Nutrition — Important Questions

Carbon dioxide, Water, Sunlight

Photosynthesis requires carbon dioxide from air, water from soil, and sunlight as energy source. Oxygen and glucose are products, not raw materials.

Humans, Animals, Fungi

Heterotrophs cannot make their own food and depend on other organisms. Humans, animals, and fungi are heterotrophs, while green plants and algae are autotrophs.

Small intestine

The small intestine is about 6-7 meters long and is the longest part of the alimentary canal. It is the main site for digestion and absorption of nutrients.

Villi, Microvilli

Villi are finger-like projections and microvilli are tiny projections on villi that greatly increase surface area for absorption. Peristalsis is movement and sphincters control flow.