Question

1. Plants can carry out both photosynthesis and respiration ____.(at the same time).

2. The primary substance we used to determine the presence or absence of CO2​ is ____.



3. When CO2​ levels decrease, the pH of the water _____. (increases/decreases).

Answer 1

1. Simultaneously (True). Plants respire all the time and photosynthesise when light is available.

2. Bromothymol blue (BTB) — a pH/CO2 indicator commonly used to detect CO2 in water. (Limewater is an alternative for detecting CO2 gas.)

3. Increases. Less dissolved CO2 means less carbonic acid, so the water becomes less acidic (pH rises).