AP Biology : Understand inputs and outputs, purpose

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #31 : Photosynthesis

Which of the following is an adaptation in plants to prevent water loss in arid climates?

Possible Answers:

Krebs cycle

CAM pathway

Glycolysis

Calvin cycle

Oxidative phosphorylation

Correct answer:

CAM pathway

Explanation:

CAM plants open their stomata only at night, when temperatures are lower and water loss is less severe. This prevents gas exchange during the day thus making them less efficient at photosynthesis, but the water conservation makes it a worthwhile trade off. The processes of glycolysis, oxidative phosphorylation, the Calvin cycle and the Krebs cycle occur in all plants.

Example Question #12 : Understand Inputs And Outputs, Purpose

Which of the following correctly illustrates how plants undergo photosynthesis?

Possible Answers:

Plants use the energy of the sun to convert ATP into glucose

Plants use the energy of the sun to convert glucose and oxygen into carbon dioxide and water

Plants use the energy of the sun to break down glucose for energy

Plants use the energy of the sun to convert glucose into ATP

Plants use the energy of the sun to convert carbon dioxide and water into glucose and oxygen

Correct answer:

Plants use the energy of the sun to convert carbon dioxide and water into glucose and oxygen

Explanation:

Plants are considered photoautotrophs, meaning that they can use the electromagnetic energy from sunlight to generate organic chemical energy. The process for this conversion is photosynthesis, which takes place in the chloroplasts of the plant cells. Sunlight excites electrons, which donate energy to form NADH and ATP. These compounds enter the Calvin cycle, which converts carbon dioxide to glyceraldehyde-3-phosphate, a sugar that can easily be converted to glucose and used for energy.

The sugars produced from photosynthesis then undergo oxidation via cellular respiration in order to actually produce ATP. Remember that plant cells contain both chloroplasts (to make sugars) and mitochondria (to make ATP).

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