Ans.a).
Chloroplasts are membrane-bound organelles, present in photosynthetic plants and contain green-colored pigment, chlorophyll. Chloroplasts help in the process of photosynthesis.
During summer, there is enough sunlight to spend energy in growing the leaves, so there are more chloroplasts and leaves appear green as chlorophyll presents at chief pigment.
In autumn, there is not enough sunlight and cells of plants stop to make chloroplasts as there is not enough sunlight that can be used for growing of leaves. Thus, there are more chloroplasts in June as compared to October.
Ans.b).
Chloroplasts are responsible for the light absorption during photosynthesis. The process of photosynthesis mainly occurs in the cells of plant leaves and green stems as compare to cells of roots as these cells are in direct contact with sunlight. Thus, there are more chloroplasts in the leaves as compare to roots.