Class 7 Science Chapter 10 HOTS Questions - Life Processes in Plants

Q1: Except plants, why can’t other living organisms prepare their food using CO₂, water and minerals?
Ans: Our body does not contain chlorophyll for absorbing solar energy which is necessary for preparing food using air, water, etc.

Q2: A unique feature in leaves allows them to prepare the food while other parts of plants cannot. Write the possible reason for this.
Ans: Leaves contain chlorophyll which is essential for food preparation and is absent in other parts of plant.

Q3: A goat eats away all the leaves of a small plant (balsam). However, in a few days, new leaves could be seen sprouting in the plant again. How did the plant survive without leaves?
Ans: The plant of balsam survived on the food stored in the stem and roots.Q4: Plants are considered an essential part of earth as they keep a check on lot of process occurring all over. What would happen if all the green plants are wiped from earth?
Ans: Green plants are the source of energy for all the living organisms so that they can perform their normal functions. If all green plants and trees disappear, all the organism depending on them for food and shelter will also die. The lack of gaseous exchange will lead to increase in amount of CO₂, causing death in humans and other animals also. The cycle of life will gradually disappear.

Q5: During a starch test, a leaf is partially covered to block light and partially exposed to sunlight. After decolourisation and applying iodine, which parts turn blue-black? What does this prove?
Ans: Only the exposed green parts turn blue-black (starch present); the covered/non-green parts stay brown (no starch). This proves that chlorophyll and sunlight are essential for photosynthesis (starch formation) in leaves.

Q6: Some plants have deep red, violet or brown coloured leaves. Can these leaves perform the photosynthesis process? 
Ans: Yes, plants having deep red, violet or brown coloured leaves can also carry out photosynthesis because they contain chlorophyll. But their green colour of chlorophyll is masked by the large amount of all other coloured pigments.
Q7: Potato and ginger are both underground parts that store food. Where is the food prepared in these plants? 
Ans: In both the plants, shoot system and leaves are above ground. They prepare food through photosynthesis and transport it to the underground part for storage.Q8: Sunlight, chlorophyll, carbon dioxide, water and minerals are raw materials essential for photosynthesis. Do you know where they are available? Fill in the blanks with the appropriate raw materials.
(a) Available in the plant: ______
(b) Available in the soil: ______
(c) Available in the air: ______
(d) Available during day : ______ 
Ans:
(a) Available in the plant: chlorophyll
(b) Available in the soil : water, minerals
(c) Available in the air : carbon dioxide
(d) Available during day : sunlight

Q9: Which of the following statements is/are correct?
(i) All green plants can prepare their own food.
(ii) Most animals are autotrophs.
(iii) Carbon dioxide is not required for photosynthesis.
(iv) Oxygen is liberated during photosynthesis.
Choose the correct answer from the options below: 
(a) (i) and (iv)
(b) only (ii)
(c) (ii) and (iii)
(d) (i) and (ii)
Ans: (a)  (i) and (iv) are correct statements and (ii) and (iii) are incorrect. Because (ii) animals are heterotrophs and (iii) CO₂ is necessary for photosynthesis. Green plants prepare their own food from CO₂ and H₂O.

Q10: Which of the following raw material is available in the air for photosynthesis? 
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen
Ans: (b) Carbon dioxide