1. The kidneys in human beings are a part of the system for (a) nutrition (b) respiration (c) excretion (d) transportation

Solution:

The answer is (c) excretion

The excretory system of human beings (Fig. 6.13) includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one on either side of the backbone. Urine produced in the kidneys passes through the ureters into the urinary bladder, where it is stored until it is released through the urethra.