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. Balance the chemical equation: C4H10 + O2 → CO2 + H2O. What is the coefficient for oxygen?

A. 5
B. 6
C. 7
D. 8

Correct answer: B

Rationale: To balance the chemical equation, we need to ensure that the number of each type of atom is the same on both sides of the equation. In this case, there are 10 oxygen atoms on the right side (5 in CO2 and 5 in H2O). To balance this, we need to add a coefficient of 6 in front of O2 on the left side, resulting in 6 O2 molecules. This change will give us a total of 12 oxygen atoms on both sides, making the equation balanced. Choice A (5) is incorrect because it does not account for all the oxygen atoms present in the products. Choices C (7) and D (8) are incorrect as they would result in an imbalance in the number of oxygen atoms on both sides of the equation.

3. What is the term for a genetic disorder caused by a mutation in a mitochondrial gene?

A. Autosomal dominant disorder
B. Autosomal recessive disorder
C. Sex-linked disorder
D. Mitochondrial disorder

Correct answer: D

Rationale: A) Autosomal dominant disorder: This type of genetic disorder is caused by a mutation in one copy of an autosomal gene. It is not related to mitochondrial gene mutations. B) Autosomal recessive disorder: This type of genetic disorder is caused by mutations in both copies of an autosomal gene. It is not related to mitochondrial gene mutations. C) Sex-linked disorder: This type of genetic disorder is caused by mutations in genes located on the sex chromosomes (X or Y). It is not related to mitochondrial gene mutations. D) Mitochondrial disorder: Mitochondrial disorders are genetic disorders caused by mutations in genes located in the mitochondria, the energy-producing structures within cells. These disorders are inherited maternally and can affect various organs and systems in the body due to the role of mitochondria in energy production.

4. Where does gas exchange take place in the respiratory system?

A. Alveoli
B. Bronchioles
C. Bronchi
D. Trachea

Correct answer: A

Rationale: Gas exchange in the respiratory system occurs in the alveoli, which are tiny air sacs in the lungs. Within the alveoli, oxygen from the inhaled air diffuses into the bloodstream, while carbon dioxide from the blood enters the alveoli to be exhaled. This exchange of gases is essential for the body to obtain oxygen and remove carbon dioxide, supporting vital bodily functions. The bronchioles (choice B), bronchi (choice C), and trachea (choice D) are part of the airway passage system that transports air to and from the alveoli but do not participate in gas exchange. Therefore, the alveoli play a crucial role in the respiratory system by facilitating gas exchange.

5. Which of the following neurotransmitters slows down the activity of neurons, preventing them from becoming overexcited?

A. Acetylcholine
B. Dopamine
C. GABA
D. Serotonin

Correct answer: C

Rationale: The correct answer is C: GABA (gamma-aminobutyric acid). GABA acts as an inhibitory neurotransmitter that reduces neuronal activity, thus preventing overexcitation. Acetylcholine (choice A) is involved in muscle control and cognitive function, but it is not primarily responsible for slowing down neuronal activity. Dopamine (choice B) plays a role in reward-motivated behavior and motor control, rather than inhibiting neuronal firing. Serotonin (choice D) is involved in mood regulation, sleep, and appetite but does not primarily slow down neuronal activity to prevent overexcitation.