The discovery that the first stable product of $CO_2$ fixation in photosynthesis is $3$-phosphoglyceric acid $(PGA)$ was made by whom?

Match the following:

$1. 1733-1804$	$p. Jan Ingenhousz$
$2. 1730-1799$	$q. T.W. Engelmann$
$3. 1897-1985$	$r. Joseph Priestley$
$4. 1843-1909$	$s. Cornelius Van Niel$

Which is the evidence to show that $O_2$ released in photosynthesis comes from water?

Variegated leaves of a plant were supplied with radioactive carbon dioxide $(^{14}CO_2)$ during an experiment. Leaf $X$ was kept in the dark and leaf $Y$ was kept in the light. At the end of the experiment,the radioactivity in the leaves was measured and found to be as shown in the diagram. What is the most likely explanation for the level of radioactivity found in the yellow zone of leaf $Y$?

Moll's half leaf experiment was done to show ...................... was required for photosynthesis.

The scientist who proved that bacteria use $H_2S$ gas and $CO_2$ to synthesize carbohydrates is