Home / Summaries / Bio H / light-energy-photosynthesis

Cellular energy - photosynthisis

17 important questions on Cellular energy - photosynthisis

What are chloroplasts and their function in photosynthesis?

Chloroplasts are large organelles that capture light energy from the Sun. They are found in plants and other photosynthetic organisms. The captured energy is stored in two energy storage molecules—ATP and NADPH—that will be used in light-independent reactions.

Describe what are photosystem I and photosystem II made of.

Photosystem I and photosystem II are made of pigments that absorb light and proteins that are important in light reactions.

What are CAM plants?

Another alternative pathway is called the CAM pathway. CAM plants live in deserts, salt marshes, and other environments where access to water is limited. Cacti and orchids are CAM plants. Carbon dioxide enters the leaves of CAM plants only at night, when the atmosphere is cooler and more humid. The plants also fix carbon dioxide into organic compounds at night. During the day, carbon dioxide is released from organic compounds in the plants. The carbon dioxide enters the Calvin cycle at that point. The CAM pathway minimizes water loss, while allowing for adequate carbon uptake.

What is the role of pigments in photosynthesis?

Thylakoids contain light-absorbing colored molecules known as pigments. Different pigments absorb different wavelengths of light. Chlorophylls are the major light-absorbing pigments in plants. They absorb energy from violet-blue light and reflect green light, giving plants their green color.

What is the main idea of the section on photosynthesis?

Light energy is trapped and converted into chemical energy during photosynthesis.

Identify on the figure, highlight the path that electrons follow. What molecule is the electron’s final destination?

The electrons move from photosystem II and move along a series of electron-carriers to photosystem I. The electrons are moved to NADP⁺, forming the energy-storage molecule NADPH.

How does electron transport work?

Photosynthesis begins when light energy causes electrons in photosystem II to go into a high energy state. The light energy also causes a water molecule to split, releasing an electron into the electron transport system, a hydrogen ion into the thylakoid space, and oxygen as a waste product. The excited electrons move from photosystem II and move along a series of electron-carriers to photosystem I. Photosystem I absorbs more light, and the excited electrons move along electron-carriers again. Finally, the electrons are moved to NADP⁺, forming the energy-storage molecule NADPH.

What is the role of rubisco in the Calvin cycle?

The enzyme rubisco changes ten 3-carbon molecules into six 5-carbon molecules to continue the cycle. Because rubisco changes carbon dioxide molecules into organic molecules that can be used by the cell, it is considered one of the most important enzymes.

How do accessory pigments assist in photosynthesis?

Accessory pigments help plants absorb additional light. For instance, carotenoids absorb blue and green light and reflect yellow, orange, and red light. Carotenoids give carrots and sweet potatoes their orange color.

Why do the leaves of some trees change colors in autumn?

Accessory pigments are the reason leaves change colors in autumn. In green leaves, there is so much chlorophyll that it masks the other pigments. In autumn, as trees prepare to lose their leaves, the chlorophyll molecules break down, revealing the colors of other pigments. The colors red, yellow, and orange can be seen.

How is ATP made during photosynthesis?

ATP is made when light energy causes the water molecule to split into oxygen and two hydrogen ions (H⁺), or protons. Protons build up inside the thylakoid. Protons diffuse through ion channels into the stroma where the concentration is lower. These channels are enzymes called ATP synthases. As protons move into the stroma, ATP is formed.

What does nearly all life on Earth depend on?

Nearly all life on Earth depends on photosynthesis.

What is the chemical equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

How many phases does photosynthesis occur in, and what are they?

Photosynthesis occurs in two phases. In phase one—the light-dependent reactions—and in phase two—the light-independent reactions.

What happens in phase one of photosynthesis?

In phase one—the light-dependent reactions—light energy is absorbed and changed into chemical energy in the form of ATP and NADPH.

What happens in phase two of photosynthesis?

In phase two—the light-independent reactions—the ATP and NADPH that were formed in phase one are used to make glucose.

How can glucose be used in cells?

Glucose can be joined with other simple sugars to form larger molecules such as complex sugars and carbohydrates. Sugar can also be changed into other molecules needed by the cell, such as proteins, lipids, and nucleic acids.

The question on the page originate from the summary of the following study material: