why is dna important for metabolic activities of the cell

HESI A2

HESI A2 Practice Test Biology

1. Why is DNA important for metabolic activities of the cell?

A. It controls the synthesis of enzymes.
B. It stabilizes the cell wall.
C. It initiates cell division.
D. It prevents diffusion of nutrients.

Correct answer: A

Rationale: The correct answer is A. DNA plays a crucial role in metabolic activities by controlling the synthesis of enzymes. Enzymes are the biological catalysts that regulate and facilitate metabolic reactions within the cell. Choice B is incorrect because DNA is not involved in stabilizing the cell wall; that role is usually associated with other components like the cell membrane. Choice C is incorrect as cell division is primarily regulated by different processes and molecules, not directly by DNA. Choice D is incorrect because DNA is not related to preventing the diffusion of nutrients; instead, it is involved in coding for proteins that aid in various cellular functions.

2. What is the binding membrane of an animal cell called?

A. Biological membrane
B. Cell coat
C. Unit membrane
D. Plasma membrane

Correct answer: D

Rationale: The correct answer is D: Plasma membrane. The plasma membrane surrounds the cell and acts as an interface between the living interior of the cell and the nonliving exterior. It plays a vital role in maintaining the cell's integrity, regulating the passage of substances in and out of the cell, and facilitating communication with other cells. Choices A, B, and C are incorrect because the term 'plasma membrane' specifically refers to the binding membrane of an animal cell, distinguishing it from other types of membranes or coatings found in cells.

3. Which one is not a reactant in photosynthesis?

A. Water
B. Light energy
C. Glucose
D. Carbon dioxide

Correct answer: C

Rationale: The correct answer is C: Glucose. Glucose is not a reactant in photosynthesis but a product. During photosynthesis, plants use water, carbon dioxide, and light energy as reactants to produce glucose and oxygen. Water is essential for the process of photosynthesis, along with carbon dioxide and light energy. Light energy is necessary for the light-dependent reactions to occur, which eventually leads to the production of glucose. Carbon dioxide is absorbed by plants through tiny pores called stomata and is used in the Calvin cycle to synthesize glucose. Therefore, glucose is the product of photosynthesis, not a reactant.

4. Which is an example of a gymnosperm?

A. Red cedar
B. Japanese cherry
C. Flowering dogwood
D. American chestnut

Correct answer: A

Rationale: Red cedar is the correct answer as it is an example of a gymnosperm. Gymnosperms are plants that produce seeds not enclosed within an ovary or fruit. In the case of red cedar, it belongs to the gymnosperm group and has naked seeds that are exposed on the surface of scales or leaves. Choices B, C, and D are angiosperms, not gymnosperms. Japanese cherry, flowering dogwood, and American chestnut are all examples of angiosperms, which are flowering plants with seeds enclosed within an ovary.

5. The mixture of gases surrounding a planet is referred to as its ______.

A. Atmosphere
B. Stratosphere
C. Biosphere
D. Troposphere

Correct answer: A

Rationale: The mixture of gases surrounding a planet is referred to as its atmosphere. The atmosphere plays a crucial role in supporting life on Earth by providing oxygen, regulating carbon dioxide levels, and shielding the planet from harmful radiation. While the stratosphere, troposphere, and other layers are part of the atmosphere, the term 'atmosphere' encompasses the entire gaseous envelope surrounding a planet. The stratosphere, troposphere, mesosphere, thermosphere, and exosphere are specific layers within the atmosphere, each with distinct characteristics and functions.