vaccines work by

ATI TEAS 7

TEAS 7 practice test science

1. How do vaccines work?

A. By directly killing pathogens
B. By introducing weakened or inactive versions of pathogens to trigger an immune response
C. By stimulating the immediate production of specific antibodies
D. None of the above

Correct answer: B

Rationale: Vaccines work by introducing weakened or inactive versions of pathogens to trigger an immune response in the body. This exposure helps the immune system recognize and remember the pathogen, enabling a faster and more effective response upon future exposure. Vaccines do not directly kill pathogens but prepare the immune system for a potential encounter, enhancing protection. They also do not stimulate the immediate production of specific antibodies as the immune response takes time to develop upon vaccination. Choice A is incorrect because vaccines do not kill pathogens directly; they prime the immune system to recognize and respond to them. Choice C is incorrect because while vaccines lead to the production of specific antibodies, it is not immediate, as it takes time for the immune response to develop and produce these antibodies.

2. Which of the following organs is NOT directly involved in urine production?

A. Kidneys
B. Urethra
C. Lungs
D. Bladder

Correct answer: B

Rationale: The correct answer is B, Urethra. The urethra is not directly involved in urine production. It is a tube that carries urine from the bladder to the outside of the body. The kidneys are responsible for filtering waste and excess substances from the blood to produce urine. The bladder stores urine until it is expelled from the body. The lungs are not involved in urine production; they are responsible for gas exchange during respiration. Choice A, Kidneys, is directly involved in urine production by filtering the blood to form urine. Choice C, Lungs, plays a role in respiration and oxygen exchange but is not directly involved in urine production. Choice D, Bladder, stores urine before it is excreted from the body and is directly involved in the final stages of urine elimination, unlike the urethra.

3. The process by which a single-celled organism divides into two identical daughter cells is called

A. Conjugation
B. Binary fission
C. Endocytosis
D. Mitosis

Correct answer: B

Rationale: Rationale: A) Conjugation is a process in which genetic material is transferred between two bacterial cells through a conjugation tube. It does not involve the division of a single-celled organism into two identical daughter cells. B) Binary fission is the process by which a single-celled organism, such as a bacterium, divides into two identical daughter cells. This is a common method of reproduction in prokaryotic organisms. C) Endocytosis is a cellular process in which cells engulf external materials by wrapping them in a vesicle. It is not a method of cell division. D) Mitosis is a type of cell division that occurs in eukaryotic cells, leading to the production of two daughter cells with identical genetic material. However, the question specifically refers to a single-celled organism, which typically undergoes binary fission for reproduction.

4. What is the relationship between genetic drift and the founder effect?

A. Founder effect is a cause of genetic drift within a small population
B. Genetic drift is a cause of the founder effect in new populations
C. They are the same phenomenon with different names
D. They are unrelated concepts.

Correct answer: A

Rationale: - The founder effect is a specific type of genetic drift that occurs when a small group of individuals establishes a new population, leading to a loss of genetic variation. - Genetic drift, on the other hand, is a broader concept that refers to random changes in allele frequencies in a population over time due to chance events. - Therefore, the founder effect is a specific scenario within the broader concept of genetic drift, where the establishment of a new population by a small number of individuals leads to genetic changes in the population.

5. What happens to the force of gravity between two objects when the distance between them is doubled?

A. The force increases by a factor of 2
B. The force increases by a factor of 4
C. The force decreases by a factor of 2
D. The force decreases by a factor of 4

Correct answer: D

Rationale: According to the law of universal gravitation, the force of gravity between two objects is inversely proportional to the square of the distance between them. When the distance is doubled, the force decreases by a factor of 2 squared, which is 4. Therefore, the force decreases by a factor of 4. Choice A is incorrect because the force doesn't increase when the distance is doubled. Choice B is incorrect as the force doesn't increase but actually decreases. Choice C is incorrect as the force decreases by a factor of 4, not 2.