Question

A scientist feels a glass container with water in places and aquatic plant inside the container, then closes the lid and places the container in direct sunlight. The scientist observed small bubbles on the surface of the plant's leaves on days one and two, but no bubbles on day three. The scientist concludes that the bubbles were caused by photosynthesis. Which substance should be added to the water in order for the bubbles to reappear? (1 point)

A) glucose

B) oxygen

C) carbon dioxide

D) hydrogen gas

Answer 1

C) carbon dioxide

Photosynthesis requires CO2 (plus light and water) to produce sugars and release O2. In a closed container CO2 can become depleted, stopping photosynthesis and bubble production; adding CO2 would restore it.