Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Photosynthesis is the fundamental process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide () and water ().
The process takes place primarily in the leaves, inside specialized organelles called chloroplasts, which contain the green pigment chlorophyll.
Chlorophyll absorbs light energy, which is used to drive the chemical reaction between and .
The primary product is glucose (), a simple sugar that serves as an energy source for the plant.
Oxygen () is produced as a byproduct and is released into the atmosphere through small pores in the leaves called stomata.
Glucose produced during photosynthesis can be converted into starch for storage, or used in respiration to provide energy for growth.
Factors that affect the rate of photosynthesis include light intensity, the concentration of , and temperature.
📐Formulae
💡Examples
Problem 1:
During an experiment, a student places an aquatic plant in a beaker of water and shines a light on it. They observe bubbles forming on the leaves. Identify the gas in the bubbles and explain why it is being produced.
Solution:
The gas is oxygen ().
Explanation:
When the plant is exposed to light, it performs photosynthesis. The chemical reaction produces oxygen as a byproduct. In aquatic plants, this oxygen is released into the water as visible bubbles.
Problem 2:
A plant is kept in a dark cupboard for 48 hours. When the leaves are tested with iodine solution, they do not turn blue-black. Why?
Solution:
The leaf contains no starch, so the iodine remains orange/brown.
Explanation:
Plants store excess glucose () as starch. Without light, the plant cannot perform photosynthesis to produce glucose. Over 48 hours, the plant uses up its stored starch for energy through respiration, leaving no starch to react with the iodine.