Understand inputs and outputs, purpose

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AP Biology › Understand inputs and outputs, purpose

Questions 1 - 10
1

Plants are an example of which of the following categories of organisms?

Autotrophs

Heterotrophs

Chemoautotrophs

Biosphere consumers

Explanation

Plants are an example of autotrophs. Autotrophs sustain themselves without consuming other organic material. Instead they create organic material from inorganic materials.

2

What are the products of photosynthesis?

Glucose and oxygen

Water and carbon dioxide

Carbon dioxide and light

Light and glucose

Oxygen and carbon dioxide

Explanation

The photosynthesis equation can be written as:

From this equation, we can see that plants take in carbon dioxide, water, and light energy as reactants and produce glucose and oxygen as products.

3

Some organisms, such as green plants, are capable of obtaining energy directly from photosynthesis. These organisms are termed __________.

autotrophs

homotrophs

primary consumers

herbivores

heterotrophs

Explanation

Autotrophs are organisms that produce complex organic compounds from substances present in the surroundings. These organisms may do this through the use of energy from light or from inorganic chemical reactions.

In contrast, heterotrophs require organic input in order to generate biological compounds and are unable to use light or inorganic materials for energy.

4

Which of the following is true of photosynthesis?

Carbon dioxide is reduced

Water is reduced

Electrons decrease in potential energy as they move from water to sugar

Carbon dioxide is oxidized

The process requires no energy

Explanation

Photosynthesis occurs in the chloroplasts of plant cells, where carbon dioxide is reduced and water is oxidized to create sugar. During this process electrons demonstrate increased potential energy as they move from water to sugar. The process requires an initial energy input, derived from photons.

5

Which of the following correctly illustrates how plants undergo photosynthesis?

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

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

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).

6

Organisms that make their organic molecules from inorganic raw materials obtained from the surrounding environment are called __________.

autotrophs

heterotrophs

auxotrophs

plants

Explanation

Autotrophs create organic material from inorganic materials. Autotrophs are self-feeders in that they do not consume other organic materials but rather create their own organic materials. Plants and other photosynthetic organisms are examples of autotrophs.

7

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

CAM pathway

Glycolysis

Krebs cycle

Calvin cycle

Oxidative phosphorylation

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.

8

Which of the following are referred to as the major sites of photosynthesis in most plants?

Leaves

Roots

Stems

Flowers

Explanation

The leaves are the major sites of photosynthesis in most plants. The chloroplasts are located in the mesophyll—interior tissues of the leaves—and are the primary sites of photosynthesis.

9

Photosynthesis is commonly divided into how many primary stages?

Two stages

One stage

Three stages

Four stages

Explanation

The correct answer is two major stages. The first stage is known as the light reactions where solar energy is converted to chemical energy. The second stage is the Calvin cycle that synthesizes sugar.

10

Which of the following is one of the end products of photosynthesis?

Glucose

Water

Carbon dioxide

Lipids

Explanation

Glucose is the six carbon sugar that is the main product of photosynthesis. Water and carbon dioxide are the reactants in photosynthesis. Lipids are fat molecules that store energy in cells.

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