Question

Give reasons for the following: 

(i) Plants begin to die when excess of soluble fertilizers are added to the soil. 

(ii) Injury to the medulla oblongata results in death. 

(iii) Gametes have a haploid number of chromosomes. 

(iv) Green leaves are thin and broad. 

(v) Lysosomes are termed suicidal bags of a cell.

Answer 1

(i) Because of plasmolysis of plant cells due to hypertonic solutions of fertilizers. 

(ii) Because due to injury in medulla oblongata, the projecting process of the axis vertebra in the neck pierces it. As a result the involuntary actions such as breathing and heart beat are stopped. 

(iii) Because gametes undergo meiosis (reduction) cell division in which the number of chromosomes becomes half. 

(iv) Green leaves are thin and broad so that more surface area is exposed to sunlight for photosynthesis.