Lack of oxygen in muscles often leads to cramps among cricketers. This results due to:

$(a)$ Draw a diagram of the human urinary system and label the following parts:
$(i)$ Kidney
$(ii)$ Ureter
$(iii)$ Urinary bladder
$(iv)$ Urethra
$(b)$ Name the two major components of normal human urine.

Why is the rate of breathing in aquatic organisms much faster than that seen in terrestrial organisms?

$(a)$ Name the protein-digesting enzyme present in pancreatic juice and the hormone secreted by the pancreas.
$(b)$ What is the function of pancreatic juice?

Which of the following statements about the autotrophs is incorrect?

Which of the following statement$(s)$ is (are) correct?
$(i)$ Pyruvate can be converted into ethanol and carbon dioxide by yeast.
$(ii)$ Fermentation takes place in aerobic bacteria.
$(iii)$ Fermentation takes place in mitochondria.
$(iv)$ Fermentation is a form of anaerobic respiration.