Photosynthesis Quiz
Questions: 16 · 10 minutes
1. In a typical plant cell, which organelle is the main site of photosynthesis?
Chloroplast
Nucleus
Mitochondrion
Vacuole
2. Carbon dioxide is suddenly removed from an illuminated plant cell while light and water remain available. What is expected shortly afterward?
Oxygen production stops instantly and all ATP is immediately depleted.
The Calvin cycle accelerates because Rubisco no longer competes with carbon dioxide.
Rubisco produces more glucose by replacing carbon dioxide with oxygen.
Carbon fixation slows, while ATP and NADPH tend to accumulate because the Calvin cycle uses less of them.
3. A plant is receiving adequate light and is kept at a suitable temperature, but carbon dioxide is well below its optimal level. What will most likely happen if more carbon dioxide is supplied?
The photosynthetic rate will rise until another factor becomes limiting.
Oxygen production will increase indefinitely, regardless of other conditions.
The photosynthetic rate will fall because additional carbon dioxide closes stomata.
The rate will remain unchanged because carbon dioxide is used only in the light-dependent reactions.
4. Where does the Calvin cycle take place within a chloroplast?
In the stroma
In the thylakoid lumen
In the space between the chloroplast membranes
In the cell wall surrounding the plant cell
5. Why do many leaves appear green under white light?
Green light is the only wavelength absorbed by chlorophyll.
Chlorophyll converts every absorbed wavelength into green light.
Chlorophyll reflects or transmits more green light than it absorbs.
Carbon dioxide inside the leaf gives chloroplasts their green color.
6. A chemical specifically prevents photosystem II from splitting water. Which immediate effect is most likely?
Oxygen production remains unchanged because oxygen is made only in the Calvin cycle.
Carbon dioxide release rises because it is a direct product of water splitting.
Oxygen production declines because water can no longer supply electrons and protons normally.
Glucose production rises because photosystem II no longer uses light energy.
7. The oxygen released during photosynthesis comes most directly from which substance?
Carbon dioxide
Water
Glucose
Chlorophyll
8. A variegated plant is destarched, exposed to light, and then tested with iodine. Its leaves have green and white sections. Which result is expected?
Only the white sections turn blue-black because they lack chlorophyll.
The entire leaf turns blue-black because light reaches every section.
Primarily the green sections turn blue-black because they produced starch.
Neither section turns blue-black because plants immediately export all sugar.
9. Which statement best summarizes the overall process of photosynthesis?
Glucose and oxygen are converted into carbon dioxide, water, and usable energy.
Carbon dioxide and water are used to form glucose and oxygen with an input of light energy.
Mineral nutrients and oxygen are combined to produce water and carbon dioxide.
Light energy is used to turn glucose directly into mineral nutrients.
10. A student measures photosynthetic rate under equal intensities of different visible wavelengths. Under which colors would the rate generally be higher for a typical green leaf?
Green and yellow, because leaves reflect those colors most strongly
Red and blue, because major photosynthetic pigments absorb them effectively
Green and far-red, because chlorophyll absorbs all green light
Yellow and green, because they contain more energy than blue light
11. On a hot, dry afternoon, a plant closes many of its stomata. What is the most direct effect on photosynthesis?
More water enters the leaf and speeds the light-dependent reactions.
Less carbon dioxide enters the leaf, which can slow carbon fixation.
More oxygen enters the leaf and directly fuels the Calvin cycle.
Chlorophyll absorbs more light because the stomata are closed.
12. Which pair of energy-carrying products from the light-dependent reactions is used by the Calvin cycle?
ADP and NADP+
Glucose and oxygen
ATP and NADPH
Pyruvate and NADH
13. An aquatic plant produces fewer oxygen bubbles after it is moved farther from the same lamp. If other conditions remain similar, what is the best explanation?
Moving the lamp caused the water to contain less carbon dioxide.
Chlorophyll absorbed more light at the greater distance.
The Calvin cycle began consuming oxygen faster than it was produced.
Lower light intensity slowed the light-dependent reactions.
14. Where do the light-dependent reactions primarily occur within a chloroplast?
In the outer chloroplast membrane
In the stroma surrounding the grana
Inside the chloroplast's DNA-containing region
In the thylakoid membranes
15. What is Rubisco's central role in the Calvin cycle?
It splits water to release oxygen.
It absorbs light and excites electrons.
It transports sugar from leaves to roots.
It catalyzes the attachment of carbon dioxide to RuBP.
16. How does a proton gradient across the thylakoid membrane contribute to ATP production?
Protons flow through ATP synthase, providing energy to form ATP from ADP and phosphate.
Carbon dioxide diffuses through ATP synthase and releases chemical energy.
Rubisco breaks down glucose to power ATP formation in the thylakoid.
NADPH donates a phosphate directly to ADP as protons collect.