photosynthesis

Question 1

How is energy related to the wavelength of light?

Answer 1

Energy is inversely proportional to wavelength; shorter wavelengths have higher energy.

Question 2

What are the main parts of a chloroplast?

Answer 2

Outer membrane, inner membrane, stroma, thylakoids, and grana.

Question 3

Where do light-dependent reactions occur in the chloroplast?

Answer 3

In the thylakoid membrane.

Question 4

Where does the Calvin cycle occur in the chloroplast?

Answer 4

In the stroma.

Question 5

What are photosynthetic pigments?

Answer 5

Molecules that absorb light energy for photosynthesis, including chlorophylls and carotenoids.

Question 6

What is an absorption spectrum?

Answer 6

The range of light wavelengths that a pigment can absorb.

Question 7

How does chlorophyll a compare to accessory pigments?

Answer 7

Chlorophyll a is the primary pigment, while accessory pigments like chlorophyll b and carotenoids broaden the range of light absorption.

Question 8

Where are photosynthetic pigments located in the chloroplast?

Answer 8

In the thylakoid membranes.

Question 9

What are the inputs and outputs of the light-dependent reactions?

Answer 9

Inputs: water, light, ADP, NADP+. Outputs: ATP, NADPH, and oxygen.

Question 10

Q: What are the inputs and outputs of the carbon fixation reactions?

Answer 10

A: Inputs: COz, ATP, NADPH. Outputs: glucose, ADP, NADP+.

Question 11

Q: What is the generalized equation for photosynthesis?

Answer 11

• A: 6 CO2 + 6H20 + light → C6H12O6 + 6O2

Question 12

Q: How is photosynthesis a redox process?

Answer 12

A: CO, is reduced to glucose, and H20 is oxidized to release oxygen.

Question 13

Q: What is the structure of a photosystem?

Answer 13

• A: A photosystem has a reaction center surrounded by light-harvesting complexes that contain pigments.

Question 14

Q: What happens in Photosystem Il?

Answer 14

• A: It absorbs light, exciting electrons, which initiates the electron transport chain and leads to ATP synthesis.

Question 15

Q: What replenishes chlorophyll a’s lost electrons in Photosystem II?

Answer 15

• A: Water is split in photolysis, releasing electrons, protons, and oxygen.

Question 16

Q: What happens when chlorophyll a absorbs a photon?

Answer 16

• A: An electron is excited to a higher energy level, starting the electron transport chain.

Question 17

• Q: What is photolysis?

Answer 17

• A: The splitting of water by light in Photosystem Il, providing electrons and producing oxygen.

Question 18

• Q: Describe the flow of electrons in noncyclic electron transport.

Answer 18

• A: Electrons flow from water through Photosystem II to Photosystem I, producing ATP and NADPH.

Question 19

Q: What products are produced in noncyclic electron transport?

Answer 19

• A: ATP, NADPH, and oxygen.

Question 20

Q: What is the final electron acceptor in noncyclic electron transport?

Answer 20

• A: NADP+, which becomes NADPH.

Question 21

Q: Describe electron flow in cyclic electron transport.

Answer 21

• A: Electrons cycle back to Photosystem I to produce additional
ATP without generating NADPH.

Question 22

Q: Describe electron flow in cyclic electron transport.

Answer 22

• A: Electrons cycle back to Photosystem I to produce additional
ATP without generating NADPH.

Question 23

Q: Why is cyclic electron transport important?

Answer 23

• A: It helps balance the ATP and
NADPH supply needed for the Calvin cycle, involving only Photosystem I.

Question 24

• Q: How is a proton gradient established in the thylakoid membrane?

Answer 24

• A: Protons accumulate inside the thylakoid, creating a gradient that drives ATP synthesis as they flow back out.

Question 25

Q: What are the three phases of the Calvin cycle?

Answer 25

• A: Carbon fixation, reduction, and regeneration of RuBP.

Question 26

• Q: What role does ATP play in the Calvin cycle?

Answer 26

• A: ATP provides energy for reactions in the Calvin cycle.

Question 27

• Q: What molecule does COz combine with in the Calvin cycle?

Answer 27

• A: RuBP (ribulose-1,5-bisphosphate).

Question 28

Q: What enzyme catalyzes carbon fixation in the Calvin cycle?

Answer 28

• A: Rubisco.

Question 29

• Q: How do the Krebs cycle and Calvin cycle differ?

Answer 29

• A: The Krebs cycle breaks down molecules to release energy, while the Calvin cycle builds glucose molecules.

Question 30

Q: Why is photosynthesis essential for life?

Answer 30

• A: It produces glucose, which fuels plant growth, and oxygen, which is essential for most organisms' respiration.

Question 31

• Q: Why do only some plant cells have chloroplasts, but all have mitochondria?

Answer 31

• A: Chloroplasts are present only in cells exposed to light for photosynthesis, while mitochondria are needed in all cells for energy production.

Question 32

Q: Why do bacteria, chloroplasts, and mitochondria all have ATP synthase complexes?

Answer 32

• A: ATP synthase is vital for producing ATP in various organisms and organelles through chemiosmosis.

Question 33

• Q: How does energy flow in photosynthesis?

Answer 33

• A: Light energy is converted into chemical energy as ATP and NADPH, which are then used to produce glucose.

Question 34

Q: How does matter flow in photosynthesis?

Answer 34

• A: Carbon dioxide and water are converted into glucose and oxygen during photosynthesis.

Question 35

Q: How are photosynthesis and respiration connected at the cellular level?

Answer 35

• A: Photosynthesis produces glucose and oxygen, which are used in cellular respiration to generate ATP, releasing COz and water as byproducts.

Question 36

• Q: How do photosynthesis and respiration interact at the ecosystem level?

Answer 36

• A: Photosynthesis produces oxygen and organic matter for organisms, while respiration releases COz, which plants use for photosynthesis.

Question 37

• Q: How can the rate of photosynthesis be measured experimentally?

Answer 37

• A: By measuring oxygen production, CO, consumption, or changes in biomass.

Question 38

Q: How can the rate of respiration be measured?

Answer 38

• A: By measuring oxygen consumption or CO, production in dark conditions.

Question 39

• Q: How do you calculate the rate of cellular respiration?

Answer 39

• A: By measuring the decrease in oxygen or increase in CO, over time.

Question 40

Q: What is net photosynthesis?

Answer 40

• A: Net photosynthesis is the total rate of photosynthesis minus the rate of cellular respiration.

Question 41

Q: How is gross photosynthesis different from net photosynthesis?

Answer 41

• A: Gross photosynthesis is the total rate of photosynthesis before subtracting respiration.

Question 42

• Q: What environmental factors can affect transpiration in plants?

Answer 42

• A: Temperature, humidity, wind, and light intensity.

Question 43

Q: How can you calculate the rate of transpiration?

Answer 43

• A: By measuring water loss over time, often using a potometer.

Question 44

Q: How do photorespiration and photosynthesis compete?

Answer 44

• A: In photorespiration, rubisco binds to 02 instead of CO2, producing a wasteful byproduct instead of glucose.

Question 45

Q: What is the outcome of photorespiration?

Answer 45

• A: Photorespiration reduces the efficiency of photosynthesis by consuming energy and releasing COz without producing glucose.

Question 46

• Q: What is one benefit of photorespiration?

Answer 46

• A: It may help protect the plant from damage when CO, levels are low and oxygen levels are high.

Question 47

Q: What are reactive oxygen species (ROS)?

Answer 47

• A: Highly reactive molecules that form as byproducts of light reactions and can damage cell structures.

Question 48

• Q: How do plants defend against ROS?

Answer 48

• A: Plants produce antioxidants and enzymes like superoxide dismutase to neutralize ROS.

Question 49

• Q: What adaptation helps some plants thrive in intense light?

Answer 49

• A: They have special pigments and photoprotection mechanisms that prevent damage from excess light.

Question 50

Q: How do CAM plants minimize photorespiration?

Answer 50

• A: CAM plants open their stomata at night to fix COz, storing it for use during the day, which reduces water loss and photorespiration.