 10 days.
Uncomplicated measles is seldom fatal;
deaths attributed to measles usually result
from secondary bronchopneumonia caused
by bacterial organisms entering the inflamed
bronchial tree. On the other hand,
complications of measles are frequent and
include a superimposed bacterial ear
infection or pneumonia or a primary measles
lung infection. Encephalitis is a rare
occurrence. Measles virus can invade
various organ systems and cause hepatitis,
appendicitis, and gangrene of the
extremities. A large percentage of cases of
severe measles are associated with
inadequate intake of vitamin A, and there is
evidence that treatment with vitamin A may
reduce measles complications. Mortality
caused by measles declined steadily in the
20th century as the health of children and
infants improved and effective treatment of
complications became possible through the
use of sulfonamide and antibiotic drugs. The
widespread use of measles vaccine,
beginning in the late 1960s, raised hopes for
the eventual eradication of the disease; but,
contrary to expectations, the incidence of
measles remains high worldwide. The main
problem is that the vaccine is not given to
infants before the age of nine months, when
the disease is most serious in the less-
6
developed countries. Another problem is
that the measles vaccine is a live vaccine,
and it rapidly becomes inert if exposed to
warm temperatures; 10 minutes in sunlight
is sufficient to kill it. This sensitivity is a great
hindrance to its use in tropical areas.
Research is currently directed toward
development of a more stable vaccine. In
developed countries, a measles vaccine is
commonly given at 12 to 15 months of age
as part of a combined measles-mumps-
rubella (MMR) vaccine.
Also called hydrophobia or lyssa, rabies is
an acute, ordinarily fatal, viral disease of the
central nervous system that is usually
spread among domestic dogs and wild
carnivorous animals by a bite. All warm-
blooded animals, including humans, are
susceptible to rabies infection. The virus, a
rhabdovirus, is often present in the salivary
glands of rabid animals and is excreted in
the saliva; thus, the bite of the infected
animal introduces the virus into a fresh
wound. Under favourable conditions, the
virus propagates along nerve tissue from the
wound to the brain and becomes
established in the central nervous system.
After a time it spreads via nerves to the
salivary glands, where it frequently produces
a foaming at the mouth. The disease
develops most often between four and six
weeks after infection, but the incubation
period may vary from 10 days to eight
months. Rabies virus travels quickly in a
bitten animal (e.g., raccoons, skunks, bats,
foxes, dogs, and cats, among other smaller
animals) from the bite to the central nervous
system. The disease often begins with
excitation of the central nervous system
expressed as irritability and viciousness. A
rabid animal is most dangerous during the
early stages of the disease because it
appears to be healthy and may seem
friendly but will bite at the slightest
provocation. Wild animals that appear to be
tame and that approach people or human
habitations in the daytime should be
suspected of having rabies. Infected dogs
usually show a short excitation phase that is
characterized by restlessness, nervousness,
irritability, and viciousness and is followed
by depression and paralysis. After a few
days they are unable to bite any more
because the muscles of the throat are
paralyzed; they seek only a quiet place to
hide and die from the rapid spread of
paralysis. Sudden death without
recognizable signs of illness is also not
uncommon. Dogs that develop the
predominantly excited type of rabies
invariably die of the infection, usually within
three to five days after the onset of
symptoms. Those that develop the paralytic
type of rabies without any evidence of
excitation or viciousness may recover on
rare occasions. Paralysis of the voice
muscles in rabid dogs may produce a
characteristic change in the sound of the
bark. Rabies in humans is similar to that in
animals. Symptoms include depression,
headache, nausea, seizures, anorexia,
muscle stiffness, and increased production
of saliva. Abnormal sensations, such as
itching, around the site of exposure are a
7
common early symptom. The muscles of the
throat become paralyzed so that the person
cannot swallow or drink, and this leads to a
dread of water (hydrophobia). The mental
state of a person infected with rabies varies
from maniacal excitement to dull apathy
the term rabies means madnessbut soon
the person falls into a coma and usually dies
in less than one week owing to cardiac or
respiratory failure. Sometimes rabies is
characterized by paralysis without any
evidence of excitation of the nervous
system. In such cases the course of the
disease may be prolonged to a week or
more. There is no cure for rabies. The
incubation period (the time that elapses
between the bite and the first symptom) is
usually one to three months but in rare
cases has been as long as several years.
This provides a chance to interrupt the
otherwise inevitable progress of the
infection. The bite should be washed
immediately because much, if not all, of the
virus can be thus removed. The bitten
patient should then receive a dose of
antirabies serum. Serum is derived from
horses or humans that have been
immunized with attenuated rabies virus; it
provides the patient with already prepared
antibodies against the rabies antigen. The
treatment is effective if given within 24 hours
after exposure but has little, if any, value if
given three or more days after infection by
rabies. Active immunization with rabies
vaccine should also be initiated to allow the
patient's body to make its own antibody. The
safest and most effective vaccines are
human diploid cell vaccine (HDCV), purified
chick embryo cell culture (PCEC), and
rabies vaccine adsorbed (RVA). With older
vaccines, at least 16 injections were
required, whereas with HDCV, PCEC, or
RVA, 5 are usually sufficient. Persons at risk
of rabies by virtue of occupation (e.g.,
veterinarians) or travel to endemic areas
should receive rabies vaccine as a form of
preexposure prophylaxis.

4. A boy with blood group A can
donate blood to all his classmates
with blood group(s)

A. B
B. AB and A
C. O
D. AB only

Answer: B (Encyclopaedia Britannica)
The human ABO blood groups were
discovered by Austrian-born American
biologist Karl Landsteiner in 1901.
Landsteiner found that there are substances
in the blood, antigens and antibodies, that
induce clumping of red cells when red cells
of one type are added to those of a second
type. He recognized three groupsA, B,
and Obased on their reactions to each
other. A fourth group, AB, was identified a
year later by another research team. Red
cells of the A group clump with donor blood
of the B group; those of the B group clump
with blood of the A group; those of the AB
group clump with those of the A or the B
group because AB cells contain both A and
8
B antigens; and those of the O group do not
generally clump with any group, because
they do not contain either A or B antigens.
The application of knowledge of the ABO
system in blood transfusion practice is of
enormous importance, since mistakes can
have fatal consequences.
Blood group AB individuals have both A and
B antigens on the surface of their red blood
cells (RBCs), and their blood serum does
not contain any antibodies against either A
or B antigen. Therefore, an individual with
type AB blood can receive blood from any
group (with AB being preferable), but can
donate blood only to another group AB
individual.
Blood group A individuals have the A
antigen on the surface of their RBCs, and
blood serum containing IgM antibodies
against the B antigen. Therefore, a group A
individual can receive blood only from
individuals of groups A or O (with A being
preferable), and can donate blood to
individuals of groups A or AB.
Blood group B individuals have the B
antigen on the surface of their RBCs, and
blood serum containing IgM antibodies
against the A antigen. Therefore, a group B
individual can receive blood only from
individuals of groups B or O (with B being
preferable), and can donate blood to
individuals of groups B or AB.
Blood group O (or blood group zero in some
countries) individuals do not have either A or
B antigens on the surface of their RBCs, but
their blood serum contains IgM anti-A
antibodies and anti-B antibodies against the
A and B blood group antigens. Therefore, a
group O individual can receive blood only
from a group O individual, but can donate
blood to individuals of any ABO blood group
(i.e., A, B, O or AB). If anyone needs a blood
transfusion in a dire emergency, and if the
time taken to process the recipient's blood
would cause a detrimental delay, O
Negative blood can be issued. Blood group
O is the most common blood type
throughout the world, particularly among
peoples of South and Central America. Type
B is prevalent in Asia, especially in northern
India. Type A also is common all over the
world; the highest frequency is among the
Blackfoot Indians of Montana and in the
Sami people of northern Scandinavia. The
ABO antigens are developed well before
birth and remain throughout life. Children
acquire ABO antibodies passively from their
mother before birth, but by three months
infants are making their ownit is believed
the stimulus for such antibody formation is
from contact with ABO-like antigenic
substances in nature. Erythroblastosis fetalis
(hemolytic disease of the newborn) is a type
of anemia in which the red blood cells of the
fetus are destroyed by the maternal immune
system because of a blood group
incompatibility between the fetus and its
mother, particularly in matings where the
mother is type O and the father type A.

5. What would be the most likely
vitamin deficiency of a patient
having bleeding gums?

9
A. C
B. K
C. A
D. D

Answer: A (Encyclopaedia Brtitannica)
Vitamin C, also known as ascorbic acid,
functions as a water-soluble antioxidant and
as a cofactor in various enzyme systems,
such as those involved in the synthesis of
connective tissue components and
neurotransmitters. Symptoms of scurvy, a
disease caused by vitamin C deficiency,
include pinpoint hemorrhages (petechiae)
under the skin, bleeding gums, joint pain,
and impaired wound healing. Although rare
in developed countries, scurvy is seen
occasionally in people consuming restricted
diets, particularly those containing few fruits
and vegetables, or in infants fed boiled
cow's milk and no source of vitamin C.
Scurvy can be prevented with relatively
small quantities of vitamin C (10 milligrams
[mg] per day), although recommended
intakes, which aim to provide sufficient
antioxidant protection, are closer to 100 mg
per day. Disease states, environmental
toxins, drugs, and other stresses can
increase an individual's vitamin C needs.
Smokers, for example, may require an
additional 35 mg of the vitamin daily to
maintain vitamin C levels comparable to
non-smokers.
Vitamin K is necessary for the formation of
prothrombin and other blood-clotting factors
in the liver, and it also plays a role in bone
metabolism. A form of the vitamin is
produced by bacteria in the colon and can
be utilized to some degree. Vitamin K
deficiency causes impaired clotting of the
blood and internal bleeding, even without
injury. Due to poor transport of vitamin K
across the placenta, newborn infants in
developed countries are routinely given the
vitamin intramuscularly or orally within six
hours of birth to protect against a condition
known as hemorrhagic disease of the
newborn. Vitamin K deficiency is rare in
adults, except in syndromes with poor fat
absorption, in liver disease, or during
treatment with certain anticoagulant drugs,
which interfere with vitamin K metabolism.
Bleeding due to vitamin K deficiency may be
seen in patients whose gut bacteria have
been killed by antibiotics.
Vitamin A deficiency is the leading cause of
preventable blindness in children and is a
major problem in the developing world,
especially in Africa and Southeast Asia; in
the poorest countries hundreds of thousands
of children become blind each year due to a
deficiency of the vitamin. Even a mild
deficiency can impair immune function,
thereby reducing resistance to disease.
Night blindness is an early sign of vitamin A
deficiency, followed by abnormal dryness of
the eye and ultimately scarring of the
cornea, a condition known as xerophthalmia.
Other symptoms include dry skin, hardening
of epithelial cells elsewhere in the body
(such as mucous membranes), and impaired
growth and development. In many areas
where vitamin A deficiency is endemic, the
incidence is being reduced by giving
10
children a single large dose of vitamin A
every six months. A genetically modified
form of rice containing beta-carotene, a
precursor of vitamin A, has the potential to
reduce greatly the incidence of vitamin A
deficiency, but the use of this so-called
golden rice is controversial.
Vitamin D (also known as vitamin D
hormone) is synthesized in the body in a
series of steps, starting in the skin by the
action of sunlight's ultraviolet rays on a
precursor compound; thus, without adequate
food sources of vitamin D, a deficiency of
the vitamin can occur when exposure to
sunlight is limited. Lack of vitamin D in
children causes rickets, a disease
characterized by inadequate mineralization
of bone, growth retardation, and skeletal
deformities such as bowed legs. The adult
form of rickets, known as osteomalacia,
results in weak muscles as well as weak
bones. Inadequate vitamin D may also
contribute to the thinning of bones seen in
osteoporosis. Individuals with limited sun
exposure (including women who completely
cover their bodies for religious reasons),
elderly or homebound persons, and those
with dark skin, particularly those who live in
northern latitudes, are at risk of vitamin D
deficiency. Vitamin D is found in very few
foods naturally; thus fortification of milk and
other foods (e.g., margarine, cereals, and
breads) with the vitamin has helped protect
those populations in which sun exposure is
inadequate. Supplemental vitamin D also
may help protect against bone fractures in
the elderly, who make and activate vitamin
D less efficiently even if exposed to sunlight.

6. Which one of the following is under
the control of the parasympathetic
nervous system?

A. Speeding up the thinking
process
B. Tension in musculature
C. Relaxation of the blood
vessels
D. Decreased blood flow to the
gut

Answer: D (Encyclopaedia Britannica)
The parasympathetic nervous system
primarily modulates visceral organs such as
glands. Responses are never activated en
masse as in the fight-or-flight sympathetic
response. While providing important control
of many tissues, the parasympathetic
system, unlike the sympathetic system, is
not crucial for the maintenance of life. The
parasympathetic nervous system is
organized in a manner similar to the
sympathetic nervous system. Its motor
component consists of preganglionic and
postganglionic neurons. Both pre- and
postganglionic neurons secrete
acetylcholine as a neurotransmitter, but, like
sympathetic ganglion cells, they also contain
other neuroactive chemical agents that
function as co-transmitters. Parasympathetic
nerve fibres regulate the iris and lens of the
eye. Various secretory glands located in the
head are under parasympathetic control.
11
These include the lacrimal gland, which
supplies tears to the cornea of the eye;
salivary glands (sublingual, submandibular,
and parotid glands), which produce saliva;
and nasal mucous glands, which secrete
mucus throughout the nasal air passages.
The parasympathetic preganglionic neurons
that regulate these functions originate in the
reticular formation of the medulla oblongata.
Preganglionic parasympathetic fibres of the
10th cranial (vagus) nerve arise from two
different sites in the medulla oblongata.
Neurons that slow heart rate arise from a
part of the ventral medulla called the
nucleus ambiguus, while those that control
functions of the gastrointestinal tract arise
from the dorsal vagal nucleus. After exiting
the medulla in the vagus nerve and traveling
to their respective organs, the fibres
synapse on ganglion cells embedded in the
organs themselves. The vagus nerve also
contains visceral afferent fibres that carry
sensory information from organs of the neck
(larynx, pharynx, and trachea), chest (heart
and lungs), and gastrointestinal tract into a
visceral sensory nucleus located in the
medulla called the solitary tract nucleus. The
parasympathetic system activates digestive
processes while the sympathetic system
inhibits them. The sympathetic system
inhibits digestive processes by two
mechanisms: (1) contraction of circular
smooth muscle sphincters located in the
distal portion of the stomach (pyloric
sphincter), small intestine (ileo-cecal
sphincter), and rectum (internal anal
sphincter), which act as valves to prevent
the oral-to-anal passage (as well as reverse
passage) of digestive products; and (2)
inhibition of motor neurons throughout the
length of the gut. In contrast, the
parasympathetic system provides messages
only to myenteric motor neurons.

7. Osmosis will continue to take place
between two solutions until they
become

A. Hypertonic
B. Hypotonic
C. Isotonic
D. Diluted

Answer: C (Wikipedia)
Osmosis is the spontaneous net movement
of water through a semi-permeable
membrane from a region of low solute
concentration to a solution with a high solute
concentration, up a solute concentration
gradient. It is a physical process in which a
solvent moves, without input of energy,
across a semi permeable membrane
(permeable to the solvent, but not the
solute) separating two solutions of different
concentrations. Osmosis releases energy,
and can be made to do work, as when a
growing tree-root splits a stone. Net
movement of solvent is from the less-
concentrated (hypotonic) to the more-
concentrated (hypertonic) solution, which
tends to reduce the difference in
concentrations. This effect can be countered
by increasing the pressure of the hypertonic
solution, with respect to the hypotonic. The
12
osmotic pressure is defined to be the
pressure required to maintain an equilibrium,
with no net movement of solvent. Osmotic
pressure is a colligative property, meaning
that the property depends on the molar
concentration of the solute but not on its
identity. Osmosis is the result of diffusion
across a semi-permeable membrane. It is
important in biological systems as many
biological membranes are semi-permeable.
In general, these membranes are
impermeable to organic solutes with large
molecules, such as polysaccharides, while
permeable to water and small, uncharged
solutes.

8. A tree with severely damaged bark
is likely to die from deprivation of

A. Water
B. Organic food
C. Oxygen
D. Mineral salts

Answer: B (Encyclopaedia Britannica)
Bark, in woody plants, are tissues external
to the vascular cambium (the growth layer of
the vascular cylinder); the term bark is also
employed more popularly to refer to all
tissues outside the wood. The inner soft
bark, or bast, is produced by the vascular
cambium; it consists of secondary phloem
tissue whose innermost layer conveys food
from the leaves to the rest of the plant. The
outer bark, which is mostly dead tissue, is
the product of the cork cambium
(phellogen). Layered outer bark, containing
cork and old, dead phloem, is known as
rhytidome. The dead cork cells are lined with
suberin, a fatty substance that makes them
highly impermeable to gases and water. Gas
exchange between the inner tissues of bark-
covered roots and stems and their
surroundings takes place through spongy
areas (lenticels) in the cork. Bark is usually
thinner than the woody part of the stem or
root. Both inner bark (secondary phloem)
and wood (secondary xylem) are generated
by the vascular cambium layer of cells: bark
toward the outside where the oldest layers
may slough off, and wood toward the inside
where it accumulates as dead tissue.

9. Which of the following animals use
echolocation for movement and
detection of objects in its path?

A. Dolphins and bats
B. Dolphins and seals
C. Seals and birds
D. Bats and birds

Answer: A (Encyclopaedia Britannica)
Echolocation is a physiological process for
locating distant or invisible objects (such as
prey) by means of sound waves reflected
back to the emitter (such as a bat) by the
objects. Echolocation is used for orientation,
obstacle avoidance, food procurement, and
social interactions. Echolocation is known to
be employed by most bats (all members of
the suborder Microchiroptera and one
genus, Rousettus, of the Megachiroptera);
most, if not all, toothed whales and
13
porpoises (Odontoceti), but apparently no
baleen whales; a few shrews; and two kinds
of birds, the oilbird (Steatornis caripensis) of
northern South America and certain cave
swiftlets (Collocalia) of Southeast Asia.
Echolocation pulses consist of short bursts
of sound at frequencies ranging from about
1,000 hertz in birds to at least 200,000 hertz
in whales. Bats utilize frequencies from
about 30,000 to about 120,000 hertz. The
pulses are repeated at varying rates (often
in a single individual, depending upon the
situation) beginning at about one per
second. The rate may reach several
hundred per second (e.g., in a bat close to
its target).

10. Proteases do not break down
carbohydrates and carbohydrases
do not break down proteins. Why is
this so?

A. Enzymes are pH sensitive
B. No protein digesting
enzymes occur in the mouth
C. No carbohydrate digesting
enzymes occur in the
stomach
D. Enzymes are substrate
specific

Answer: D (Encyclopaedia Britannica)
An enzyme will interact with only one type of
substance or group of substances, called
the substrate, to catalyze a certain kind of
reaction. Because of this specificity,
enzymes often have been named by adding
the suffix -ase to the substrate's name (as
in urease, which catalyzes the breakdown of
urea). Not all enzymes have been named in
this manner, however, and to ease the
confusion surrounding enzyme
nomenclature, a classification system has
been developed based on the type of
reaction the enzyme catalyzes. There are
six principal categories and their reactions:
(1) oxidoreductases, which are involved in
electron transfer; (2) transferases, which
transfer a chemical group from one
substance to another; (3) hydrolases, which
cleave the substrate by uptake of a water
molecule (hydrolysis); (4) lyases, which form
double bonds by adding or removing a
chemical group; (5) isomerases, which
transfer a group within a molecule to form an
isomer; and (6) ligases, or synthetases,
which couple the formation of various
chemical bonds to the breakdown of a
pyrophosphate bond in adenosine
triphosphate or a similar nucleotide.
Proteases and carbohydrases fall under
hydrolases, a class of more than 200
enzymes that catalyze the hydrolysis of
several types of compounds. Esterases
include lipases, which break ester bonds
(between a carboxylic acid and an alcohol)
in lipids, and phosphatases, which act
analogously upon phosphates; a narrower
category comprises the nucleases, which
are phosphatases that hydrolyze nucleic
acids. Glycosidases sever bonds between
sugar molecules in carbohydrates.
Peptidases hydrolyze peptide bonds
(between the carboxylic acid group of one
14
amino acid and the amino group of another)
within protein molecules. Specific
hydrolases also catalyze reactions that
break ether (C-O) bonds; carbonnitrogen
(C-N) bonds other than peptide bonds; acid
anhydride bonds; carboncarbon (C-C)
bonds; or phosphorusnitrogen (P-N) bonds.

11. Which one of the following is true
about growth responses in plants?

A. Roots are positively
geotropic and negatively
hydrotropic
B. Shoots are negatively
phototropic and positively
geotropic
C. Shoots are positively
phototropic and negatively
geotropic
D. Roots are negatively
geotropic and positively
phototropic

Answer: C (Encyclopaedia Brittanica)
Tropism is a respose or orientation of a plant
or certain lower animals to a stimulus that
acts with greater intensity from one direction
than another. It may be achieved by active
movement or by structural alteration. Forms
of tropism include phototropism (response to
light), geotropism (response to gravity),
chemotropism (response to particular
substances), hydrotropism (response to
water), thigmotropism (response to
mechanical stimulation), traumatotropism
(response to wound lesion), and
galvanotropism, or electrotropism (response
to electric current). Most tropic movements
are orthotropic; i.e., they are directed toward
the source of the stimulus. Plagiotropic
movements are oblique to the direction of
stimulus. Diatropic movements are at right
angles to the direction of stimulus.

12. Identify the correct combination of
characteristics for a good absorption
surface in the human body

A. Thin walled, large surface
area, dense blood capillary
network
B. Thin walled, small surface
area, dense capillary
network
C. Thick walled, large surface
area, dense blood capillary
network
D. Thin walled, large surface
area, sparse blood capillary
network

Answer: A (Encyclopaedia Britannica)
The best example of this absorption surface
is the small intestine. It is a long, narrow,
folded or coiled tube extending from the
stomach to the large intestine; it is the
region where most digestion and absorption
of food takes place. It is about 6.7 to 7.6
metres (22 to 25 feet) long, highly
convoluted, and contained in the central and
lower abdominal cavity. A thin membranous
material, the mesentery, supports and
somewhat suspends the intestines. The
15
mesentery contains areas of fat that help
retain heat in the organs, as well as an
extensive web of blood vessels. Nerves lead
to the small intestine from two divisions of
the autonomic nervous system:
parasympathetic nerves initiate muscular
contractions that move food along the tract
(peristalsis), and sympathetic nerves
suppress intestinal movements.

13. All of the following positively
contribute to the conservation of
animal species except one

A. Protection of habitats
B. Regulation of trophy hunting
C. Environmental legislation
D. Inbreeding within species

Answer: D (Encyclopaedia Britannica)
Inbreeding may be defined as mating of
individuals more closely related than the
average of the population. It increases the
homozygosity and decreases the
heterozygosity of the inbred animals. The
so-called inbreeding coefficient is a measure
of the loss of heterozygosity due to
inbreeding, and it is expressed as a fraction,
or percentage, of the amount of
heterozygosity present when inbreeding
started. After one generation of mating
between full sibs or mating of sire with
daughter or dam with son, the
heterozygosity of the offspring is reduced by
25 percent (or the inbreeding coefficient is
25 percent). In the mating of half-sibs or
double first cousins the inbreeding
coefficient is 12.5 percent. Mating of single
first cousins gives an inbreeding coefficient
of 6.25 percent, and that of half first cousins
3.12 percent. Mating between full sibs in two
successive generations decreases the
heterozygosity by 37.5 percent, and in three
generations by 50 percent. So-called inbred
lines are produced by continuous
consanguineous matings in several
generations; genetic variation decreases
within each line and increases between
separate lines. Inbreeding increases the
homozygosity of unfavourable as well as
favourable genes. As a result there is a
segregation of various kinds of congenital
defects and, more important, a general
decline in fertility and viability of the inbred
animals.

14. Which one of the following is not a
classification group or taxon?

A. Species
B. Family
C. Population
D. Class

Answer: C (Wikipedia)
Scientific classification or biological
classification is a method by which biologists
group and categorize species of organisms.
Scientific classification also can be called
scientific taxonomy, but should be
distinguished from folk taxonomy, which
lacks scientific basis. Modern classification
has its root in the work of Carolus Linnaeus,
who grouped species according to shared
16
physical characteristics. These groupings
have since been revised to improve
consistency with the Darwinian principle of
common descent. Molecular systematics,
which uses DNA sequences as data, has
driven many recent revisions and is likely to
continue to do so. Scientific classification
belongs to the science of taxonomy or
biological systematics. There are 7 main
taxonomic ranks: kingdom, phylum/division,
class, order, family, genus, species. There
are slightly different ranks for zoology and
different ranks for botany. As an example,
the classification of a human being is:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: H. sapiens
That of an apple is:
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Rosales
Family: Rosaceae
Subfamily: Maloideae
Genus: Malus
Species: M. domestica

15. Which one of the following is not an
adaptation against water loss?

A. Hairy leaves
B. Stomata on the under
surface of leaves
C. Tolerance of a narrow
temperature range
D. Tough exoskeletons of
insects

Answer: C (Wikipedia)
Land animals and plants have adapted to
their relatively dry environments and those
in areas where water is scarce, even more
so. Drought tolerance refers to the degree to
which a plant is adapted to arid or drought
conditions. Desiccation tolerance is an
extreme degree of drought tolerance. Plants
naturally adapted to dry conditions are
called xerophytes. Drought tolerant plants
typically make use of either C4 carbon
fixation or crassulacean acid metabolism
(CAM) to fix carbon during photosynthesis.
Both are improvements over the more
common but more basal C3 pathway in that
they are more energy efficient. CAM is
particularly good for arid conditions because
carbon dioxide can be taken up at night,
allowing the stomata to stay closed during
the heat of day and thus reducing water
loss. Many adaptations for dry conditions
are structural, including the following: (i)
adaptations of the stomata to reduce water
loss, such as reduced numbers or waxy
surfaces; (ii) water storage in succulent
above-ground parts or water-filled tubers;
(iii) adaptations in the root system to
increase water absorption and (iv) trichomes
(small hairs) on the leaves to absorb
atmospheric water. The exoskeletons of
arthropods (i.e. insects, spiders, myriapods
and crustaceans) contain rigid and resistant
17
components that fulfil a set of functional
roles including protection, excretion,
sensing, support, feeding and (for terrestrial
organisms) acting as a barrier against
desiccation. Some mammals are also
extraordinarily adapted to habitats. An
example is the Kangaroo rat, found in arid
and semi-arid areas of Canada, the United
States and Mexico that retain some grass or
other vegetation. They have very efficient
kidneys. The kangaroo rat has a longer loop
of Henle in the nephrons which permits a
greater magnitude of countercurrent
multiplication and thus a larger medullary
vertical osmotic gradient. As a result, these
rodents can produce urine that is
concentrated up to an osmolarity of almost
6,000 mosm/liter, which is five times more
concentrated than maximally concentrated
human urine at 1,200 mosm/liter. Because
of this tremendous concentration ability,
kangaroo rats never have to drink; the H
2
O
produced metabolically within their cells
during oxidation of foodstuff (food plus O
2

yields CO
2
+ H
2
O + energy) is sufficient for
their body. Kangaroo rats lose so little water
that they can recover 90% of the loss by
using metabolic water gaining the remaining
10% from the small amount of water in their
diet. Kangaroo rats lose water mainly by
evaporation during gas exchange and gain
water mainly from cellular metabolism.

16. The pyrimidine bases of DNA are

A. Guanine and Cytosine
B. Adenine and Guanine
C. Adenine and Thymine
D. Cytosine and Thymine

Answer: D (Encyclopaedia Britannica)
The nucleotide of DNA consists of a
deoxyribose sugar molecule to which is
attached a phosphate group and one of four
nitrogenous bases: two purines (adenine
and guanine) and two pyrimidines (cytosine
and thymine). The nucleotides are joined
together by covalent bonds between the
phosphate of one nucleotide and the sugar
of the next, forming a phosphate-sugar
backbone from which the nitrogenous bases
protrude. One strand is held to another by
hydrogen bonds between the bases; the
sequencing of this bonding is specifici.e.,
adenine bonds only with thymine, and
cytosine only with guanine. The nitrogenous
bases in RNA are adenine, guanine,
cytosine, and uracil.



17. The tendency of living organisms to
maintain their internal environment
constant within narrow limits is
referred to as.

A. Equilibrium
18
B. Physiology
C. Homeostasis
D. Osmotic potential

Answer: C (Encyclopaedia Britannica)
Homeostasis is a self-regulating process by
which biological systems tend to maintain
stability while adjusting to conditions that are
optimal for survival. If homeostasis is
successful, life continues; if unsuccessful,
disaster or death ensues. The stability
attained is actually a dynamic equilibrium, in
which continuous change occurs yet
relatively uniform conditions prevail. The
control of body temperature in humans is a
good example of homeostasis in a biological
system. In humans, normal body
temperature fluctuates around the value of
98.6 F, but various factors can affect this
value, including exposure, hormones,
metabolic rate, and disease, leading to
excessively high or low temperatures. The
body's temperature regulation is thought to
be controlled by a region in the brain called
the hypothalamus. Feedback about body
temperature is carried through the
bloodstream to the brain and results in
compensatory adjustments in the breathing
rate, the level of blood sugar, and the
metabolic rate. Heat loss in humans is aided
by reduction of activity, by perspiration, and
by heat-exchange mechanisms that permit
larger amounts of blood to circulate near the
skin surface. Heat loss is reduced by
insulation, decreased circulation to the skin,
and cultural modification such as the use of
clothing, shelter, and external heat sources.
The range between high and low body
temperature levels constitutes the
homeostatic plateauthe normal range
that sustains life. As either of the two
extremes is approached, corrective action
(through negative feedback) returns the
system to the normal range.

18. A patient whose gall bladder is
surgically removed is most likely to
encounter problems with.

A. Production of acids
B. Excretion of urea
C. Breakdown of fats
D. Absorption of mineral salts

Answer: C (Encyclopaedia Britannica)
The bile acids and their salts are detergents
that emulsify fats in the gut during digestion.
They are synthesized from cholesterol in the
liver by a series of reactions that introduce a
hydroxyl group into ring B and ring C and
shorten the acyl side chain of ring D to
seven carbons with the terminal carbon
changed to a carboxyl group. The resulting
molecule, cholic acidas well as
chenodeoxycholic acid (a close relative
lacking the OH on ring C)are usually
found in the form of their salts, in which the
amino acids taurine and glycine are
chemically linked to the side-chain carboxyl
group. These detergents are secreted from
the liver into the gall bladder, where they are
stored before being released through the
bile duct into the small intestine. After
performing an emulsifying action that is
19
essential in fat digestion, they are
reabsorbed in the lower small intestine,
returned through the blood to the liver, and
reused. This cyclic process, called the
enterohepatic circulation, handles 20 to 30
grams of bile acids per day in human
beings. The small fraction that escapes this
circulation is lost in the faeces. This is the
major excretory route for cholesterol (though
a smaller fraction is lost through the normal
sloughing of dead skin cells).

19. An unknown food sample can be
tested for the presence of starch
and proteins by using

A. Benedicts solution and
ethanol and filter paper
B. Iodine solution and
Benedicts solution
C. Millons reagent and
Benedicts solution
D. Iodine solution and Millons
reagent

Answer: D (Wikipedia)
The Iodine test is used to test for the
presence of starch. Iodine solution iodine
dissolved in an aqueous solution of
potassium iodide reacts with starch
producing a deep blue-black color. This
reaction is the result of the formation of
polyiodide chains from the reaction of starch
and iodine. The amylose, or straight chain
portion of starch, forms helices where iodine
molecules assemble, forming a dark
blue/black colour. The amylopectin, or
branched portion of starch, forms much
shorter helices and iodine molecules are
unable to assemble, leading the colour to be
of an orange/yellow hue. As starch is broken
down or hydrolyzed into smaller
carbohydrate units, the blue-black colour is
not produced. Therefore, this test can
determine completion of hydrolysis when a
colour change does not occur. Iodine
solution will also react with glycogen,
although the colour produced is browner and
much less intense.
Millon's reagent is mercuric nitrate and nitric
acid as used in the Millon reaction- the
reaction of phenolic compounds (e.g.,
tyrosine in protein) with Hg(NO
3
)
2
in HNO
3

(and a trace of HNO
2
) to give a red colour.
Benedict's reagent (also called Benedict's
solution or Benedict's test) is a chemical
reagent named after an American chemist,
Stanley Rossiter Benedict. Benedict's
reagent is used as a test for the presence of
reducing sugars such as glucose, fructose,
galactose, lactose and maltose, or more
generally for the presence of aldehydes
(except aromatic ones). It can be prepared
from sodium carbonate, sodium citrate and
copper(II) sulfate. It is often used in place of
Fehling's solution. Benedict's reagent
contains blue copper(II) ions (Cu
2+
) which
are reduced to copper(I) (Cu
+
). These are
precipitated as red copper(I) oxide which is
insoluble in water.
Fehling's solution is a solution used to
differentiate between water soluble aldehyde
and ketone functional groups. The
substance to be tested is heated together
20
with Fehling's solution; a red precipitate
indicates the presence of an aldehyde.
Ketones (except alpha hydroxy ketones) do
not react. An example for its use is to screen
for glucose in urine, thus detecting diabetes.
It was developed by German chemist
Hermann von Fehling.

20. Athletes who do their training at high
altitudes usually do well during
running competitions. The best
explanation for this is that their.

A. Leg muscles relax and
contract easily
B. Bodies are very resistant to
water loss
C. Lung capacity is large
D. Blood oxygen-carrying
capacity is large.

Answer: D (Wikipedia)
Altitude training traditionally called training at
an altitude camp, or now commonly using
altitude simulation tents or mask based
hypoxicator systems is the practice by some
endurance athletes of training at high
altitude, usually over 2,500 m (8,000 ft)
above sea level, for several weeks. At this
altitude although the air still contains
approximately 20.9% oxygen, the barometric
pressure and thus the partial pressure of
oxygen is reduced. The body adapts to the
relative lack of oxygen by increasing the
concentration of red blood cells and
hemoglobin. Proponents claim that when
such athletes return to sea level (where they
are competing) they will still have a higher
concentration of red blood cells for 10-14
days. Some athletes live permanently at
high altitude, only returning to sea level to
compete, but their training may suffer due to
less available oxygen for workouts. A larger
concentration of red blood cells allows more
oxygen to be supplied to the muscles
allowing higher performance. Increases in
red blood cell mass are stimulated by an
increase in erythropoietin (EPO). The body
naturally produces EPO to regulate red
blood cell mass and should not be confused
with synthetic EPO. Synthetic EPO
injections and blood doping are illegal in
athletic competition because they cause an
increase in red blood cells beyond the
individual athlete's natural limits. This
increase, unlike the increase caused by
altitude training, can be dangerous to an
athlete's health as the blood may become
too thick and cause heart failure. The natural
secretion of EPO by the human kidneys can
be increased by altitude training, but the
body has limits on the amount of natural
EPO that it will secrete, thus avoiding the
harmful side effects of the illegal doping.

21. Why is it important to keep newly
born babies in warm clothing?
Because they.

A. are very susceptible to
diseases and the clothing
serves as a barrier to germs
21
B. are most used to
confinement and not used
to openness
C. have a large surface area to
volume ratio and lose a lot
of heat
D. have a small surface area to
volume ratio and lose a lot
of heat

Answer: C (Wikipedia)
The ratio between the surface area and
volume of cells and organisms has an
enormous impact on their biology. For
example, many aquatic microorganisms
have increased surface area to increase
their drag in the water. This reduces their
rate of sink and allows them to remain near
the surface with less energy expenditure. If
you have 3 cubes: one 2 cm each side, one
1 cm each side and one 0.5 cm each
side...the SA/Vol ratio will double every
single time i.e.: 2 cm cube would be 3:1
(surface area of a cube is length x breadth
and there are 6 sides thus 2x2x6 = 24 cm
2
.
Its volume is length x breadth x height =
2x2x2 = 8); the 1 cm cube would be 6:1 and
the 0.5 cm cube would be 12:1 This
practically shows that every single time, the
surface area doubles. Humans cannot rely
on diffusion for their whole body. However,
animals such as flatworms and leeches can,
as they have less volume. An increased
surface area to volume ratio also means
increased exposure to the environment. The
many tentacles of jellyfish and anemones
are the result of increased surface area for
the acquisition of food. Greater surface area
allows more of the surrounding water to be
sifted for food. Individual organs in animals
are often based on the principle of greater
surface area. The lung is an organ with
numerous internal branching that increases
the surface area through which oxygen is
passed into the blood and carbon dioxide is
released from the blood. The intestine has a
finely wrinkled internal surface, increasing
the area through which nutrients are
absorbed by the body. This is done to
increase the surface area in which diffusion
of oxygen and carbon dioxide in the lungs
and diffusion of nutrients in villi of the small
intestine can occur. Cells can get around
having a low surface area to volume ratio by
being long and thin (nerve cells) or
convoluted (microvilli). Increased surface
area can also lead to biological problems.
More contact with the environment through
the surface of a cell or an organ (relative to
its volume) increases loss of water and
dissolved substances. High surface area to
volume ratios also present problems of
temperature control in unfavourable
environments.

22. Where best would you grow a
garden fern?

A. Open, windy place
B. Sunny, dry place
C. Dry, shady place
D. Moist, shady place

Answer: D (Wikipedia)
22
The ferns are extremely diverse in habitat,
form, and reproductive methods. In size
alone they range from minute filmy plants
only 2 to 3 millimetres (0.08 to 0.12 inch) tall
to huge tree ferns 10 to 25 metres (30 to 80
feet) in height. Some are twining vines;
others float on the surface of ponds. The
majority of ferns inhabit warm, damp areas
of the Earth. Growing profusely in tropical
areas, ferns diminish in number with
increasingly higher latitudes and decreasing
supplies of moisture. Few are found in dry,
cold places. There are four particular types
of habitats that ferns are found in: moist,
shady forests; crevices in rock faces,
especially when sheltered from the full sun;
acid wetlands including bogs and swamps;
and tropical trees, where many species are
epiphytes.

23. Moodley severely damaged his
tongue and lost the ability to taste
and recognise sweetness. Which
part of his tongue was damaged?

A. The anterior free end
B. The middle part
C. The posterior edge close to
the throat
D. The sides

Answer: A (Encyclopaedia Britannica)
The mammalian tongue consists of a mass
of interwoven, striated muscles interspaced
with glands and fat and covered with
mucous membrane. In humans the front tips
and margins of the tongue usually touch the
teeth, aiding in swallowing and speech. The
top surface, or dorsum, contains numerous
projections of the mucous membrane called
papillae. They contain taste buds sensitive
to food flavours and serous glands that
secrete some of the fluid in saliva, a
substance that moistens the oral cavity and
helps lubricate food particles. The base, or
upper rear portion, of the tongue has no
papillae, but aggregated lymphatic tissue
(lingual tonsils) and serous and mucus-
secreting glands are present. The inferior, or
under, surface leads from the tip of the
tongue to the floor of the mouth; its mucous
membrane is smooth, devoid of papillae,
and purple in colour from the many blood
vessels present. The root, the remainder of
the underside that lies on the mouth's floor,
contains bundles of nerves, arteries, and
muscles that branch to the other tongue
regions. Nerves from the tongue receive
chemical stimulation from food in solution
that gives the sensation of taste. There are
four fundamental taste sensations, which
derive from receptors that have specific
topographical distribution: salt and sweet at
the tip of the tongue, bitter at the base, and
acid or sour along the borders. The total
flavour of a food comes from the
combination of taste, smell, touch, texture or
consistency, and temperature sensations.
Small taste buds situated on the tongue's
top surface transmit these flavour
sensations to the nervous system. Among
the disorders to which the tongue is subject
are cancer, leukoplakia (white patches),
fungus infection, congenital defects, and a
23
variety of symptoms caused by disease
elsewhere in the body. Surgical removal of
this organ makes speech and swallowing
difficult.

24. Both plant and animal cells
possess.

A. Cell walls
B. Nuclei
C. Plastids
D. Large vacuoles

Answer: B (Encyclopaedia Britannica)
A cell is enclosed by the plasma membrane
(plant, bacterial and fungal cells have cell
walls in addition), which forms a selective
barrier allowing nutrients to enter and waste
products to leave. The interior is organized
into many specialized compartments, or
organelles, each surrounded by a separate
membrane. One major organelle, the
nucleus, contains the genetic information
necessary for cell growth and reproduction.
Each cell contains only one nucleus; other
types of organelles are present in multiple
copies in the cellular contents, or cytoplasm.
The mitochondria are responsible for the
energy transactions necessary for cell
survival. The lysosomes digest unwanted
materials within the cell. The endoplasmic
reticulum and the Golgi apparatus play an
important role in the internal organization of
the cell by synthesizing selected molecules
and then processing, sorting, and directing
them to their proper locations. (Plant cells, in
addition to all the above organelles, contain
chloroplasts, which are responsible for
photosynthesis, whereby the energy of
sunlight is used to convert molecules of
carbon dioxide [CO
2
] and water [H
2
O] into
carbohydrates.) Between all of these
organelles is the space in the cytoplasm
called the cytosol, which is organized
around a framework of fibrous molecules
constituting the cytoskeleton. The cytosol
contains more than 10,000 different kinds of
molecules involved in cellular biosynthesis.

25. Which one of the following is a
wrong deduction from the dental
formula

2 1 2 3
2 1 2 3

A. There are 32 teeth
altogether
B. There are four incisors in
the upper jaw
C. There are four premolars in
the lower jaw
D. There are three molars in
the lower jaw

Answer: D (Wikipedia)
All mammals except the monotremes, the
edentates, the pangolins, and the cetaceans
have up to four distinct types of teeth, with a
maximum number for each. These are the
incisor (cutting), the canine, the premolar,
and the molar (grinding). Mammals that
have distinct types of teeth are heterodont;
others are homodont. The number of teeth
24
of each type is written as a dental formula
for one side of the mouth, with the upper
and lower teeth shown on separate rows.
The number of teeth in a mouth is twice that
listed as there are two sides. In each set, the
first number indicates incisors, the second,
canines, the third, premolars, and the last,
molars. For example, the formula 2.1.2.3 for
upper teeth indicates 2 incisors, 1 canine, 2
premolars, and 3 molars on one side of the
upper mouth.

26. Why are arteries thicker walled than
veins?

A. Arteries carry oxygenated
blood
B. Arteries branch to form
arterioles
C. Arteries carry blood under
pressure
D. Arteries convey blood to all
organs

Answer: C (Encyclopaedia Britannica)
In human physiology, an artery is any of the
vessels that, with one exception, carry
oxygenated blood and nourishment from the
heart to the tissues of the body. The
exception, the pulmonary artery, carries
oxygen-depleted blood to the lungs for
oxygenation and removal of excess carbon
dioxide. Arteries are muscular and elastic
tubes that must transport blood under a high
pressure exerted by the pumping action of
the heart. The pulse, which can be felt over
an artery lying near the surface of the skin,
results from the alternate expansion and
contraction of the arterial wall as the beating
heart forces blood into the arterial system
via the aorta. Large arteries branch off from
the aorta and in turn give rise to smaller
arteries until the level of the smallest
arteries, or arterioles, is reached. The
threadlike arterioles carry blood to networks
of microscopic vessels called capillaries,
which supply nourishment and oxygen to the
tissues and carry away carbon dioxide and
other products of metabolism by way of the
veins. The largest artery is the aorta, which
arises from the left ventricle of the heart.
The aorta arches briefly upward before
continuing downward close to the backbone;
the arteries that supply blood to the head,
neck, and arms arise from this arch and
travel upward. As it descends along the
backbone, the aorta gives rise to other major
arteries that supply the internal organs of the
thorax. After descending to the abdomen,
the aorta divides into two terminal branches,
each of which supplies blood to one leg.
Each artery, no matter what its size, has
walls with three layers, or coats. The
innermost layer, or tunica intima, consists of
a lining, a fine network of connective tissue,
and a layer of elastic fibres bound together
in a membrane pierced with many openings.
The tunica media, or middle coat, is made
up principally of smooth (involuntary) muscle
cells and elastic fibres arranged in roughly
spiral layers. The outermost coat, or tunica
adventitia, is a tough layer consisting mainly
of collagen fibres that act as a supportive
element. The large arteries differ structurally
25
from the medium-sized arteries in that they
have a much thicker tunica media and a
somewhat thicker tunica adventitia.

27. Which one of the following practices
in a zoo is ethical?

A. Allowing lions to feed on live
antelopes
B. Allowing courtship between
different species of civets
C. Putting to death by
euthanasia a severely
injured parrot
D. Dissection and display of
the alimentary canal of a
live rat for a group of grade
12 learners

Answer: C
Allowing lions to feed on live antelopes is
cruel; one cannot cage animals to be killed
by their natural predators. Allowing courtship
between different species of civets might
lead to cross-breeding which results in
hybrid offspring having characteristics of
both parents. Whilst this is not reprehensible
(cross-breeding does occur in nature, e.g. a
mule is a cross between a donkey and a
horse) allowing caged animals to do so is
questionable. Dissection of animals such as
mice is done routinely for educational
purposes in schools, universities and
research laboratories. However, doing it in a
zoo where most of the visitors are not
science students, will cause revulsion.

28. The biological study of insects is
known as

A. Insectivore
B. Anthropology
C. Ichthyology
D. Entomology

Answer: D
Insectivore is a common name applied to
any of 450 or so species of mammals
comprising hedgehogs, golden moles, true
moles, true shrews, the moonrat,
gymnures, solenodons, and tenrecsthat
subsist primarily on insects, other
arthropods, and earthworms.
Anthropology, the science of humanity,
which studies human beings in aspects
ranging from the biology and evolutionary
history of Homo sapiens to the features of
society and culture that decisively
distinguish humans from other animal
species. Because of the diverse subject
matter it encompasses, anthropology has
become, especially since the middle of the
20th century, a collection of more
specialized fields. Physical anthropology is
the branch that concentrates on the biology
and evolution of humanity. The branches
that study the social and cultural
constructions of human groups are variously
recognized as belonging to cultural
anthropology (or ethnology), social
anthropology, linguistic anthropology, and
psychological anthropology. Archaeology as
the method of investigation of prehistoric
cultures, has been an integral part of
26
anthropology since it became a self-
conscious discipline in the latter half of the
19th century.
Ichthyology is the scientific study of fishes,
including, as is usual with a science that is
concerned with a large group of organisms,
a number of specialized sub-disciplines:
e.g., taxonomy, anatomy (or morphology),
behavioral science (ethology), ecology, and
physiology. Because of the great importance
of fishes as human food, economic
ichthyology is a significant segment of the
field.
Entomology is a branch of zoology dealing
with the scientific study of insects. The
Greek word entomon, meaning notched,
refers to the segmented body plan of the
insect. The zoological categories of
genetics, taxonomy, morphology,
physiology, behaviour, and ecology are
included in this field of study. Also included
are the applied aspects of economic
entomology, which encompasses the
harmful and beneficial impact of insects on
humans and their activities.

29. Suppose that in the sweet pea T is
the gene for tallness and t is the
gene for shortness. In a genetic
cross between two plants, one
heterozygous and the other
homozygous tall, which one of the
following would be true about the
offspring?

A. They are all phenotypically
similar
B. They all have similar
genotypes
C. Three are tall and one is
short
D. One is tall and three are
short

Answer: A
The cross over is best depicted as follows:

PARENT PEA1 PARENT PEA2
TT
Tt
Gamete production
through flowering
T T T t
Cross-pollination,
fetilization, germination
and growthof seeds
TT TT Tt Tt
Offspringgenotype
(homozygous tall) (heterozygous tall)


Since T is dominant, the offspring will all
be tall even though half of them are
heterozygous short.

30. Which one of the following plant
tissues and functions are not
correctly matched?

Tissue Function
A. Epidermis Protection
B. Xylem Transport of water
and minerals
C. Meristem Growth
D. Parenchyma Translocation of
organic food

Answer: D (Wikipedia)
27
Parenchyma is the most common ground
tissue. It forms, for example, the cortex and
pith of stems, the cortex of roots, the
mesophyll of leaves, the pulp of fruits, and
the endosperm of seeds. Parenchyma cells
are still meristematic, which means that they
are capable of cell division even after
maturation. They have thin but flexible cell
walls, and are generally cube-shaped and
loosely packed. They have large central
vacuoles, which allows the cells to store
nutrients and water. Parenchyma cells have
a variety of functions: (1) In leaves, they
form the mesophyll and are responsible for
photosynthesis and the exchange of gases;
(2) Storage; (3) Secretion (e.g. epithelial
cells lining the inside of resin ducts); (4)
Healing and (5) Other specialized functions.
The form of parenchyma cells varies with
their function. The epidermal parenchyma
cells of a leaf are barrel shaped and have no
chloroplasts. This tissue serves as a barrier
wall and protects the internal tissues from
injury. In the spongy mesophyll of a leaf,
parenchyma cells are spherical and loosely
arranged with large intercellular spaces.
These cells, with the epidermal guard cells
of the stomata, form a system of air spaces
and chambers that regulate the exchange of
gases. Translocation of organic food (from
leaves, the sites of photosynthesis, to the
rest of the plant) is done by the phloem.

31. Why would it be impossible to drown
and kill a cockroach by holding its
head down under water?

A. Cockroaches have lived for
many centuries and are
tolerant of many dangers
B. Cockroaches can survive
without oxygen for many
hours
C. Cockroaches take in air
through holes situated
elsewhere away from the
head
D. Cockroaches have no blood
and respire anaerobically

Answer: C (Wikipedia)
Cockroaches, like all insects, breathe
through a system of tubes called tracheae.
The tracheae of insects are attached to the
spiracles, excluding the head. Thus, all
insects, including cockroaches, can breathe
without a head. The valves open when the
CO
2
level in the insect rises to a high level;
then the CO
2
diffuses out of the tracheae to
the outside and fresh O
2
diffuses in. The
tracheal system brings the air directly to
cells because they branch continually like a
tree until their finest divisions tracheoles are
associated with each cell, allowing gaseous
oxygen to dissolve in the cytoplasm lying
across the fine cuticle lining of the tracheole.
CO
2
diffuses out of the cell into the
tracheole. Insects do not have lungs and
thus do not actively breathe in the vertebrate
lung manner. However, in some very large
insects the diffusion process may not be
sufficient to provide oxygen at the necessary
rate and body musculature may contract
rhythmically to forcibly move air out and in
28
the spiracles and one can actually call this
breathing.

32. Mycorrhiza can be described as the
association of pine roots and .

A. Bacteria
B. Fungi
C. Ferns
D. Algae

Answer: B (Encyclopaedia Britannica)
Mycorrhiza, also spelled Mycorhiza, is an
intimate association between the branched,
tubular filaments (hyphae) of a fungus
(kingdom Fungi) and the roots of higher
plants. The association is usually of mutual
benefit (symbiotic): a delicate balance
between host plant and symbiont results in
enhanced nutritional support for each
member. The establishment and growth of
certain plants (e.g., citrus, orchids, pines) is
dependent on mycorrhiza; other plants
survive but do not flourish without their
fungal symbionts. The two main types of
mycorrhiza are endotrophic, in which the
fungus invades the hosts' roots (e.g.,
orchids), and ectotrophic, in which the
fungus forms a mantle around the smaller
roots (e.g., pines). Exploitation of these
natural associations can benefit forestry,
horticulture, and other plant industries.

33. How best can the population of
elephants in the Kruger Park be
determined?

A. Mark-release-recapture
method
B. Quadrats methods
C. Direct counting through
game drives
D. Direct counting through
aerial survey

Answer: D
The Kruger Park with an area of 7,523
square miles (19,485 square km, almost as
big as the State of Israel!), is about 200
miles (320 km) long and 25 to 50 miles (40
to 80 km) wide. Thus, marking, releasing
and recapturing all elephants in the park
would be an unnecessary, labour intensive
and very expensive exercise given the sheer
size of the park. The area has a generally
flat terrain with low ranges of hills traversed
by nearly 5,000 miles of paved and gravel
roads, but direct counting through game
drives is not feasible too because in addition
to the above reason, the animals move
about. The quadrats method is also not
feasible for the same reasons. A quadrat is
a measured and marked square, used in
field biology to isolate a sample area for the
purpose of counting the population of
different species within that area. By
sampling many quadrats, biologists can
create data sets for statistical analysis. This
leaves direct counting by aerial survey as
the only feasible option and indeed this is
widely used.

34. Tabulated below are the tests and
results from three food samples
29

Tests Results
Iodine solution to
food X
Blue-black
Millons/Biuret test
on food Y
Colourless
Benedicts/Fehlings
test on food Z
Orange-red
precipitate

What was contained in foods X, Y and Z?

Food X Food Y Food Z
A. Starch Proteins Fat
B. Starch Proteins Starch
C. Fat Starch Proteins
D. Starch No proteins Glucose

Answer: D
A blue-black colour during an iodine test on
food X indicates the presence of starch. The
Biuret and Millon tests detect the presence
of proteins. In the Biuret test, peptide bonds
react with Cu(II) ions to give a violet colour.
The Millon test hinges on the reaction of
phenolic compounds (e.g., tyrosine in
protein) with Hg(NO
3
)
2
in HNO
3
(and a trace
of HNO
2
) to give a red colour. No colour
change in both cases means there are no
proteins in food Y. Benedict's reagent is
used as a test for the presence of reducing
sugars such as glucose, fructose, galactose,
lactose and maltose, or more generally for
the presence of aldehydes. Benedict's
reagent contains blue copper(II) ions (Cu
2+
)
which are reduced to copper(I) (Cu
+
). These
are precipitated as red copper(I) oxide which
is insoluble in water. Fehling's solution is
also used to test for aldoses (a.k.a. reducing
sugars). Also based on Cu(II) chemistry, a
red precipitate indicates the presence of an
aldehyde.

35. Cellular respiration involves the
substances below

(i) Oxygen
(ii) Carbon dioxide
(iii) Energy
(iv) Water
(v) Carbohydrates

Which one of the following equations
correctly represents the substances in
cellular respiration?

A. (ii) +(iii) = (i) +(iv) + (v)
B. (v) +(iv) = (i) +(ii) + (iii)
C. (iii) +(v) = (i) +(ii) + (iv)
D. (v) +(i) = (ii) +(iii) + (iv)

Answer: D (Encyclopaedia Britannica)
Cellular respiration is the process by which
organisms combine oxygen with foodstuff
molecules, diverting the chemical energy in
these substances into life-sustaining
processes and discarding, as waste
products, carbon dioxide and water.
Organisms that do not depend on oxygen
degrade foodstuffs in a process called
fermentation. One objective of the
degradation of foodstuffs is to transduce the
energy contained in chemical bonds into the
energy-rich compound adenosine
triphosphate (ATP). In eukaryotic cells the
30
enzymes that catalyze the individual steps
involved in respiration and energy
conservation are located in highly organized
rod-shaped compartments of the cell called
mitochondria. In micro-organisms the
enzymes occur as components of the cell
membrane. A liver cell has about 1,000
mitochondria; large egg cells of some
vertebrates have up to 200,000. For the
most part, the major foodstuffs
(carbohydrates, fats, and proteins) are made
available for the energy-yielding process by
degradation to a two-carbon fragment
(acetyl group) that, when combined as
acetyl coenzyme A, provides the fuel for an
important sequence of metabolic reactions
called the tricarboxylic acid cycle (TCA cycle
or the Krebs/ citric acid cycle cycle). Each
pair of hydrogen atoms removed from a
participant in the TCA cycle provides a pair
of electrons thatthrough the action of a
series of iron-containing hemoproteins, the
cytochromeseventually reduces one atom
of oxygen to form water. In 1951 it was
discovered that the transfer of one pair of
electrons to oxygen results in the formation
of three molecules of ATP. This process,
called oxidative phosphorylation, or
respiratory-chain phosphorylation, is the
major mechanism by which the large
amounts of energy in foodstuffs are
conserved and made available to the cell.
The series of steps by which electrons flow
to oxygen permits a gradual lowering of the
energy of the electrons.

36. The temporary blindness which
follows movement from the bright
sunny outside to a dim lighted room
is associated with

A. Changes in the shape of the
eye lens
B. Changes in the ciliary
muscle and body
C. Changes in the suspensory
ligaments
D. Changes in the diameter of
the pupil

Answer: D (Encyclopaedia Britannica)
Flash blindness is caused by bleaching
(oversaturation) of the retinal pigment. As
the pigment returns to normal, so too does
sight. In daylight the eye's pupil constricts,
thus reducing the amount of light entering
after a flash. At night, the dark-adapted pupil
is wide open so flash blindness has a
greater effect and lasts for a longer time.
The pupil is the opening within the iris
through which light passes before reaching
the lens and being focused onto the retina.
The size of the opening is governed by the
muscles of the iris, which rapidly constrict
the pupil when exposed to bright light and
expand (dilate) the pupil in dim light.
Parasympathetic nerve fibres from the third
(oculomotor) cranial nerve innervate the
muscle that causes constriction of the pupil,
whereas sympathetic nerve fibres control
dilation. The pupillary aperture also narrows
when focusing on close objects and dilates
for more distant viewing.
31

37. DNA replication is needed for.

A. Mitosis only
B. Meiosis only
C. Mitosis and meiosis
D. Either mitosis or meiosis
depending on the type of
cell

Answer: C (Encyclopaedia Britannica)
The process of meiosis is characteristic of
organisms that reproduce sexually. Such
species have in the nucleus of each cell a
diploid (double) set of chromosomes,
consisting of two haploid sets (one inherited
from each parent). These haploid sets are
homologousi.e., they contain the same
kinds of genes, but not necessarily in the
same form. In humans, for example, each
set of homologous chromosomes contains a
gene for blood type, but one set may have
the gene for blood type A and the other set
the gene for blood type B. Prior to meiosis,
each of the chromosomes in the diploid
germ cell has replicated and thus consists of
a joined pair of duplicate chromatids.
Meiosis begins with the contraction of the
chromosomes in the nucleus of the diploid
cell. Homologous paternal and maternal
chromosomes pair up along the midline of
the cell. Each pair of chromosomescalled
a tetrad, or a bivalentconsists of four
chromatids. At this point, the homologous
chromosomes exchange genetic material by
the process of crossing over. The
homologous pairs then separate, each pair
being pulled to opposite ends of the cell,
which then pinches in half to form two
daughter cells. Each daughter cell of this
first meiotic division contains a haploid set of
chromosomes. The chromosomes at this
point still consist of duplicate chromatids. In
the second meiotic division, each haploid
daughter cell divides. There is no further
reduction in chromosome number during this
division, as it involves the separation of each
chromatid pair into two chromosomes, which
are pulled to the opposite ends of the
daughter cells. Each daughter cell then
divides in half, thereby producing a total of
four different haploid gametes. When two
gametes unite during fertilization, each
contributes its haploid set of chromosomes
to the new individual, restoring the diploid
number.
During mitosis, one cell gives rise to two
genetically identical daughter cells. Strictly
applied, the term mitosis is used to describe
the duplication and distribution of
chromosomes, the structures that carry the
genetic information. A brief treatment of
mitosis follows. Prior to the onset of mitosis,
the chromosomes have replicated and the
proteins that will form the mitotic spindle
have been synthesized. Mitosis begins at
prophase with the thickening and coiling of
the chromosomes. The nucleolus, a rounded
structure, shrinks and disappears. The end
of prophase is marked by the beginning of
the organization of a group of fibres to form
a spindle and the disintegration of the
nuclear membrane. The chromosomes,
each of which is a double structure
32
consisting of duplicate chromatids, line up
along the midline of the cell at metaphase.
In anaphase each chromatid pair separates
into two identical chromosomes that are
pulled to opposite ends of the cell by the
spindle fibres. During telophase, the
chromosomes begin to decondense, the
spindle breaks down, and the nuclear
membranes and nucleoli re-form. The
cytoplasm of the mother cell divides to form
two daughter cells, each containing the
same number and kind of chromosomes as
the mother cell. The stage, or phase, after
the completion of mitosis is called
interphase. Mitosis is absolutely essential to
life because it provides new cells for growth
and for replacement of worn-out cells.
Mitosis may take minutes or hours,
depending upon the kind of cells and
species of organisms. It is influenced by
time of day, temperature, and chemicals.

38. The table below lists a number of
diseases and their causative agents.
Choose the one disease for which
antibiotic treatment would be
appropriate.

Disease Causative Agent
influenza virus
food poisoning bacterium
ringworm fungus
malaria protozoan

A. influenza
B. food poisoning
C. ringworm
D. malaria

Answer: B, but also C and D (Wikipedia)
An antibiotic is a chemotherapeutic agent
that inhibits or abolishes the growth of
micro-organisms, such as bacteria, fungi, or
protozoans. The term originally referred to
any agent with biological activity against
living organisms; however, "antibiotic" now
is used to refer to substances with anti-
bacterial, anti-fungal, or anti-parasitic
activity. The first antibiotic compounds used
in modern medicine were produced and
isolated from living organisms, such as the
penicillin class produced by fungi in the
genus Penicillium, or streptomycin from
bacteria of the genus Streptomyces. With
advances in organic chemistry many
antibiotics are now also obtained by
chemical synthesis, such as the sulfa drugs.
Many antibiotics are relatively small
molecules with a molecular weight less than
2000 Da.

39. The principles of genetics and
evolution are employed in animal
and plant breeding in which natural
selection is then replaced by .

A. artificial selection
B. deliberate selection
C. isolation
D. natural breeding

Answer: A (Encyclopaedia Britannica)
Artificial selection is the selective breeding
of plants and animals by humans. It differs
33
from natural selection in that heritable
variations in a species are manipulated by
humans through controlled breeding. The
breeder attempts to isolate and propagate
those genotypes that are responsible for a
plant or animal's desired qualities in a
suitable environment. These qualities are
economically or aesthetically desirable to
humans, rather than useful to the organism
in its natural environment.

40. The giraffe is a mammal and it has
. cervical (neck) vertebrae.

A. 14
B. 21
C. 7
D. none of the above

Answer: C (Encyclopaedia Britannica)
Giraffes (Giraffa camelopardalis) have only
seven neck (cervical) vertebrae, but they are
elongated. Thick-walled arteries in the neck
have extra valves to counteract gravity when
the head is up; when the giraffe lowers its
head to the ground, special vessels at the
base of the brain control blood pressure.
The gait of the giraffe is a pace (both legs on
one side move together). In a gallop it
pushes off with the hind legs and the front
legs come down almost together, but no two
hooves touch the ground at the same time.
The neck flexes so that balance is
maintained. Speeds of 50 km (31 miles) per
hour can be maintained for several
kilometres, but 60 km (37 miles) per hour
can be attained over short distances.

41. The first living photosynthetic
organisms on earth were

A. proto-cells
B. green plants
C. cyanobacteria (blue-green
algae)
D. gymnosperms

Answer: C (Wikipedia)
The biochemical capacity to use water as
the source for electrons in photosynthesis
evolved once, in a common ancestor of
extant cyanobacteria. The geological record
indicates that this transforming event took
place early in our planet's history, at least
2450-2320 million years ago (Ma), and
possibly much earlier. Geobiological
interpretation of Archean (>2500 Ma)
sedimentary rocks remains a challenge;
available evidence indicates that life existed
3500 Ma, but the question of when oxygenic
photosynthesis evolved continues to
engender debate and research. A clear
paleontological window on cyanobacterial
evolution opened about 2000 Ma, revealing
an already-diverse biota of blue-greens.
Cyanobacteria remained principal primary
producers throughout the Proterozoic Eon
(2500-543 Ma), in part because the redox
structure of the oceans favored
photautotrophs capable of nitrogen fixation.
Green algae joined blue-greens as major
primary producers on continental shelves
near the end of the Proterozoic, but only
with the Mesozoic (251-65 Ma) radiations of
34
dinoflagellates, coccolithophorids, and
diatoms did primary production in marine
shelf waters take modern form.
Cyanobacteria remain critical to marine
ecosystems as primary producers in oceanic
gyres, as agents of biological nitrogen
fixation, and, in modified form, as the
plastids of marine algae.

42. Parasitic fungi obtain their nutrients
(food) from .

A. living host tissue
B. the mycelium
C. bacteria
D. dead organic matter

Answer: A (Encyclopaedia Britannica)
In contrast with the saprobic fungi, which
feed on dead organic matter, parasitic fungi
attack living organisms, penetrate their outer
defenses, invade them, and obtain
nourishment from living cytoplasm, causing
disease and sometimes the death of the
host. Most pathogenic (disease-causing)
fungi are parasites of plants, but several are
known to cause diseases of humans and
lower animals. Most parasites enter the host
through a natural opening, such as a
stomate (microscopic air pore) in a leaf, a
lenticel (small opening through bark) in a
stem, a broken plant hair or a hair socket in
a fruit, or a wound in the plant or animal
epidermis (skin). Such wounds may be
insect punctures or accidentally inflicted
scratches, cuts, or bruises. Among the most
common and widespread diseases of plants
caused by fungi are the various downy
mildews (e.g., of grape, onion, tobacco), the
powdery mildews (e.g., of grape, cherry,
apple, peach, rose, lilac), the smuts (e.g., of
corn, wheat, onion), the rusts (e.g., of wheat,
oats, beans, asparagus, snapdragon,
hollyhock), apple scab, brown rot of stone
fruits, and various leaf spots, blights, and
wilts. These diseases cause great damage
annually throughout the world.

43. Which is not true regarding the
mammals?

A. They include groups that lay
eggs
B. They include several sub-
classes including the pouch
animals
C. Produce mothers milk from
the mammary glands
D. Are ectothermic (cold-
blooded)

Answer: D (Encyclopaedia Britannica)
A mammal is any member of the group of
vertebrate animals in which the young are
nourished with milk from special mammary
glands of the mother. In addition to these
characteristic milk glands, mammals are
distinguished by several other unique
features. Hair is a typical mammalian
feature, although in many whales it has
disappeared except in the fetal stage. The
mammalian lower jaw is hinged directly to
the skull, instead of through a separate bone
(the quadrate) as in all other vertebrates. A
35
chain of three tiny bones transmits sound
waves across the middle ear. A muscular
diaphragm separates the heart and the
lungs from the abdominal cavity. Only the
left aortic arch persists. (In birds the right
aortic arch persists; in reptiles, amphibians,
and fishes both arches are retained.) Mature
red blood cells (erythrocytes) in all mammals
lack a nucleus; all other vertebrates have
nucleated red blood cells. Except for the
monotremes (an egg-laying order of
mammals comprising echidnas and the
duck-billed platypus), all mammals are
viviparousthey bear live young. In the
placental mammals (including humans), the
young are carried within the mother's womb,
reaching a relatively advanced stage of
development before birth. In the marsupials
(kangaroos, opossums, and allies), the
newborn are incompletely developed at birth
and continue to develop outside the womb,
attaching themselves to the female's body in
the area of her mammary glands. Some
marsupials have a pouch-like structure or
fold, the marsupium, that shelters the
suckling young.

44. The marsupials such as the
kangaroos are .

A. placental mammals
B. lay eggs and are therefore
kinds of reptiles
C. known as pouch animals
D. know as cold-blooded
mammals

Answer: C (Encyclopaedia Britannica)
Marsupials, of which there are more than
250 species, belong to the infraclass
Metatheria (sometimes called Marsupialia),
a mammalian group characterized by
premature birth and continued development
of the newborn while attached to the nipples
on the lower belly of the mother. The pouch,
or marsupium, from which the group takes
its name, is a flap of skin covering the
nipples. Although prominent in many
species, it is not a universal featurein
some species the nipples are fully exposed
or are bounded by mere remnants of a
pouch. The young remain firmly attached to
the milk-giving teats for a period
corresponding roughly to the latter part of
development of the foetus in the womb of a
placental mammal (eutherian). A placenta is
the vascular (supplied with blood vessels)
organ in most mammals that unites the
foetus to the uterus of the mother. It
mediates the metabolic exchanges of the
developing individual through an intimate
association of embryonic tissues and of
certain uterine tissues, serving the functions
of nutrition, respiration, and excretion.
Marsupials and monotremes do not have a
placenta.

45. Setae (chaetae) are:

A. hairs or bristles of the
annelids used in locomotion
B. excretory organs in annelids
C. locomotory organs found in
flatworms
36
D. digestive organs in the
annelids

Answer: A (Encyclopaedia Britannica)
Annelids have a thin, horny cuticle pierced
by pores through which epidermal glands
secrete mucus. In some marine annelids,
glands are also present that secrete
materials constituting a parchmentlike or
calcareous tube within which the worm
dwells. Earthworms and leeches secrete
cocoons from a specialized epidermis in a
region of the body known as the clitellum. A
major feature of all annelids except leeches
is the possession of bristles, or chaetae, of
which there are many varieties. The bulk of
each chaeta is secreted by a single cell,
though the surrounding lateral cells may
contribute materials that bring about its
hardening. Setae help earthworms attach to
the surface and prevent backsliding during
peristaltic motion. These hairs are what
make it difficult to pull a worm straight from
the ground.

46. Which of the following are examples
of vestigial structures?

A. your tailbone
B. nipples on male mammals
C. sixth fingers found on some
humans
D. your kneecap

Answer: A (Wikipedia)
Vestigial structures are those that have their
original function in a species through
evolution. In humans, examples are the
vermiform appendix,. the coccyx, or tailbone
(a remnant of a lost tail); the plica
semilunaris on the inside corner of the eye
(a remnant of the nictitating membrane);
and, muscles in the ear and other parts of
the body.


47. The widespread use of . To
control insect pests has lead to the
evolution of resistance to this
chemical by many species.

A. ARVs
B. DNA
C. DDT
D. Antibiotics

Answer: C (Encyclopaedia Britannica)
DDT is the abbreviation of
dichlorodiphenyltrichloroethane, also called
1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane
a synthetic insecticide belonging to the
family of organic halogen compounds, highly
toxic toward a wide variety of insects as a
contact poison that apparently exerts its
effect by disorganizing the nervous system.
DDT, prepared by the reaction of chloral
with chlorobenzene in the presence of
sulfuric acid, was first made in 1874; its
insecticidal properties were discovered in
1939 by a Swiss chemist, Paul Hermann
Mller. During and after World War II, DDT
was found to be effective against lice, fleas,
and mosquitoes (the carriers of typhus, of
plague, and of malaria and yellow fever,
37
respectively) as well as the Colorado potato
beetle, the gypsy moth, and other insects
that attack valuable crops. Many species of
insects rapidly develop populations resistant
to DDT; the high stability of the compound
leads to its accumulation in insects that
constitute the diet of other animals, with
toxic effects on them, especially certain
birds and fishes. These two disadvantages
had severely decreased the value of DDT as
an insecticide by the 1960s, and severe
restrictions were imposed on its use in the
United States in 1972. Pure DDT is a
colourless, crystalline solid that melts at
109 C (228 F); the commercial product,
which is usually 65 to 80 percent active
compound, along with related substances, is
an amorphous powder that has a lower
melting point. DDT is applied as a dust or by
spraying its aqueous suspension.

48. What term refers to the mass of
threads that forms the body of most
fungi?

A. hyphae
B. mycelium
C. sporangia
D. basidium

Answer: B (Encyclopaedia Britannica)
A typical fungus consists of a mass of
branched, tubular filaments enclosed by a
rigid cell wall. The filaments, called hyphae
(singular hypha), branch repeatedly into a
complicated, radially-expanding network
called the mycelium, which makes up the
thallus, or undifferentiated body, of the
typical fungus. Some fungi, notably the
yeasts, do not form a mycelium but grow as
individual cells that multiply by budding or, in
certain species, by fission. The mycelium
grows by utilizing nutrients from the
environment and, upon reaching a certain
stage of maturity, formseither directly or in
special fruiting bodiesreproductive cells
called spores. The spores are released and
dispersed by a wide variety of passive or
active mechanisms; upon reaching a
suitable substrate, the spores germinate and
develop hyphae that grow, branch
repeatedly, and become the mycelium of the
new individual. Fungal growth is mainly
confined to the tips of the hyphae.

49. If you put an unripe banana in a bag
with an apple, it will quickly ripen
because of the hormone .
produced by the apple.

A. cytokinin
B. gibberellin
C. abscisic acid
D. ethylene

Answer: D (Encyclopaedia Britannica)
Growth in plants is regulated by a variety of
plant hormones, including auxins,
gibberellins, cytokinins, and growth
inhibitors, primarily abscisic acid and
ethylene. The distribution of auxins, which
promote the lengthwise growth of plants, is
correlated with the distribution of the growth
regions of the plant. In addition to promoting
38
normal growth in plant length, auxins
influence the growth of stems toward the
light (phototropism) and against the force of
gravity (geotropism). The phototropic
response occurs because greater quantities
of auxin are distributed to the side away
from the light than to the side toward it; the
geotropic response occurs because more
auxin accumulates along the lower side of
the coleoptile than along the upper side. The
downward growth of roots is also associated
with a greater quantity of auxin in their lower
halves.
Gibberellins are named after the fungus
Gibberella fujikuroi, which produces
excessive growth and poor yield in rice
plants. One gibberellin is gibberellic acid
(GA
3
), which is present in higher plants as
well as in fungi; many related compounds
have structural variations that correlate with
marked differences in effectiveness.
Gibberellins, abundant in seeds, are also
formed in young leaves and in roots; they
move upward from the roots in the xylem
(woody tissue) and thus do not show the
movement characteristic of auxins. Evidence
suggests that gibberellins promote the
growth of main stems, especially when
applied to the whole plant.
Cytokinins are compounds derived from a
nitrogen-containing compound (adenine).
One cytokinin is 6-furfurylaminopurine
(kinetin); other compounds derived from
adenine with effects similar to those of
kinetin, and certain compounds derived from
another nitrogen-containing compound,
urea, are conveniently referred to as
cytokinins, although not all are natural
products. Cytokinins are synthesized in
roots, from which, like the gibberellins, they
move upward in the xylem and pass into the
leaves and the fruit. Required for normal
growth and differentiation, cytokinins act, in
conjunction with auxins, to promote cell
division and to retard senescence, which, at
least in its early stages, is an organized
phase of metabolism and not just a
breakdown of tissue. An example of
senescence is the yellowing of isolated
leaves, which occurs as proteins are broken
down and chlorophyll is destroyed.
Cytokinins, which prevent yellowing by
stabilizing the content of protein and
chlorophyll in the leaf and the structure of
chloroplasts, are used commercially in the
storage of green vegetables.
Growth inhibitors of various types have been
identified in plants. The best characterized
one is abscisic acid, which is chemically
related to the cytokinins. It is probably
universally distributed in higher plants and
has a variety of actions; for example, it
promotes abscission (leaf fall), the
development of dormancy in buds, and the
formation of potato tubers. The mode of
action of abscisic acid has not yet been
clarified but is thought to involve the direct
inhibition of the synthesis of RNA and
protein.
Another growth inhibitor is ethylene, which is
a natural product of plants, formed possibly
from linolenic acid (a fatty acid) or from
methionine (an amino acid). Ethylene
promotes abscission in senescent leaves,
39
perhaps by facilitating the destruction of
auxin. Its effects extend beyond that of
inhibiting growth; in fruit, for example,
ethylene is regarded as a ripening hormone.
Involved in its action in fruit is another factor,
perhaps auxin or another growth-regulating
hormone, which influences the ethylene
sensitivity of the tissues.

50. Roots turn downward in a process
known as?

A. reverse phototropism
B. taxis
C. apical dominance
D. gravitropism

Answer: D
Refer to Question 11 for a detailed
explanation on tropism.

51. Which of the following is an
advantage of social groupings of
animals?

A. increased ability to detect,
repel or confuse predators
B. increased hunting efficiency
C. increased likelihood of
finding mates
D. touch, maintains social
bonds

Answer: All Correct (Encyclopaedia
Britannica)
By social behaviour animals gain: (1) food
and other resources, (2) reproductive
advantages, and (3) shelter and space.
They are enabled to avoid (4) physical and
other small hazards, (5) competitors, and (6)
predators or other large dangers. The first
and third of these gains are reactions to
desirable things of small (1) and medium to
large size (3) respectively; the fourth and
sixth are reactions to undesirable things of
these sizes. The value of being social in
getting food is obvious in the case of hunting
bands. Cooperative hunting has been found
among wolves and African hunting dogs,
hyenas, lions, killer whales, porpoises,
cormorants, white pelicans, pairs of eagles
and of ravens, tuna when chasing small fish,
army ants, primitive and modern men, and
many other animals. Animals that hunt
cooperatively can trap, chase, and tear apart
prey that would otherwise be too fast,
strong, or large for them. It was noted that
sex is a way of combining desirable genes
from different lines, genes that otherwise
might slowly or never get together. In many
lines of animals, parental behaviour is
clearly useful in protecting or teaching the
young. This normally requires the adult to
have fewer young. The careful parent loses
in time and energy and number of offspring
but comes to prevail in evolution if it has
more descendants than does a careless
parent that lets its young die. Social
behaviour is often used in habitat selection
and shelter selection, even to the extent of
making it possible for the animal to improve
the environment it finds. Cooperative
building of structures is well known in
humans, prairie dogs, rats (whose tunnel
40
systems rival the catacombs in complexity),
beavers, certain weaver finches, wasps,
bees, termites, and many others; symbiotic
use of structures occurs in many animals.
Social behaviour can also help animals
avoid small hazards. This includes avoiding
heat or cold and wet or dry situations as well
as preening or grooming to keep off dirt,
parasites, and other small environmental
hazards. A goose cleaving the air for its
companions at the front of a V-shaped flock,
a parent bird brooding its young or
sheltering it from the Sun, a group of
creepers roosting together to help each
other survive the cold winter night, and a
group of baboons grooming each other to
pick off ticks furnish other examples.
Dangers from competition are avoided by
agonistic behaviour. The five basic types of
agonistic behaviour are aggressive display
(threat), submissive display (appeasement),
attack, avoidance, and fighting. The final
reason for social behaviour, and one of the
most important, is to avoid predators or
other large dangers. Just as animals can
sometimes overcome large prey by grouping
to attack it, so they can sometimes
overcome large predators by grouping to
defend against them. Cooperative and
spirited attacks upon predators occur in
most animals that protect their young and
are a regular phenomenon in gull and tern
colonies, in baboon troupes, in bees and
wasps, and many others. Mobbing is a
similar phenomenon in which the attack is
not carried all the way to the predator but so
harasses it that it departs or at least is
prevented from getting its prey. The massed
effect of many mobbing birds is more
intimidating to a predator than is mobbing by
one or two birds. Grouping also helps
against predators because a predator is
distracted by the confusion effect of so
many shapes, sounds, or smells. Another
advantage of the group or flock is that many
eyes can see a predator more quickly than
can one pair of eyes.

52. When a male rat defeats another
male and takes his harem, the new
male often kills any current litters.
What principle does this behaviour
represent?

A. altruism
B. kin selection
C. operant conditioning
D. parental investment

Answer: D (Wikipedia)
Infanticide based on sexual competition has
the general theme of the killer (often male)
becoming the new sexual partner of the
victim's parent which would otherwise be
unavailable to it. This represents a gain in
fitness by the killer, and a loss in fitness by
the parent of the offspring killed. This is a
form of sexual conflict and is a type of
evolutionary struggle between the two
sexes, in which the victim sex may have its
own counter-adaptations which reduce the
success of this practice. When a male tries
to take over a group, there is a violent
struggle with the existing male. If successful
41
in overthrowing the previous male, infants of
the females are then killed. This infanticidal
period is limited to the window just after the
group is taken over. This behaviour not only
reduces intraspecific competition between
the incumbent's offspring and those of other
males and increases the parental
investment afforded to their own young, but
also allows females to become sexually
receptive sooner. This is because females of
many mammals, do not ovulate during the
period in which they produce milk. It then
becomes easier to see how this behaviour
could have evolved. If a male kills a female's
young, they stop lactating and are able to
become pregnant again. As males are in a
constant struggle to protect their group,
those that express infanticidal behaviour will
contribute a larger portion to future gene
pools. The behaviour has been observed in
many species, including monkeys, rats and
lions.
Parental investment means any investment
by the parent in an individual offspring that
increases the offspring's chance of surviving
(and hence reproductive success) at the
cost of the parent's ability to invest in other
offspring.
In the science of ethology (the study of
behaviour), and more generally in the study
of social evolution, altruism refers to
behaviour by an individual that increases the
fitness of another individual while
decreasing the fitness of the actor (potential
self-sacrifice).
Kin selection means the evolution of
characteristics which favour the survival of
close relatives of the affected individual, by
processes which do not require any
discontinuities in the population breeding
structure. Parental care is, therefore, a form
of altruism readily explained by kin selection.
Kin selection extends beyond the
relationship between parents and their
offspring. It facilitates the development of
altruistic behaviour when the energy
invested, or the risk incurred, by an
individual is compensated in excess by the
benefits ensuing to relatives. Adult zebras,
for instance, will turn toward an attacking
predator to protect the young in the herd
rather than fleeing to protect themselves.
Operant conditioning is the use of
consequences to modify the occurrence and
form of behaviour.
Operant conditioning is distinguished from
Pavlovian conditioning in that operant
conditioning deals with the modification of
"voluntary behaviour" through the use of
consequences, while Pavlovian conditioning
deals with the conditioning of behaviour so
that it occurs under new antedecent
conditions.

53. Why do many animals defend
territories?

A. to monopolise the resources
within the territory
B. to avoid predation
C. to secure over-wintering
sites
D. to avoid each other

42
Answer: A (Wikipedia)
The term territory refers to any geographical
area that an animal of a particular species
consistently defends against conspecifics
(and, occasionally, animals of other
species). Animals that defend territories in
this way are referred to as capricornius. The
most obvious examples of the "classic"
territory are birds and fish. Animals like
these defend territories that contain their
nest site and sufficient food resources for
themselves and their young. Defence rarely
takes the form of overt fights: more usually
there is a highly noticeable display, which
may be visual (as in the red breast of the
robin), auditory (as in much bird song, or the
calls of gibbons) or olfactory, through the
deposit of scent marks. Many territorial
mammals use scent-marking to signal the
boundaries of their territories; the marks
may be deposited by urination, by
defecation, or by rubbing parts of the bodies
that bear specialised scent glands against
the substrate. For example, dogs and other
canids scent-mark by urination and
defecation, while cats scent-mark by rubbing
their faces and flanks against objects.
Territoriality is only shown by a minority of
species. More commonly, an individual or a
group of animals will have an area that it
habitually uses but does not necessarily
defend; this is called its home range. The
home ranges of different groups often
overlap, and in the overlap areas the groups
will tend to avoid each other rather than
seeking to expel each other. Within the
home range there may be a core area that
no other individual group uses, but again
this is as a result of avoidance rather than
defence. Behavioural ecologists have
argued that food distribution determines
whether a species will be territorial or not.
Territoriality is only expected to emerge
where there is a focused resource that
provides enough for the individual or group,
within a boundary that is small enough to be
defended without the expenditure of too
much effort.

54. If a population is above carrying
capacity, what must happen?

A. It must immediately crash
B. It can remain stable
indefinitely
C. If the species is territorial, it
can continue to increase
D. It must eventually decline

Answer: D (Encyclopaedia Britannica)
Carrying capacity is the average population
density or population size of a species below
which its numbers tend to increase and
above which its numbers tend to decrease
because of shortages of resources. The
carrying capacity is different for each
species in a habitat because of that species'
particular food, shelter, and social
requirements.

55. Which of the following is an example
of commensal relationship?

43
A. orchids growing on tree
limbs
B. flowering plants and their
pollinators
C. lupines and blue butterflies
D. monarch and viceroy
butterflies

Answer: A (Wikipedia)
Commensalism is a term employed in
ecology to describe a relationship between
two living organisms where one benefits and
the other is not significantly harmed or
helped. It is derived from the English word
commensal, meaning the sharing of food,
and used of human social interaction. The
word derives from the Latin com mensa,
meaning sharing a table. Commensalism
can be in several forms, for example: (i)
Phoresy: One animal attaching to another
animal for transportation only. This concerns
mainly arthropods, examples of which are
mites on insects (such as beetles, flies, or
bees), pseudoscorpions on mammals and
millipedes on birds. Phoresy can be either
obligate or facultative (induced by
environmental conditions); (ii) Inquilinism:
Using a second organism for housing.
Examples are epiphytic plants (such as
many orchids) which grow on trees, or birds
that live in holes in trees; (iii) Metabiosis: A
more indirect dependency, in which the
second organism uses something the first
created, however after the death of the first.
An example is the hermit crabs that use
gastropod shells to protect their bodies.

56. Why do scientists think that human-
induced global warming will be more
harmful to plants and animals than
were past, natural climate
fluctuations?

A. because temperature will
change fast
B. because the temperature
changes will be larger
C. because species now are
less adaptable than species
in the past
D. because ecosystems are
now more complicated than
they used to be

Answer: B (Encyclopaedia Britannica)
Global warming is an increase in global
average surface temperature resulting from
an increase in the amount of carbon dioxide,
methane, and certain other trace gases in
the atmosphere. These gases are known
collectively as greenhouse gases because
they contribute to a warming of the Earth's
surface and lower atmosphere, a
phenomenon called the greenhouse effect.
In part because the emission of carbon
dioxide is related to the essential use of
carbon-based energy sources, the issue of
global warming incorporates a broad
scientific and political debate about its
significance and consequences. Increasing
global temperature will cause sea level to
rise, and is expected to increase the
intensity of extreme weather events and to
change the amount and pattern of
44
precipitation. Other effects of global warming
include changes in agricultural yields, trade
routes, glacier retreat, species extinctions
and increases in the ranges of disease
vectors. Concerned about such projections
and their potentially severe consequences
for human populations and the environment,
nations around the world in the late 1980s
and early 1990s focused their attention on
developing policies to control greenhouse
gases. One step was to organize the
scientific community to provide information
on a periodic basis to policy makers. Toward
this end the World Meteorological
Organization and the United Nations
Environment Programme formed the
Intergovernmental Panel on Climate Change
(IPCC) in 1988. The IPCC has produced
several major assessments for policy
makers. In February 2007 the panel
released a summary from its first working
group on the science of climate change in
anticipation of the release of its fourth
assessment report later in the year. The
IPCC largely reaffirmed the conclusions of
its earlier reports, indicating that it is now 90
percent certain that most of the warming
observed over the previous half century
could be attributed to greenhouse gas
emissions produced by human activities
(i.e., primarily industrial processes and
transportation). In 2001 the panel had
concluded that the previous 100 years had
seen an increase in global average surface
temperature of 0.6 C (1.1 F), with an error
range of 0.2 C (0.4 F). The 2001 report
predicted that the average surface
temperature would increase by 1.4 to 5.8 C
(2.5 to 10.4 F) by 2100, according to the
best estimate values over a range of
scenarios for greenhouse gas emissions.
Revised estimates from the fourth
assessment report in 2007 forecast a 1.8
4.0 C (3.27.2 F) rise in average surface
temperature over the same period.

57. The reservoir for carbon is.

A. coal, oil and natural gas
B. plants
C. CO
2
in the atmosphere
D. methane (CH
4
) in the
atmosphere

Answer: C (Wikipedia)
The carbon cycle is the biogeochemical
cycle by which carbon is exchanged
between the biosphere, geosphere,
hydrosphere, and atmosphere of the Earth.
The cycle is usually thought of as four major
reservoirs of carbon interconnected by
pathways of exchange. The reservoirs are
the atmosphere, the terrestrial biosphere
(which usually includes freshwater systems
and non-living organic material, such as soil
carbon), the oceans (which includes
dissolved inorganic carbon and living and
non-living marine biota), and the sediments
(which includes fossil fuels). The annual
movements of carbon, the carbon
exchanges between reservoirs, occur
because of various chemical, physical,
geological, and biological processes. The
ocean contains the largest active pool of
45
carbon near the surface of the Earth, but the
deep ocean part of this pool does not rapidly
exchange with the atmosphere. The global
carbon budget is the balance of the
exchanges (incomes and losses) of carbon
between the carbon reservoirs or between
one specific loop (e.g., atmosphere -
biosphere) of the carbon cycle. An
examination of the carbon budget of a pool
or reservoir can provide information about
whether the pool or reservoir is functioning
as a source or sink for carbon dioxide.
Carbon exists in the Earth's atmosphere
primarily as the gas carbon dioxide (CO
2
).
Although it is a very small part of the
atmosphere overall (approximately 0.04%
on a molar basis, though rising), it plays an
important role in supporting life. Other gases
containing carbon in the atmosphere are
methane and chlorofluorocarbons (the latter
is entirely anthropogenic). The overall
atmospheric concentration of these
greenhouse gases has been increasing in
recent decades, contributing to global
warming. Carbon is taken from the
atmosphere in several ways:
(i) When the sun is shining, plants perform
photosynthesis to convert carbon dioxide
into carbohydrates, releasing oxygen in the
process. This process is most prolific in
relatively new forests where tree growth is
still rapid; (ii) At the surface of the oceans
towards the poles, seawater becomes cooler
and more carbonic acid is formed as CO
2

becomes more soluble. This is coupled to
the ocean's thermohaline circulation which
transports dense surface water into the
ocean's interior. Carbon can be released
back into the atmosphere in many different
ways:
(i) Through the respiration performed by
plants and animals. This is an exothermic
reaction and it involves the breaking down of
glucose (or other organic molecules) into
carbon dioxide and water; (ii) Through the
decay of animal and plant matter. Fungi and
bacteria break down the carbon compounds
in dead animals and plants and convert the
carbon to carbon dioxide if oxygen is
present, or methane if not; (iii) Through
combustion of organic material which
oxidizes the carbon it contains, producing
carbon dioxide (and other things, like water
vapor); (iv) Burning fossil fuels such as coal,
petroleum products, and natural gas
releases carbon that has been stored in the
geosphere for millions of years; (v)
Production of cement: carbon dioxide is
released when limestone (calcium
carbonate) is heated to produce lime
(calcium oxide), a component of cement; (vi)
At the surface of the oceans where the
water becomes warmer, dissolved carbon
dioxide is released back into the
atmosphere; (vii) Volcanic eruptions and
metamorphism release gases into the
atmosphere. Volcanic gases are primarily
water vapor, carbon dioxide and sulfur
dioxide. The carbon dioxide released is
roughly equal to the amount removed by
silicate weathering; so the two processes,
which are the chemical reverse of each
other, sum to roughly zero, and do not affect
46
the level of atmospheric carbon dioxide on
time scales of less than about 100,000 yr.

58. The biological process whereby
carbon is returned to its reservoir is:

A. photosynthesis
B. glycolysis
C. cellular respiration
D. nitrification

Answer: C
See the answer to question 57 above for a
detailed discussion.

59. Which continent has the highest rate
of human population growth?

A. Asia
B. Africa
C. North America
D. South America

Answer: B (Wikipedia/Britannica)
Globally, the growth rate of the human
population has been steadily declining (i.e.,
population is growing more slowly than in
the recent past, although the last 50 years
have seen a rapid increase in population
due to medical advances and massive
increase in agricultural productivity

made by
the Green Revolution. The actual annual
growth in the number of humans is in
decline, from 87 million per annum in the
late 1980s, down to 75 million per annum in
2006. Growth remains high in the Middle
East, South Asia, Southeast Asia, Latin
America, and primarily in Sub-Saharan
Africa. In some countries there is negative
population growth (i.e., net decrease in
population over time), especially in Central
and Eastern Europe (mainly due to low
fertility rates) and Southern Africa (due to
the high number of HIV-related deaths).
Within the next decade, Japan and some
countries in Western Europe are also
expected to encounter negative population
growth due to sub-replacement fertility rates.
The greatest population growth rates were
reached in Latin America and in Asia during
the mid- to late 1960s. Since then, these
regions have experienced variable but
sometimes substantial fertility declines along
with continuing mortality declines, resulting
in usually moderate and occasionally large
declines in population growth. The most
dramatic declines have been those of the
People's Republic of China, where the
growth rate was estimated to have declined
from well over 2 percent per year in the
1960s to about half that in the 1980s,
following official adoption of a concerted
policy to delay marriage and limit
childbearing within marriage. The
predominance of the Chinese population in
East Asia means that this region has
experienced the most dramatic declines in
population growth of any of the developing
regions. Over the same period population
growth rates have declined only modestly
and in some cases have actually risenin
other developing regions. In South Asia the
rate has declined only from 2.4 to 2.0
percent; in Latin America, from about 2.7 to
47
about 2.3 percent. Meanwhile, in Africa
population growth has accelerated from 2.6
percent to more than 3 percent over the
same period, following belated significant
declines in mortality not accompanied by
similar reductions in fertility.

60. Abnormal . counts are used to
determine the progress of HIV/AIDS

A. white blood cell
B. red blood cell
C. haemoglobin
D. blood platelets

Answer: A (Encyclopaedia Britannica)
The main cellular target of HIV is a special
class of white blood cells critical to the
immune system known as helper T
lymphocytes, or helper T cells. Helper T
cells are also called CD4+ T cells because
they have on their surfaces a protein called
CD4. Helper T cells play a central role in
normal immune responses by producing
factors that activate virtually all the other
immune system cells. These include B
lymphocytes, which produce antibodies
needed to fight infection; cytotoxic T
lymphocytes, which kill cells infected with a
virus; and macrophages and other effector
cells, which attack invading pathogens.
AIDS results from the loss of most of the
helper T cells in the body. The human
immunodeficiency virus (HIV) destroys a
special class of white blood cells called
T4.HIV is a retrovirus, one of a unique family
of viruses that consist of genetic material in
the form of RNA (instead of DNA)
surrounded by a lipoprotein envelope. HIV
cannot replicate on its own and instead
relies on the mechanisms of the host cell to
produce new viral particles. HIV infects
helper T cells by means of a protein
embedded in its envelope called gp120.
Once the virus has infected a T cell, HIV
copies its RNA into a double-stranded DNA
copy by means of the viral enzyme reverse
transcriptase; this process is called reverse
transcription because it violates the usual
way in which genetic information is
transcribed. Because reverse transcriptase
lacks the proofreading function that most
DNA synthesizing enzymes have, many
mutations arise as the virus replicates,
further hindering the ability of the immune
system to combat the virus. These
mutations allow the virus to evolve very
rapidly, approximately one million times
faster than the human genome evolves. This
rapid evolution allows the virus to escape
from antiviral immune responses and
antiretroviral drugs. The next step in the
virus life cycle is the integration of the viral
genome into the host cell DNA. Integration
occurs at essentially any accessible site in
the host genome and results in the
permanent acquisition of viral genes by the
host cell. Under appropriate conditions these
genes are transcribed into viral RNA
molecules. Some viral RNA molecules are
incorporated into new virus particles, while
others are used as messenger RNA for the
production of new viral proteins. Viral
proteins assemble at the plasma membrane
48
together with the genomic viral RNA to form
a virus particle that buds from the surface of
the infected cell, taking with it some of the
host cell membrane that serves as the viral
envelope. Embedded in this envelope are
the gp120/gp41 complexes that allow
attachment of the helper T cells in the next
round of infection. Most infected cells die
quickly (in about one day). The number of
helper T cells that are lost through direct
infection or other mechanisms exceeds the
number of new cells produced by the
immune system, eventually resulting in a
decline in the number of helper T cells.
Physicians follow the course of the disease
by determining the number of helper T cells
(CD4+ cells) in the blood. This
measurement, called the CD4 count,
provides a good indication of the status of
the immune system. Physicians also
measure the amount of virus in the
bloodstreami.e., the viral loadwhich
provides an indication of how fast the virus
is replicating and destroying helper T cells.
Because of the high rate at which the
genetic material of HIV mutates, the virus in
each infected individual is slightly different.
Genetic variants of HIV have been
categorized into several major subtypes, or
clades, which have different geographical
distributions. Variation occurs throughout the
genome but is especially pronounced in the
gene encoding the gp120 protein. By
constantly changing the structure of its
predominant surface protein, the virus can
avoid recognition by antibodies produced by
the immune system.

61. Examples of crustaceans are:

A. a crayfish and a crab
B. an octopus and a crab
C. a snail and a crab
D. all of the above

Answer: A (Encyclopaedia Britannica)
A crustacean is any member of the
subphylum Crustacea (phylum Arthropoda),
a group of invertebrate animals consisting of
some 39,000 species distributed worldwide.
Crabs, lobsters, shrimps, crayfish and wood
lice are among the best-known crustaceans,
but the group also includes an enormous
variety of other forms without popular
names. Crustaceans are generally aquatic
and differ from other arthropods in having
two pairs of appendages (antennules and
antennae) in front of the mouth and paired
appendages near the mouth that function as
jaws. Because there are many exceptions to
the basic features, however, a satisfactory
inclusive definition of all the Crustacea is
extraordinarily hard to frame. Crustaceans
include such arthropods as crabs, lobsters,
shrimps, barnacles, and many other forms.
For a number of crustacean species,
reactions to food chemicals or other
substances have been used to locate the
body regions that bear chemoreceptors. The
list is impressive. Distance chemoreceptors
are borne on the antennae and the smaller
antennules, specialized structures
(esthetascs) on the tips of the antennules
being particularly sensitive. Contact
49
chemoreceptors are borne chiefly on the tips
of the walking legs, the mouthparts,
antennules, tail flap (telson), walls of the gill
chambers, and, in some species, on the
general body surface.
A gastropod is any member of the class
Gastropoda, the largest group of the phylum
Mollusca, consisting of about 65,000
species. Gastropod, which means belly-
footed, refers to the broad tapered foot on
which these animals glide. The class
comprises the snails, which have a shell into
which the animal can withdraw, and the
slugssnails whose shells have been
reduced to an internal fragment or
completely lost in the course of evolution.
Gastropods are among the few groups of
animals to have successfully radiated in the
ocean, fresh waters, and on land. Because
of the challenges presented by these
diverse habitats, gastropods are very difficult
to characterize. A few are used as food, a
very few transmit animal diseases (only a
fraction of these have been found to carry
the agents of human and animal disease),
and the shells of some are used as
ornaments or in making jewellery. The main
role of gastropods is as scavengers, feeding
on dead plant or animal matter, or as
predators. Octopuses, or Octopi, in general,
are eight-armed cephalopod (octopod)
mollusk of the order Octopoda; the true
octopuses are members of the genus
Octopus, a large group of widely distributed,
shallow-water cephalopods. (See
cephalopod.) Octopuses vary greatly in size;
the smallest, O. arborescens, is about 5 cm
(2 inches) long, while the largest species
may grow to 5.4 m (18 feet) in length and
have an armspan of almost 9 m (30 feet).
The typical octopus has a saccular body: the
head is only slightly demarcated from the
body and has large, complex eyes and eight
contractile arms. Each arm bears two rows
of fleshy suckers that are capable of great
holding power. The arms are joined at their
bases by a web of tissue known as the skirt,
at the centre of which lies the mouth. The
latter organ has a pair of sharp, horny beaks
and a filelike organ, the radula, for drilling
shells and rasping away flesh. The octopus
takes water into its mantle and expels the
water after respiration through a short funnel
called a siphon. Most octopuses move by
crawling along the bottom with their suckers,
though when alarmed they may shoot swiftly
backward by ejecting a jet of water from the
siphon. When endangered, they eject an
inky substance, which is used as a screen;
the substance produced by some species
paralyzes the sensory organs of the
attacker. The best-known octopus is the
common octopus, O. vulgaris, a medium-
sized species that is widely distributed in
tropical and temperate seas throughout the
world. This species is thought to be the most
intelligent of all invertebrate animals. O.
vulgaris also has highly developed pigment-
bearing cells and can change its skin
colours to an astonishing degree with great
rapidity.

62. What is the difference between
solitary and sedentary?
50

A. solitary animals do not
move; sedentary animals
move slowly if at all
B. solitary animals live alone;
sedentary animals live
together
C. solitary animals live alone,
sedentary animals move
slowly, if at all
D. solitary animals move
slowly; sedentary animals
live on their own

Answer: C
The term sedentary in biology applies to
organisms and species that are not
migratory but rather remain at a single
location (permanently fixed or otherwise).
Examples in zoology include such sessile
organisms as barnacles, corals and
mussels. A solitary (Latin solus, meaning
alone) person, animal or object is one which
is not usually in the companionship of others
of its type. Some animals live a mostly
solitary life, only looking for others in mating
season, e.g. feral cats and bears.

63. What is the difference between a
predator and a scavenger?

A. a predator feeds only on
plants; a scavenger feeds
only on animals
B. a predator eats both plants
and animals; a scavenger
feeds only on plants
C. a predator eats only dead
organisms; a scavenger is
an active hunter of flesh
D. a predator is an active
hunter of flesh; a scavenger
feeds on dead or dying
organisms;

Answer: D (Wikipedia)
In ecology, predation describes a biological
interaction where a predator organism feeds
on another living organism or organisms
known as prey. A true predator is one which
kills and eats another organism. Whereas
other types of predator all harm their prey in
some way, this form results in their instant
death. Some predators kill large prey and
dismember or chew it prior to eating it, such
as a jaguar, while others may eat their
(usually much smaller) prey whole, as does
a bottlenose dolphin or any snake. In some
cases the prey organism may die in the
mouth or digestive system of the predator.
Baleen whales, for example, eat millions of
microscopic plankton at once, the prey being
broken down well after entering the whale.
Seed predation is another form of true
predation, as seeds represent potential
organisms. Predators of this classification
need not eat prey entirely, for example some
predators cannot digest bones, while others
can. Some may merely eat only part of an
organism, as in grazing below, but still
consistently cause its direct death.
Scavengers are animals that consume
already dead animals (carrion). Scavengers
play an important role in the ecosystem by
51
contributing to the decomposition of dead
animal remains. Decomposers complete this
process, by consuming the remains left by
scavengers. Well known scavengers include
vultures, burying beetles, blowflies,
yellowjackets, and raccoons. Many large
carnivores that hunt regularly--such as
hyenas and lions--will scavenge if given the
chance. Animals which consume faeces,
such as dung beetles, are also referred to as
scavengers. Animals which primarily
consume dead plants (litter) are referred to
as detritivores.

64. With regard to the human skeleton,
the skeleton can be divided into
axial and .. skeletons which are
both composed of numerous bones.

A. central
B. appendicular
C. cartilage
D. synovial

Answer: B ( Wikipedia)
The human skeleton consists of both fused
and individual bones supported and
supplemented by ligaments, tendons,
muscles and cartilage. It serves as a
scaffold which supports organs, anchors
muscles, and protects organs such as the
brain, lungs and heart. The longest and
heaviest bone in the body is the femur, and
the smallest is the stapes bone in the middle
ear. In an adult, the skeleton comprises
around 20% of the total body weight. Fused
bones include those of the pelvis and the
cranium. Not all bones are interconnected
directly: There are 6 bones in the middle ear
called the ossicles (three on each side) that
articulate only with each other. The hyoid
bone, which is located in the neck and
serves as the point of attachment for the
tongue, does not articulate with any other
bones in the body, being supported by
muscles and ligaments.


The human skeleton can be divided into the
axial skeleton and the appendicular
skeleton. The axial skeleton consists of the
80 bones in the head and trunk of the
human body. It is composed of five parts;
52
the human skull, the ossicles of the inner
ear, the hyoid bone of the throat, the chest,
and the vertebral column. The appendicular
skeleton consists of 126 bones in the human
body which make motion possible and
protects the organs of digestion, excretion,
and reproduction. The word appendicular
means referring to an appendage or
anything attached to a major part of the
body, such as the upper and lower
extremities.

65. In the mammalian eye the receptor
cells, cones and rods are located in
the .. on which light rays are
brought into focus.

A. retina
B. lens
C. cornea
D. cochlea

Answer: A (Wikipedia)
The structure of the mammalian eye owes
itself completely to the task of focusing light
onto the retina. This light causes chemical
changes in the photosensitive cells of the
retina, the products of which trigger nerve
impulses which travel to the brain. The
retina contains two forms of photosensitive
cells important to visionrods and cones.
Though structurally and metabolically
similar, their function is quite different. Rod
cells are highly sensitive to light allowing
them to respond in dim light and dark
conditions, however, they cannot detect
colour. These are the cells which allow
humans and other animals to see by
moonlight, or with very little available light
(as in a dark room). This is why the darker
conditions become, the less colour objects
seem to have. Cone cells, conversely, need
high light intensities to respond and have
high visual acuity. Different cone cells
respond to different wavelengths of light,
which allows an organism to see colour. The
differences are useful; apart from enabling
sight in both dim and light conditions,
humans have given them further application.
The fovea, directly behind the lens, consists
of mostly densely-packed cone cells. This
gives humans a highly detailed central
vision, allowing reading, bird watching, or
any other task which primarily requires
staring at things. Its requirement for high
intensity light does cause problems for
astronomers, as they cannot see dim stars,
or other celestial objects, using central
vision because the light from these is not
enough to stimulate cone cells. Because
cone cells are all that exist directly in the
fovea, astronomers have to look at stars
through the "corner of their eyes" (averted
vision) where rods also exist, and where the
light is sufficient to stimulate cells, allowing
an individual to observe faint objects.

66. Behaviour that is disadvantageous
for the individual performing it, but
helpful to another individual is said
to be .

A. reciprocal
B. learning
53
C. socialization
D. altruistic

Answer: D
Refer to Question 52 for a detailed
explanation.

67. External fertilization is found in .

A. aquatic organisms and
some terrestrial organisms
such as frogs
B. aquatic organisms only
C. organisms with an organ to
introduce sperm into the
females body
D. in terrestrial animals only

Answer: A (Wikipedia)
External fertilization is a form of fertilization
in which a sperm cell is united with an egg
cell external to the body of the female. Thus,
the fertilization is said to occur "externally".
This is distinct from internal fertilization
where the union of the egg and sperm occur
inside the female after insemination through
copulation. In sexual reproduction, there
must be some way of getting the sperm to
the egg. Since sperm are designed to be
motile in a watery environment, aquatic
animals can make use of the water in which
they live. In many aquatic animals such as
coral or Hydra, eggs and sperm are
simultaneously shed into the water, and the
sperm swim through the water to fertilize the
egg in a process known as broadcast
fertilization. In many fish species, including
salmon, the female will deposit unfertilized
eggs in the substrate and the male will swim
by and fertilize them. Many land plants make
use of external fertilization as well. For
example, bees and butterflies brush against
pollen when gathering nectar from flowers
and spread them to another flower of the
same species, pollinating that plant.

68. The progressive sequence of
changes which a species goes
through from fertilization in one
generation to fertilization in the next
is known as

A. the evolutionary cycle
B. the lactation period
C. the life cycle
D. the generational cycle

Answer: D (Wikipedia)
A generation has traditionally been defined
as the average interval of time between the
birth of parents and the birth of their
offspring." This places a generation at
around 20 years in span and this matches
the generations up to and including
Americas Baby Boomers. However, while in
the past this has served sociologists well in
analysing generations, it is irrelevant today.
More relevantly, a generation is the time
span from birth to sexual maturity.

69. Some animals have a larva in the
course of their development which
develops into the adult by .

54
A. metamorphosis
B. fertilization
C. differentiation
D. growth

Answer: A (Encyclopaedia Britannica)
Metamorphosis is the striking change of
form or structure in an individual after
hatching or birth. Hormones called moulting
and juvenile hormones, which are not
species specific, apparently regulate the
changes. These physical changes as well as
those involving growth and differentiation
are accompanied by alterations of the
organism's physiology, biochemistry, and
behaviour. The immature forms, or larvae,
are adapted to environments and modes of
life that differ from those of the adult forms.
These differences may be of significance in
assuring that larvae and adults of the same
species do not engage in direct competition
for food or living space. Examples of
metamorphosis include the tadpole, an
aquatic larval stage that transforms into the
land-dwelling frog (class Amphibia).
Starfishes and other echinoderms undergo a
metamorphosis that includes a change from
the bilateral symmetry of the larva to the
radial symmetry of the adult. Metamorphic
patterns are well-known in crabs, lobsters,
and other crustaceans and also in snails,
clams, and other mollusks. The larval form
of the urochordate (e.g., the tunicate, or sea
squirt) is tadpole-like and free swimming; the
adult is sessile and somewhat degenerate.
Among the most dramatic and thoroughly
studied examples of metamorphosis are the
insects. Because development is not the
same in all insects, it is convenient to group
them into major categories according to the
pattern of structural changes: ametabolous,
hemimetabolous, and holometabolous. In
ametabolous development there is simply a
gradual increase in the size of young until
adult dimensions are attained. This kind of
development occurs in the silverfish,
springtail, and other primitive insects. In
more advanced insects (e.g., grasshoppers,
termites, true bugs) a phenomenon known
as gradual, or hemimetabolous,
metamorphosis occurs. The
hemimetabolous life cycle consists of egg,
nymph, and adult. The nymph, or immature
insect, resembles the adult in form and
eating habits, differing in size, body
proportions, and colour pattern.
Rudimentary wings are visible and develop
externally. Development is gradual through
a series of moults (periodic shedding of the
outer skeleton), the adult emerging from the
final moult. Complete, or holometabolous,
metamorphosis is characteristic of beetles,
butterflies and moths, flies, and wasps. Their
life cycle includes four stages: egg, larva,
pupa and adult. The larva differs greatly
from the adult. It is wingless, and its form
and habits are suited for growth and
development rather than reproduction. The
change to the adult occurs during the
inactive, non-feeding pupal stage. At this
time the larva undergoes a transformation in
which the wings appear externally, larval
organs and tissues are broken down, and
adult structures are developed.
55
Hypermetamorphosis, a form of complete
metamorphosis, occurs in some beetles,
flies, and other insects and is characterized
by a series of larval stages.

70. In flowering plants, the embryo
develops into a seedling when the
seed

A. fertilizes
B. germinates
C. differentiates
D. grows

Answer: B (Encyclopaedia Britannica)
Germination is the sprouting of a seed,
spore, or other reproductive body, usually
after a period of dormancy. The absorption
of water, passage of time, chilling, warming,
oxygen availability, and light exposure may
all operate in initiating the process.
Germination sometimes occurs early in the
development process; the mangrove
(Rhizophora) embryo develops within the
ovule, pushing out a swollen rudimentary
root through the still-attached flower. In peas
and corn (maize), the cotyledons (seed
leaves) remain underground; in other
species (beans, sunflowers, etc.), the
hypocotyl (embryonic stem) grows several
inches above the ground, carrying the
cotyledons into the light, in which they
become green and often leaf-like. The
carefully controlled mass germination of
cereal seeds supplies enzymes for the
making of alcoholic beverages and for other
industries as well. Spores of the
commercially cultivated edible mushroom
Agaricus brunescens are also mass
germinated.