why is polarity the most important characteristic of water

HESI A2

HESI A2 Biology Practice Test

1. Why is polarity the most important characteristic of water?

A. the results of the polarity are hydrogen bonding, a high specific heat value, and its versatile solvent properties
B. the results of the polarity are covalent bonding, a low specific heat value, and its versatile solvent properties
C. the results of the polarity are ionic bonding, a high specific heat value, and its versatile solvent properties
D. the results of the polarity are hydrogen bonding, a low specific heat value, and its versatile solvent properties

Correct answer: A

Rationale: Polarity is the most important characteristic of water because it results in hydrogen bonding, a high specific heat value, and its versatile solvent properties. These unique properties enable water to form hydrogen bonds with other substances, resist temperature changes, and dissolve a wide variety of solutes, making it essential for life processes. Choice B is incorrect because water exhibits hydrogen bonding, not covalent bonding. Choice C is incorrect as water does not form ionic bonds. Choice D is incorrect because water has a high, not low, specific heat value, which is vital for its role in temperature regulation.

2. The phases of mitosis include:

A. Prophase, interphase, metaphase, anaphase, and telophase
B. Prophase, prophase, metaphase, anaphase, and cytokinesis
C. Prophase, prometaphase, metaphase, anaphase, and telophase
D. Prophase, interphase, prophase, anaphase, and telophase

Correct answer: C

Rationale: The correct phases of mitosis are prophase, prometaphase, metaphase, anaphase, and telophase. Prophase is the first phase where chromatin condenses into chromosomes, the nuclear envelope breaks down, and the mitotic spindle forms. Prometaphase follows prophase, involving the full disintegration of the nuclear envelope and the attachment of spindle fibers to the kinetochores of the chromosomes. Metaphase is where chromosomes align along the metaphase plate. Anaphase is the phase where sister chromatids separate and move towards opposite poles. Telophase marks the final stage of mitosis, involving the decondensation of chromosomes and the reformation of the nuclear envelope. Choice A is incorrect because it includes interphase, which is not a phase of mitosis. Choice B is incorrect as it repeats prophase, which is the initial phase. Choice D is incorrect because it includes interphase and repeats prophase.

3. 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.

4. Phenotype refers to the _ of an individual.

A. Genetic makeup
B. Actual physical appearance
C. Recessive alleles
D. None of the above

Correct answer: B

Rationale: Phenotype refers to the actual physical appearance and characteristics of an individual, which are determined by the interaction of both genetic makeup (genotype) and environmental factors. It includes visible traits such as height, eye color, and hair type. Choice A, genetic makeup, refers to the genotype, which is the genetic constitution of an organism. Choice C, recessive alleles, is a specific type of gene variant and does not encompass the entire concept of phenotype. Choice D, none of the above, is incorrect as phenotype does refer to the actual physical appearance of an individual.

5. Select the option that best shows complementary base pairing in DNA:

A. A and G
B. A and C
C. A and A
D. A and T

Correct answer: D

Rationale: The correct answer is D. A purine (A) must pair with a pyrimidine (T) in DNA. This eliminates options A and C as they do not follow the rule of complementary base pairing. Adenine (A) always pairs with thymine (T) due to their specific shape and bonding properties in DNA structure. Choice B is incorrect because adenine does not pair with cytosine in DNA.