BIOLOGY

NUTRITION:
- Is a characteristic of all living things
- Is defined as the process of acquiring energy and materials

2 major types of nutrition:

- Autotrophic Nutrition - auto means self, trophic means feeding.

❖ Autotrophic Nutrition refers to the use of an inorganic source (not derived from
living matter) of carbon (CO2) to manufacture complex organic (derived from
living matter) substances, either in the aid of light or energy from respiration. Any
organism which carries out Autotrophic Nutrition is an Autotroph e.g plants,
bacteria.

- Heterotrophic Nutrition- hetero means other, trophic means feeding.

❖ Heterotrophic Nutrition refers to the use of organic carbon,(obtained from the

digestion of complex organic substances which came from autotrophs) to utilise
for the synthesis (production of an organic compound in a living thing, especially
as aided by enzymes) of required substances. Any organism which carries out
Heterotrophic Nutrition is a Heterotroph e.g. dog, crocodile.

Importance of Nutrition: for growth, repair and maintenance of cells

Heterotrophic Nutrition- All heterotrophs follow this sequence of processes in order to

utilise the organic carbon, obtained from other organisms.

1. Ingestion- is the process of taking in food, into the body.

2. Digestion- is the process by which large organic molecules are broken down into
simpler ones .
- Physical/ mechanical digestion- the breaking or tearing of food into smaller
pieces-- assisted by teeth.

- Chemical digestion- the breaking down of large, insoluble organic molecules

into smaller ones by the aid of enzymes. Enzymes carry out Hydrolysis
reactions(hydrolysis reaction is a chemical process by which water is used to
break the bonds of a substance).

3. Absorption- is the uptake of soluble small molecules from the digestive region.
Involves passing through a membrane and into the bloodstream. Basically when the
food is in your stomach, some bits of it are absorbed into your blood.
 4. Assimilation- the process by which the absorbed molecules are incorporated into
the body’s cells and tissues (after being taken into the bloodstream ofc).

5. Egestion- is the process by which undigested food materials are removed from the
body.

Saprotrophic Nutrition - is a form of heterotrophic nutrition. Sapros means rotten. This form
of heterotrophic nutrition obtains its organic components from dead or decaying matter.
Organisms which use this form of nutrition are known as saprotrophs. Egs. of saprotrophs
include fungi and some bacteria.

Fungi digests the substrate or organic matter by secreting enzymes onto the surface of the
food. Digestion occurs external to the organism, and is known as extracellular digestion.
These digested nutrients are then absorbed and utilised by the organism.

Symbiosis - This is the close or intimate relationship between organisms of different

species. There are different types of symbiotic relationships, these include:

- Parasitism- close or intimate relationship, in which one organism (parasite) benefits,

whilst the other is harmed (host). Parasite benefits by gaining a source of nutrition
through the digested substances transported in the blood of the host. The host is
losing nutrients to the parasite. Parasites can be found on the outside of the host
(ectoparasites), or inside of the host (endoparasites). Parasites also gain protection
and shelter from predators by living on the host.

- Commensalism- this is the close or intimate relationship between organisms, in

which one organism benefits, but the other is neither harmed nor benefits. E.g the
epiphyte (orchid) and the tree, in which the tree is used for support. The orchid
benefits by gaining support to obtain sunlight.The tree is not harmed, or benefits.

- Mutualism- this is the close or intimate relationship between organisms, in which both
organisms benefit from the relationship. E.g Rhizobium and root nodules of legumes.
NUTRIENTS
-A nutrient is an essential substance, which is needed by the body for good functioning.
-There are 7 main types of nutrients:Carbohydrates, Proteins, Lipids, Minerals, Vitamins,
Water and Fibre.

CARBOHYDRATES
- Composed of Carbon(C), Hydrogen(H) and Oxygen(O) only.
- Can be grouped as either a sugar or a starch.
- All carbohydrates have the ratio of H:O as 2:1 and have the general formula of
C(x) (H2O)y.
- Carbohydrates can be divided into three major groups, based entirely on structure:
Monosaccharides, Disaccharides and Polysaccharides.
- Role of carbohydrates: for structural purpose, storage molecule or the primary source
of energy for organisms.

Monosaccharides: Mono means one and saccharide means sugar unit.

- Egs: include glucose, galactose and fructose.
- All monosaccharides have the following characteristics:
❖ Soluble- dissolves in water easily
❖ Small- smallest and simplest of carbohydrates
❖ Sweet
❖ Sugars- exist as crystals
❖ Reducing Sugars- They act as reducing agents, by causing reduction in other
substances but they are oxidised as a result.

[REDUCTION AND OXIDATION]- are chemical reactions that occur simultaneously.

Oxidation - O.I.L - Oxidation is the gain of Oxygen, loss of Hydrogen and Electrons
Reduction - R.I.G - Reduction is the loss of Oxygen, gain of Hydrogen and Electrons

Disaccharides: Di means two and saccharide means sugar unit.

- E.g.s include: sucrose = glucose + fructose, maltose = glucose + glucose,
lactose = glucose + galactose.
- All disaccharides have the same characteristics as monosaccharides, except that
some can be reducing sugars or non-reducing sugars. Disaccharides also are more
complex in structure than the monosaccharides, as they are formed from the
condensation reaction involving 2 monosaccharides.

- Condensation reaction - a chemical reaction in which two molecules are combined

and produce at least one water molecule as a by-product.See below diagram.
Polysaccharides: Poly means many and saccharide means sugar unit.
These are formed from numerous condensation reactions, which join together to form
a polypeptide chain.

- Egs include: Starch, cellulose and glycogen

- Polysaccharides either have a structural or storage role. Starch is a good storage

molecule, as it is unreactive, large- so a large amount can be stored, and is insoluble.
Cellulose is a very rigid carbohydrate with a high tensile strength. It is a vital
component of the cell walls of plant cells,which offer support to these cells, and
prevent them from bursting during osmosis.
Glycogen is a storage molecule, used by animal cells to store food.

FOOD TESTS FOR CARBOHYDRATES:

FOOD TEST OBSERVATION BASIS OF TEST

Starch- If starch is present a blue Component of starch forms

Add 2 cm3 of unknown black colour would be a polyiodide complex with
solution to a test tube. Add present iodine.
3-4 drops of Iodine or
Potassium Iodide to the
unknown. Shake

Benedict’s Test/ Test for Initial blue colour of the Copper Sulphate is present
Reducing Sugars mixture turns green→ in Benedict’s solution. The
yellow→ orange→ red copper ions are in the Cu2+
Add 2 cm3 of unknown precipitate. state in Benedict’s solution.
solution to a test tube. Add 2 As you move from blue→ These copper ions
cm3 of Benedict’s Solution. red precipitate, there is undergo reduction to
Shake and boil for 5 mins increasing quantities of become Cu+, which is a red
maximum. reducing sugar insoluble solid, which is
seen as a precipitate. The
reducing sugar acts as a
reducing agent causing the
above reduction.

Non-Reducing Sugar Test Effervescence occurs, only The disaccharide is

NB: this test is only carried in the presence of sodium hydrolysed into its
out if the Benedict’s Test is hydrogen carbonate. monosaccharides, by the
negative use of HCl. The
The results are the same monosaccharides will then
Add 2 cm3 of unknown to a as Benedict’s Test give a positive, as
test tube. Add 1cm3 of dilute indicated in the Benedict’s
HCl. Boil for 1 minute and Test.
neutralise solution, either by
adding 1cm3 of NaOH or by
adding sodium Hydrogen
Carbonate, until the
effervescence stops. Carry
out Benedict’s test.
PROTEINS
- Composed of elements: C,H,O,S (sometimes) N.

- Formed from condensation reactions with amino acids, which are the monomers (a
molecule that can be bonded to other identical molecules to form a polymer) for the
protein macromolecules. Basically proteins are made up of amino acids.

- Role of proteins: growth and repair. Proteins form most of the components in an
organism, from muscles, enzymes, hormones, antibodies.

- Proteins are the last source of energy for organisms, as they form vital components
of organisms. Imagine, when you starve yourself your body has to start to take from
it’s tissue etc. to give you energy, that’s why you get so skinny.

- Egs. of food sources which are high in protein: any legumes, eggs, fish, meat or dairy
products- yoghurt, cheese, milk, cream.

Structure of amino acids:

- All amino acids have a basic structure in common. All have a carboxyl group
(COOH), an amino group (NH2) and a Hydrogen atom and an R group - this is the
variable group, which determines the properties of an amino acid.

Fig: structure of an amino acid

Formation of a dipeptide:

A dipeptide is a molecule formed from the condensation reaction involving 2 amino acids

Keratin- a structural protein, which forms hair, hooves, feathers, nails. It is known for its
strength.

Collagen- is an essential component of the body. It forms the connective tissues- ligaments
and tendons, skin.

Protein Test
Test Observation Basis

Biuret Test:- A mauve or purple colour Test for peptide bonds. In an

Add 2cm3 of unknown to a appears alkaline solution and the
test tube.Add an equal Copper Sulphate solution, the
volume of KOH and mix. N atoms from the peptide
Add two drops of 1% copper chain form a purple complex
sulphate solution and mix. with Cu2+ ions .
LIPIDS
- Lipids consist of fat and oils. It is defined as water insoluble, organic substances,
which can be extracted by organic solvents.

- Consist of elements: C, H, and O only.

- All lipids are formed from the condensation reaction between 3 fatty acid molecules
and 1 glycerol molecule:

Source for image: https://courses.lumenlearning.com/microbiology/chapter/lipids/

- Fatty acids are composed of a head and tail region.The head region consists of the
carboxyl group (COOH) and the hydrocarbon tail , which is made up of repeated
units of C and H atoms. The tail region can be made of many single bonds or double
bonds. If it is only formed from single bonds, then the fatty acid is described as being
Saturated, however, if it contains double bonds, then it is considered to be
Unsaturated. These bonds influence the melting point of the fatty acid and thus the
state of matter in which the lipid will naturally exist.

Importance of lipids:

❖ formation of cell membranes - they help to form the lipid bilayer in cell
membranes
❖ source of insulation in organisms - organisms which live in cold climates/
hibernating organisms contain a thick layer of fat under the skin, to reduce
heat loss
❖ buoyancy - organisms e.g. whales have a thick layer of fat called blubber
which contributes to buoyancy, as fat is less dense than water.
❖ energy storage - one lipid molecule yields three times of energy than that of
one molecule of glucose. Some plants like coconut, also store lipids for
germination
❖ source of metabolic water - some organisms like camels and the kangaroo
rat, store fat, which, once metabolised, will yield metabolic water
Food test for lipids:

Test Observation Basis of test

Emulsion Test A cloudy white Lipids are immiscible in polar solvents,

Add 2cm3 of the unknown suspension like water, thus they will not dissolve.
to a test tube, add 2cm3 of Ethanol is nonpolar and will dissolve the
absolute ethanol and lipid, causing them to break into smaller
shake. Decant a little of droplets. These droplets when added to
the mixture into a test water, will cause reflection of light to give
tube containing water the white appearance.

Grease Spot Test A permanent

Rub or add a little of the transparent spot
sample into a piece of on the paper
filter paper. Outline the appears.
area where the food was
added.
VITAMINS & MINERALS
- Refer to page 72 in the Biology Text book for table 5.2 for vitamins and 5.3 for
minerals.

Vitamin Foods that Why is it needed Deficiency

contain it disease

A Butter, egg yolk, cod To keep the cells Infections of cells

liver oil, carrots lining the gas lining the gas
exchange system exchange system;
healthy, to make night blindness
pigment in the rod
cells of the eye,
needed for seeing in
dim light

B (there are Wholemeal bread, Involved in many Beri-beri, which

yeast extract, liver, chemical reactions causes muscular
different B vitamins
brown rice in the body, such as weakness and
but usually occur
respiration paralysis
together)

C Citrus fruits (such as To make the Scurvy, which

oranges, limes) stretchy protein causes pain in joints
cherries, raw collagen, found in and muscles,
vegetables skin and other bleeding from gums
tissues in good and other places
repair

D Butter, egg yolk (and Helps calcium to be Rickets, in which the

can be made by the absorbed, for bones become soft
skin when sunlight making bones and and deformed
falls on it) teeth

E Vegetable oils Supports your Crohn's disease,

(such as wheat immune system and cystic fibrosis, and
germ, sunflower, helps cells to certain rare
safflower, corn, regenerate genetic diseases
and soybean oils)
Nuts (such as
almonds, peanuts,
and
hazelnuts/filberts)
Seeds (such as
sunflower seeds)
Green leafy
vegetables (such
as spinach and
broccoli)
K Green leafy It's important for Excessive
vegetables, fish, blood clotting and bleeding and
liver, meat, eggs, healthy bones and bruising and, in
and cereals also has other severe cases, can
(contain smaller functions in the lead to fatal
amounts) body. bleeding into the
brain

Mineral Element Foods that Why is it needed Deficiency

contain it disease

Calcium, Ca Milk and other dairy For bones and Brittle bones and
products, bread teeth, for blood teeth; poor blood
clotting clotting

Phosphorus, P Milk For bones and teeth Brittle bones and

teeth

Fluorine, F Fluoride toothpaste; Makes tooth enamel Bad teeth

some drinking water resistant to decay

Iodine, I Seafood, table salt For making the Goitre, a swelling in

hormone thyroxine the neck; reduced
metabolic rate

Iron, Fe Liver, red meat, egg For making Anaemia, in which

yolk, dark green haemoglobin, the there are not
vegetables red pigment in the enough red blood
blood which carries cells so the tissues
oxygen do not get enough
oxygen delivered to
them

WATER
- Water has a variety of functions in living cells. It acts as a solvent allowing ions and
other substances (nutrients and waste) to be transported in solution. Aids in
temperature regulation.

FIBRE
- Is a complex mixture of indigestible compounds. These are usually derived from plant
cell walls. This is composed of polysaccharides like cellulose. Fibre helps to promote
peristalsis, which pushes food and waste through the alimentary canal.
DIGESTION
Encyclopedia Definition:

The process by which organisms break down solid food into small particles that can be used
in the body.

Process:

❖ Digestion begins in the mouth where food is cut up into smaller particles by the teeth.
❖ The food is mixed with saliva containing an enzyme that breaks down starch into
sugar
❖ The food is then swallowed and passes, via a tube called the oesophagus, into the
stomach
❖ In the stomach fluid, the gastric juice is released which contains hydrochloric acid
and enzymes
❖ The stomach has muscular walls and is able to expand and contract and further
manipulate the food
❖ Proteins are broken down and eventually and semi-acidic solid mass (known as
chyme) is passed into the small intestine
❖ Alkaline fluid from an organ pancreas (pancreatic juice) is added here, and this
contains more enzymes
❖ Bile, a thick fluid produced by the liver and stored in the gallbladder is located nearby,
is added to the food in the intestine. This contains bile salt, bile pigments and
cholesterol and aids in the digestion of fatty substances
❖ As the food passes along the highly coiled length of the small intestine, it continues
to be broken down into minute particles (molecules) that can be absorbed into fine
blood vessels present in the intestinal wall. The blood circulation carries the food to
all the parts of the body where it is used by cells to perform all the functions of life
and to provide energy
❖ Any food substances which cannot be digested, such as fibre, are passed to the
large intestine, which is the final part of the alimentary canal or digestive system.
RESPIRATION

A feature of living things

Equation:

Glucose + Oxygen → Carbon Dioxide + Energy + Water (aerobic respiration; is oxidized

and in doing so a large amount of energy is released) check textbook for details

Sugar → Alcohol + Carbon Dioxide + Energy

An organism needs energy for everything. Including breathing, thinking, or moving in

general. Once you stop respiring you are no longer considered to be a living thing.

Energy is stored in your liver or as fat. Or stored in little packets known as ATP (adenosine
triphosphate). Energy is released when it becomes ADP (adenosine diphosphate) because a
bond is broken. It occurs when the bond is either formed or broken.

It saves the energy from being wasted because if it was in a huge packet it could easily be
wasted. Compare it to a large pack of a snack and how easily everything could go stale
rather than when you put it into smaller packets. It allows energy to be released by a simple
reaction (quickly). The energy is stored in a form that can be used in any reaction and can
be released anywhere via this simple reaction

Aerobic Respiration vs Anaerobic Respiration

Aerobic Respiration Anaerobic Respiration

Needs oxygen Does not need oxygen

There is an exchange of gases during the There is no exchange of gas (some gases
process (oxygen is absorbed and carbon like sulfur and nitrogen are released)
dioxide is released)

After glycolysis (the process by which one Occurs only in the cytoplasm
molecule of glucose is converted into two
molecules of pyruvate, two hydrogen ions
and two molecules of water) it occurs in the
mitochondria of eukaryotes and cytoplasm
of prokaryotes

38 ATPs are produced, some of which are Only 2 ATPs are formed (150KJ in animals
lost (releases 2880KJ) and 210KJ in plants)

Incomplete oxidation of carbs takes place Incomplete oxidation takes place

 - Aerobic respiration takes longer than anaerobic respiration.
- Aerobic respiration takes place in organisms such as plants and animals. Anaerobic
respiration takes place in primitive prokaryotes.

Fermentation: (a form of anaerobic respiration)

- A metabolic process that produces chemical changes in organic substrates through

the action of enzymes. In biochemistry, it is narrowly defined as the extraction of
energy from carbohydrates in the absence of oxygen.
- A process carried out by certain microorganisms eg. yeast, bacteria and moulds
which break down organic substances (those containing carbon, hydrogen and
oxygen) into simpler molecules, containing energy.

Uses of Fermentation:

1. Alcoholic fermentation is a process that has been harnessed for centuries. In it, yeast
converts sugar to alcohol and carbon dioxide, and it is used to produce drinks such
as wine, beer and cider.

2. Used in biotechnology.

3. It is important in the manufacturing of cheese, yoghurt and bread

4. Used in the production of drugs such as antibiotics.

The breathing rate increases with increasing levels of carbon dioxide in the body.
 Blood Group Antibody Antigen

(a or b)

A Antibody b
So that useful cells with Antigen A
would not be attacked

B Antibody a
So that useful body cells with
Antigen B would not be attacked

AB None
So that useful body cells (containing
both Antigens A and B) would not
be attacked

O Both antibodies a and b

Body cells have no antigens so
there is no risk of antibodies
attacking these cells

BLOOD DONOR

RECIPIENT

A B AB-universal O
recipient

DONORS AG (A) AB(b) AG (B) AB(a) AG (A,B) AG (none)

AB(none) AB(a,b)

A- AG (A) yes no yes yes

AB(b)

B-AG(B) AB(a) no yes yes no

AB- AG(A,B) no no yes no

AB(none)

O - universal yes yes yes yes

donor-
AG(none)
AB(a,b)