how do efferent fibers exit the spinal cord

ATI TEAS 7

ATI TEAS Science Practice Test

1. How do efferent fibers exit the spinal cord?

A. Through the anterior aspect
B. Through the dorsal aspect
C. Through the ventral aspect
D. Through the lateral aspect

Correct answer: C

Rationale: Efferent fibers, which carry motor commands, exit the spinal cord through the ventral aspect, also known as the anterior aspect. The correct answer is C, 'Through the ventral aspect.' Efferent fibers exiting through the ventral aspect are responsible for carrying motor commands from the spinal cord to the muscles and glands. Choices A, B, and D are incorrect. Efferent fibers do not exit through the dorsal, lateral, or anterior aspects of the spinal cord.

2. Which law of motion explains the behavior of rockets in space?

A. Newton's First Law
B. Newton's Second Law
C. Newton's Third Law
D. None of the above

Correct answer: C

Rationale: The correct answer is Newton's Third Law. Newton's Third Law states that for every action, there is an equal and opposite reaction. In the case of rockets in space, the action is the expulsion of gas from the rocket engines, and the reaction is the forward motion of the rocket. This law explains how rockets are able to propel themselves forward in the vacuum of space. Choices A and B are incorrect because Newton's First Law (inertia) and Second Law (F=ma) do not directly explain the behavior of rockets in space. Choice D is incorrect as Newton's Third Law specifically addresses the principle behind rockets' motion in space.

3. Which of the following is NOT a mechanism that can directly cause evolution by natural selection?

A. Mutations in genes
B. Differential survival and reproduction based on traits
C. Inheritance of acquired characteristics (like strong muscles from working out)
D. Competition for resources in an environment

Correct answer: C

Rationale: A) Mutations in genes can introduce new genetic variations into a population, which can be acted upon by natural selection. B) Differential survival and reproduction based on traits is a key component of natural selection, as individuals with advantageous traits are more likely to survive and pass on their genes to the next generation. C) Inheritance of acquired characteristics, also known as Lamarckism, is not a mechanism of evolution by natural selection. Traits acquired during an individual's lifetime (such as strong muscles from working out) are not passed on to offspring. D) Competition for resources in an environment can drive natural selection by favoring individuals with traits that help them better compete for limited resources. Therefore, the correct answer is C) Inheritance of acquired characteristics (like strong muscles from working out), as it is not a mechanism that can directly cause evolution by natural selection.

4. Which of the following items is NOT a primary function of a healthy immune system?

A. The immune system helps the body avoid infections.
B. The immune system detects infections.
C. The immune system eliminates infections.
D. The immune system creates infections.

Correct answer: D

Rationale: The correct answer is D. The primary functions of a healthy immune system do not involve creating infections. A healthy immune system helps the body avoid infections by providing defense mechanisms, detects infections by recognizing harmful pathogens, and eliminates infections by attacking and clearing out pathogens. Creating infections goes against the protective role of the immune system and is not a function it performs. Therefore, choices A, B, and C are correct functions of a healthy immune system, while choice D is incorrect.

5. Blood type is a trait determined by multiple alleles, with IA and IB being co-dominant: IA codes for A blood and IB codes for B blood, while i codes for O blood and is recessive to both. If an A heterozygote individual and an O individual have a child, what is the probability that the child will have A blood?

A. 25%
B. 50%
C. 75%
D. 100%

Correct answer: B

Rationale: If an A heterozygote (IAi) and an O individual (ii) have a child, there is a 50% chance the child will inherit the IA allele and have A blood. The A heterozygote can pass on either the IA or i allele, while the O individual can only pass on the i allele. Therefore, the possible genotypes for the child are IAi (A blood) or ii (O blood), resulting in a 50% chance of the child having A blood. Choice A (25%) is incorrect as it does not take into account the possibility of inheriting the IA allele. Choice C (75%) and Choice D (100%) are incorrect as they overestimate the probability of the child having A blood.