$$6CO_2 + 6H_2O + \text{Light energy} \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 1

Which of the following best describes the greenhouse effect?

Accepted Answer

The trapping of heat in Earth's atmosphere by greenhouse gases, which act like a blanket and re-radiate heat back to the surface.

Question 2

Which of the following is the correct balanced chemical equation for photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{Light energy} ightarrow C_6H_{12}O_6$ + 6O_2$$

Question 3

Why is water slow to change temperature compared to other substances?

Accepted Answer

Hydrogen bonds between water molecules require extra energy to break before temperature can increase.

Question 4

Which molecule is produced during the light reactions of photosynthesis?

Accepted Answer

Oxygen

Question 5

What is the primary role of stomata in land plants?

Accepted Answer

To allow carbon dioxide to enter and oxygen to exit, while regulating water loss.

Question 6

Photorespiration is considered detrimental to plants because:

Accepted Answer

It causes rubisco to add oxygen to RuBP, producing glycolate, which cannot be used in the Calvin cycle and must be destroyed.

Question 7

Which of the following is a direct anthropogenic cause of increased atmospheric carbon dioxide?

Accepted Answer

Combustion of fossil fuels such as coal, oil, and natural gas

Question 8

During the Calvin cycle, what is the initial molecule that carbon dioxide is added to?

Accepted Answer

Ribulose biphosphate (RuBP)

Question 9

Which of the following statements about fossil fuels is TRUE?

Accepted Answer

Fossil fuels are produced from the carbohydrates of ancient, buried organisms transformed by heat and pressure.

Question 10

Which of the following is a final product of the light-independent reactions (Calvin cycle) in photosynthesis?

Accepted Answer

Glyceraldehyde 3-phosphate (G3P)

Question 11

How do C4 and CAM plants reduce photorespiration compared to C3 plants?

Accepted Answer

By concentrating carbon dioxide in specialized cells or storing it as an acid at night.

Question 12

Which of the following best explains why deforestation contributes to global climate change?

Accepted Answer

It reduces the number of trees available to absorb carbon dioxide, increasing atmospheric CO$$_2.$$

Question 13

Which of the following is the largest source of carbon dioxide emissions for most countries?

Accepted Answer

Industry

Question 14

What evidence from ice cores supports the link between carbon dioxide and global temperature?

Accepted Answer

Fossil air bubbles in ice cores reveal that current CO$$_2$$ levels are the highest in over 400,000 years and correlate with temperature increases.

Question 15

Which of the following actions would most effectively decrease your personal greenhouse gas emissions?

Accepted Answer

Using energy-efficient appliances and recycling materials.

Question 16

Which of the following is a consequence of global climate change on biological systems?

Accepted Answer

Loss of habitat, extinction of temperature-sensitive species, and spread of tropical diseases.

Question 17

Which process in photosynthesis directly uses ATP and NADPH produced in the light reactions?

Accepted Answer

The Calvin cycle (light-independent reactions)

Question 18

If a plant closes its stomata during a hot, dry day, what is the most likely immediate effect on photosynthesis?

Accepted Answer

Photosynthesis will decrease because carbon dioxide cannot enter the leaf.

Question 19

Which of the following best describes the relationship between the light reactions and the Calvin cycle in photosynthesis?

Accepted Answer

The light reactions produce ATP and NADPH, which are used by the Calvin cycle to fix carbon dioxide into sugars.

Question 20

Which of the following is NOT a greenhouse gas contributing to the greenhouse effect?

Accepted Answer

Nitrogen ($$N_2)$$

Photosynthesis, Climate Change, and the Carbon Cycle: Study Notes

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