Chapter. 1. Nutrition in Living Organisms—Plants, The Living World, Class – VII, DAV Board, The Best Solutions.

Keywords To Remember

1. Glucose
   A simple sugar that is the end product of photosynthesis and used by plants for energy and growth.
2. Starch
   A complex carbohydrate formed by the conversion of glucose in plants; stored in leaves and other parts.
3. Guard Cells
   Specialized cells that surround the stomata and control their opening and closing.
4. Raw Materials
   The basic substances (carbon dioxide, water, sunlight, chlorophyll) used by plants to perform photosynthesis.
5. Vaseline
   A greasy substance used in experiments to block stomata and observe effects on plant leaves.
6. Pigments
   Substances in plant cells that give color to the plant and help absorb light for photosynthesis (e.g., chlorophyll, anthocyanin).
7. Chloroplasts
   Cell organelles in green plant cells where photosynthesis takes place.
8. Sunlight
   Natural light from the sun; main source of energy for photosynthesis.
9. Carbon Dioxide (CO₂)
   A gas taken in by plants from the atmosphere through stomata and used in photosynthesis.
10. Oxygen (O₂)
    A by-product of photosynthesis; released by plants into the atmosphere and used by living organisms for respiration.
11. Parasite
    An organism that lives on or inside another organism (the host) and gets its food from the host, often harming it.
12. Host Plant
    A plant that provides nutrition and shelter to a parasite.
13. Cuscuta (Amarbel)
    A parasitic plant that wraps around other plants and absorbs nutrients from them.
14. Pitcher Plant
    An insectivorous plant whose modified leaf traps and digests insects.
15. Nitrogen
    A nutrient essential for plant growth; needed to build proteins.
16. Nitrogen Fixation
    The process of converting atmospheric nitrogen into a usable form by bacteria like Rhizobium.
17. Fertilizers
    Man-made or natural substances added to the soil to replenish nutrients.
18. Manure
    Organic matter, mainly derived from animal feces, used to enrich the soil.
19. Decomposition
    The natural process of breaking down dead plant and animal matter, which adds nutrients back to the soil.
20. Fungi
    A group of organisms that feed on decaying matter; includes molds and mushrooms.
21. Algae
    Simple autotrophic organisms, some of which form symbiotic relationships with fungi (as in lichens).
22. Lichen
    A symbiotic association between a fungus and an alga where both benefit from each other.
23. Symbiosis
    A relationship between two organisms where both gain benefits from each other.
24. Extra-cellular Digestion
    Digestion that takes place outside the organism’s body using secreted digestive juices.
25. Rhizobium
    A nitrogen-fixing bacterium that lives in the root nodules of leguminous plants and helps enrich the soil with nitrogen.

Something To Know

A. Fill in the blanks.

1. Animals are ____________ as they cannot synthesise their own food.

Answer – heterotrophs

2. The____________, of a plant, absorb water and minerals from the soil.

Answer – roots

3. During photosynthesis plants take in ____________ and release ____________.

Answer – carbon dioxide and release oxygen

4. ____________ are the tiny pores through which leaves exchange gases.

Answer – Stomata

5. Insect eating plants are called ____________ plants.

Answer – insectivorous

6. An essential raw material needed for the process of photosynthesis, and

(a) available in the soil is. ____________.

Answer – water

(b) available in the air is ____________.

Answer – carbon dioxide.

B. Match the following:

1. Chlorophyll (a) Autotrophs
2. Lichens (b) Saprotrophs
3. Fungi (c) Symbiotic relationship
4. Amarbel (d) Leaf
5. Plants (e) Parasite

Answer –

Chlorophyll – (d) Leaf

Lichens – (c) Symbiotic relationship

Fungi – (b) Saprotrophs

Amarbel – (e) Parasite

Plants – (a) Autotrophs

C. Tick (✓) the correct option.

1. Green plants, that can synthesise their own food, are known as—

heterotrophs

autotrophs

parasite

insectivorous

Answer – autotrophs

2. The food factory, of the plant, is its—

flower

leaf

root

stem 

Answer – leaf

3. Which of the following is an insectivorous plant?

pitcher plant

green plant

leguminous plant

amarbel

Answer – pitcher plant

4. Mushroom is an example of a/an—

saprotroph

autotroph

parasite

insectivorous

Answer – saprotroph

5. An organism, that fixes nitrogen in the soil, is—

mushroom

rhizobium

mucor

Cuscuta

Answer – rhizobium

D. Answer the following questions in brief.

1. Why is nutrition important for a living organism?

Answer – Nutrition is important because it provides the energy and nutrients required for growth, repair, and maintenance of the body.

2. How do green plants synthesise their food?

Answer – Green plants synthesise their food through photosynthesis using sunlight, carbon dioxide, and water in the presence of chlorophyll.

3. State the role of ‘vessels’ present in a plant.

Answer – Vessels transport water and minerals from the roots to the leaves and other parts of the plant.

4. Define the following terms:

(a) Symbiotic relationship

Answer – A relationship between two organisms in which both benefit from each other.

(b) Nutrients

Answer – Essential substances in food that help organisms grow, repair, and function.

(c) Saprotrophic mode of nutrition

Answer – A mode in which organisms obtain nutrients by decomposing dead and decaying matter.

(d) Photosynthesis

Answer – The process by which green plants prepare food using carbon dioxide, water, and sunlight in the presence of chlorophyll.

5. When some wheat dough was left in the open for a few days, it started emitting a foul smell. State, why?

Answer – Fungi and bacteria grow on the dough, breaking it down and producing a foul smell due to decomposition.

E. Answer the following questions

1. Why would life not be possible on the earth in the absence of photosynthesis?

Answer – Without photosynthesis, there would be no oxygen and no food for animals and humans, leading to the collapse of all life.

2. Give reasons for the following:

(a) Mushroom is a saprotroph.

Answer – It feeds on dead and decaying organic matter.

(b) Sun is the ultimate source of energy for all living organisms.

Answer – Plants convert solar energy into food, which supports all life directly or indirectly.

(c) The leaf of a plant ‘dies out’ if its stomata are blocked.

Answer – It cannot exchange gases needed for photosynthesis and respiration.

(d) Leaf 15 known as the food factory of the plant.

Answer – It performs photosynthesis and synthesises food for the plant.

(e) Lichen is a ‘living partnership’ between a fungus and an alga and this ‘partnership’ is beneficial to both.

Answer – The fungus provides shelter and water while the alga prepares food.

3. Why do some plants feed on insects? How does a pitcher plant catch insects?

Answer – Such plants live in nitrogen-poor soils and get nitrogen by digesting insects. A pitcher plant traps insects in its modified leaf, where they are digested.

4. How do rhizobium bacteria and leguminous plants help each other in their survival?

Answer – Rhizobium fixes atmospheric nitrogen for the plant; the plant provides food and shelter to the bacteria.

5. Complete the web chart.

Answer – Plant
├── Sunlight
├── Carbon dioxide
│ └── From air
├── Water
│ └── Absorbed by root
├── Chlorophyll
├── Results in formation of
│ ├── Food (Glucose)
│ └── Oxygen

Value Based Questions

The teacher told her students the story of the film Dost. She told them that, in that film, the friendship, between a visually challenged boy and a lame boy, helps them both to face, and overcome, the very many challenges of their day-to-day life. She went on to compare their friendship with the ‘symbiotic relationship’ between two organisms.

1. Suggest any two ‘values’ that, according to you, must have been there in the two friends of the film Dost.

Answer – Cooperation

Empathy and support

2. In what way is the friendship, between the two boys, similar to the ‘symbiotic relationship’ between two organisms?

Answer – Both involve mutual help and dependence for better living.

3. Give one example of a ‘symbiotic relationship’ between two organisms.

Answer – Lichen – between a fungus and an alga.

Something To Do

1. Compose a few lines/poem on the ‘utility of plants’.

Answer – “O green trees, you bless the land,

With food and air, by nature’s hand.

You cool the earth and shade the street,

In your presence, life is sweet.”

2. Why is it important to increase the ‘forest cover’?

Answer – Forests maintain ecological balance, provide oxygen, support biodiversity, and prevent soil erosion.

3. Keep a stale, moist piece of bread in a warm corner of the kitchen and observe it for 3-4 days. Can you identify the organism growing on the piece of bread? Identify its mode of nutrition.

Answer – Organism: Bread mould (Rhizopus)
Mode of nutrition: Saprotrophic

4. Solve the crossword puzzle with the help of the clues given below.

ACROSS ->

1. A plant parasite.
2. The process by which green plants prepare their food.
3. The process of obtaining, and utilising, food.
4. Green pigment present in the leaves of plants.

DOWN

1. Two different organisms that live together and thereby, benefit from each other.
2. Organism feeding on dead matter.
3. An organism deriving food from another living organism.
4. Organism that cannot prepare its own food

Answer – ACROSS

Cuscuta

Photosynthesis

Nutrition

Chlorophyll

DOWN

Symbiosis

Saprotroph

Parasite

Heterotroph

Additional Questions and Answer – 01

Fill in the Blanks (with Answers)

1. The green pigment responsible for photosynthesis is called ____________.
   Answer – chlorophyll
2. ____________ is the process by which green plants make their own food.
   Answer – Photosynthesis
3. Plants that obtain their food from dead and decaying matter show ____________ mode of nutrition.
   Answer – saprotrophic
4. Plants like ____________ feed on insects to fulfil their nitrogen requirements.
   Answer – pitcher plant
5. The ____________ in the leaves allow the exchange of gases.
   Answer – stomata
6. ____________ is the bacterium that converts atmospheric nitrogen into a usable form.
   Answer – Rhizobium
7. Organisms which depend on others for food are called ____________.
   Answer – heterotrophs
8. ____________ is a yellow, leafless parasite that grows on other plants.
   Answer – Cuscuta (amarbel)
9. Insectivorous plants grow mostly in ____________ deficient soil.
   Answer – nitrogen
10. The product of photosynthesis is initially ____________, which later gets converted to starch.
    Answer – glucose

Multiple Choice Questions (MCQs) (with Answers)

1. Which pigment is essential for photosynthesis?
   a) Hemoglobin
   b) Chlorophyll
   c) Keratin
   d) Melanin
   Answer – b) Chlorophyll
2. Which of the following does not perform photosynthesis?
   a) Mango
   b) Rose
   c) Cuscuta
   d) Neem
   Answer – c) Cuscuta
3. The ultimate source of energy for all living organisms is—
   a) Earth
   b) Moon
   c) Sun
   d) Water
   Answer – c) Sun
4. The pore through which plants exchange gases is—
   a) Guard cell
   b) Leaflet
   c) Stomata
   d) Cuticle
   Answer – c) Stomata
5. Which plant traps insects for food?
   a) Money plant
   b) Pitcher plant
   c) Rose
   d) Mango
   Answer – b) Pitcher plant

1. True/False (with Answers)
2. All green plants are autotrophs.
   True
3. Mushrooms are autotrophic organisms.
   False
4. Chlorophyll is present only in dark green leaves.
   False
5. Rhizobium helps in fixing nitrogen in the soil.
   True
6. Insectivorous plants perform photosynthesis.
   True
7. Saprotrophs get their nutrition from living hosts.
   False
8. Stomata are found only on the upper surface of leaves.
   False
9. The leaf is known as the food factory of the plant.
   True

Short Answer Questions (with Answers)

1. What is photosynthesis?
   Answer – It is the process by which green plants make their own food using sunlight, carbon dioxide, and water.
2. What are heterotrophs?
   Answer – Organisms that depend on others for food are called heterotrophs.
3. Why are leaves called the food factories of plants?
   Answer – Because they contain chlorophyll and are the main sites for photosynthesis.
4. Name the raw materials required for photosynthesis.
   Answer – Carbon dioxide, water, and sunlight.
5. What is the function of guard cells?
   Answer – Guard cells control the opening and closing of stomata.

Competency-Based Questions (Assertion & Reasoning)

1. Assertion: Cuscuta is a parasite.
   Reason: It can perform photosynthesis.
   a) Both A and R are true, and R is the correct explanation of A.
   b) Both A and R are true, but R is not the correct explanation of A.
   c) A is true, but R is false.
   d) A is false, but R is true.
   Answer – c) A is true, but R is false.
2. Assertion: Rhizobium is helpful to leguminous plants.
   Reason: It helps in the absorption of sunlight.
   Answer – c) A is true, but R is false.
3. Assertion: Fungi grow on stale bread.
   Reason: Fungi have a saprotrophic mode of nutrition.
   Answer – a) Both A and R are true, and R is the correct explanation of A.

Higher Order Thinking Skills (HOTS) Questions

1. Why do insectivorous plants still perform photosynthesis if they consume insects?
   Answer – Because they need food (carbohydrates) produced via photosynthesis; they consume insects to fulfil their nitrogen requirement only.
2. Explain how plants and animals are interdependent in terms of gaseous exchange.
   Answer – Plants release oxygen needed by animals and take in carbon dioxide released by animals, maintaining a balance in nature.
3. Why does the blockage of stomata result in the death of the leaf?
   Answer – Because gases like CO₂ and O₂ cannot enter or exit, which hampers photosynthesis and respiration.

Long Answer Questions (50–60 words each)

1. Describe the process of photosynthesis and its importance.
   Answer – Photosynthesis is the process by which green plants use sunlight, carbon dioxide, and water to produce glucose and oxygen. It occurs in the presence of chlorophyll. This process is important because it is the primary source of food and oxygen, making it essential for the survival of all living organisms.
2. What is a symbiotic relationship? Explain with two examples.
   Answer – A symbiotic relationship is one in which two organisms live closely and benefit from each other. For example, lichens consist of an alga and a fungus living together, and Rhizobium bacteria live in leguminous plant roots, helping fix nitrogen while receiving food and shelter.
3. Explain different modes of heterotrophic nutrition in plants with examples.
   Answer – Heterotrophic nutrition includes parasitic (e.g., Cuscuta), saprotrophic (e.g., mushrooms), and symbiotic (e.g., lichens). Parasitic plants depend on hosts, saprotrophs feed on dead matter, and symbiotic plants live in mutual cooperation with other organisms.

Additional Questions and Answer – 02

Fill in the Blanks

1. The process of obtaining and utilizing food by an organism is called ________.

Answer: Nutrition

2. Green plants prepare their own food through the process of ________.

Answer: Photosynthesis

3. The green pigment in leaves that captures sunlight is called ________.

Answer: Chlorophyll

4. Carbon dioxide enters the leaves through tiny pores called ________.

Answer: Stomata

5. Plants that feed on insects for their nitrogen requirements are called ________ plants.

Answer: Insectivorous

6. The mode of nutrition in which organisms feed on dead and decaying matter is called _______ nutrition.

Answer: Saprotrophic

7. Cuscuta is an example of a ________ plant that derives nutrition from a host.

Answer: Parasitic

8. The bacterium that converts atmospheric nitrogen into a usable form for plants is called ________.

Answer: Rhizobium

9. During photosynthesis, the initial product formed is a carbohydrate called ________.

Answer: Glucose

10. The relationship where two organisms live together and benefit each other is called a ________ relationship.

Answer: Symbiotic

Multiple Choice Questions (MCQs)

1. Which of the following is NOT a component of food?
2. a) Carbohydrates
3. b) Proteins
4. c) Chlorophyll
5. d) Vitamins

Answer: c) Chlorophyll

2. What is the primary source of energy for photosynthesis?
3. a) Moonlight
4. b) Sunlight
5. c) Artificial light
6. d) Heat

Answer: b) Sunlight

3. Which gas is released by plants during photosynthesis?
4. a) Nitrogen
5. b) Oxygen
6. c) Carbon dioxide
7. d) Hydrogen

Answer: b) Oxygen

4. Which plant is an example of an insectivorous plant?
5. a) Cuscuta
6. b) Pitcher plant
7. c) Lichen
8. d) Rhizobium

Answer: b) Pitcher plant

5. What is the role of stomata in plants?
6. a) Absorb water
7. b) Exchange gases
8. c) Store food
9. d) Transport nutrients

Answer: b) Exchange gases

6. Which of the following organisms exhibits saprotrophic nutrition?
7. a) Green plants
8. b) Rhizopus (bread mould)
9. c) Cuscuta
10. d) Pitcher plant

Answer: b) Rhizopus (bread mould)

7. What is the main product of photosynthesis that later gets converted to starch?
8. a) Glucose
9. b) Protein
10. c) Fat
11. d) Nitrogen

Answer: a) Glucose

8. Which of the following is a symbiotic relationship?
9. a) Cuscuta on a host plant
10. b) Lichen (fungus and alga)
11. c) Pitcher plant trapping insects
12. d) Bread mould on stale bread

Answer: b) Lichen (fungus and alga)

9. How do plants obtain nitrogen for protein synthesis?
10. a) Directly from the air
11. b) From sunlight
12. c) Through bacteria like Rhizobium
13. d) From chlorophyll

Answer: c) Through bacteria like Rhizobium

10. What blocks the stomata in the Activity 1 experiment, causing the leaf to turn yellow?
11. a) Water
12. b) Vaseline
13. c) Sunlight
14. d) Soil

Answer: b) Vaseline

True/False Questions

1. All green plants are autotrophs.

Answer: True

2. Chlorophyll is responsible for the red color in some leaves.

Answer: False (Chlorophyll gives green color; other pigments cause red or other colors)

3. Photosynthesis occurs in the roots of plants.

Answer: False (Photosynthesis occurs in leaves)

4. Cuscuta is an example of an insectivorous plant.

Answer: False (Cuscuta is a parasitic plant)

5. Stomata are surrounded by guard cells.

Answer: True

6. Saprotrophic organisms feed on dead and decaying matter.

Answer: True

7. All leaves with yellow patches can perform photosynthesis.

Answer: False (Yellow patches lack chlorophyll and cannot perform photosynthesis)

8. Rhizobium bacteria live in the roots of leguminous plants.

Answer: True

9. Sunlight is not necessary for photosynthesis.

Answer: False (Sunlight is essential for photosynthesis)

10. Manures and fertilizers are used to replenish nutrients in the soil.

Answer: True

Short Questions and Answers

1. What is nutrition?

Answer: Nutrition is the process of obtaining and utilizing food by a living organism.

2. Name the two main types of nutrition in living organisms.

Answer: Autotrophic and heterotrophic nutrition.

3. What is the role of chlorophyll in plants?

Answer: Chlorophyll captures sunlight energy to help plants synthesize food during photosynthesis.

4. What are stomata?

Answer: Stomata are tiny pores on the surface of leaves that allow the exchange of gases like carbon dioxide and oxygen.

5. What is the primary product of photosynthesis?

Answer: The primary product of photosynthesis is glucose.

6. Name one example of a parasitic plant.

Answer: Cuscuta (amarbel or dodder).

7. What is the function of guard cells in plants?

Answer: Guard cells surround stomata and control their opening and closing to regulate gas exchange.

8. How do insectivorous plants obtain nitrogen?

Answer: Insectivorous plants obtain nitrogen by trapping and digesting insects.

9. What is a symbiotic relationship?

Answer: A symbiotic relationship is when two organisms live together and both benefit from the association.

10. How is nitrogen made available to plants?

Answer: Nitrogen is made available to plants through bacteria like Rhizobium, which convert atmospheric nitrogen into a usable form.

Competency-Based Questions (Reasoning and Assertion)

1. Assertion (A): Photosynthesis occurs in the leaves of green plants. Reason (R): Leaves contain chlorophyll, which captures sunlight for food synthesis.
2. a) Both A and R are true, and R is the correct explanation of A.
3. b) Both A and R are true, but R is not the correct explanation of A.
4. c) A is true, but R is false.
5. d) A is false, but R is true.

Answer: a) Both A and R are true, and R is the correct explanation of A.

2. Assertion (A): Cuscuta is a heterotrophic plant. Reason (R): Cuscuta lacks chlorophyll and depends on a host plant for nutrition.
3. a) Both A and R are true, and R is the correct explanation of A.
4. b) Both A and R are true, but R is not the correct explanation of A.
5. c) A is true, but R is false.
6. d) A is false, but R is true.

Answer: a) Both A and R are true, and R is the correct explanation of A.

3. Assertion (A): Insectivorous plants are autotrophic. Reason (R): Insectivorous plants can perform photosynthesis but also trap insects for nitrogen.
4. a) Both A and R are true, and R is the correct explanation of A.
5. b) Both A and R are true, but R is not the correct explanation of A.
6. c) A is true, but R is false.
7. d) A is false, but R is true.

Answer: d) A is false, but R is true. (Insectivorous plants are heterotrophic for nitrogen but can perform photosynthesis.)

4. Assertion (A): Rhizobium bacteria help plants by providing nitrogen. Reason (R): Rhizobium converts atmospheric nitrogen into a soluble form for plants.
5. a) Both A and R are true, and R is the correct explanation of A.
6. b) Both A and R are true, but R is not the correct explanation of A.
7. c) A is true, but R is false.
8. d) A is false, but R is true.

Answer: a) Both A and R are true, and R is the correct explanation of A.

5. Assertion (A): Saprotrophic organisms digest food outside their body. Reason (R): Saprotrophic organisms secrete digestive juices onto dead and decaying matter.
6. a) Both A and R are true, and R is the correct explanation of A.
7. b) Both A and R are true, but R is not the correct explanation of A.
8. c) A is true, but R is false.
9. d) A is false, but R is true.

Answer: a) Both A and R are true, and R is the correct explanation of A.

High Order Thinking Skill (HOTS) Questions and Answers

1. Why do some plants, like Cuscuta, lack chlorophyll, and how do they survive?

Answer: Cuscuta lacks chlorophyll, so it cannot perform photosynthesis to make its own food. It survives by adopting a parasitic mode of nutrition, deriving nutrients from a host plant, which it harms in the process.

2. How would the absence of photosynthesis affect life on Earth?

Answer: Without photosynthesis, plants would not produce food or oxygen, leading to the starvation of herbivores, which would affect carnivores. The lack of oxygen would also make survival impossible for most living organisms.

3. Why do variegated leaves with yellow patches fail to perform photosynthesis?

Answer: Yellow patches on variegated leaves lack chlorophyll, which is essential for capturing sunlight energy. Without chlorophyll, these areas cannot synthesize food through photosynthesis.

4. How does the symbiotic relationship between Rhizobium and leguminous plants benefit both?

Answer: Rhizobium converts atmospheric nitrogen into a usable form for leguminous plants, aiding protein synthesis. In return, the plants provide Rhizobium with food and shelter, benefiting both in a mutualistic relationship.

5. Why do farmers add fertilizers to the soil, and how is this different from nutrient replenishment in forests?

Answer: Farmers add fertilizers to replenish nutrients removed by plants, ensuring soil fertility. In forests, nutrients are naturally replenished through the decomposition of dead leaves and organic matter, without human intervention.

Long Questions and Answers (50-60 words)

1. Explain the process of photosynthesis and its importance to living organisms.

Answer: Photosynthesis is the process where green plants use sunlight, carbon dioxide, and water to synthesize glucose in the presence of chlorophyll. It occurs in leaves, producing oxygen as a byproduct. Photosynthesis is vital as it provides food for plants and oxygen for all living organisms, forming the basis of the food chain.

2. Describe how insectivorous plants like the pitcher plant obtain their nutrients.

Answer: Insectivorous plants like the pitcher plant trap insects to meet their nitrogen needs. The plant’s leaf forms a pitcher with a lid and downward-pointing hairs. Insects enter, get trapped, and are digested by juices at the pitcher’s base, providing nitrogen, while the plant performs photosynthesis for other nutrients.

3. How do saprotrophic organisms obtain their food, and give two examples?

Answer: Saprotrophic organisms feed on dead and decaying matter by secreting digestive juices that break down the material outside their body. The soluble nutrients are then absorbed. Examples include Rhizopus (bread mould), which grows on stale bread, and Agaricus (mushroom), which grows on rotting wood.

4. What is a symbiotic relationship? Explain with an example involving plants.

Answer: A symbiotic relationship is a mutually beneficial association between two organisms. For example, Rhizobium bacteria live in the roots of leguminous plants, converting atmospheric nitrogen into a usable form for the plant. In return, the plant provides food and shelter to the bacteria, supporting both organisms’ survival.

5. How are nutrients replenished in the soil in agricultural fields and forests?

Answer: In agricultural fields, farmers replenish soil nutrients by adding manures and fertilizers to maintain productivity. In forests, nutrients are naturally replenished through the decomposition of dead leaves, plants, and animal matter, facilitated by microorganisms, ensuring the soil remains fertile without human intervention.