Question

Why can't animals and humans make food from carbon dioxide and water in the presence of light, like plants do?

Answer 1

Its because the cell lacks of chlorophyll and are heterotropic.

Amd for the process of photosynthesis chlorophyl is essential.

Answer 2

Plants cell contain chloroplast in which chlorophyll is present which absorb ☀ and helps in exchanging the gases. Though the animal and human doesn't have chloroplast in which chlorophyll is present and they don't take carbon dioxide that's why they can't make their own food