Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra.

“All plants give out oxygen during day and carbon dioxide during night”. Do you agree with this statement? Give reason.

Name any two substances which are selectively reabsorbed from the tubules of a nephron.

$(a)$ Name the following:
$(i)$ Part in which urine is produced.
$(ii)$ Part which stores the urine.
$(iii)$ Part which connects $(i)$ and $(ii)$.
$(iv)$ Part from which urine is passed out.
$(b)$ Name the factors on which the amount of water reabsorbed along the tubular part of the nephron depends.

Explain the process by which the energy requirements of autotrophic organisms are fulfilled. In which form are the unused carbohydrates stored?

When a sportsman runs,he gets muscle cramps. Why?