PHOTOSYNTHESIS: CALVIN CYCLE || Grade 9 Science _ BIOLOGY

Summary

This educational video delves into the light-independent reaction of photosynthesis, known as the Calvin Cycle. It explains how plants convert carbon dioxide and water into glucose using ATP and NADPH from the light-dependent reaction. The Calvin Cycle, named after Nobel laureate Melvin Calvin, occurs in the chloroplast stroma and consists of three stages: carbon fixation, reduction, and regeneration. The video uses an interactive simulation to illustrate these stages, concluding with a summary of photosynthesis, emphasizing the conversion of light energy into chemical energy stored in glucose.

Takeaways

• 🌿 Photosynthesis is a process where plants make their own food using light energy, carbon dioxide, and water.
• 🔬 The process involves two stages: the light-dependent reaction and the light-independent reaction, also known as the Calvin cycle.
• 🏆 The Calvin cycle is named after Melvin Calvin, who won the 1961 Nobel Prize for his work on this set of chemical reactions.
• 🌱 The Calvin cycle occurs in the chloroplast stroma and is initiated after the light-dependent reaction, which provides ATP and NADPH.
• ➡️ The cycle has three stages: carbon fixation, reduction, and regeneration, each catalyzed by different enzymes.
• 🔄 Carbon fixation involves the combination of CO2 with RuBP (ribulose bisphosphate) to form an unstable 6-carbon compound, which then splits into two 3-PGA (3-phosphoglycerate) molecules.
• ⚡️ The reduction phase uses ATP and NADPH to convert 3-PGA into G3P (glyceraldehyde 3-phosphate), which involves the enzyme glyceraldehyde 3-phosphate dehydrogenase.
• 🔁 The regeneration stage involves using G3P to regenerate RuBP, allowing the cycle to continue, with energy from ATP.
• 🌱 For every six CO2 molecules that enter, two molecules of glucose are produced, and the rest are used to regenerate RuBP for the next cycle.
• 🔗 The Calvin cycle is crucial for converting inorganic carbon into organic compounds like glucose, which are essential for plant growth and energy storage.

Q & A

What is the meaning of the term 'photosynthesis'?

Photosynthesis means to put together by light, referring to the process where plants make their own food using light energy.

What are the raw materials needed for photosynthesis?

The raw materials needed for photosynthesis are carbon dioxide and water.

What are the products of the light-dependent reaction in photosynthesis?

The products of the light-dependent reaction are ATP, NADPH, and oxygen.

Who is the Calvin cycle named after and why?

The Calvin cycle is named after Melvin Calvin, who won the 1961 Nobel Prize for working out the complex set of chemical reactions involved in this cycle.

Where does the Calvin cycle occur in a plant cell?

The Calvin cycle occurs in the chloroplast stroma of plant cells, just after the light reaction of photosynthesis.

What are the three stages of the Calvin cycle?

The three stages of the Calvin cycle are carbon fixation, reduction, and regeneration.

What is the role of ATP and NADPH in the Calvin cycle?

ATP provides the energy for the Calvin cycle, and NADPH provides the reducing ability, both of which are supplied by the light-dependent reactions of photosynthesis.

How does carbon dioxide enter the Calvin cycle?

Carbon dioxide enters the Calvin cycle by diffusing into the stroma of the chloroplast and combining with RuBP (ribulose bisphosphate).

What is the enzyme that catalyzes the carbon fixation stage of the Calvin cycle?

The enzyme that catalyzes the carbon fixation stage of the Calvin cycle is RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase).

What is the role of G3P (glyceraldehyde 3-phosphate) in the Calvin cycle?

G3P is the final product of the Calvin cycle, with one molecule being used to form glucose and the others being recycled to regenerate RuBP for the continuation of the cycle.

How does the Calvin cycle regenerate RuBP?

The Calvin cycle regenerates RuBP by using five G3P molecules, which are converted back into RuBP using energy from ATP.