Section outline

    • Q1. Why do organisms take food?

      Ans:

      Organisms take food:

      • To obtain energy & nutrients.
      • For growth & maintenance of their bodies.
      • To repair damaged parts.
      • For survival.
      Q2. Distinguish between a parasite and a saprotroph.

      Ans:

      Parasite Saprophyte
      It derives nutrients from a host plant, often harming it. It derives nutrients from dead & decaying matter.
      Eg: Cuscuta Eg: fungi, mushroom
      Q3. How would you test the presence of starch in leaves? 

      Ans:

      • The presence of starch and leaves can be tested using iodine test.
      • Boil a green leaf in water for few minutes till it becomes soft.
      • Then soak this leaf in alcohol till it decolorizes it. This removes the chlorophyll from the leaf.
      • Now dip this leaf in iodine solution.
      • The leaf turns bluish black.
      • This indicates the presence of starch in the leaf.
      Q4. Give a brief description of the process of synthesis of food in green plants.

      Ans:

      • Green plants synthesize their food through the process of photosynthesis.
      • They have chlorophyll in their leaves.
      • Chlorophyll captures sunlight to convert carbon dioxide & water into carbohydrate (glucose) & oxygen is released.

      Q5. Show with the help of a sketch that plants are the ultimate source of food.

      Ans:

      Food chain

      Q6. Fill in the blanks:

      Ans:

      (a) Green plants are called autotrophs.

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

      (c) In photosynthesis, solar energy is absorbed by chlorophyll.

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

      Q7. Name the following:

      Ans:

      (i) A parasitic plant: Cuscuta.

      (ii) A partially autotrophic plant: Pitcher plant.

      (iii) Pores for gas exchange: Stomata.

      Q8. Tick the correct answer:

      Ans:

      (a) Cuscuta is an example of: (ii) parasite.

      (b) The plant that traps insects is: (iii) pitcher plant.

      Q9. Match the items given in Column I with those in Column II:

      Ans:

      Column I Column II
      Chlorophyll Leaf
      Nitrogen Rhizobium 
      Cuscuta Parasite
      Animals Heterotrophs
      Insects Pitcher Plant
      Q10. Mark ‘T’ if the statement is true and ‘F’ if it is false:

      Ans:

      (i) Carbon dioxide is released during photosynthesis. = F

      (Oxygen & water is released during photosynthesis)

      (ii) Plants that synthesize food are called saprotrophs. = F

      (They are called autotrophs)

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

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

      Q11. Choose the correct option from the following:

      Ans:

      Which part of the plant takes in carbon dioxide from the air for photosynthesis? (ii) Stomata

      Q12. Choose the correct option from the following:

      Ans:

      Plants take carbon dioxide mainly through their: (iv) leaves

      Q13. Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?

      Ans:

      • Farmers use greenhouses to create controlled environments that optimize light, temperature, heat & humidity for required for the growth of fruits and vegetable crops.
      • This leads to better yields & protection from pests.

      Advantages:

      • It protects the crops from pests, diseases & external climatic conditions.
      • It increases the crop production.