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. What is the term for the chemical reaction that involves the loss of electrons?

A. Reduction
B. Oxidation
C. Neutralization
D. Precipitation

Correct answer: B

Rationale: Oxidation is the process where a substance loses electrons. In an oxidation reaction, the substance being oxidized loses electrons, which are gained by another substance. Reduction is the opposite process, where a substance gains electrons. Neutralization is a reaction between an acid and a base to form a salt and water. Precipitation is the formation of a solid from a solution. Therefore, in the context of a chemical reaction involving the loss of electrons, the correct term is oxidation (Choice B).

3. Which of the following is a common characteristic of alkynes?

A. They have a triple bond between carbon atoms.
B. They are saturated hydrocarbons.
C. They contain only single bonds.
D. They are aromatic compounds.

Correct answer: A

Rationale: The correct answer is A. Alkynes are hydrocarbons characterized by at least one triple bond between carbon atoms. This triple bond sets them apart from alkanes, which only have single bonds, and alkenes, which feature at least one double bond. The presence of a triple bond makes alkynes unsaturated hydrocarbons. Choice B is incorrect as alkynes are unsaturated hydrocarbons, not saturated. Choice C is incorrect because alkynes contain at least one triple bond, making them different from compounds with only single bonds. Choice D is incorrect because aromatic compounds have a distinct cyclic structure with resonance stabilization, a feature not shared by alkynes.

4. What is a condition characterized by an overactive thyroid gland and excessive production of thyroid hormones called?

A. Diabetes mellitus
B. Hyperthyroidism
C. Hypothyroidism
D. Cushing's syndrome

Correct answer: B

Rationale: Hyperthyroidism is a condition where the thyroid gland is overactive and produces an excessive amount of thyroid hormones. This can lead to symptoms such as weight loss, rapid heartbeat, sweating, and nervousness. Diabetes mellitus is a condition characterized by high blood sugar levels due to either insufficient insulin production or the body's inability to respond to insulin. Hypothyroidism is the opposite of hyperthyroidism, where the thyroid gland is underactive and produces insufficient thyroid hormones. Cushing's syndrome is a disorder that occurs when the body has a high level of the hormone cortisol for a long time.

5. The hypodermis is primarily composed of which tissue?

A. Adipose
B. Connective
C. Epithelial
D. Muscle

Correct answer: A

Rationale: The hypodermis, also known as the subcutaneous layer, is primarily composed of adipose (fat) tissue. Adipose tissue in the hypodermis serves as an insulator, energy reserve, and cushioning for the body. Choice B, Connective tissue, is a broad category that includes various types of tissue like adipose, but the hypodermis is specifically rich in adipose tissue. Choice C, Epithelial tissue, is not the primary component of the hypodermis; it is mainly found covering body surfaces and lining cavities. Choice D, Muscle tissue, is not a major component of the hypodermis; muscle tissue is mainly located deeper in the body and serves in movement and support functions.