Questions: Photosynthesis Introduction

Question 1

What are the raw materials (inputs) needed for photosynthesis?

• A. Glucose and oxygen
• B. Carbon dioxide, water, and sunlight
• C. Soil, minerals, and water
• D. Oxygen and glucose

Answer: (B)

Photosynthesis uses three inputs: carbon dioxide (from the air, entering through leaf pores called stomata), water (absorbed by roots from the soil), and sunlight (captured by chlorophyll in chloroplasts). These are converted into glucose (the plant's food) and oxygen (released as a byproduct). Glucose and oxygen are the OUTPUTS, not inputs.

Question 2

Plants get their food by absorbing it from the soil through their roots.

• T. True
• F. False

Answer: False

Plants absorb water and minerals from the soil, but their actual food — glucose — is made inside the plant through photosynthesis. The carbon in glucose comes from carbon dioxide in the air, not from the soil. This is one of the most common misconceptions in biology: plants make their own food using light energy.

Question 3

Explain why photosynthesis is important not just for plants but for almost all life on Earth.

Model answer: Photosynthesis produces glucose, which is the energy source at the base of nearly every food chain — herbivores eat plants, carnivores eat herbivores, and so on. It also produces oxygen, which most organisms (including animals and the plants themselves) need for cellular respiration. Without photosynthesis, there would be almost no food and very little oxygen on Earth.

Photosynthesis connects to two fundamental requirements of life: food (energy) and oxygen. It is the process that makes Earth habitable — the oxygen in our atmosphere was produced by photosynthetic organisms over billions of years.