a neuron consists of three main parts these are

ATI TEAS 7

ATI TEAS Science Test

1. Which of the following represents the three main parts of a neuron?

A. effector, cell body, axon
B. dendrites, axon, cell body
C. dendrites, axon, receptor
D. synapse, axon, cell body

Correct answer: B

Rationale: A neuron consists of three main parts: dendrites, axon, and cell body. Dendrites receive signals from other neurons or sensory receptors. The cell body (soma) contains the nucleus and organelles essential for neuron function. The axon transmits electrical impulses away from the cell body to other neurons, muscles, or glands. Choice A is incorrect because an effector is not a part of a neuron. Choice C is incorrect because a receptor is not a component of a neuron but rather interacts with neurons. Choice D is incorrect because the synapse is a junction between neurons for signal transmission, not a structural part of a neuron.

2. Which term refers to a molecule of DNA and structural protein?

A. Lysosome
B. Centrosome
C. Chromosome
D. Genome

Correct answer: C

Rationale: The correct answer is C: Chromosome. A chromosome is a structure composed of DNA and proteins that carries genetic information. It is the condensed form of DNA associated with structural proteins, not just a molecule of DNA or protein. Lysosomes are membrane-bound organelles containing digestive enzymes, not DNA and protein. Centrosomes are involved in cell division, not related to DNA and protein together. A genome refers to an organism's complete set of DNA, not specifically a molecule containing both DNA and structural protein.

3. What is the function of valves in arteries?

A. To maintain high blood pressure for the proper diffusion of nutrients in capillaries.
B. To prevent backflow of blood due to high pressure away from the heart.
C. As a vestigial trait from evolution, like the appendix, that serves no purpose.
D. Valves are absent in arteries but present in veins.

Correct answer: B

Rationale: Valves in arteries serve the crucial function of preventing backflow of blood. Arteries carry blood at high pressure away from the heart, and the valves ensure that blood flows in one direction, towards the capillaries, to maintain efficient circulation. Without these valves, there would be a risk of blood flowing backward, compromising the effectiveness of blood circulation in the body. Choices A, C, and D are incorrect. Choice A incorrectly suggests that valves maintain high blood pressure for nutrient diffusion in capillaries, which is not their function. Choice C inaccurately compares valves to vestigial traits, like the appendix, implying they serve no purpose, which is untrue. Choice D is incorrect as valves are indeed present in arteries to regulate blood flow, not just in veins.

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. What is the neural pathway that triggers a reflex action?

A. Reflex loop
B. Reflex arc
C. Neural pathway
D. Reflex reaction

Correct answer: B

Rationale: The correct answer is 'B: Reflex arc.' A reflex arc is the neural pathway that triggers an automatic, involuntary reflex action in response to a stimulus. It involves sensory neurons, interneurons in the spinal cord, and motor neurons, allowing for a rapid response without conscious thought. Choice A, 'Reflex loop,' is incorrect as the term commonly used is 'Reflex arc' to describe this neural pathway. Choice C, 'Neural pathway,' is too general and does not specifically refer to the pathway involved in reflex actions. Choice D, 'Reflex reaction,' is not the commonly accepted term to describe the neural pathway that triggers reflex actions.