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 muscular chamber of the heart receives blood from the body and pumps it to the lungs?

A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle

Correct answer: A

Rationale: The correct answer is the right atrium. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava. It then pumps this deoxygenated blood to the lungs via the pulmonary artery for oxygenation. The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle. The right ventricle receives oxygen-poor blood from the right atrium and pumps it to the lungs. The left ventricle receives oxygenated blood from the left atrium and pumps it to the rest of the body.

3. Which statement about white blood cells is true?

A. B cells are responsible for antibody production.
B. White blood cells are produced in the bone marrow before entering the bloodstream.
C. Platelets, a specialized class of blood cells, function to clot blood and stop bleeding.
D. The majority of white blood cells are active throughout life, providing immunity across all age groups.

Correct answer: A

Rationale: The correct answer is A: B cells, a type of white blood cell, are responsible for producing antibodies in response to pathogens. Antibodies play a crucial role in identifying and neutralizing foreign substances like bacteria and viruses in the body, aiding in the immune response and protecting against infections. This function is essential for maintaining a healthy immune system. White blood cells, including B cells, are produced in the bone marrow before entering the bloodstream. Platelets, not white blood cells, are a specialized class of blood cells that function to clot blood and stop bleeding. While white blood cells provide immunity, not all of them are active throughout life as some have specific lifespans and functions.

4. What is a gene, and what is the relationship between genes, genotype, and phenotype?

A. A gene is a sequence of amino acids; genes make up proteins; genotype determines phenotype
B. A gene is a portion of DNA; genes determine traits; genotype is the genetic makeup; phenotype is the physical manifestation
C. A gene is a protein; proteins determine traits; genotype is the set of all genes
D. A gene is a lipid; lipids determine traits; phenotype is the physical manifestation

Correct answer: B

Rationale: A gene is a portion of DNA that contains the instructions for a specific trait. Genotype refers to the genetic makeup of an organism, encompassing all its genes. Phenotype, on the other hand, is the observable physical manifestation resulting from the interaction between an organism's genotype and environmental factors. Choice A is incorrect because genes do not consist of amino acids directly; they are sequences of nucleotides. Choice C is incorrect as genes do not determine traits directly but provide the instructions for proteins that may influence traits. Choice D is incorrect as genes are not lipids, and lipids do not determine traits; they are a type of biomolecule with different functions.

5. Which part of the cell serves as the control center for all cell activity?

A. Nucleus
B. Cell membrane
C. Cytoplasm
D. Mitochondria

Correct answer: A

Rationale: The corrected question and answer are accurate. The correct answer is A: Nucleus. The nucleus is known as the control center of the cell as it contains the cell's genetic material (DNA) and directs all cell activities including growth, metabolism, and reproduction. The other organelles listed in the choices, while important for various cellular functions, do not serve as the central control center for overall cell activity.