(i) Green plants are the only organisms present nature can trap solar energy with the help of green chlorophyll to make their own food through photosynthesis. The other organisms directly or indirectly depend on plants. Herbivores directly depend on plants while carnivores get their food through herbivores which in turn get their food from plants.
(ii) The erythrocyte lacks nucleus and mitochondria to accommodate more hemoglobin pigment in it. Lack of mitochondria in erythrocyte cell will help to save the oxygen to be transported to the cells and tissues of the body.
(iii) The cells of potato cube have hyper-tonic solution when compared to outer hypo tonic water. Due to end osmosis water enter into potato cells and become turgid. Due to this potato cubes become firm and rigid.
(iv) In summer through perspiration our body loose more water. Less water is involved in the formation of and hence it is thicker. During winter, water loss through sweating is very minimum and hence more water is available for the formation of and hence it is thinner as well as more in quantity.
(v) Simple goiter is caused due to the nutritional deficiency of iodine. The crops grown in hilly region do not contain any iodine due to leaching away of the iodine during rains. Such food taken from these crops leads to deficiency of iodine and causes this defect to the people.
