Study the given flow chart about respiratory structures in different organisms. Identify the organisms P, Q, R, S, and select the correct option.

Three test tubes are set-up as shown. The indicator used here changes from red to yellow when exposed to increased levels of carbon dioxide. At the start of the experiment, the indicator in each test tube was red.

What will be the colour of the indicator in each test tube after two hours?

The given diagram shows a respirometer that is used to measure gaseous exchange in gram seeds. The apparatus is maintained at a constant temperature.

Which of the following is correct regarding it?
(i) The gas pressure in $\mathrm{X}$ will fall as ${\mathrm{O}}_2$ is absorbed during respiration and ${\mathrm{CO}}_2$ is absorbed by potassium hydroxide solution.
(ii) The fluid level at $\mathrm{Y}$ will fall to compensates the loss of pressure in $\mathrm{X}$.
(iii) The gas pressure in $\mathrm{X}$ will rise as ${\mathrm{O}}_2$ is given out by seeds and ${\mathrm{CO}}_2$ is released by potassium hydroxide solution.
(iv) The fluid level at $\mathrm{Z}$ will rise due to loss of pressure in $\mathrm{X}$.

Rohan set-up an experiment as shown in the figure. What will he observe after sometime?