Grade 9 · Biology

Grade 9 Biology — Photosynthesis questions and answers

A top US biology search: sun, CO₂, and glucose. Written in American English for students, parents, and teachers in the United States.

Practice quiz

Question and answer list

Open a card to see the answer. These are original practice items for US elementary students — not a state test copy.

1. Photosynthesis mainly occurs in

Answer: chloroplasts

Chlorophyll captures light.

2. The overall products of photosynthesis are

Answer: glucose and oxygen

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.

3. Plants take in carbon dioxide through

Answer: stomata

Guard cells open and close stomata.

4. The energy source for photosynthesis is

Answer: sunlight

Light energy becomes chemical energy.

5. Chlorophyll appears green because it

Answer: reflects green wavelengths

It absorbs red and blue light more.

6. Cellular respiration

Answer: breaks down glucose to make ATP

It is roughly the reverse energy path of photosynthesis.

7. A limiting factor for photosynthesis can be

Answer: light intensity, CO₂, or temperature

Too little light slows the rate.

8. Oxygen released by plants comes mainly from

Answer: water

Light reactions split water.