Life Sciences - Term 3 - Week 1

Photosynthesis is the biochemical process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. This process primarily occurs in the chloroplasts of plant cells, where chlorophyll captures sunlight. The overall equation for photosynthesis can be summarized as: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2. This means that carbon dioxide and water, in the presence of light, are transformed into glucose and oxygen.

Let's analyze the photosynthesis equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2. Here, 6 molecules of carbon dioxide and 6 molecules of water react to produce one molecule of glucose and 6 molecules of oxygen. This illustrates how plants utilize carbon dioxide from the atmosphere and water from the soil, releasing oxygen as a byproduct, which is essential for the survival of aerobic organisms.

In groups, discuss the factors that can influence the rate of photosynthesis. Consider elements such as light intensity, carbon dioxide concentration, temperature, and water availability. For example, increased light intensity generally enhances the rate of photosynthesis up to a certain point, after which it may plateau. Record your findings and be prepared to share with the class.

Design an experiment to investigate how light intensity affects the rate of photosynthesis in aquatic plants, such as Elodea. Outline your hypothesis, the materials you will need, the procedure you will follow, and how you will measure the rate of photosynthesis. Be sure to consider control variables to ensure a fair test.

• Chlorophyll
• Carotene
• Xanthophyll
• Melanin

Answer: Chlorophyll

Chlorophyll is the main pigment that absorbs light energy for photosynthesis.

• Carbon dioxide
• Glucose
• Water
• Oxygen

Answer: Glucose

Glucose is produced during photosynthesis as a form of stored energy.

• Oxygen
• Nitrogen
• Carbon dioxide
• Hydrogen

Answer: Carbon dioxide

Plants absorb carbon dioxide from the atmosphere to use in photosynthesis.

Answer: Sunlight provides the energy needed to drive the chemical reactions of photosynthesis.

Without sunlight, plants cannot convert carbon dioxide and water into glucose.

• Light intensity
• Temperature
• Soil pH
• Carbon dioxide concentration

Answer: Soil pH

While soil pH can affect plant health, it does not directly influence the rate of photosynthesis.

Answer: Light-dependent reactions and light-independent reactions (Calvin cycle).

These stages work together to convert light energy into chemical energy.

• To produce oxygen
• To create glucose
• To absorb carbon dioxide
• To release energy

Answer: To create glucose

The primary purpose of photosynthesis is to produce glucose, which serves as energy for the plant.