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#### Question A:

Solve the following crossword puzzle:
figure

Across
3. A green pigment found in leaves
4. It is a plant parasite
5. It is a fertilizer

Down
1. This solution is used to test the starch
2. Organism that provides nourishment to the parasite
3. It is an omnivore

#### Question B.1:

Haustoria in some plants are
(a) sucking roots
(b) sucking stem
(c) sucking branch
(d) sucking leaves

(a) sucking roots

Haustoria are special sucking roots that are found in some parasitic plants like dodder.

#### Question B.2:

Association of two different organisms in which both are benefited is called
(a) symbiosis
(b) nutrition
(c) saprophytic
(d) parasitic

(a) symbiosis

Symbiosis is the association of two different organisms in which both are benefited.

#### Question B.3:

The green colour pigment in the leaves is called
(a) chlorophyll
(b) chloroplast
(c) anthocyanin
(d) none of these

(a) chlorophyll

The green-coloured pigment present in leaves is called chlorophyll.

#### Question B.4:

Tiny pores found on the lower side of the leaves is called
(a) stomata
(b) guard cell
(c) both of these
(d) none of these

(a) stomata

Stomata are tiny pores present on the lower side of leaves.

#### Question B.5:

Which one of  the following is a parasite?
(a) Mushroom
(b) Dodder
(c) Fungi
(d) Pitcher's plant

(b) Dodder

Dodder (Amarbel) is a plant parasite that derives its food from the host plant with the help of its special sucking roots called haustoria.

#### Question B.6:

Rhizobium is a good example
(a) insectivorous plant
(b) symbiosis
(c) parasitic plant
(d) none of these

(b) symbiosis

Rhizobium and leguminous plants have a symbiotic relationship. Leguminous plants provide food and shelter to the bacteria and the bacteria provide nitrogen to the plants.

#### Question B.7:

Autotrophic nutrition is found only in
(a) plants
(b) animals
(c) both of these
(d) none of these

(a) plants

Autotrophic nutrition is found only in plants because only plants can produce their own food.

#### Question C:

Fill in the blanks:
1. ............................ pigment is necessary for photosynthesis.
2. Iodine turns blue-black on reacting with ............................ .
3. ............................ and ............................ are insectivorous plants.
4. Plants produce ............................ and ............................ with the help of energy derived from Sun.
5. Lichen is the mutual combination of ............................ and ............................ .
6. Dodder is an example of ............................ .

1. Chlorophyll pigment is necessary for photosynthesis.

2. Iodine turns blue-black on reacting with starch.

3. Drosera and pitcher plant are insectivorous plants.

4. Plants produce glucose and oxygen with the help of energy derived from Sun.

5. Lichen is the mutual combination of alga and fungus.

6. Dodder is an example of parasite.

#### Question D:

Match the items in Column A with the items in Column B:

 Column A Column B 1. Dodder (Amarbel) (a) Saprohytes 2. Lichen (b) Insectivorous 3. Mushroom (c) Autotrophs 4. Venus flytrap (d) Stomata 5. Green plants (e) Symbiosis (f) Parasite

 Column A Column B Dodder (Amarbel) Parasite Lichen Symbiosis Mushroom Saprophytes Venus flytrap Insectivorous Green plants Autotrophs

#### Question E:

Write True (T) or False (F) against the following statements in the given brackets:
1. Symbiotic association involves a host and a parasite. ( )
2. Stomata helps in the exchange of carbon dioxide and oxygen. ( )
3. Pitcher plant is an example of parasite. ( )
4. Saprophytes are green plants. ( )
5. Peas and beans are leguminous plant. ( )
6. Rhizobium bacterial are present in the roots of all green plants. ( )

1. False (F)
Symbiotic association involves an interaction between any two different organisms in which both the partners are mutually benefited.

2. True (T)

3. False (F)
Pitcher plant is an example of insectivorous plant.

4. False (F)
Saprophytes are non-green in colour because these plants lack chlorophyll.

5. True (T)

6. False (F)
Rhizobium bacteria are found in the root nodules of leguminous plants.

#### Question F:

Following diagram shows photosynthesis in green plants. Label the diagram with the words and sentences:

 • Glucose made in the leaves transported to different plant parts • Solar energy • Carbon dioxide taken from atmosphere • Chlorophyll • Sun • Oxygen given out by the plant • Water and minerals absorbed from the soil

figure

a. Sun
b. Solar energy
c. Chlorophyll
d. Carbon dioxide taken from the atmosphere
e. Glucose made in the leaves transported to different plant parts
f. Water and minerals absorbed from the soil
g. Oxygen released by the plant

#### Question 1:

Why are nitrogenous fertilisers not added to the soil in which leguminous plants grow?

Leguminous plants contain Rhizobium bacteria in their root nodules. These bacteria have the ability to convert atmospheric nitrogen into a plant-usable form of nitrogen. Hence, farmers need not add nitrogenous fertilisers in the fields where leguminous plants grow.

#### Question 2:

Sometimes, when you eat yam (zimikand), you feel a burning sensation in the throat. Why?

Yam (zimikand) is a root vegetable that contains calcium oxalate crystals. These crystals are in the shape of sharp pins. When we eat this vegetable, these sharp crystals prick our throat; this, in turn, produces a burning sensation.

#### Question 3:

Like plants we also make our food. Are we autotroph too?

No, we are not autotrophs because we depend on green plants for our food either directly or indirectly. We make our food from products obtained from plants or animals; hence, we are known as heterotrophs. Only plants are classified as autotrophs because they produce their own food using sunlight, carbon dioxide and water.

#### Question 4:

Why do fallen leaves not turn blue-black on being tested with iodine?

Fallen leaves do not turn blue-black on being tested with iodine because they lack starch. These leaves are not attached to a plant and so do not get water and minerals to perform photosynthesis. Hence, fallen leaves cannot produce food for themselves.

#### Question 5:

If we provide carbon dioxide, water and sunlight to a person, can he make food like plants? Why and why not?

No, this is not possible.

Plants produce their own food through photosynthesis, which is a process by which chlorophyll present in the leaves of a plant traps sunlight and produces food. Humans cannot produce their own food even if carbon dioxide, water and sunlight are provided, as the human cells do not contain chlorophyll and also do not have the ability to capture sunlight.

#### Question A.1:

What is nutrition?

Nutrition is a process by which any living organism takes in food and uses it to derive energy required for its growth and development.

#### Question A.2:

What are the two main types of nutrition prevalent in living organisms?

The two main types of nutrition prevalent in living organisms are:
1. Autotrophic nutrition
2. Heterotrophic nutrition

#### Question A.3:

How do autotrophs differ from heterotrophs?

 Autotrophic Organisms Heterotrophic Organisms Organisms that can produce their own food are called autotrophic organisms. Organisms that cannot produce their own food are called heterotrophic organisms. Green plants are autotrophs because they produce their own food. Animals and non-green plants  are heterotrophs because they cannot produce their own food and depend on autotrophs either directly or indirectly for their food. Autotrophic organisms are also called producers. Heterotrophic organisms are also called consumers.

#### Question A.4:

Why are green plants called producers?

Green plants are called producers because they produce their own food through the process of photosynthesis.

#### Question A.5:

Name the bacteria present in the roots of leguminous plants.

Rhizobium bacteria is present in the roots of leguminous plants.

#### Question A.6:

Differentiate between parasites and saprophytes by giving an example.

 Parasites Saprophytes Plants or animals that live on other living organisms and obtain their food from them are called parasites. Plants that live on dead or decaying organic matter and obtain their food from such matter are called saprophytes. Example: Dodder Example: Bacteria and fungi

#### Question A.7:

Write a word equation for photosynthesis.

The word equation for photosynthesis is as follows:
Carbon dioxide + Water $\underset{\mathrm{chlorophyll}}{\overset{\mathrm{sunlight}}{\to }}$ Glucose + Oxygen

#### Question A.8:

What is the role of stomata in plants?

Stomata are tiny pores present on the undersurface of the leaves. They help in the exchange of gases in plants.  Plants take up carbon dioxide from the atmospheric air and release oxygen and water vapour into the atmosphere through the stomata.

#### Question B.1:

Why do insectivorous plants trap insects? Name any two insectivorous plants.

Insectivorous plants trap insects to derive certain nutrients that they cannot obtain from soil. These plants have special methods to trap and consume insects to get their supply of nitrogenous compounds.

Examples: Pitcher plant and Utricularia.

#### Question B.2:

What is photosynthesis? Explain the process diagrammatically.

Photosynthesis is a process by which green plants synthesise nutrients from carbon dioxide and water with the help of energy derived from the sun. A green pigment called chlorophyll present in the leaves of the plants absorbs energy from the sun and converts carbon dioxide and water into oxygen and glucose. The chemical equation of this reaction is represented as follows:

6CO2      +      6H2O     $\underset{\mathrm{Chlorophyll}}{\overset{\mathrm{Sunlight}}{\to }}$     C6H12O6   +   6O2
Carbon dioxide     Water                          Glucose        Oxygen

#### Question B.3:

Name the three groups of animals on the basis of their eating habits.

Animals are divided into three groups on the basis of their eating habits:
1. Herbivorous animals: Animals that feed on plants are called herbivorous animals or herbivores. For example, cow, goat and buffalo.
2. Carnivorous animals: Animals that feed on the flesh of other animals are called carnivorous animals or carnivores. For example, lion, tiger and wolf.
3. Omnivorous animals: Animals that feed on both plants and flesh of other animals are called omnivorous animals or omnivores. For example, human beings, pig and cockroach.

#### Question B.4:

What is symbiosis?

Symbiosis is an interaction between two different organisms living in close association in which both the partners get mutually benefited. Symbiosis is also called mutualism. Lichen, which is a combination of an alga and a fungus, is a typical example of symbiotic association.

#### Question B.5:

What is the importance of photosynthesis in nature?

Photosynthesis is important in nature for the following reasons:
1. Plants make their food through this process.
2. It is the primary source for the production of food for all other living organisms.
3. It helps in maintaining a balance between oxygen and carbon dioxide in the atmosphere.

#### Question B.6:

How do cells derive energy from food we eat?

Cells derive energy from the food we eat through a process called cellular respiration. During cellular respiration, energy is released by the chemical breakdown or oxidation of food substances.

#### Question B.7:

How do plants exchange gases?

Plants exchange gases through stomata, which are tiny pores present on the undersurface of their leaves. The guard cells in the stomata regulate their opening and closing. During photosynthesis, the guard cells around the stomata open to take in carbon dioxide from the atmospheric air and give out oxygen produced into the atmosphere.

#### Question B.8:

Lichen is a combination of an alga and a fungus. How do they help each other?

Lichen is a combination of an alga and a fungus. It is a typical example of symbiosis, where both the organisms benefit from each other. The fungus provides water and minerals and also shelter to the alga, which in return supplies organic food prepared through photosynthesis to the fungus.

#### Question C.1:

How do rhizobium bacteria help in replenishment of nutrients in the soil?

Leguminous crops, such as peas, pulses and gram, have Rhizobium bacteria in their root nodules. The Rhizobium bacteria have the ability to convert the atmospheric nitrogen into a form that can be used by the plants. Thus, these bacteria help in replenishing nutrients in the soil by providing nitrogen to the plants. The bacteria in turn get their food and shelter from the leguminous plants.

#### Question C.2:

How would you show that chlorophyll is necessary for photosynthesis?

Take a variegated leaf (partly green and partly white) of a croton plant that was kept in the sunlight for a few hours. The green parts of the leaf contain chlorophyll, whereas the white parts do not contain chlorophyll. Immerse the leaf in boiling water and let it boil for a few minutes so that the cells in the leaf are killed. Now boil this leaf in rectified spirit to decolourise it. After the leaf has decolourised, wash it with hot water to remove any chlorophyll sticking to it. Now, place this leaf in a solution of dilute iodine.

We observe that the parts of the leaf that were green turn blue-black. This confirms the presence of starch in these areas. The parts of the leaf that were white do not change colour. This confirms that no starch is present in these areas of the leaf. This experiment shows that chlorophyll is essential for photosynthesis, as only the green portion of the leaf had starch.

#### Question C.3:

How does a pitcher plant trap insects?

Pitcher plant is an insectivorous plant that derives nitrogenous compounds by trapping and consuming insects. The leaf of a pitcher plant is modified to form a pitcher-like structure. When an insect sits on the pitcher, the lid of the pitcher gets closed and the insect gets trapped inside. The insect is then digested by the enzymes secreted by the plant. In this manner, pitcher plants fulfil their requirement of nitrogen by feeding on insects.

#### Question C.4:

How would you show that carbon dioxide is necessary for photosynthesis?

Experiment:
Take a wide-mouthed bottle and pour some caustic potash solution into it. Now take a potted plant and insert one half of a leaf into the bottle through the split cork. Leave the plant undisturbed in the sunlight  for at least two days. On the third day, pluck the leaf and test it for the presence of starch with iodine solution.

Observation:
The part of the leaf that was outside the bottle turns blue-black, but the other portion of the leaf that was inside the bottle does not turn blue-black. This shows that the part of the leaf inside the bottle could not synthesise food. Although this part of the leaf had chlorophyll and also access to water, minerals and sunlight, it did not have carbon dioxide.

Inference:
Carbon dioxide present in the bottle was absorbed by caustic potash solution. Hence, the leaf was deprived of carbon dioxide and therefore, could not synthesise food.

Conclusion:
Carbon dioxide is necessary for photosynthesis.

#### Question C.5:

How dodder (amarbel) draw its nutrients from the host? Explain.

Dodder (Amar bel) is a plant parasite, which is essentially leafless and derives its food from the host plant. It is a vine-like parasitic plant that has special sucking roots known as haustoria. These roots absorb nutrients from the host plant. Dodder attaches itself to the host plant with the help of its special roots. Once it has wrapped itself around the host plant, it loses its root system. It then obtains all the nutrient requirements from the host plant.

#### Question C.6:

What are the methods by which nutrients in the soil can be replenished?

Nutrients in the soil can be replenished by three methods:
1. By applying fertilisers rich in nitrogen, phosphorous and potassium in the fields, depending on the soil and crop requirements.
2. By adding manure, which is obtained by the decomposition of plant residues and animal wastes.
3. By growing leguminous crops such as peas, pulses and beans. The Rhizobium bacteria present in the roots of the leguminous crops help in fixing atmospheric nitrogen into a form that can be used by plants.

#### Question C.7:

In which respect are manures better than fertilisers?