Question

Osmoregulation is essential to all organisms as it maintains homeostasis of the organism's water content.
Osmoregulation in unicellular freshwater organisms like amoebas and paramecia involves an organelle called the contractile vacuole, which collects excess water as it accumulates in the cell and pumps it out. The graphs above plot contraction rate in contractile vacuoles vs. surrounding solution concentrations.
Which of the graphs correctly illustrates the results obtained when Paramoecium is placed in increasingly hypertonic solutions?

• A. A
• B. B
• C. C
• D. D

Answer 1

The correct option is A A

Contractile vacuoles are the special types of vacuoles present in unicellular organisms like Paramoecium and multicellular organisms like sponges and hydras. These vacuoles help in maintaining the osmolarity of the cell by pumping out water and also storing it. When the concentration of the water increases in the cell, these vacuoles will perform the active contraction for removing it. Higher the concentration of water more will be the contractions performed by these vacuoles. As the concentration of the water in the cell decreases, their contractions will also decrease.

Hence, the correct answer is 'Option A'