which of the following is always true about molecules

HESI A2

Biology HESI A2 Practice Test

1. Which of the following is always true about molecules?

A. They cannot travel through all cell membranes
B. They move from low concentration to high concentration without using energy
C. They move from high concentration to low concentration without using energy
D. They cannot move

Correct answer: C

Rationale: The statement that molecules move from high concentration to low concentration without using energy is always true due to the natural process of diffusion. This movement occurs to reach equilibrium and does not require any additional energy input directly from the molecule itself. Choice A is incorrect because not all molecules can travel through all cell membranes. Choice B is incorrect as molecules typically move from high concentration to low concentration in a process known as passive transport. Choice D is incorrect as molecules are in constant motion due to factors like temperature and kinetic energy.

2. A scientist needs 12 mL of a solution. They have a bottle with 12L in it. Do they have enough?

A. Yes, they have exactly what they need
B. Yes, they have more than what they need
C. No, they do not have enough
D. None of the above

Correct answer: B

Rationale: 1 liter has 1000 milliliters. To convert from milliliters to liters, the decimal point moves three places to the left. So, the bottle has 12000 mL of solution, which is a lot more than the required 12 mL. Therefore, the scientist has more than what they need. Choice A is incorrect as the bottle has more than the required amount. Choice C is incorrect as the bottle contains significantly more solution than needed. Choice D is incorrect as the scientist does have more than enough solution.

3. What are the two catabolic pathways that lead to cellular energy production?

A. Fermentation and internal respiration
B. Fermentation and external respiration
C. Fermentation and cellular respiration
D. Fermentation and anaerobic respiration

Correct answer: C

Rationale: The correct answer is 'Fermentation and cellular respiration.' Fermentation is an anaerobic catabolic process that occurs in the absence of oxygen, producing limited amounts of ATP. Cellular respiration, on the other hand, is the aerobic catabolic pathway that occurs in the presence of oxygen and is the most efficient way of producing ATP. Choices A, B, and D are incorrect because internal respiration, external respiration, and anaerobic respiration are not the correct pathways leading to cellular energy production.

4. What is the role of ribosomes in the cell?

A. Break down cellular waste
B. Organize cellular division
C. Synthesize proteins
D. Provide cellular structure

Correct answer: C

Rationale: The correct answer is C: Synthesize proteins. Ribosomes are responsible for protein synthesis by linking amino acids together. Choice A is incorrect because ribosomes do not break down cellular waste. Choice B is incorrect as ribosomes do not organize cellular division. Choice D is incorrect because ribosomes do not provide cellular structure.

5. How many pairs of homologous chromosomes do humans have?

A. 13
B. 23
C. 26
D. 46

Correct answer: D

Rationale: The correct answer is D: 46. Humans have 23 pairs of chromosomes, which include 22 pairs of autosomes and 1 pair of sex chromosomes. Homologous chromosomes are pairs of chromosomes that contain the same genes, one from each parent. Therefore, humans have a total of 46 chromosomes, with 23 pairs of homologous chromosomes. Choices A, B, and C are incorrect as they do not represent the total number of chromosomes in humans or the number of pairs of homologous chromosomes.