Question

Give reasons for the following:
a) All plants are autotrophic. Do you agree?
b) Why food need to be digested?
c) Why is nitrogenous fertilizers not added in soil in which leguminous plants are grown?

Answer 1

a. no all plants are not autotrophic as some of plants lacks green pigment chlorophyll.And they are of parasitic nature. 
b. foods needed to be digested as when we intake food then it is in complex form and it need to be break down into simpler form to be absorbed by organs to perform life process activities
c.because in leguminous plants (i.e gram and pea ) there are nitrogen fixing bacteria present in the root nodules of the leguminous plants.

Answer 2

a. all plants are not autotrophic because  autotrophic plants can make their own food with the help of abiotic components but there are parasitic plant which is totally dependent upon its host
b. it is necessary for food to get digested because the food which we eat is complex ,  it  is broken down and digested into simpler form so that all the nutrients are easily reached to different organs in our body
c. leguminous plants have a bacteria named rhizobium  in its roots which converts the nitrogen gas into nitrates which is then absorbed by the plant .pulses,soyabean are leguminous plant they are rich in protein because nitrates help the plant to make more protein