Class 7 Science Ch 01: Nutrition in Plants

    I. Multiple Choice Questions (MCQs).

    I. Multiple Choice Questions (MCQs).
    Q.1. The components of food are called
    a) nutrients
    b) vitamins
    c) minerals
    d) carbohydrates
    Answer: a) nutrients
    Q.2. The mode of nutrition in which a living organism can make its own food is called
    a) saprophytic
    b) heterotrophic
    c) parasitic
    d) autotrophic
    Answer: (d) autotrophic

    Q.3. Which of the following parts of the plants are called the food factory of the plant?
    a) Roots
    b) Stems
    c) Leaves
    d) Fruit
    Answer: c) Leaves
    Q.4. The green pigment present in green parts of the plant is called
    a) stomata
    b) chlorophyll
    c) guard cell
    d) chloroplast
    Answer: (b) chlorophyll
    Q.5. The gas essential for photosynthesis is
    a) oxygen
    b) nitrogen
    c) carbon dioxide
    d) sulphur dioxide
    Answer: (c) carbon dioxide
    II. Fill in the blanks by selecting appropriate words from the given list.
    List : Rhizobium, haustoria, Roots, Parasites, Water
    Q.1. _______________ absorb water along with minerals from the soil and it is transported to different parts of the plant.
    Q.2. _______________ are those organisms which obtain food from the other living organism called host.
    Q.3. _______________ converts atmospheric nitrogen into nitrates and nitrites that can be used by plants.
    Q.4. _______________ helps to keep a plant cell rigid and turgid and helps plants to stand upright.
    Q.5. Cuscuta has special tubular structures called _______________.
    Answer: 1- roots,
    2- Parasites,
    3- Rhizobium,
    4- water,
    5- haustoria

    III. Match the items of Column A with those of Column B.

    Column A

    Column B

    1. The process of obtaining and utilising food by organisms.

    (a) Saprophytes

    2. The plants which trap insects.

    (b)
    Heterotrophs 

    3. The organisms which depend on
    plants and other   animals for their
    food. 

    (c) Nutrition

    4. A complex carbohydrate.                                 

    (d)
    Insectivorous plants 

    5. The organisms which take nutrients
    from dead  and decaying matter.

    (e) Starch

    Answer: 1-(c), 2-(d), 3- (b) 4- (e ), 5-(a)

    IV. Write ‘T’ for the true and ‘F’ for the false statements.
    Q.1. Plants can make their own food by the process of photosynthesis.

    Q.2. Chlorophyll molecules are the principal sites of light absorption during photosynthesis.

    Q.3. The alga provides shelter, water and minerals to fungus in a lichen.

    Q.4. Parasitic plants can make their own food.

    Q.5. In pitcher plant a part of leaf modifies to form a pitcher like structure which is covered with a lid.

    Answer: 1- T, 2-T, 3-F, 4-F, 5-T
    V. Very Short Answer Questions.
    What are the functions of nutrients?
    Answer: Nutrients provides energy, helps in repair and growth of the body, helps to fight against diseases, etc.
    Q.1. List the kinds of nutrition found in living organisms.
    Answer: Nutrition is mainly of two types:
    (a) Autotrophic Nutrition
    (b) Heterotrophic Nutrition.

    Q.2. What colour does iodine solution give with starch?
    Answer: Iodine solution gives blue-black colour with starch.

    Q.3. Give two examples of saprophytic plants.
    Answer: fungi (Mushroom) Indian orchid

    Q.4. Define heterotrophs with the help of examples.

    Answer: The organisms which obtain food from plants or other organisms. The Cuscuta is a parasitic plant. It has special tubular structures called haustoria that penetrate into the tissues of the tree from which it gets food.

    VI. Short Answer Questions.
    Q.1. What do you mean by symbiosis?
    Answer: Symbiosis is a relationship between two organisms in which both the organisms are benefitted from each other.

    Q.2. Why do insectivorous plants trap insects?

    Answer: insectivorous plants trap insects with the help of special leaves present in them to get the supply of nitrogenous compounds.

    Q.3. Briefly describe how Euglena gets nutrition.
    Answer: In the presence of light Euglena produces food by photosynthesis but in dark it feeds on other unicellular organisms. In this way Euglena gets nutrition.

    Q.4. What are the different modes of nutrition in living organisms? Explain with examples.

    Answer: Modes of Nutrition in living organisms mainly of two types:
    (a) Autotrophic Nutrition: The mode of nutrition in which a living organism can make its own food is called autotrophic nutrition. Organisms having this type of nutrition are called autotrophs. Plants can make their own food by the process of photosynthesis and they are called autotrophs. Algae and some bacteria are also examples of autotrophs.

    (b) Heterotrophic Nutrition: The mode of nutrition in which organisms depend on the plants and other animals for their food, are called heterotrophic nutrition. Human, dog, cow are some example of heterotrophs.

    Q.5. (a) What do you mean by photosynthesis? Explain briefly.
    (b) Why do only plants show photosynthesis and not animals?
    Answer. (a) Photosynthesis is a process in which chlorophyll containing green plants, in the presence of sunlight, uses carbon dioxide and water to synthesise their food.

    b) Animal cells are not capable of Photosynthesis, because animal cells do not have chloroplasts. Chloroplasts are the only organelles that can carry out Photosynthesis.

    VII. Long Answer Questions.
    Q.1. (a) What are the functions of chlorophyll and sunlight in photosynthesis?
    (b) Draw a labelled diagram showing the process of photosynthesis.

    Answer: a) Chlorophyll helps the Leaves to capture the energy from sunlight and this energy is utilised for the synthesis of food from carbon dioxide and water. Plants can manufacture food only in the presence of sunlight because sun is the only and ultimate source of energy.

    b)

    Q.2. (a) How can you show that sunlight is necessary for photosynthesis? Verify with an experiment.
    (b) How can you show that carbon dioxide is necessary for photosynthesis? Verify with an experiment.
    Answer: (a) Aim: To show that sunlight is necessary for photosynthesis.
    Requirements: Green plant, black paper, clip, iodine solution, alcohol, beaker, petridish and test tube.
    Procedure: Destarch the plant by keeping it in a dark room for three days. Cover a part of the leaf of destarched plant using a strip of black paper. Now place this plant in sunlight for about 6 hours. Pluck the covered leaf at sunset and test it for the presence of starch.

    Starch Test: Put the leaf in boiling water for 2 minutes. Take out the leaf from water and keep it in a test tube containing alcohol. Heat the test tube containing water till the leaf loses its green colour. Take out the leaf and wash it with freshwater. Put it on a watch glass and add a few drops of iodine solution.

    Observation: Covered portion remains light brown while rest of the leaf turns blueblack.

    Conclusion: The portion of leaf which is covered with black strip does not receive sunlight. So this part of leaf does not turn blue-black. This shows that sunlight is essential for photosynthesis.

    b) Aim : To show that carbon dioxide is necessary for photosynthesis.
    Requirements: A potted plant, a wide mouthed bottle, caustic potash, iodine solution, beaker, watch glass, test tube, alcohol and cork.
    Procedure : Make a slit in a cork and fit it into the mouth of the bottle having caustic potash solution.
    Insert about half Leaf of a potted plant into the bottle through the slit present in the cork. Keep this whole arrangement in the sunlight for one day. Pluck the Leaf and test it for the presence of starch.

    Observation : The portion of Leaf situated inside the bottle does not turn blue-black while outer portion of the Leaf turns blue-black.

    Conclusion : The portion of the Leaf situated outside the bottle synthesises starch in the presence of carbon dioxide and sunlight by the process of photosynthesis and hence, turns blue-black with iodine solution. But caustic potash present in the bottle absorbs carbon dioxide from the bottle and no photosynthesis takes place. This shows that carbon dioxide is essential for photosynthesis.

    Q.3. (a) What are the types of heterotrophic mode of nutrition in plants? Explain with examples.
    (b) What do you mean by insectivorous plants? Explain briefly.
    Answer: a) heterotrophic mode of nutrition in plants are of the following types:

    Parasitic : Mode of nutrition in which organisms depend on other living organisms. For example Cuscuta.

    Saprotrophic : Mode of nutrition in which organisms depend on dead decaying matter. e.g. yeast, moulds, mushroom.

    Symbiotic : Mode of nutrition in which two living organisms live together for mutual benefit. e.g. Rhizobium, lichen

    b) Some plants trap insects with the help of special leaves present in them to get the supply of nitrogenous compounds. These plants are called insectivorous plants. Pitcher plant, venus fly trap, bladderwort, sundew are the examples of insectivorous plants.

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