Plant Energy and Gas Exchange Practice Quiz (11 questions)

1. A cell breaks down glucose during cellular respiration. Which energy transformation occurs in this process?

A. Kinetic and thermal energy become chemical energy

B. Chemical energy becomes kinetic and thermal energy

C. Chemical energy becomes light energy

D. Light energy becomes stored chemical energy

Answer: (B)

Explanation

During cellular respiration, chemical energy stored in glucose is converted into kinetic and thermal energy. Converting light energy into stored chemical energy describes photosynthesis; storing rather than transforming energy reverses the process; and light energy is not the stated output.

2. A student describes cellular respiration in a cell as glucose being converted into waste products while its stored energy changes form. Which classification best describes the process?

A. Storage of energy without a transformation of substances

B. Both a transformation of substances and a transformation of energy

C. A transformation of substances without a transformation of energy

D. A transformation of energy without a transformation of substances

Answer: (B)

Explanation

Cellular respiration involves both changes in substances and a change in energy form. The substance-only and energy-only choices each omit one part of the process, while energy storage mischaracterizes respiration.

3. An organism obtains glucose by eating other organisms, while a nearby plant makes its own glucose. How should the organism and the plant be classified, respectively?

A. Heterotrophic and heterotrophic

B. Autotrophic and autotrophic

C. Autotrophic and heterotrophic

D. Heterotrophic and autotrophic

Answer: (D)

Explanation

Organisms that obtain glucose through food are heterotrophic, whereas plants that produce glucose themselves are autotrophic. Reversing these labels confuses the two modes; assigning the same label to both overlooks their different sources of glucose.

4. A plant absorbs water from the soil through its roots and takes in carbon dioxide through its leaves. What does it produce from these substances during glucose production?

A. Glucose and oxygen gas

B. Glucose and carbon dioxide

C. Water and carbon dioxide

D. Oxygen gas and water

Answer: (A)

Explanation

Plants use water absorbed through their roots and carbon dioxide taken in through their leaves to produce glucose; oxygen gas is also produced. Water and carbon dioxide are inputs, and producing carbon dioxide instead of oxygen confuses glucose production with respiration.

5. A plant receives light and has access to carbon dioxide and water. Which substances does it produce through photosynthesis?

A. Glucose and oxygen gas

B. Carbon dioxide and water

C. Glucose and carbon dioxide

D. Water and carbon dioxide

Answer: (A)

Explanation

In chloroplasts, photosynthesis uses carbon dioxide, water, and light energy to produce glucose and oxygen gas. Carbon dioxide and water are the inputs, while carbon dioxide as a product is associated with cellular respiration.

6. A plant is illuminated while carrying out photosynthesis. Which change in energy occurs during this process?

A. Radiant energy becomes kinetic energy and chemical energy

B. Chemical energy becomes radiant energy and heat

C. Radiant energy becomes chemical energy and heat

D. Chemical energy becomes kinetic energy and heat

Answer: (C)

Explanation

Photosynthesis converts radiant energy from sunlight into chemical energy and heat. The conversion of glucose’s chemical energy into kinetic and thermal energy describes cellular respiration.

7. A potted plant is placed beside a window, and its stems and leaves gradually bend toward the brighter side. Which adaptation does this demonstrate?

A. Climbing stems rise above nearby plants

B. Upper leaf surfaces contain more chloroplasts

C. Leaves spread out to avoid mutual shading

D. Stems and leaves grow toward sunlight

Answer: (D)

Explanation

Plant stems and leaves grow toward sunlight, helping them capture light. Climbing above other plants, avoiding leaf overlap, and having more chloroplasts on upper leaf surfaces are separate light-related adaptations.

8. A leaf appears greener on its upper surface than on its lower surface. What best explains this difference?

A. The upper surface avoids shading by neighboring leaves

B. The lower surface contains more chloroplasts for gas exchange

C. The lower surface receives more sunlight and contains more chloroplasts

D. The upper surface receives more sunlight and contains more chloroplasts

Answer: (D)

Explanation

The upper surface generally receives more sunlight and contains more chloroplasts, so it usually appears greener. Avoiding shade depends on leaf arrangement, while gas exchange through stomata does not explain this color difference.

9. A plant is photosynthesizing in daylight and continues cellular respiration. Through which plant structure does it exchange gases with its surroundings during both processes?

A. The leaves

B. The stems

C. The leaves during photosynthesis but not respiration

D. The roots

Answer: (A)

Explanation

Plants exchange gases with their surroundings through their leaves during both photosynthesis and cellular respiration. The roots are associated with water uptake, while the stem is not the identified route for this gas exchange.

10. What is a stoma in a plant leaf?

A. A pair of cells that surrounds a leaf vein

B. A chloroplast that releases gases during photosynthesis

C. An opening between guard cells for gas exchange

D. A vessel that carries water through the leaf

Answer: (C)

Explanation

A stoma is the opening between guard cells through which a plant exchanges gases with its surroundings. Guard cells border the opening; chloroplasts and vessels have different roles.

11. During a dry spell, a plant’s guard cells become less turgid and move closer together. What happens to the stoma?

A. It closes as the guard cells move closer together

B. It opens as the guard cells move closer together

C. It stays open because the guard cells lose turgidity

D. It stays unchanged because the guard cells move

Answer: (A)

Explanation

When guard cells lose turgidity during drought, they move closer together and close the stoma. The alternative that predicts opening reverses the relationship between turgidity and stomatal state.