CBSE Class 10 Answered

A) Dark yellow urine indicates concentrated urine and the excretion of waste products in a smaller quantity of water. During summer, we sweat more in order to maintain our body temperature. So, more water is lost from our body. If we do not drink sufficient water, then there is a greater chance of excreting yellowish urine in summer.

B) The mucous cells and gastric pits produce mucosa. The stomach is protected by the epithelial cells, which produce and secrete a bicarbonate-rich solution that coats the mucosa. Bicarbonate is alkaline, a base, and neutralizes the acid secreted by the parietal cells, producing water in the process.