CBSE Class 10 Science Advanced Biology Nutrition MCQs Set 03

Answer: (b) pepsin

Explanation:
1. HCl turns the inactive pepsinogen into active pepsin and gives it the acid medium it needs.
2. The answer is pepsin.

Teacher's Note:
1. Salivary amylase works in a nearly neutral medium and is stopped by stomach acid.
2. Trypsin works in an alkaline medium.

Answer: (a) Cooking oil

Explanation:
1. Cooking oils (such as mustard oil) are sometimes adulterated with the poisonous argemone oil.
2. When concentrated nitric acid is added to such oil, it turns red to orange-red, which shows the adulteration.
3. So the test is for cooking oil.

Teacher's Note:
1. The printed key was (b) milk. The nitric acid test for argemone oil is the standard test for edible oils, so the key has been changed to (a).
2. Adulterated argemone oil causes epidemic dropsy.

Answer: (b) autotrophs

Explanation:
1. Auto means self and troph means food.
2. Organisms that make their own food are autotrophs.

Teacher's Note:
1. Heterotrophs depend on others.
2. Decomposers and parasites are heterotrophs.

Answer: (d) Ptyalin

Explanation:
1. Saliva contains salivary amylase, also called ptyalin, which acts on starch.
2. Pepsin is in gastric juice; trypsin and chymotrypsin are in pancreatic juice.
3. The answer is ptyalin.

Teacher's Note:
1. Ptyalin means 'saliva enzyme'.
2. It works in a slightly alkaline medium.

Answer: (b) Small Intestine

Explanation:
1. Starch is partly digested in the mouth.
2. Its digestion is completed in the small intestine by pancreatic amylase and the intestinal enzymes, which produce glucose.
3. The answer is small intestine.

Teacher's Note:
1. The stomach has no carbohydrate-digesting enzyme.
2. The large intestine only absorbs water.

Answer: (d) Ingestion → Digestion → Absorption → Assimilation → Egestion

Explanation:
1. Food is first taken in (ingestion), then broken down (digestion), the digested food is taken into the blood (absorption), then used by cells (assimilation), and finally the waste is removed (egestion).
2. The answer is option (d).

Teacher's Note:
1. Memory aid: I-D-A-A-E.
2. Egestion is always last.

Answer: (b) Large intestine

Explanation:
1. The large intestine absorbs most of the remaining water and minerals from the undigested food, making the waste nearly solid.
2. The answer is large intestine.

Teacher's Note:
1. The book's key (large intestine) is followed. The small intestine absorbs mainly digested nutrients.
2. The rectum then stores the faeces.

Answer: (b) Pepsin

Explanation:
1. Lipase digests fats, sucrase digests sucrose and amylase digests starch.
2. Pepsin digests proteins, so the answer is pepsin.

Teacher's Note:
1. The ending -ase shows an enzyme; the beginning shows the substrate.
2. Other protein enzymes are trypsin and peptidase.

Answer: (b) Bile

Explanation:
1. Insulin is secreted by the pancreas and gastric juice by the stomach glands.
2. The liver secretes bile.

Teacher's Note:
1. The liver is the largest gland of the body.
2. Bile is stored in the gall bladder.

Answer: (a) Cuscuta

Explanation:
1. Cuscuta (amarbel) has no chlorophyll or leaves and sucks food from the host plant through haustoria.
2. Mushroom is a saprotroph; giloe and fern are green and make their own food.
3. The parasite is Cuscuta.

Teacher's Note:
1. Cuscuta is a total stem parasite.
2. A parasite harms its host.

Answer: (d) Algae and Fungi

Explanation:
1. A lichen is a partnership in which an alga makes food by photosynthesis and a fungus gives shelter, water and minerals.
2. Both gain from the association, which is symbiosis.
3. The partners are algae and fungi.

Teacher's Note:
1. Lichens are symbiotic, not parasitic.
2. They can live on bare rocks.

Answer: (d) water

Explanation:
1. Glucose and oxygen are products of photosynthesis and nitrogen is not used.
2. Water is a raw material, so the answer is water.

Teacher's Note:
1. Raw materials: CO₂ and water.
2. Glucose and oxygen are products.

Answer: (d) Magnesium

Explanation:
1. A chlorophyll molecule has a magnesium atom at the centre of its ring.
2. The answer is magnesium.

Teacher's Note:
1. Haemoglobin has iron at the centre, chlorophyll has magnesium.
2. Lack of magnesium makes leaves yellow.

Answer: (c) Drosera

Explanation:
1. Drosera (sundew) traps and digests insects with its sticky tentacles.
2. Cuscuta and Rafflesia are parasites and tulsi is an ordinary green plant.
3. The answer is Drosera.

Teacher's Note:
1. Other examples: pitcher plant, Venus flytrap, bladderwort.
2. They live in nitrogen-poor soil.

Answer: (b) autoclaved soil is devoid of bacteria .

Explanation:
1. Root nodules are formed when Rhizobium bacteria from the soil infect the roots of a legume.
2. Autoclaving kills all bacteria, so no Rhizobium is left and nodules cannot form.
3. The answer is autoclaved soil is devoid of bacteria.

Teacher's Note:
1. Rhizobium fixes atmospheric nitrogen in the nodules.
2. Autoclaving means heating under steam pressure to sterilise.

Answer: (c) Night blindness

Explanation:
1. Vitamin A is needed for the pigment of the retina, and lack of it causes night blindness.
2. Beri-beri is due to lack of B₁, anaemia to lack of iron or B₁₂, and scurvy to lack of vitamin C.
3. The answer is night blindness.

Teacher's Note:
1. Vitamin A is found in carrots, milk and green leaves.
2. Link each vitamin with one disease.

Answer: (d) All of them

Explanation:
1. A plant uses sunlight as the energy, chlorophyll to trap it, and CO₂ and water as raw materials.
2. The answer is all of them.

Teacher's Note:
1. All options are correct, so choose the combined one.
2. Temperature is also an influencing factor.

Answer: (c) Small Intestine

Explanation:
1. The small intestine is about 6.5 m long, while the large intestine is only about 1.5 m and the oesophagus about 25 cm.
2. The answer is small intestine.

Teacher's Note:
1. It is called small only because it is narrow.
2. It is the longest part of the alimentary canal.

Answer: (b) Pepsin and HCl

Explanation:
1. Gastric juice contains hydrochloric acid, pepsin and mucus.
2. Trypsin and amylase are from the pancreas, so the answer is pepsin and HCl.

Teacher's Note:
1. Reject options with trypsin or amylase.
2. Mucus protects the stomach wall.

Answer: (d) ATP

Explanation:
1. Photosynthesis produces oxygen, glucose, ATP and NADPH in its light reaction; respiration produces CO₂, water and ATP.
2. The product that both make is ATP.

Teacher's Note:
1. Oxygen is a product only in photosynthesis and CO₂ only in respiration.
2. ADP is converted to ATP in both.

Answer: (c) Nitrogen

Explanation:
1. Sunlight, chlorophyll and CO₂ are all essential.
2. Nitrogen is not used in the process, so the answer is nitrogen.

Teacher's Note:
1. Nitrogen is needed for making proteins, but not for photosynthesis.
2. Read 'not essential' carefully.

Answer: (b) H₂O

Explanation:
1. During the light reaction, water is split (photolysis): 4H₂O → 4H⁺ + O₂ + 4e⁻ + 2H₂O.
2. The oxygen comes from water, so the answer is H₂O.

Teacher's Note:
1. The oxygen is not from CO₂; this was proved with heavy-oxygen water.
2. Hydrogen from water goes to NADP.

Answer: (b) Chloroplast

Explanation:
1. The chloroplast has stacks of thylakoids called grana, lying in the stroma.
2. The answer is chloroplast.

Teacher's Note:
1. Mitochondria have cristae and a matrix.
2. Grana for the light reaction and stroma for the dark reaction.

Answer: (c) NADPH and ATP

Explanation:
1. The light reaction produces ATP, NADPH₂ and O₂.
2. ATP and NADPH supply the energy and hydrogen for the dark reaction, while O₂ is released. RuBP is a CO₂ acceptor, not a product of the light reaction.
3. The answer is NADPH and ATP.

Teacher's Note:
1. Light reaction products used later: ATP and NADPH.
2. O₂ leaves the plant.

Answer: (b) Vitamin B2

Explanation:
1. Lack of riboflavin (vitamin B₂) causes sore, cracked lips and corners of the mouth.
2. The answer is vitamin B₂.

Teacher's Note:
1. Vitamin K is for blood clotting and C for scurvy.
2. B₂ is riboflavin.

Answer: (b) Nitrogen

Explanation:
1. Insectivorous plants make up for a lack of nitrogen in the soil by digesting insect proteins.
2. The answer is nitrogen.

Teacher's Note:
1. Same concept as Exercise 2 Q11.
2. These plants still photosynthesise.

Answer: (d) All of the above

Explanation:
1. Autotrophic nutrition needs CO₂ and water, chlorophyll and sunlight.
2. So the answer is all of the above.

Teacher's Note:
1. All three items are required in photoautotrophs.
2. This repeats the idea of NTSE Q3.

Answer: (c) Pepsin

Explanation:
1. Pancreatic juice contains amylase, lipase and trypsin.
2. Pepsin is secreted by the stomach, so the answer is pepsin.

Teacher's Note:
1. Pancreatic enzymes work in the alkaline duodenum.
2. Pepsin needs acid.

Answer: (a) Vit. A

Explanation:
1. Retinol is vitamin A. B₁ is thiamine, B₂ is riboflavin and C is ascorbic acid.
2. The answer is vitamin A.

Teacher's Note:
1. Retinol, retina and vision are linked.
2. Carotene in carrots is changed into retinol.

Answer: (a) Holozoic

Explanation:
1. Amoeba ingests solid food by phagocytosis and digests it inside, which is holozoic nutrition.
2. The answer is holozoic.

Teacher's Note:
1. Same as the Exercise 1 question on amoeba.
2. Autotroph is a type of organism, not a mode of feeding of amoeba.

Answer: (c) Pre-molar

Explanation:
1. The milk teeth of a child are 20: i 2/2, c 1/1, pm 0/0, m 2/2 (per half jaw).
2. The premolars are 0, so they are absent. The answer is premolar.

Teacher's Note:
1. Premolars appear only in the permanent set (pm 2/2).
2. Milk molars are replaced by premolars.