Class 7 Science Lesson 4: Nutrition in Living Organisms – Questions & Answers

 

🧬 Lesson 4: Nutrition in Living Organisms

Questions and Answers

Q.1. Classify according to food-type.

Given: Tiger, cow, vulture, bacteria, deer, goat, human, fungus, lion, sparrow, buffalo, frog, cockroach, tick.

🌿 Herbivores

Cow, Deer, Goat, Buffalo

🥩 Carnivores

Tiger, Vulture, Lion, Frog

🍽️ Omnivores

Human, Sparrow, Cockroach

🍄 Saprophytes

Bacteria, Fungus

🦠 Parasite

Tick

Q.2. Match the pairs.

Group ‘A’	Group ‘B’
(1) Parasitic plant	(a) Mushroom
(2) Insectivorous plant	(b) Lichen
(3) Saprophytic plant	(c) Drosera
(4) Symbiotic plant	(d) Cuscuta

✅ Answer:

1 – (d) Cuscuta
2 – (c) Drosera
3 – (a) Mushroom
4 – (b) Lichen

Q.3 .Answer the following questions in your own words.

(a). Why do living organisms need nutrition?

✅ Solution:

Nutrition is the process of taking in nutrients from food and utilizing them for various functions of the cells. Nutrition is required for purposes like:

• supplying the energy required for doing work.
• growth and development of the body.
• fighting diseases and maintaining good health.
• replacing damaged cells and repairing tissues.

Q.3 (b) Explain the process of production of food in plants.

✅ Answer:

Leaves are the food factories of plants. They contain a green pigment called chlorophyll. Chlorophyll helps the leaves to use sunlight to prepare food from carbon dioxide and water. This process is called photosynthesis. The food produced is stored in the form of starch.

Q.3 (c) What is meant by parasitic plants? Name their different types with examples of each.

✅ Answer:

Plants which depend on another plant for their food and survival are called parasitic plants. The plant on which they grow is called the host plant.

1. Ectoparasitic plants – They grow on the surface of the host plant.
   Example: Cuscuta
2. Endoparasitic plants – They grow inside the host plant.
   Example: Rafflesia

Q.3 (d) Explain the various steps of nutrition in animals.

✅ Answer:

The main steps of nutrition in animals are:

1. Ingestion – Taking food into the body.
2. Digestion – Breaking down food into a soluble form.
3. Absorption – Absorbing nutrients from digested food.
4. Assimilation – Using the absorbed nutrients for various life processes.
5. Egestion – Removing undigested food from the body.

Q.3 (e) Name some unicellular organisms in which all life-processes take place within their unicellular body.

✅ Answer:

Amoeba, Paramecium and Euglena are unicellular organisms in which all life processes take place within their single-cell body

🧬 Lesson 4: Nutrition in Living Organisms

Q.4 Give Reasons – Exam Ready Answers

Class 7

Q.4 (a) Give reasons: Insectivorous plants are attractively coloured.

✅ Answer:

Insectivorous plants are attractively coloured to attract insects and feed on them. They grow in soil or water that is deficient in nitrogen compounds. Therefore, they feed on insects to fulfil their nitrogen requirement.

Q.4 (b) Give reasons: Butterflies have a long tube-like proboscis.

✅ Answer:

Butterflies have a long, tube-like proboscis. It is a straw-like structure that helps them to drink juices and nectar from flowers. It remains coiled when it is not in use.

Q.6 (a) We prepare a variety of foodstuffs and dishes at home. Are we then autotrophic organisms?

✅ Answer:

No, we are not autotrophic organisms. Autotrophs can prepare their own food. We humans depend on plants and other organisms for our food. Therefore, we are heterotrophs.

Q.6 (b) Which organisms are greater in number – autotrophs or heterotrophs? Why?

✅ Answer:

Autotrophs are greater in number than heterotrophs. Heterotrophs depend on autotrophs for their food. Therefore, a sufficient number of autotrophs is necessary to support heterotrophs.

Q.6 (c) The number of heterotrophs found in desert regions is smaller. However, they are found in greater numbers in the sea. Why is this so?

✅ Answer:

Deserts have very little water and harsh conditions, so fewer organisms can survive there. Hence, fewer heterotrophs are found in deserts. The sea provides water and abundant food and supports many organisms. Therefore, more heterotrophs are found in the sea.

Q.6 (d) What damage or harm do ectoparasitic and endoparasitic animals cause?

✅ Answer:

Ectoparasites and endoparasites obtain food from their host and deprive it of nutrients. They may also cause diseases. Lice and ticks are examples of ectoparasites, while roundworm (Ascaris) is an example of an endoparasite.

Q.6 (e) Why is plant food not produced in any other parts of the plant except the green ones?

✅ Answer:

Plant food is produced by the process of photosynthesis. Photosynthesis requires chlorophyll, which is present in chloroplasts of green parts of plants. Therefore, food is mainly produced in the green parts of plants.

📚 Class 7 | Lesson 4: Nutrition in Living Organisms

⭐ Simple • Clear • Exam Ready

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