Fotosíntesis

Q & A

What is the primary function of chloroplasts in plant cells?

Chloroplasts are specialized organelles in plant cells responsible for photosynthesis. They contain a pigment called chlorophyll, which gives plants their green color and allows them to absorb light energy for the photosynthetic process.

How is the structure of a chloroplast designed to support photosynthesis?

Chloroplasts have a double membrane structure that encloses a fluid-filled space called the stroma. Inside the stroma are thylakoids, which are disk-like structures where the light-dependent reactions of photosynthesis occur.

What is the significance of the thylakoids in chloroplasts?

Thylakoids are membrane-bound structures that contain chlorophyll, the pigment responsible for capturing light energy. The light-dependent reactions of photosynthesis take place in the membranes of the thylakoids.

What is the difference between the light-dependent and light-independent (dark) reactions of photosynthesis?

The light-dependent reactions occur in the thylakoid membranes and require light to generate energy molecules like ATP and NADPH. The light-independent reactions, or Calvin Cycle, occur in the stroma and use ATP and NADPH to convert carbon dioxide into glucose.

What is the role of water in photosynthesis?

Water is absorbed by the plant roots and is split in the light-dependent reactions. This process, called photolysis, releases oxygen as a byproduct and provides electrons and hydrogen ions necessary for the formation of ATP and NADPH.

What are ATP and NADPH, and why are they important in photosynthesis?

ATP (adenosine triphosphate) and NADPH are energy molecules produced during the light-dependent reactions. ATP serves as a battery for energy storage, while NADPH is used to provide reducing power in the Calvin Cycle to produce glucose.

What happens during the photosystem II process in the light-dependent reactions?

In Photosystem II, chlorophyll molecules absorb light energy, exciting electrons. These excited electrons pass through a series of molecules in an electron transport chain, releasing energy used to pump protons and generate ATP.

What is the function of the Calvin-Benson Cycle in photosynthesis?

The Calvin-Benson Cycle, or dark reactions, occurs in the stroma and involves the fixation of carbon dioxide into organic molecules. It uses ATP and NADPH produced during the light-dependent reactions to form glucose and other organic compounds.

How does the Calvin-Benson Cycle begin and what are the products formed?

The Calvin-Benson Cycle begins with the capture of carbon dioxide by ribulose bisphosphate (RuBP). The unstable compound formed quickly splits into two molecules of 3-phosphoglycerate (PGA), which are further reduced to form sugars like glucose.

Why is photosynthesis crucial for life on Earth?

Photosynthesis is vital because it produces oxygen, which is necessary for the survival of aerobic organisms. It also forms glucose, the primary energy source for most life forms, and reduces the amount of carbon dioxide in the atmosphere, helping to maintain Earth's climate balance.