CBSE Class 7 Science Advanced Biology Nutrition in Plants and Animals MCQs Set 01

Answer: (b) Cuscuta

Explanation:
1. A parasite takes food from a living host and gives nothing back.
2. Cuscuta is a plant that lives on another living plant and takes its food, so it is a parasite.
3. A tiger is a carnivore, a fungus feeds on dead matter and a pitcher plant traps insects.

Teacher's Note:
1. Ask one question: is the food taken from a living host?
2. Cuscuta is the standard parasitic plant, and head lice is the standard parasitic animal.

Answer: (a) parasitic

Explanation:
1. Head lice live on the hair of humans and feed on the host.
2. The host gets no benefit and may be harmed, which is parasitic nutrition.
3. They do not eat dead matter (saprophytic), animals (carnivorous) or trapped insects (insectivorous).

Teacher's Note:
1. Lice, ticks and tapeworms are all parasites.
2. Write the host and the parasite clearly in answers.

Answer: (d) nitrogen

Explanation:
1. Insectivorous plants usually grow in soil that lacks nitrogen.
2. They trap and digest small insects to obtain this missing nutrient.
3. So the plants get nitrogen from the insects.

Teacher's Note:
1. Remember: insects supply nitrogen.
2. Pitcher plant and Venus flytrap are examples.

Answer: (c) A-(ii), B-(iv), C-(i), D-(iii)

Explanation:
1. Cuscuta lives on a plant host, so A matches (ii) parasitic nutrition.
2. Fungus feeds on dead and decaying matter, so B matches (iv) saprophyte.
3. A human takes in food, digests it and egests the waste, so C matches (i) holozoic nutrition.
4. A dog eats flesh, so D matches (iii) carnivorous.
5. The combination A-(ii), B-(iv), C-(i), D-(iii) is option (c).

Teacher's Note:
1. Match the easy pairs first and cross out options.
2. Fungus is always a saprophyte in this chapter.

Answer: (c) Fungus feed on dead and decaying matter for nutrition.

Explanation:
1. (a) is wrong: dead matter is used in saprophytic nutrition, while holozoic nutrition means taking in solid or liquid food and digesting it.
2. (b) is wrong: organisms that make food by photosynthesis are autotrophs.
3. (c) is true: a fungus is a saprophyte and feeds on dead and decaying matter.
4. (d) is wrong: the pitcher plant is insectivorous.
5. So the correct statement is (c).

Teacher's Note:
1. Test every option, do not stop at the first that looks right.
2. Keep saprophytic, parasitic and insectivorous clearly apart.

Answer: (b) prey

Explanation:
1. A carnivore that hunts and kills is the predator.
2. The animal that is hunted and eaten is the prey.
3. Example: the tiger is the predator and the deer is its prey.

Teacher's Note:
1. Predator hunts, prey is hunted.
2. Do not confuse prey with host; a host belongs to parasites.

Answer: (c) (i), (ii), (iii) and (iv)

Explanation:
1. Photosynthesis uses carbon dioxide and water as raw materials.
2. It needs sunlight as the energy source.
3. Chlorophyll is the green pigment that absorbs the light.
4. All four are needed, so the answer is (i), (ii), (iii) and (iv).

Teacher's Note:
1. Learn the two raw materials, one energy source and one pigment.
2. Products are glucose and oxygen.

Answer: (d) plants

Explanation:
1. Herbivores depend directly on plants such as grass and leaves.
2. So they feed on plants.

Teacher's Note:
1. Herb means plant.
2. Cow, goat and elephant are herbivores.

Answer: (c) plants and animals

Explanation:
1. Omni means all, so omnivores eat all kinds of food.
2. They feed on both plants and animals, for example bear and human.
3. Feeding on dead matter is saprophytic nutrition, so the answer is plants and animals.

Teacher's Note:
1. Omni means all or everything.
2. Bear and human are the book examples.

Answer: (b) assimilation

Explanation:
1. Absorption means taking digested food into the blood.
2. Using the absorbed food for body activities is assimilation.
3. Ingestion is taking in food and egestion is removing waste.

Teacher's Note:
1. Put the five steps in order and see which one uses the food.
2. Assimilation comes just before egestion.

Answer: (c) pharynx

Explanation:
1. The pharynx is the tube behind the mouth.
2. It opens into the oesophagus through the gullet.
3. Villi are in the small intestine and the pancreas is a gland, so the answer is pharynx.

Teacher's Note:
1. Mouth, then pharynx, then oesophagus.
2. Gullet is only the opening of the pharynx into the oesophagus.

Answer: (a) Bile

Explanation:
1. Fat arrives in the duodenum as large lumps.
2. Bile, made in the liver and stored in the gall bladder, breaks fat into tiny droplets.
3. This is called emulsification, so the answer is bile.

Teacher's Note:
1. Liver makes bile, gall bladder stores it.
2. Saliva acts on starch and HCl helps in the stomach.

Answer: (a) stomach

Explanation:
1. The gastric juice in the stomach contains hydrochloric acid and the enzyme pepsin.
2. Pepsin changes proteins into peptones.
3. So protein digestion starts in the stomach.

Teacher's Note:
1. Mouth starts starch digestion, stomach starts protein digestion.
2. Fat digestion starts in the small intestine.

Answer: (b) A-(iii), B-(iv), C-(i), D-(ii)

Explanation:
1. Water is reabsorbed in the large intestine, so A-(iii).
2. Protein digestion starts in the stomach, so B-(iv).
3. Pancreatic juice is poured into the small intestine, so C-(i).
4. Bile juice helps in fat digestion, so D-(ii).
5. The pairs A-(iii), B-(iv), C-(i), D-(ii) make option (b).

Teacher's Note:
1. Match what you know best first.
2. Pancreatic juice is released into the first part of the small intestine.

Answer: (b) pharynx

Explanation:
1. After chewing, the bolus is pushed from the mouth to the pharynx.
2. From the pharynx it is swallowed into the oesophagus.
3. So food from the mouth first enters the pharynx.

Teacher's Note:
1. Follow the path: mouth, pharynx, oesophagus, stomach.
2. Do not jump straight to the oesophagus.

Answer: (c) Chemical digestion of food occurs in oesophagus.

Explanation:
1. (a) is true: pepsin acts on proteins in the stomach.
2. (b) is true: teeth chew the food (mechanical) and amylase in saliva acts on starch (chemical).
3. (c) is wrong: no digestion occurs in the oesophagus, food only moves down by peristalsis.
4. (d) is true: the rectum holds waste until it is egested.
5. So the wrong statement is (c).

Teacher's Note:
1. Read the question carefully: you must pick the wrong one.
2. The oesophagus only passes the food on.

Answer: (d) Both (a) and (b)

Explanation:
1. Food enters the digestive system through the mouth and waste leaves through the anus.
2. Both open to the outside of the body.
3. The gullet is inside the body, so the answer is both mouth and anus.

Teacher's Note:
1. The canal has exactly two openings to the outside.
2. Gullet is the opening between the pharynx and the oesophagus.