BIOLOGY 3 Marks Question

1. Thrombin and fibrinogen – They help in blood clotting.
2. Antigen (antibody) – It helps in blood transfusion.
3. Insulin – It helps in maintaining blood glucose level in the body.
4. Renin – It helps in osmoregulation.

Proteins are also commonly used in the manufacture of cosmetics, toxins, and as biological buffers.

1. Effect of substrate concentration:

1. With the increase in substrate concentration, the velocity of enzyme reaction increases upto a certain limit.
2. But the reaction reaches a maximum and does not increase any further with the increase in the concentration of substrate; this is because, there is no free enzyme molecule for the substrate to bind with. 

2. Differences: ​​​​​​​

3.  An amino acid is a substituted methane, because there are four substituent groups occupying the four valency positions of the a-carbon; they are hydrogen, carboxyl group, amino group and a variable group (R-group).

1. A heteropolymer is a polymer made of different kinds of monomers; since proteins are made of a number of different kinds of monomers (amino acids), they are heteropolymers.
2. A homopolymer is a polymer made of only one type of a monomer, repeating 'n' number of times; hence protein is not a homopolymer.​​​​​​​

2. Essential amino acids are those amino acids which our body cannot synthesise; so they have to be taken in the form of food.

1. Starch and glycogen are the major storage food of organic world.
2. On hydrolysis, storage carbohydrates provide both energy and carbon chains.
3. Chitin is the structural carbohydrate of fungal walls and exoskeleton of arthropods. (insects).
4. Cellulose is the structural substance of cell walls in most of the plants.
5. Cellulose is economically important in the production of
6. Furniture, shelter, fuel, paper, textiles, ropes, rayon, cellophane, plastics, etc.

1. Rubber is extracted from Have abrasiliensis (rubber tree).
2. It is a byproduct of the lactiferous tissue of the vessels that are in the form of latex.
3. It is the largest of the terpenoids because it contains over 400 isoprene units.
4. It is elastic, water proof and a good electrical conductor.

1. Examples of inorganic ions are calcium ions (activates the enzyme thrombokinase to convert prothrombin into thrombin during the blood clotting process) and chloride ions (activates salivary amylase to convert starch into maltose).
2. Examples of coenzymes are NAD, acetyl coenzyme A, ATP and NADP.
3. Prosthetic groups are molecules that are permanently attached to the enzyme.Examples of prosthetic groups are haem and FAD.

1. A heterocyclic compound (base).
2. A monosaccharide.
3. A phosphoric acid or a phosphate.

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• In the primary structure, the protein exists as a long chain of amino acids, where the left end is represented by the first amino acid and the right end the last amino acid; the amino acids are linked by peptide bonds.

• In the secondary structure of proteins, there is interaction between every fourth amino acid by formation of hydrogen bonds; the polypeptide assumes a helical shape (a-helix) e.g., keratin.
• Only right handed (a-helix) helices are seen.

• When a polypeptide chain is folded upon itself like a hollow woollen ball, it is said to be in its tertiary structure; this gives the 3-dimensional structure of a protein.

1. Carotene, anthocyanin.
2. Morphine, codeine.
3. Monoterpenes, diterpenes.
4. Abrin, Ricin.
5. Rubber, gums, resins.

1. Starch and glycogen are the major storage foods of organic world. On hydrolysis, storage carbohydrates provide both energy and carbon chains.
2. Chitin is the structural carbohydrate of fungal walls and exoskeleton of arthropods. Cellulose is the structural substance of cell walls in most of the plants.

1. Acidic amino acids.

Example: Glutamic acid.

2. Basic amino acids,

 Example: Lysine.

3. Neutral amino acids.

Example: Valine.

1. DNA forms the genome of living organism and is a type of macromolecule present in the cells. DNA is an abbreviation of deoxyribonucleic acid. DNA is almost 99% similar in all individuals, i.e., the variation is only about 1% or even less.
2. Each nucleotide unit of DNA consists of three different molecules, i.e., phosphate, a 5-carbon deoxyribose sugar and a nitrogenous base.
3. DNA sequencing of human genome will help in the identification of genes regulating various processes as well as cause of various genetic diseases in man.
4. Nutan's grandfather was a critical thinker, had asthetic values and had habit of clarifying doubts.

1. A glycosidic bond is formed between two carbon atoms of two adjacent monosaccharides.
2. A peptide bond is formed between the carboxyl group of one amino acid and the amino group of the next amino acid.
3. A phosphodiester bond refers to the bond between a phosphate moiety and the 3' carbon of sugar of one nucleotide on one side and the 5' carbon of the sugar of another nucleotide on the other side.

1. Each enzyme (E) has a substrate binding site(S) in order to form a highly reactive enzyme substrate complex(ES). The complex, so formed is short lived and dissociated into its product which results in the intermediate formation of the enzyme product complex(EP).
2. Enzymes are also called biocatalysts because these are useful in catalysing biochemical reactions in ilving cells.
3. Values reflected from Ankita's character was awareness about the process, attentive in class, critical thinking and seriousness about studies.

1. Figure is showing the activation energy requirement for non catalysed and enzyme catalysed reactions.
2. Substances marked on arrows A and B are A-Substrate B-End products.
3. Arrows marked shows:

• C- Energy of activation without enzyme.
• D- Energy of activation with enzymes.
• E- Free energy difference between the substrate and
• the end product.

1. The type of inhibition of succinic dehydrogenase by malonate is competitive inhibition.
2. The inhibitor competes with the substrate for the active sites of enzyme molecules as it has a structure similar to the substrate that allows it to combine with the active site, preventing any substrate molecule from occupying that site. This reduces the rate of the reaction since, the substrate can only use the enzyme molecules that are not occupied by the inhibitor, resulting in the same quantity of product being formed at a slower rate.