Q: What is the balanced chemical equation for photosynthesis?

$$6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + \text{light energy} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{O}_2$$

Question 1

Which of the following best describes the flow of matter and energy between plants and animals in an ecosystem?

Accepted Answer

Plants convert light energy into chemical energy, which is then consumed by animals; both release energy as heat and recycle matter through respiration and decomposition.

Question 2

Which of the following is an example of a heterotroph?

Accepted Answer

A mushroom decomposing a fallen log in a forest.

Question 3

Which structure in the chloroplast is the primary site of the light-dependent reactions of photosynthesis?

Accepted Answer

Thylakoid membrane

Question 4

How do stomata and veins in plant leaves contribute to photosynthesis?

Accepted Answer

Stomata allow gas exchange (CO$$_2 in$$, O$$_2$$ out), while veins transport water to the leaf and sugars away from the leaf.

Question 5

What is the balanced chemical equation for photosynthesis?

Accepted Answer

$$6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + 	ext{light energy} ightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{O}_2$$

Question 6

Which statement best explains the relationship between the wavelength of light and its energy?

Accepted Answer

Shorter wavelengths have higher energy than longer wavelengths.

Question 7

A leaf appears green because:

Accepted Answer

Chlorophyll absorbs red and blue light but reflects green light.

Question 8

Which of the following best describes the difference between an absorption spectrum and an action spectrum?

Accepted Answer

An absorption spectrum shows wavelengths absorbed by pigments; an action spectrum shows wavelengths that drive photosynthesis.

Question 9

What happens when a photon of light strikes a chlorophyll molecule?

Accepted Answer

An electron in the chlorophyll is excited to a higher energy state.

Question 10

When an excited electron in chlorophyll returns to its ground state, which of the following can occur?

Accepted Answer

Energy is released as heat or fluorescence.

Question 11

Which of the following correctly matches the source of electrons for Photosystem II (PSII) and the terminal electron acceptor for the light reactions?

Accepted Answer

Water is the source for PSII; NADP$$^+ is $$the terminal electron acceptor.

Question 12

How is ATP produced during the light reactions of photosynthesis?

Accepted Answer

By chemiosmosis, as protons flow through ATP synthase from the thylakoid space to the stroma.

Question 13

Which of the following lists the three phases of the Calvin cycle in the correct order?

Accepted Answer

Carbon fixation, reduction, regeneration of RuBP

Question 14

Why are ATP and NADPH required for the Calvin cycle?

Accepted Answer

They provide the energy and reducing power needed to convert CO$$_2$$ into G3P (a sugar).

Question 15

In a closed system containing only plants and no animals, what would you expect to happen to the levels of O$$_2$$, CO$$_2$$, and glucose over time during the day?

Accepted Answer

O$$_2$$ increases, CO$$_2$$ decreases, glucose increases

Question 16

A scientist exposes a plant to only green light. What is the most likely result regarding the rate of photosynthesis?

Accepted Answer

The rate of photosynthesis will decrease because green light is mostly reflected, not absorbed.

Question 17

Which of the following best explains why plants are considered autotrophs?

Accepted Answer

They produce organic molecules from inorganic CO$$_2$$ using energy from sunlight.

Question 18

If a mutation caused a plant to lack ATP synthase in its thylakoid membranes, which process would be directly affected?

Accepted Answer

Synthesis of ATP during the light reactions

Question 19

During the light reactions, what is the primary function of the electron transport chain between PSII and PSI?

Accepted Answer

To create a proton gradient that drives ATP synthesis

Photosynthesis Study Guide – Step-by-Step Guidance

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