Photosynthesis: Comparing C3, C4 and CAM

Summary

This tutorial explains the three types of photosynthesis: C3, C4, and CAM. C3 photosynthesis is the most common, involving the fixation of CO2 into a 3-carbon molecule, but can be limited in hot or dry conditions. C4 photosynthesis modifies the location of the process, reducing oxygen buildup during dry conditions, while CAM photosynthesis changes the timing, with CO2 fixation occurring at night. These adaptations help plants thrive in diverse environments, such as those that are too hot or dry for typical C3 plants.

Takeaways

• 😀 Photosynthesis is the process where plants capture sunlight to make carbohydrates.
• 😀 There are three types of photosynthesis: C3, C4, and CAM, each adapted to different environmental conditions.
• 😀 C3 photosynthesis is the most common type, used by around 85% of plants.
• 😀 The name 'C3' refers to the 3-carbon molecule produced during the process of photosynthesis.
• 😀 In C3 photosynthesis, CO2 is taken up and directly transported to the Calvin Cycle in mesophyll cells.
• 😀 When stomata are closed during hot or dry conditions, oxygen buildup occurs, reducing the efficiency of C3 photosynthesis.
• 😀 C4 photosynthesis involves CO2 being fixed into a 4-carbon molecule in mesophyll cells, offering better performance in hot or dry climates.
• 😀 C4 plants have a distinct anatomical structure, with chloroplasts in both mesophyll cells and bundle sheath cells.
• 😀 C4 photosynthesis shields plants from oxygen buildup when stomata are closed by moving CO2 to bundle sheath cells for the Calvin Cycle.
• 😀 CAM photosynthesis alters the timing of photosynthesis, with CO2 being absorbed at night and stored as a 4-carbon molecule for use during the day.
• 😀 CAM plants, like cacti, thrive in dry climates due to their ability to fix CO2 at night and avoid water loss during the day.

Q & A

What is photosynthesis?

Photosynthesis is the process by which plants capture the energy from the sun to produce carbohydrates, which are used as a source of energy for the plant.

Why are there variations in how plants perform photosynthesis?

There are variations in photosynthesis due to environmental factors. Plants adapt to different conditions like temperature and moisture, leading to variations in the process.

What are the three types of photosynthesis discussed in the script?

The three types of photosynthesis discussed are C3, C4, and CAM photosynthesis.

What does the 'C3' in C3 photosynthesis refer to?

The 'C3' refers to the type of carbon molecule produced during the process, specifically a 3-carbon molecule formed in the Calvin Cycle.

What is the role of the mesophyll cells in C3 photosynthesis?

In C3 photosynthesis, the mesophyll cells are where CO2 is taken up and directly transported to the Calvin Cycle, where it is fixed into a 3-carbon molecule.

How does the stomata influence photosynthesis in C3 plants?

When the stomata are open, CO2 enters the plant and oxygen exits. However, in hot or dry conditions, when the stomata close, oxygen accumulates and inhibits the production of C3.

What is C4 photosynthesis, and how is it different from C3?

C4 photosynthesis involves CO2 being fixed into a 4-carbon molecule in the mesophyll cells, which is then moved to bundle sheath cells. This adaptation helps the plant overcome oxygen buildup during dry conditions.

How does the anatomy of C4 plants differ from C3 plants?

In C4 plants, chloroplasts are found in both mesophyll cells and bundle sheath cells, surrounding the leaf vein, which is not the case in C3 plants.

What is CAM photosynthesis, and how does it differ from C4?

CAM photosynthesis is similar to C4 but differs in timing. CO2 is taken up at night when the stomata are open and stored as a 4-carbon molecule until daylight, allowing the plant to perform photosynthesis in drier climates.

Why is CAM photosynthesis beneficial for plants in drier climates?

CAM photosynthesis allows plants to conserve water by opening their stomata at night rather than during the heat of the day, making it an effective adaptation for survival in arid environments.