Nutrition in Living Organisms
Chapter 4 — Question & Answer Solutions
Classify the following according to food type: tiger, cow, vulture, bacteria, deer, goat, human, fungus, lion, sparrow, buffalo, frog, cockroach, tick.
Ans:🌾 Herbivores
Cow, Deer, Goat, Buffalo
🦁 Carnivores
Tiger, Lion, Frog
🍽️ Omnivores
Sparrow, Human, Cockroach
🦅 Scavengers
Vulture
🍄 Decomposers / Saprotrophic
Bacteria, Fungus
🕷️ Parasitic
Tick
Match the pairs: Group A — (1) Parasitic plant (2) Insectivorous plant (3) Saprophytic plant (4) Symbiotic plant; Group B — (a) Mushroom (b) Lichen (c) Drosera (d) Cuscuta
Ans:Answer the following questions in your own words.
(a) Why do living organisms need nutrition?
Ans:Living organisms need nutrition for the following reasons:
- To supply the energy required for carrying out different activities.
- For the proper growth and development of the body.
- To replace damaged cells and repair tissues.
- To fight against diseases.
(b) Explain the process of production of food in plants.
Ans:
- Plants produce their own food through the process of photosynthesis.
- With the help of sunlight and chlorophyll, plants make their food in their leaves.
- They also use water, nutrients from the soil, and carbon dioxide from the air.
- Thus, plants convert light energy into chemical energy and store it in the form of food.
(Carbon dioxide + Water → Food (Glucose) + Oxygen)
(c) What is meant by parasitic plants? Name their different types with examples of each.
Ans:
- Plants that depend on other plants for their food are called parasitic plants.
- Parasitic plants are heterotrophic in their mode of nutrition. Some of them lack chlorophyll and so cannot carry out photosynthesis on their own.
- There are two types of parasitic plants:
- Completely parasitic plants — for example, Cuscuta and Dodder.
- Partially parasitic plants — for example, Loranthus.
(d) Explain the various steps of nutrition in animals.
Ans:Ingestion
Feeding, or taking food into the body.
Digestion
Enzymes act on complex food and convert it into soluble nutrients in the alimentary canal.
Absorption
Digested, soluble nutrients are absorbed into the blood.
Assimilation
Nutrients reach every cell through blood circulation, and energy is released and used.
Egestion
Undigested, unabsorbed matter is thrown out of the body.
(e) Name some unicellular organisms in which all life processes take place within their unicellular body.
Ans:Amoeba, Paramoecium and Euglena are unicellular organisms in which all the life processes take place within a single cell.
Give reasons.
(a) Insectivorous plants are attractively coloured.
Ans:
- Insectivorous plants feed on insects.
- They need to capture insects in order to survive.
- To attract these insects towards the plant, they are attractively coloured.
(b) Butterflies have a long, tube-like proboscis.
Ans:
- Every insect has mouth parts suited to how it feeds.
- Butterflies feed on nectar and pollen from flowers.
- They therefore have a tube-like proboscis to suck this food from the flower.
Prepare and complete the flowchart according to the type of nutrition.
Ans:Think and answer.
(a) We prepare a variety of foodstuffs and dishes at home. Are we then autotrophic organisms?
Ans:No, we are not autotrophic organisms; we are heterotrophic organisms. This is because we do not have chlorophyll and cannot make our own food using sunlight. We depend on plants for grains, pulses and vegetables, and on animals for meat and eggs. Thus, we depend on both plants and animals for our food.
(b) Which organisms are greater in number — autotrophs or heterotrophs? Why?
Ans:Autotrophs are greater in number. This is because autotrophs have chlorophyll, so they can make their own food through photosynthesis. They do not depend on other organisms for their nutrition and survival.
(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?
Ans:
- In desert regions, autotrophs are fewer in number, and so are the heterotrophs that depend on them. Since food is scarce, the number of heterotrophs also reduces.
- In oceans and seas, there are vast numbers of zooplankton and phytoplankton. Phytoplankton are tiny, microscopic floating plants that we may not even see, and the sea’s food chain depends on these planktonic species.
- Therefore, heterotrophs are fewer in desert regions but far more numerous in the sea.
(d) What damage or harm do ectoparasitic and endoparasitic animals cause?
Ans:
- Parasitic organisms depend on other animals for their nutrition.
- Ectoparasites live on the surface of an animal’s body and may cause intense itching and skin damage. Blood-sucking endoparasites may also lead to blood loss in animals — for example, lice, bedbugs and ticks.
- Endoparasites live inside the bodies of other animals and may cause digestive problems — for example, tapeworms and roundworms.
(e) Why is plant food not produced in any other parts of the plant except the green ones?
Ans:Chlorophyll is present only in the green parts of a plant, and photosynthesis — the process that produces food — takes place only in these parts. The non-green parts do not produce food because they lack chlorophyll.