Question 4
A green plant takes in water, carbon dioxide and light. Why is it still called autotrophic?
The right answer is the one marked above.
Because none of those is food — the plant assembles the food itself. Water and carbon dioxide are raw materials and light is an energy source. Autotrophic means making your own food, not needing nothing.
And grade 10 made the matching point: a plant still has to respire to get the energy out of the food it made. Photosynthesis is nutrition, not respiration.