Physiological structure and life process

Circulatory system

The system of the body which helps in transport of nutrients, hormones and oxygen to tissues and collects
their waste product is called circulatory system. it is also called internal transportation system. it broadly
consists three major components:

a. Blood (circulatory medium)

b. Blood vessels (arteries,veins, capillaries) and,
c. Heart (pumping organ).

Blood:

The red-colored fluid connective tissue and being circulatory medium is called blood. It is salty in taste,
slightly alkaline with a pH range of 7.3 to 7.5 and its specific gravity is 1.05-1.06. the body of a healthy
adult person/ human has about 5.5 liters of blood and constitutes nearly about 8% of the body weight.

Composition:

Human blood consists of 55% plasma and 45% blood cells. There are three types of blood cells, red
blood cells, white blood cells and platelets.

Plasma:

The transparent pale-yellowish/ straw-colored fluid part of blood in which the blood cells are suspended
is called plasma. It consists of 90% water and 20% of solids in the form of protein, fats, minerals, salts,
carbohydrates, etc. It forms 55% of the total volume of blood in the human body.

Major Functions of plasma

a) Plasma transports digested food products such as glucose and amino acids to various parts of the
body.
b) It transport oxygen in dissolved state in the plasma.
c) It transport carbon dioxide from tissues to the lungs for elimination
d) It regulates water content of the cell and keeps water balanced in the body.
e) Plasma proteins maintain the blood pH.
f) It transport hormones to the target organ.
g) Plasma also helps to transport of excretory wastes from the tissue to the kidney for removal.
h) It helps to maintain the temperature inside the body.

If there is low level of fibrinogen in blood , there occurs a disease called hemophilia in which there is no
clotting of blood so that continuous bleeding occurs from the cuts or wounds.

Blood Cells or Blood Corpuscles: There are three types of Blood Cells:

a. R.B.C. Red blood corpuscles (Erythrocytes)

b. W.B.C. White blood corpuscles (Leucocytes) and

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 c. Platelets (Thrombocytes).
a) Red Blood Corpuscles (R.B.C./Erythrocytes):

Shape and size: They are small, circular/disc like, biconcave. They are medium sized blood cells (with
average size 7 𝜇𝑚 in diameter).

Nucleus: They have no nucleus i.e. they are non-nucleated.

Number: About 4.5 millions to 5 millions per cubic millimeter of blood.

Color: RBCs are red due to presence of hemoglobin.

Site of formation- They are formed in bone-marrow (especially of sternum, ribs and vertebrae, long bones
and skull bones

Life span: 120 to 127 days (about 4 months)

Site of Destruction: They destroyed in the liver and spleen.

Effect of Disorder:

The deficiency or excessive loss/ decrease of RBC or hemoglobin in the blood, the person suffers form
anemia. Hemoglobin is a red- colored respiratory pigment made up of iron containing pigment called
harming (4%) and a type of protein called globing (96%). It combines with oxygen in the lungs to form
oxyhaemoglobin which gives oxygen to the cells/ tissues. It combines with carbon dioxide and forms
carboxyhemoglobin, Which collects the carbon dioxide from cells/tissues to the lungs.

Functions of hemoglobin:

a. It plays an important role to transport oxygen and carbon dioxide gas.

b. It helps to balance the acid-base balance in the body.

Symptoms of anemia:

a. Weakness, tiredness even in a short walk/exercise.

b. Loss in weight, c. Loss in appetite
d. Slow and retarded growth
e. pale and dull colour of skin, etc.

Functions of Red blood cells:

a. They mainly transport O2 and CO2 between the lungs and all parts of the body.
b. Their surfaces absorb the amino acids and transport them to the cells from the alimentary canal.
c. They maintain the viscosity of the blood and ion-balance.
b) white Blood Cells (W.B.C./Leucocytes):

Shape and size: They have irregular/amoeboid shape.

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They are the biggest blood cells (diameter: 8-15 𝜇𝑚).

Nucleus: Nucleus is present in them. i.e. they are nucleated.

Number: Their average number -4,000 to 10,000 per cubic millimeter of blood .

Color: Their cytoplasm is colorless.

Site of Formation: They are formed in bone marrow and lymph glands.

Life span: Their lifespan is about 2 weeks (about 15 days).

Site of Destruction: They destroyed in infection portions of the body and in lymphatic system..

Types of Leucocytes (White blood Cells):

Leucocytes are of two types. These are:

a. Granulocytes: These are the leucocytes having granules in their cytoplasm and lobed nucleus.
Example: neutrophils, eosinophils and basophils.
b. Agranulocytes: These are the leucocytes without granules in their cytoplasm and unpiloted
nucleus. Examples: coenocytes and lymphocytes.

Effects of their Disorder:

a. Excessive decrease of WBCs: The sharp decrease of WBC count in blood [about below
4000/(mm)3] causes leucopenia due to which the different diseases may attack due to lack of
immunity/ resistivity. It is caused due to the fall in neutrophil cells.
b. Excessive increment of WBCs in the blood cell can destroy RBCs and may cause leukemia
which is a blood cancer.

Functions of WBCs:

a. WBCs help in destroying bacteria by engulfing them and hence they defend the body from
various diseases.
b. They fight against disease-causing germs and destroy the damaged cells by phagocytosis.
c. They also help in the formation of antibodies which neutralize or kill the germs that enter our
body.
c) platelets(Thrombocytes):

Shape and Size : They are irregular shaped cell fragments. They are the smallest blood cells.

Nucleus: They have no nucleus i.e. they are non-nucleated.

Number: About 0.2 millions to 0.4 million per (mm).3

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Color: Cytoplasm is colorless.

Site of formation: They are formed in bone marrow.

Site of destruction: They are destroyed in liver and spleen.

Life span: About 2-3 days.

Function: Helps in blood clotting. A type of protein, named fibrinogen of platelets, helps in clotting the
blood in wounds/cuts.

Effect of Disorder:

a. Deficiency/sharp decrease of platelets below the normal value causes thrombopenia/

thrombocytopenia which cause the difficulty in blood clotting.
b. Excessive increase of platelets more then the normal value causes thrombocythemia, which causes
unnecessary clotting the blood inside the blood vessels to and causes the disorder of blood-clotting
mechanism.

The Major Functions of the Blood:

Transportation Function of Blood :

a. To transport nutrients: The digested food substances are absorbed by blood at the site of absorption
(intestine ) and transported to different parts of the body.
b. To transport respiratory gases: Blood transports oxygen from lungs to the tissues and carbon
dioxide from the tissues to the lungs.
c. To transport waste products: the metabolic waste materials produced in the body are transported
by blood to the organs meant for their removal from the body.
d. To transport body secretions: Blood transports chemical secretions like hormones from the site of
their secretion to the target organ.

Protective Functions of Blood:

a. To defense against infection and diseases: WBCs present in the blood help to prevent the body
against infection.
b. To prevent the blood loss: Fibrinogen and prothrombin proteins present in platelets and plasma
help in blood clotting at the site of injury and thus prevents loss of blood.

Balancing/Regulatory Functions of Blood:

a. To regulate body temperature: Blood (plasma) helps to regulate the body temperature.
b. To balance the amount and flow of water: Blood (plasma) maintains the flow and amount of
water in the body.

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Blood group

Different people have different blood group. There are two types of protein present in blood which
determine the blood group. They are,

a) Antigen- Found in surface of erythrocytes, generally called agglutinogens (Corpuscular factor).

b) Antibody- Found in plasma, generally called agglutinins (Plasma factor).
There are four types of blood group.
Group A Group B Group AB Group O
A B AB O

Antibody Antibody None Antibody

Antibodies in B A A and B
plasma
Antigen Antigen Antigen None
Antigen in Red A B A and B
blood cells

Each group of blood is divided into further on the presence and absence of next protein called Rhesus
factor (Rh factor), a protein noticed in Rhesus macaque, a monkey in Africa. If the protein present it is
called Rh positive and the without the protein it is negative making the total eight blood group.

Blood group and Donor Compatibility

Blood Type Gives Receives

A+ A+, AB+ A+, A-, O+, O-

B+ B+, AB+ B+, B-, O+, O-

AB+ AB+ Everyone

O+ O+, A+, B+, AB+ O+, O-

A- A+, A-, AB+, AB- A-, O-

B- B+, B-, AB+, AB- B- ,O-

AB- AB+, AB- AB-, A-, B-,O-

O- Everyone O-

Universal donor and Universal receiver-

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Blood group O can be donated to persons with any other blood group (Blood group O does not have any
antigens), therefore the blood group O are called universal donor. Blood group AB can accepted blood
from persons with any group of blood ( Blood group AB does not have any antibody), therefore the
blood group AB are called universal receiver.

Heart Attack- The condition when the tissues of the heart do not receive sufficient pure blood is called
heart attack.

Risk factors of heart attack

Age, Tobacco consumption, High blood pressure, High cholesterol, Obesity, Diabetes, Family history,
Diet and exercise, Stress, Use of drugs

Symptoms of heart attack

 Sudden chest pain and discomfort which is unbearable, this pain may spread to the neck ,
shoulder, hands and to the lower part of the body.
 Shortness of breath, felling tired, exhausted, fatigued, body becomes stiff and cold.
 Headache, nausea, dizziness, vomiting and head ache

Preventive measure of heart attack

 We should be conscious about our health, exercise and diet intake for prevention of heart attack.
 We have to give up the habit of chewing tobacco, cigarette smoking and alcohol consumption.
 Maintain the body mass index within the range of 25.
 Stress management is very important.
 Treatment of the disease alike blood pressure and diabetes should be done in time.

Angioplasty- The process of widening or opening the blocked coronary artery is called angioplasty.

Heart bypass surgery- The process of using a saphenous vein to create new path to flow pure blood
across the blockage into the heart is called bypass surgery.

Coronary artery and coronary vein- The artery which carry pure blood inside the heart muscle is
called coronary artery and the vein which carries impure blood inside the heart muscle to right
auricle to the heart is called coronary vein.

Blood vessels:

The tubes/vessels through which the blood flows (that carry the blood to and from the heart and the body
parts)is called blood vessels

They are mainly of three types: i) Arteries ii) Veins and iii) Capillaries.

Arteries:

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  The blood vessels that carry the blood away from the heart to different parts of the body is called
arteries.
 All other arteries carry the pure blood, except the pulmonary artery i. e. only the pulmonary artery
carries impure/ deoxygenated blood from heart to the lungs.
 Arteries are deep seated in the muscle and can bear great pressure. The blood flows inside artery
with high pressure and at a high speed.
 Arteries have thick walls to withstand high pressure of the blood as the blood flows inside artery
with high pressure and at a high speed so that to withstand such greater pressure of pure blood
through them, they are strong enough with thick walls.
 Valves are absent in arteries except at their origin in the heart.
 Arteries have narrow lumen.

Arterioles: the branches of arteries are called arterioles.

Veins:

 The blood vessels which carry the blood towards the heart from different parts of the body is
called veins.
 All other veins carry impure/deoxygenated blood, except the pulmonary veins.
 Veins are superficial and cannot bear great pressure. Veins are provided with valves (semi-lunar
valves) which open towards the heart to stop/ prevent the reverse flow/ backward flow of the blood
as the blood moves against the gravity and under low pressure and low speed. The branches of the
veins are called vacuoles.
 Veins have thin walls as the impure blood flows through tem in a very low pressure and at a very
low seed so that they need not to be strong enough with thick walls.
 Veins have wider lumen so that the blood flows easily with low speed under low pressure through
them.

Capillaries:

 The microscopic, extremely narrow and thin-walled blood vessels connecting arterioles to the
venules is called capillaries.
 Their wall is made up of a single layer of endothelium.
 Capillaries exchange various materials like oxygen, food, carbon dioxide and wastes, etc. between
the blood and body cells.

Write the Difference between Artery and Vein

Blood Circulation:

The blood circulation in human mainly takes place through two routes:

1) Systemic Blood Circulation 2) Pulmonary Blood Circulation:

1) Systemic Blood Circulation: The circulation of blood in between the heart and different parts of
the body except the lungs is called systemic circulation. It has the longer route (path)

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 2) Pulmonary Blood Circulation: The blood circulation between the heart and the lungs through the
pulmonary artery and pulmonary veins is called Pulmonary circulation. It has the shorter route
(path)

Heart Beat: The rhythmic contraction and relaxation of the heart is called heart . Each heart beat
include one contraction phase (systolic) and one relaxation phase (diastolic) of the heart. Heart of an
adult person normally beats about 60-100 times in minute (average 72 beats/minute). The heart beat rate
increases (varies) while walking, during exercise, excitement, fear, fever , grief , etc. The rate of heart
beat is generally higher in children than in adults.

Blood pressure:

The pressure exerted by blood on the walls of the blood vessels in called the blood pressure. Or, the
pressure exerted by the flow of blood on the walls of arteries is called blood pressure.

The blood pressure depends upon:

a) The force created by the pumping of the heart

b) The volume of circulating blood and
c) The size of the blood vessels

Note- The blood pressure is measured by sphygmomanometer and represented as mmHg as the two
phases of the blood pressure are systolic and diastolic blood pressure.

Types of Blood pressure:

Blood pressure can be studied as two types:

i) Systolic blood pressure and ii) Diastolic blood pressure

Systolic Blood pressure:

The greatest blood pressure during the contraction of the ventricles of the heart, which is called Systolic
blood pressure. OR When the heart (left ventricle ) contracts and pushes the blood into the aorta, the
exerted pressure is called the systolic blood pressure . It is called the upper or higher limit of arterial
blood pressure. Its range in healthy adults is about 90mm Hg to 130 mm of Hg and the average is taken as
120 mm of Hg.

ii) Diastolic Blood pressure:

The lowest blood pressure during the relaxation of the ventricles of the heart, which is called diastolic
blood pressure. It is also called the lower limit of arterial blood pressure. Its range in healthy adults is
about 60 mm Hg to 90mm of Hg and the Average 80 mm of Hg.

Note- The normal blood pressure of a healthy adult human is taken to be 120/80 mm Hg. If the blood
pressure increases beyond 140/90 mmHg, this condition will be called high blood pressure, similarly if
the blood pressure decreases 100/60 mmHg, this condition will be called low blood pressure

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The blood pressure of a person is 120/80 mm Hg, what does it means?

The blood pressure of a person is 120/80 mm Hg means that person has 120 mm of Hg systolic blood
pressure (upper limit) and 80 mm of Hg diastolic (lower limit) blood pressure. The figures of the blood
pressure may vary according to the time of a day, mental stage , excitement, exercise/ motion of the body,
age and sex, etc.

Some Diseases:

High blood pressure/ Hypertension: If the blood pressure of a person is more than the normal blood
pressure, then the person is said to have a high blood pressure or hypertension.

causes of high blood pressure:

a) Smoking
b) Obesity and overweight
c) Lack of physical exercises
d) Drinking/ Consuming more alcohol/ regular and excessive use of alcohol
e) Consumption of more salt in diet
f) Age more than 40 years
g) Adrenal and thyroid disorder in the body
h) Genetic/ hereditary cause
i) Over stress or tension, lack of sufficient sleep
j) More consumption of fatty, spicy and fried foods, etc.

Symptoms

i) Headache and suffocation occurs i.e. persons finds difficulty in breathing.

j) Sometimes bleeding occurs from nostrils.
k) Sweating may occur and person will feel uneasy
l) Sometimes dizziness occurs and person will be in a state of fear.
m) person may feel stressed and can not sleep.
n) Vomiting may occur.

Effects

a) It damages the blood vessels.

b) It causes heart failure
c) It causes vision loss, stroke, kidney disease and other health problems.
d) It is considered as silent killer.

Prevention (preventive measures) of high blood pressure:

a) Balanced and better diet should be consumed. More salty, more fatty, more spicy and more
fried foods should be avoided.
b) physical exercises should be done regularly.
c) Over stress or over tension should be reduced or avoided.

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 d) Smoking and consumption of alcohol should be avoided.
e) Obesity and overweight should be reduced.
f) By taking medicine according to the prescription of the doctor.

Diabetes/ Diabetes mellitus:

A diseases caused due to the increase of sugar level (or due to the high concentration of sugar) in
the blood above the normal level is called diabetes. The pancreas is a mixed gland that produces
a hormone is called insulin. When pancreas produce less insulin, the sugar level increase in blood
. Before meal (preprandial), normal sugar level in blood is 70-99 mg/dl. The postprandial sugar
taken 2 hours after meal should be less than 140 mg/dl. If the sugar level crosses the limit, it
causes diabetes.

Symptoms:

a) Frequent urination (polyuria)

b) Excessive thrust (polydipsia) and hunger (polyphagia)
c) Passing out of sugar in urine
d) Tiredness
e) Muscle cramping
f) Blurred vision
g) Delay in wound healing
h) viii) Fall in weight
i) Dizziness

Effects of diabetes:

a) It can create high level of toxic chemicals, including acids and keton, which may lead to a
condition called diabetic ketoacidosis. It's symtomps include extreme thirst, excessive
urination and fatigue.
b) It damages kidney.
c) It causes high blood pressure.
d) It damages blood vessels.
e) It may result into heart failure.
f) It causes diabetic retinopathy.

Prevention/ preventive Measures of diabetes:

a) Consuming the balanced diet and changing the lifestyle (for food and exercise)
b) Reducing obesity and overweight
c) Avoiding the use of alcohol, tobacco and smoking.
d) Consuming green vegetables and fruits in a sufficient amount.
e) Maintaining regular physical exercises, morning walks, etc.
f) Check up blood sugar in regular intervals of time by visiting doctors.

Uric Acid:

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 The chemical substances (C5H4N4O3) which is produced by the breakdown of purines, present in the
cells and foods is called uric acid. Most of the uric acid dissolves in blood and is transported to the
kidney, from there it is passed out in the form of urine. Uric acid helps in removal of poisonous
substances, plaques in the walls of the arteries and helps in free blood circulation. If the body
produces too much uric acid or the proper amount of uric acid is not removed from the body, it makes
us sick. The high level of uric acid in blood is called hyperuricemia. Normal value of uric acid in
blood ranges between 3.5 to 7.2 mg/dl.

Some causes of high uric acid in blood :

a) Kidney disorders,
b) Overweight of the body,
c) Excessive consumption of alcohol, proteins, etc.
d) Excessive consumption of fatty and red meat, sea foods, legumes etc, in diet.
e) Family history of gout, etc.

Some symptoms/ effects of high uric acid in blood :

a) Swelling and pain in the joint with a burning sensation.

b) It causes gout ( a type of arthritis ) and also causes difficulty in movement/ walking .
c) Swelling, pain, redness and burning sensation in shins.
d) Cardiovascular diseases

Some preventive measures of high uric acid in the blood:

a) Drinking sufficient water helps to reduce the high uric acid in blood.
b) Use/Drinking of more baking soda(solution) help to reduce the high uric acid level in the
blood because soda is alkaline in nature .
c) Use of cherries and purple and blue colored berries help to recue the burning sensation is the
body and reduce the high uric acid level in the blood because these fruits contain
anthocyanins.
d) By reducing the use of fatty foods. sea foods, red meat and other protein-rich foods like
legumes, etc. and avoiding/ reducing the use of alcohols and maintaining the health food
habits and lifestyles.

Systematic Position

Kingdom- Animalia
Sub-Kingdom- Invertebrata

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Phylum- Arthropoda
Class-Insecta
Order-Hymenoptera
Family-Apidae
Genus- Apis
Species- mellifera
1. Honey Bee- Honey bees are very useful insects. They belongs to the phylum arthropoda.
They live in big colony/hive feed on pollen grains and nectar or juices of flowers.
2. Honey bees are social insect why?
Honey bees are social insects because, they live in big colony, produce honey ho and have a
strong discipline, leadership, higher understanding, unity and division of labour.
3. Apiculture- The artificial or domesticated rearing of honey bees for the production of honey
on commercial scale is called apiculture. There are several speci
species
es of bees in the world. Out
of them two are common in Nepal, they are Apis mellifera and Apis cerena.. These two are the
only honey producing bees in Nepal.
4. External Structure of Honey bee

a. Honey bee body is divided into three parts, i,e head, thorax and abdomen.
b. Head consist of a pair of large compound eyes, a pair of antennae and the mandibles(
mouth parts).
c. Honey bees have chewing and lapping type of mouth parts.
d. The middle part of the body is called thorax and it connects head and abdomen
abdo and it is
the centre of the movement.
e. They are two pairs of wings, forewings and hind wings, forewings are larger in size and
hind wings are smaller in size.
f. They have six legs, forelegs are slightly shorter in length than the hind length and hind
legs have pollen basket.
5. Types of honey bee- Bees live in colony of bee hive. Each beehive consists of about 20000 to
80000 bees. There are three types in a beehive, they are
a. Queen bee- (Fertile female) Which is egg egg-laying
laying female, one in a colony. Number of
chromosomes 32
b. Drone/Male bee- (Fertile male) A few hundred in a colony. Number of chromosomes 16

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 c. Worker bee- (Sterile females) About 20 to 80 thousands in a colony. Number of
chromosomes 32.
6. Queen bee-
Characteristics
 Queen be is the longest bee in a colony or hive but has the shortest wings.
 It is bigger than drones and worker bees.
 It's head is smaller and proboscis is shorter than others
 All the drones and workers identify their colony on the basis of the special smell or
odour produced by the queen.It is fed a diet of royal jelly and may live for 2 to 5
years.

Function/ Roles of Queen bee

a. The main function of queen bee is to lay eggs to populate the colony and produce the
offspring. It mates with the drone bees.
b. To produce special chemical smell/Scent/odour that is recognized accepted by all
honey bees of the colony/hive which helps to regulate unity of the colony and to
find/Identify the colony.
c. To begin new colony through swarming
d. To lead control and regulate all the bees in a colony as required.
7. Swarming- The process by which a new honey bee colony is formed when the queen bee
leaves the colony with a large group of worker bees is called swarming.
Conditions for swarming
i. There are excessively large numbers of bees in a hive.
ii. If more than one queen bee is formed in the hive.
8. Drones/Male bee
Characteristics
 Drones are the fertile male honey bees which are the product of unfertilized eggs.
 They have bigger eyes and they lack stings.
 Their bodies are more black and hairy than worker bees.
 They are smaller than queen and slightly larger than worker bees.
 They do not have poison gland, nectar gland and pollen sac.
 They are fed by workers
Function
a. The only function of drone bees is to fertilize the queen bee.
9. Workers bee
Characteristics
 Workers are the female bees, whose reproductive organ do not function.
 Workers are the smallest bees in a colony but have the largest number of individuals.
 They are also called busiest and hard working bees.
 Their mouth parts are modified for chewing and lapping type.
 Their legs consist of pollen basket to collect nectar.
 Worker bee may live average 15-38 days in the summer and 150-200 days in the
winter.

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 Function/Role of worker
a. To collect nectar from flowers, to collect pollen, water etc to make honey and
store those materials in the hive.
b. To make bee hive , to to-secrete
secrete wax and makes the wax cells/ honey comb.
c. To protect/ guard hive/colonies from the enemies with their poison gland and
sting.
d. To make care of the larvae and feed them.
e. Regulate the tempr within the colony/hive.
10. Life cycle of honey bee bee-Like
Like other insects, the life cycle of honey bee completes into
different four stages, they are Egg, Larva, Pupa and Adult

a. Larva Stage

 After mating, queen be starts laying eggs, she lays about 3000 eggs per day and
1500000 eggs during her life time.
 She lays fertilized eggs for queen and worker and unfertilized eggs for Drones.
 Eggs are Small, pearly, white and spindle shaped. Size of the eggs are 1 mm to
1.5 mm
 Time of egg stage is 3 days, first day egg is vertically aligned in the brood cells
and second, third day is horizontal.
a. Larva Stage
 After 3 days, eggs hatch into larva.
 Drone develops from unfertilized eggs and Queen and worker depends upon their
receive diet (Royal Jelly).
 All larva fed royal jelly for about three days
days,, after 3 days queen larva fed royal
jelly continue, Drone and Worker fed honey bread (Mixture of honey and
pollen).
 Larva stage for queen bee about 5.5 days and For Drone and worker bee about 6
days.

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  Larva of honey bee changes it's skin for about 4 to 5 days. This process is called
moulting.
b. Pupa stage
 Pupa stage of honey bee is dormant (inactive) stage, as does not eat any thing.
 In this stage development of various organs like 3 pairs of legs, wings and mouth
parts
 The pupa stage of queen bee about 8 days, Drone bee about 14 days and worker
bee about 12 days.
c. Adult stage
 After Pupa stage Adult bees come out of the cell by breaking the layer of wax
with the help of mandible.
 After emerge worker bee starts the maintenance of hive
 The worker bees work inside the hive about 3 weeks. After that they start to work
outside the hive.
 As soon as a new queen comes out, the old queen leaves out the hive with
workers.
 The new queen undertakes nuptial flight and the life process continues
11. Mating Flight or Nuptial flight- The flight of the queen bee outside the hive to copulate (to
mate) with the male bees is called mating flight or nuptial flight.
12. Royal jelly- A type of milky, yellow materials, which is secrete from glands of young worker,
inside their heads and is very nutritious diet for the larva and queens is called royal jelly.
13. Bee bread- The mixture of nectar and pollen, which is used to feed larva of drone and worker
is called bee bread.
14. Honey is a good diet/food for human body, why?
 The honey contains most of the nutrients such as vitamins, proteins, sugar, enzymes,
etc necessary for the healthy growth of the human body, so it is a good diet/food for
the human body.
15. Honey bees are called Vital pollinators, why?
 Honey bees are called vital pollinators because they help in cross pollination in large
scales to ensure fertilization in many flowering flowers.
16. Moulting- The process of shedding or casting of the outer covering of the body is called
moulting.
17. Metamorphosis- The transformation of a larva into an adult involving sudden and series of
continuous changes into body of an organisms during it's life cycle is called metamorphosis.
18. There are eggs in the cells A, B and C of a bee hive. At what conditions do the eggs A
develop into drone, egg B into queen and egg C into worker bee. Draw a conclusion.
The egg of the cell 'A' will be developed into a drone bee if this egg is unfertilized egg, kept
in the drone cell (Which is 6 mm across) and the larva hatched from the egg of this cell is
feed with the royal jelly for first 3 days and the after is is feed honey bread for the remaining
3 days.
The egg of the cell 'B' will be developed into queen bee if this egg is fertilized egg kept in
the queen cell (Which is longer and made individually) and royal jelly is feed during all larval
period.

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 The egg of the cell 'C' will be into a worker bee, if this egg is in the fertilized egg kept in the
worker cell (which is more about 5 mm across) and the larva hatched from the egg of this cell
is feed with the royal jelly for first 3 days and the after is is feed honey bread for the
remaining 3 days.
Conclusion- The type of fertilized and unfertilized eggs, the type of cells in which the eggs
are kept and the nature of food (royal jelly, honey bread or both) provided and duration the
quantity of the food feed them to their larva decide the honey bees i'e queen, drone or worker
bee to be formed from the eggs in a colony.
19. Time duration of various stages of honey bee
Bee Queen Drone Worker
Egg (days) 3 3 3
Larva (days) 5.5 6 6
Pupa (days) 7.5 14.5 12
Adult (total days) 16 23.5 21

20. Work division of various castes of honey bee according to their age.
S.N Type and Age Functions
1 Drones (Throughout Their sole function is to fertilize queen. They maintain the
their life) temperature of the hive.
2 Queen (Throughout Queen bee is responsible for laying eggs for colony. She
their life) secretes pheromones which helps to identify the members
of the hive and it also helps to run the activities of the hive
smoothly.
3 Workers They cover egg, larva and pupa and keep the hive warm.
1-3 days They clean cells of the comb.
4 4-6 days They feed the honey bread to young.
5 7-11 days They produce gland on their head and produce royal jelly
and feed them to the larva and queen.
6 12-17 days They manufacture wax from the recently developed 4
pairs of wax glands and help to build new cells in the hive
and form cap of the cells.
7 18-20 days They develop venom gland and protect the bee hive.
8 21 days They collect nectar, pollen grains, sticky resin, gum and
water. They defend the nest from robber bees or wasps.

4.3 CHROMOSOMES

1) Chromosomes

The thread like structure found in the nucleus of a cell which is long, coiled and capable of duplication
that carries heredity information is called chromosomes. Chromosomes are made up of a DNA and
proteins. Each chromosomes consists of two threads are called chromatids.

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2) Centromere – The two chromatids of chromosomes, which are jointed together at a point is called
centromere. It is also called kinetochore.

3) Function of chromosomes

 Chromosomes are responsible for transmitting hereditary characteristics from one generation to
another generation, so they also called the vehicles of hereditary.
 They bring out variation and helps in organic evolution.
 They control protein synthesis and cell metabolism.

4) Types of chromosomes- On the basis of found in body, they are two types

a. Autosomes chromosomes b. Sex chromosomes.

5) Autosomes chromosomes

 All the chromosomes in a cell (except the sex chromosomes) are called autosome chromosomes.
 Autosome chromosomes are non-sex chromosomes, which are also called somatic chromosomes.
 The number of autosome chromosomes are equal in both male and female.
 There are 22 pairs of autosome chromosomes are found in human body and they are responsible
for the determine the somatic characteristics of human body.

6) Sex- chromosomes

 The chromosomes which determine the sex of organisms is called sex-chromosomes.

 The nucleus of human body consist of one pair of sex chromosomes that is (XX in female and
XY in male).

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  Human female producing two similar sex chromosomes (XX) are called homogametic organisms,
where as human male producing two dissimilar sex chromosomes called heterogametic
organisms.

7) How many chromosomes are there on the basis of position of centromere in the chromosomes?

On the basis of position of position of centromere in the chromosomes, there are four types of
chromosomes.

a. Metacentric chromosomes.
b. Sub-metacentric chromosomes
c. Acrocentric chromosomes
d. Telocentric chromosomes.

8) Metacentric chromosomes- The chromosomes in which centromere are located near the middle point
is called metacentric chromosomes. In these chromosomes, two arms are almost equal in length.

9) Sub-metacentric- The chromosomes in which centromere is located a little away from the middle point
is called Sub- metacentric chromosomes. In these chromosomes one arm is slightly short and another arm
is slightly long.

9) Acrocentric chromosomes- The chromosomes in which centromere are located near the end point is
called acrocentric chromosomes. In these chromosomes, one arm is slightly one arm is very short and
another arm is very long.

10) Telocentric chromosomes- The chromosomes in which centromere are located at its tip point is called
telocentric chromosomes.

11) The number of chromosomes in different chromosomes

Human beings -23 pair House flies -6 pair Chimpanzee- 24 pair Onion- 8 pair

Pine- 12 pair Maize – 10 pair Garden pea 7 pair Mouse – 20 pair

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Frog- 13 pair Solanum- 8 pair Sugarcane- 40 pair Rice- 12 pair Yeast- 1 pair

12) Diploid cell (2n)

 The cell having the chromosomes in pairs or having two(double) complete set of chromosomes (
one from each parents) is called diploid cell.
 The diploid cells are represented by ‘2n’
 The number of chromosomes in somatic cells or body cells/ vegetative cells is diploid.
 They are responsible for develop somatic characters.

13) Haploid cells (n)

 The cells having single set of chromosomes from one parent is called haploid cell.
 Haploid cells are represented by ‘n’.
 Haploid cells are formed as result of meiosis cell division that is gamete.
 They are responsible for sex determination

14) What is sex determination? How is a son or daughter determined? Explain

The process by which the sex of a person is determined is called sex determination. There are two types
of sex chromosomes, one is called X chromosomes and other is called Y chromosomes for sex
determination.

 A male gamete (sperm) of human beings has one X chromosome and one Y chromosome. It
means half of the male gamete (sperm) will have X chromosome and half will have Y
chromosome. A female gamete (egg) of human beings has two X chromosomes. It means all the
female gamete will have X chromosomes.
 The sex of a child depends on, what happened at fertilization, if a sperm carrying X
chromosomes fertilize with an ovum which carries X chromosomes, the child born will be
daughter. Similarly if a sperm carrying Y chromosomes fertilize with an ovum, which carries X
chromosomes, then the child born will be son. So there is 50% chance of boy and 50% chance of
a girl.

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 15) Difference between X chromosomes and Y chromosomes.

X chromosomes Y chromosomes
1. It is only present in Male.
1. It occurs paired in female and single in male. 2. It is smaller than X chromosomes.
2. It is five times larger than Y chromosome. 3. It contains genes for male sex
3. It contains gene for female sex determination determination.

15) Sex-linked disease – The disease that occurs only in particular type of sex (either male or female
only) is called sex-linked disease. For e.g. Hemophilia in Male and Breast cancer in female.

Gene- A particular segment of DNA molecule, which determine the heredity of particular trait is called
gene. It is located in chromosomes.

13) Genetics – The branch of biology which deals about facts and laws of heredity and inherited
variations is called genetics. Gregor Johnn Mendel (1822-1884) is called father of genetics.

14) What are the seven pair of contrasting characters of in pea (Pisum sativum) plants?

Mendel selected seven pairs of contrasting characters in pea plants. They are

a. Size of the plants- tall (TT) and dwarf (tt)

b. Positions of the flowers- axial (AA) and Terminal (aa)
c. Shape of the ripen seeds- Round (RR) and Wrinkled (rr)
d. Colour of the flower- Purple (PP) and White (pp)
e. Colour of the ripen cotyledon- Green (GG) and yellow (gg)
f. Colour of the ripen pods – Yellow (YY) and green (yy).
g. Form the ripen pods- inflated (II) and Constricted (ii).

15) Why Mendel selected pea plants for his experiment. ?

Mendel selected pea plants, because of the following reasons.

 Easy to grow and maintain.

 Short life cycle.
 Have many contrasting characters.
 Easily available and can be cultivated easily.
 Flowers are bisexual and naturally self fertilizing.
 Easy for cross pollination.

16) Dominant Character- The characters which is appeared or expressed phenotypically in successive
generations is called dominant characters.

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17) Recessive characters- The characters which is suppressed or unexpressed phenotypically in
successive generations is called recessive characters.

18) Phenotype- The external morphological appereance of organisms for the particular character is called
phenotype. E.g tall, dwarf, round etc.

19) Genotype- The genetic composition of an organisms is called genotype.

20) Alle or allomorphs- A pair of genes controlling a pair of charcaters is called alle. Or Two or more
alternative forms of a genes is calle allomorphs. E.g. the allelic pair of Tt, Rr etc.

21) Hybrid and Hybridization- The organisms which is produced by crossing two genetically different
parents are called hybrid and the process of crossing between two alternating characters is called
hybridization.

22) Monohybrid cross- The process of cross involving only one pairs of contrasting characteristics is
called monohybrid cross.

23) Dihybrid cross- The process of cross involving two pairs of contrasting characteristics is called
dihybrid cross.

24) First filial (F1) generation- The offspring obtained by crossing two pure breeding parents is called f1
generations.

25) Second filial (F2) generations- The offspring obtained interbreeding the parental stocks of f1-
genartions is called second filial generations.

26) Mendel’s Law

a) Law of Dominance- This law state that “In a cross made between two pure contrasting characters, only
one characters express phenotypically in F1 generation”.

b) Law of segregation or law of purity of gametes- This law state that “The two members of a pair of
allele (the hybrids of f1 generation) segregate or separate during gamete formation”.

c) Law of independent assortment- This law state that “When two pairs of contrasting characters
present in parents inherited to offspring, one pair of character is independent to another pair of character
and they do not remain linked and assort randomly”.

4.3 Nucleic Acid

1) Nucleic Acids- The naturally occurring chemical compounds that allow the organisms to transfer
genetic information from one generation to another generation are called nucleic acids.

2) Genetic materials- The materials which carry the genetic information from one generation to next
generation is called genetic materials. In most of the organisms the DNA acts as genetic materials and in
some viruses RNA acts as genetic materials. They are commonly called as nucleic acids.

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3) Explain the structure of DNA (Deoxyribonucleic Acid)

DNA is a carrier of genetic information in most of organisms. It is polymer of deoxy-ribonucleotides. It is

found in the nucleus, mitochondria and chloroplast.

James Watson and Francis Crick proposed the most satisfactory, double helical and molecular
model of DNA in 1953. For which they awarded by Nobel Prize in 1962. DNA contains following
structural components.

 A DNA molecule contains two unbranched complementery strands, which are coiled around the
common axis.
 The strands of DNA are antiparallel to each other but they run in opposite direction.
 DNA is formed by cross linking of deoxyribose sugar, Phosphoric acid and nitrogen bases.
 There are two types of nitrogen bases found in DNA, they are purine and pyrimidine. The purines
are adenine (A) and guanine (G), where as the pyrimidine are cytosine (C) and thymine (T).
 In DNA adenine (A) is attached with thymine (T) by two hydrogen bonds, where as cytosine (C)
attached with guanine (G) by three hydrogen bonds.
 The diameter of DNA is 20 Ao and length of one complete turn of helix is 34 Ao.
 Distance between two adjacent nitrogen base of same strands is 3.4 Ao
 The deoxyribonucleotides are joined with the help of phosphodiester bonds.

4) DNA replication- The process by which a DNA forms it’s exact copy that is replica is called DNA
replication. It takes place inside the nucleus during DNA replication. Each strands of DNA acts as a

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template strands for the formation of a new and complementary strands to form two new daughter DNA,
which is identical to each other.

5) Function of DNA

 DNA is responsible for passing genetic information from parents to their offspring.
 It controls the biological activities of cell
 It controls the growth and development of cell.
 It helps in synthesize RNA by the process of transcription.

6) RNA (Ribonucleic Acid)

RNA is the polymer of ribonucleotides. It is single stranded structure, it is found in nucleus, cytoplasm,
ribosomes, mitochondria, chloroplast etc. It is formed by the DNA by the process of transcription. It
contains major chemicals ribose sugar, phosphoric acid and nitrogenous base. The purine bases of RNA
are (adenine and guanine) and pyrimidine bases are (cytosine and uracil).

There are three types of RNA.

a. m-RNA (Messenger RNA)

b. r-RNA (Ribosomal RNA)
c. t-RNA( Transfer RNA)

m-RNA- It is the most heterogeneous in size and stability. It has highest molecular weight among all
types of RNA. It constitutes about 5-10% of the total RNA. It helps to carry genetic information from
DNA.

r-RNA- It is the most abundant and stable types of RNA consist 70-80% of total RNA. R-RNA present in
ribosome and regulate the process of protein synthesis.

t-RNA- It is the second stable type of RNA. It consist 10-15% of total RNA. It helps to transfer amino
acids to ribosome for synthesized protein.

Function of RNA

 It facilitates the translation of DNA into proteins.

 It serves as messenger between the DNA and the ribosomes.
 They are the carrier of genetic information in all living things.
 All the three types of RNA are necessary for protein synthesis.

Difference between DNA and RNA

DNA RNA

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 1. It is found in nucleus, cytoplasm,
1. It is found in the nucleus, mitochondria and ribosomes, mitochondria and chloroplast.
chloroplast. 2. It is mostly single stranded.
2. It is usually double stranded. 3. RNA makes complementary of DNA.
3. DNA can make RNA. 4. It is responsible for protein synthesis.
4. It is responsible for hereditary characters. 5. It has the pentose sugar ribose.
5. It has the pentose sugar deoxyribose. 6. It contains adenine, guanine, cytosine and
6. It contains adenine, guanine, cytosine and uracil nitrogen bases.
thymine nitrogen bases.

Cell Division

The process by which a mature cell divides and formed new cells, which resembles the mother cell in a
number of characters is called cell division. Cell division was first studied by Prevost and Dumas in 1824
AD in zygote of frog. The division of the cell is achieved by two integral activities such as division of
nucleus that is karyokinesis reported by Schleicher in 1887 and the division of the cytoplasm that is
cytokinesis reported by Whiteman in 1887 AD.

Types of cell division -The cells may divide any of the following method

1. Direct cell division or amitosis.

2. Indirect cell division or mitosis
3. Reductional cell division or meiosis.

Amitosis cell division- It is the simple and most primitive type of cell division. The amitosis cell division
means asexual reproduction, which is commonly, occurs in some bacteria, protozoan, yeasts etc.

Mitosis cell division- The process by which a mature somatic cell divides and formed two new cells,
which resembles mother cell in a number of characters is called mitosis cell division. These types of cell
division are also called equational cell division. The mitosis cell division is described in following steps

a. Interphase –The stage between the end of one cell division to beginning to next cell division is
called interphase
b. Karykinesis- The process of division of nucleus during cell division phases is called karyokinesis.
It includes following four stages. They are Prophase, Metaphase, Anaphase and Telophase
c. Cytokinesis- The process of division of cytoplasm is called cytokinesis. In plant cells it takes
place by cell plate method and animal cell by cleavage constriction method.

Significance of mitosis cell division-

 Mitosis cell division helps in growth and development in multicellular organisms.

 It helps in vegetative propagation and asexual reproduction in organisms.
 Injured and wound part is healed by mitosis cell divisions of surrounding healthy cells.
 It keeps the chromosomes number constant and genetic stability in daughter cells.

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Meiosis cell division- The type of cell division in which single parental or germinal reproductive cell
divides to form four daughter cells having half number of chromosomes is called meiosis cell division.
Meiosis completes in two successive stsges

a) Meiosis I – It consist of
 Prophase- I
Leptotene Zygotene Pachytene Diplotene Dikinesis
 Metaphase-I
 Anaphase-I
 Telophase- I
b) Meiosis II- It Consist of
 Prophase- II
 Metaphase-II
 Anaphase-II
 Telophase- II

Significance of mitosis cell division-

 It is essential for life cycle of sexually reproducing organisms because it helps in the formation of
haploid gametes.
 Crossing over occurs in meiosis that helps in formation of new characters in organisms, which
helps in evolution.
 It maintains the fixed number of chromosomes in generation to generation.

Synapsis- The process of pairing of the homologous chromosomes is called synapsis. It takes place
during zygotene stage.

Crossing over- The process of exchange of genetic materials between two non-sister homologous
chromosomes is called crossing over. It takes place during the pachytene stage.

Chaistmata- The points of overlap where crossing over takes place is called chaismata. It is visible in the
diplotene stage.

Terminalization- The process of movement of chaismata towards the terminal end of chromosomes is
called terminalization. It takes palce during diakinesis stage.

Some important terms of unit 2

1. Body cavity or Coelom- The fluid filled cavity between the body wall and the digestive tract is
called coelom. It is three types
a) Acoelomate- Animals which lack the body cavities (coelom) are called acoelomates, For e.g-
Porifera, Coelenterata and platyhelminthes.
b) Pseudocoelomate- Animals which have false body cavities (coelom) is called
pseudocoelomates. for eg Nemathehelminthes

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 c) Coelomates- Animals which have true body cavities (coelom) is called coelomates. for eg
annelids. molluscs and chordates.
2. Bilateral symmetry- The body of animal can be divided into two similar halves, the left and
right halves (mirror image of one another) through only one dividing plane is called bilateral
symmetry. for eg Some invertebrates and All vertebrates.
3. Radial symmetry- The body of animal can be divided into two equal and identical halves by
many dividing lines passing through the center is called radial symmetry. for eg Some Porifera,
Coelenterata and adult echinodermata.
4. Diploblastic-Animals which have two primary germ layar(Ecoterm and Endoderm) is called
diploblastic animlas. For eg- porifera, coelentera
5. Triploblastic- Animals which have three primary germ layar(Ectoderm, mesoderm and
Endoderm) is called triploblastic animlas. eg Some invertebrates and chordates.
6. Protochordata- The organisms whose notochord do not change into the vertebral column are
called protovhordata.. it is three types
a) Hemichordata-Those organisms which have notochord extends to half of the length of the
body is called hemichordate. eg Balanoglossus (tongue worm)
b) Urochordata- Those organisms which have notochord only present tail of larva and
disappears in adult is called urochordata. eg Herdmania (Sea squirt), Salpa, Doliolum etc.
c) Cephalochordata- Those organisms which have notochord extends the entire length of the
body and persist through out the life is called cephalochordate.eg Amphioxus
(Branchiostomata), Asymmeteron
7. Vertebrta or Cranita- Those organisms which have back bone (Vertebral column) is called
Vertebrta or Cranita. eg Pisces, Amphibia, Reptilia, Aves and mammalia.
8. Alternation of generation- The appearance of sporophytic generation and gametophytic
generation alternately in the life cycle of bryophytes and pteridophytes is called alternation of
generation.

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