Class 7 Science Chapter 1 Sample Question Paper – Pdf Download CBSE

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Class – 7  Science

CHAPTER – 1

Nutrition in Plants

Book Exercise: –

Q 1 : Why do organisms need to take food?

Answer:

All living organisms require food to survive. It gives them energy to perform various activities. All activities such as playing, running, walking, studying, etc. require energy. The various components present in our food such as carbohydrates and proteins,

minerals provide energy to our body. These are also important for growth and development of the body.

Q2 : Distinguish between a parasite and a saprotroph.

Answer:

Parasite: – The organism that grows on the body of organism and derives nutrients from it known as a parasite.  Ex. Cuscuta and orchids

Saprotrophs:- The organism that obtains nutrients from another dead and decaying organic matter is called saprotroph. Ex. Fungi and some bacteria.

Q 3 : How would you test the presence of starch in leaves?

Answer:

1. Take a potted plant with variegated leaves – for example, money plant etc.
2. Keep the plant in a dark room for three days so that all the starch gets used up.
3. Now select a leaf cover its portion with a black strip paper and keep the plant in sunlight for about six hours.
4. Pluck the leaf from the plant. Mark the uncovered area in it and trace them on a sheet of paper.
5. Dip the leaf in boiling water for a few minutes.
6. After this, immerse it in a beaker containing alcohol.
7. Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil.
8. Now dip the leaf in a dilute solution of iodine for a few minutes.
9. Take out the leaf and rinse off the iodine solution.

You observe that the presence of starch in various areas of the leaf which was uncovered.

Q: 4 Give a brief description of the process of synthesis of food in green plants.

 Answer:

Photosynthesis is defined as the process in which the chlorophyll-containing plant cells synthesis food in the form of carbohydrates, using carbon dioxide and water in the presence of solar energy

During photosynthesis, chlorophyll containing cells of leaves, in the presence of sunlight, use carbon dioxide and water to synthesis carbohydrates the process can be represented as an equation:

                                               sunlight

carbohydrate. + water  _⎯⎯⎯⎯⎯⎯→   Carbon dioxide + oxygen

                                         chlorophyll

During the process oxygen is released. The carbohydrates ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis. The starch is also a carbohydrate.

Q: 5 Show with the help of a sketch that the plants are the ultimate source of food. 

Answer:                            

All the living being depends on plants whether directly or indirectly. For example, the plant eater animals depend directly on plants but carnivore depends indirectly on plants. The following sketch shows some examples of plant dependency.  

6. Fill in the blanks:

(a) Green plants are called autotrophs since they synthesis their own food.

(b) The food synthesized by the plants is stored as starch.

(c) In photosynthesis solar energy is captured by the pigment called chlorophyll.

(d) During photosynthesis plants take in carbon dioxide and release oxygen.

7. Name the following:

(i) A parasitic plant with yellow, slender and tubular stem. cascuta

(ii) A plant that has both autotrophic and heterotrophic mode of nutrition. Pitcher plants

(iii) The pores through which leaves exchange gases.     

8. Tick the correct answer:

(a) Amarbel is an example of:

(i) autotroph (ii) parasite (iii) saprotroph (iv) host  

(b) The plant which traps and feeds on insects is:

(i) Cuscuta (ii) china rose (iv) pitcher plant (iv) rose    

Answer:

(a) (ii) parasite     

(b) (iv) pitcher plant   

 Q: 9 Match the items given in Column I with those in Column II:

Column I                                      Column II

Chlorophyll                                Bacteria

Nitrogen                                     Heterotrophs

Amarbel                                     Pitcher plant

Animals                                      Leaf

Insects                                       Parasite

Answer 9:

Column I                                Column II

Chlorophyll                           Leaf

Nitrogen                               Bacteria

Amarbel                                Parasite

Animals                                Heterotrophs

 Insects                                 Pitcher plant

Q:10. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) Carbon dioxide is released during photosynthesis. (T/F)

(ii) Plants which synthesis their food themselves are called saprotrophs. (T/F)

(iii) The product of photosynthesis is not a protein. (T/F)

(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)

Answer:

(i) Carbon dioxide is released during photosynthesis. (False)

(ii) Plants which synthesis their food themselves are called saprotrophs.   (False)

(iii) The product of photosynthesis is not a protein. (True)

(iv) Solar energy is converted into chemical energy during photosynthesis. (True)

Q: 11. Choose the correct option from the following:

Which part of the plant takes in carbon dioxide from the air for photosynthesis?

(i) Root hair (ii) Stomata (iii) Leaf veins (iv) Sepals

Answer:

(ii) Stomata

Q: 12 Choose the correct option from the following:

Plants take carbon dioxide from the atmosphere mainly through their:        (i) roots (ii) stem (iii) flowers (iv) leaves

Answer:

(iv) leaves