NEET Biology Biomolecules MCQs Set 12

Answer: (b) Protein, nucleic acid, carbohydrate, lipid

Explanation:
1. Average cell composition: proteins 10-15 %, nucleic acids 5-7 %, carbohydrates about 3 %, lipids about 2 %.
2. So the order is protein, nucleic acid, carbohydrate, lipid.

Teacher's Note:
1. Remember the order as 15, 7, 3, 2.
2. Water is the most abundant compound but it is inorganic, so it is not in this list.

Answer: (a) liver and muscles

Explanation:
1. Glycogen is the storage carbohydrate of animals.
2. It is stored mainly in the liver and the skeletal muscles.

Teacher's Note:
1. Liver glycogen maintains blood glucose.
2. Muscle glycogen is used by the muscle itself.

Answer: (d) P

Explanation:
1. Proteins always contain C, H, O and N, and S in cysteine and methionine.
2. Phosphorus is a characteristic element of nucleic acids and phospholipids, not of ordinary proteins.

Teacher's Note:
1. Link P with nucleic acids and phospholipids.
2. Link S with cysteine and methionine.

Answer: (c) Wax

Explanation:
1. Starch and glycogen are polysaccharides and glucose is a monosaccharide.
2. Wax is a simple lipid (ester of a long-chain fatty acid and a long-chain alcohol).

Teacher's Note:
1. Lipids are insoluble in water and soluble in organic solvents.
2. In lipids the H : O ratio is not 2 : 1.

Answer: (a) collagen

Explanation:
1. Collagen forms the ground substance between cells and is the commonest protein of the animal world.

Teacher's Note:
1. Collagen is the most abundant protein in the animal world.
2. RuBisCO is the most abundant protein in the whole biosphere.

Answer: (c) protein

Explanation:
1. Feathers contain keratin and silk contains fibroin; both are fibrous proteins.

Teacher's Note:
1. Fibrous proteins give structural strength.
2. Hair, nails, horns and hooves also contain keratin.

Answer: (c) trehalose

Explanation:
1. Trehalose (glucose + glucose) is the blood sugar of insects.

Teacher's Note:
1. Remember: insect blood sugar is trehalose.
2. Lactose is milk sugar, maltose is malt sugar.

Answer: (b) two amino acids linked by one peptide bond

Explanation:
1. Two amino acids join by condensation, losing one water molecule.
2. The linkage formed is a single peptide bond.

Teacher's Note:
1. n amino acids give n - 1 peptide bonds in a straight chain.
2. So two amino acids give one bond.

Answer: (b) keratin

Explanation:
1. These are epidermal structures of vertebrates made of the fibrous protein keratin.
2. Chitin occurs in arthropod exoskeletons and fungal cell walls.

Teacher's Note:
1. Keratin is a protein; chitin is a polysaccharide.
2. Do not mix the two.

Answer: (b) protein

Explanation:
1. Haemoglobin and chlorophyll occur only in some organisms.
2. Proteins (including enzymes) are present in every living cell.

Teacher's Note:
1. Enzymes, structural parts and receptors are all proteins.
2. Hence proteins are universal in living things.

Answer: (c) polyhydroxy aldehydes or ketones

Explanation:
1. Simple sugars carry many -OH groups along with a free aldehyde or ketone group.
2. So carbohydrates are polyhydroxy aldehydes or ketones and their derivatives.

Teacher's Note:
1. Aldoses carry -CHO; ketoses carry C=O.
2. Glucose is an aldose and fructose is a ketose.

Answer: (b) Fats

Explanation:
1. Carbohydrates and proteins give about 4 kcal per gram.
2. Fats give about 9 kcal per gram, more than double.

Teacher's Note:
1. Fats are rich in C-H bonds and poor in oxygen.
2. That is why they store more energy.

Answer: (d) glycogen in liver and muscles

Explanation:
1. Mammals store carbohydrate as glycogen, mainly in liver and muscles, not as free glucose.

Teacher's Note:
1. Free glucose would raise osmotic pressure.
2. Glycogen is osmotically inactive.

Answer: (b) glycogen

Explanation:
1. The body first draws on its stored glycogen, then on fats, and only last on proteins.

Teacher's Note:
1. Order of use: glycogen, then fat, then protein.
2. Protein breakdown means serious starvation.

Answer: (c) casein

Explanation:
1. Casein is the main milk protein; myosin is a muscle protein and pepsin is an enzyme.

Teacher's Note:
1. Lactose is milk sugar.
2. Casein is milk protein.

Answer: (d) proteins

Explanation:
1. Almost all enzymes are globular proteins; only a few catalytic RNAs (ribozymes) are exceptions.

Teacher's Note:
1. Enzymes are biocatalysts.
2. Trypsin is a protein enzyme.

Answer: (b) essential

Explanation:
1. Such amino acids must be taken in the diet, so they are called essential amino acids.

Teacher's Note:
1. There are 10 essential amino acids in this treatment.
2. Arginine and histidine are semi-essential.

Answer: (c) proteins

Explanation:
1. Proteins supply the amino acids for building new cells and repairing tissues.

Teacher's Note:
1. Proteins are body-building foods.
2. Carbohydrates and fats are energy foods.

Answer: (a) pulses

Explanation:
1. Pulses (dal) are rich in protein; potato is rich in starch; egg and meat are not vegetarian.

Teacher's Note:
1. Pulses are legume seeds.
2. Combine pulses with cereals for complete protein.

Answer: (b) Saccharin

Explanation:
1. Saccharin is an artificial sweetener with no sugar structure.
2. Starch and protein are not sweet and lactose is a sugar.

Teacher's Note:
1. Artificial sweeteners give no calories.
2. Saccharin is much sweeter than sucrose.

Answer: (b) sucrose

Explanation:
1. Sucrose is the non-reducing, stable disaccharide carried in phloem.

Teacher's Note:
1. Non-reducing sugars are safer for transport.
2. Starch is the stored form.

Answer: (a) glucose and fructose

Explanation:
1. Sucrose is glucose joined to fructose by a glycosidic bond.

Teacher's Note:
1. Lactose = glucose + galactose.
2. Maltose = glucose + glucose.

Answer: (a) Maltose

Explanation:
1. Maltose is glucose + glucose.
2. Sucrose gives glucose and fructose; lactose gives glucose and galactose.

Teacher's Note:
1. Trehalose also gives two glucose units.
2. Hydrolysis adds water to break the glycosidic bond.

Answer: (b) Ribose

Explanation:
1. ATP is a nucleotide of adenine, ribose and three phosphates.

Teacher's Note:
1. DNA has deoxyribose; RNA and ATP have ribose.
2. Both are pentoses.

Answer: (c) kwashiorkor

Explanation:
1. Rickets is vitamin D deficiency and scurvy is vitamin C deficiency.
2. Kwashiorkor is caused by protein deficiency.

Teacher's Note:
1. Marasmus is deficiency of both protein and calories.
2. Kwashiorkor shows swelling of the abdomen.

Answer: (a) beta-1,4 linkage, unbranched

Explanation:
1. Cellulose is a linear polymer of beta-D-glucose joined by beta-1,4 glycosidic bonds.
2. It has no branches.

Teacher's Note:
1. Starch has alpha linkages.
2. Glycogen is the highly branched one.

Answer: (a) gamma globulins

Explanation:
1. Antibodies are proteins of the gamma-globulin fraction of blood plasma.

Teacher's Note:
1. They fight infectious agents.
2. Albumin keeps osmotic balance.

Answer: (b) fructose

Explanation:
1. Fructose, found in honey and sweet fruits, is the sweetest natural sugar.
2. Saccharin is artificial.

Teacher's Note:
1. Fructose is called fruit sugar.
2. Glucose is called grape sugar.

Answer: (b) furanose

Explanation:
1. A five-membered ring (four C and one O) resembles furan, so it is a furanose; six-membered is pyranose.

Teacher's Note:
1. Glucose is pyranose, fructose often furanose.
2. Ring form is found in solution.

Answer: (d) Sucrose

Explanation:
1. Benedict's test detects reducing sugars with a free aldehyde or ketone group.
2. In sucrose both anomeric carbons are tied in the glycosidic bond, so it is non-reducing.

Teacher's Note:
1. Reducing: glucose, fructose, maltose, lactose.
2. Non-reducing: sucrose and polysaccharides.