Nokea
Which valve prevents blood from entering the left atrium when the ventricles contract?
- A. Pulmonary valve
- B. Tricuspid valve
- C. Mitral valve
- D. Aortic valve
Correct Answer: C
Rationale: The correct answer is the mitral valve, also known as the bicuspid valve. The mitral valve prevents blood from flowing back into the left atrium during ventricular contraction. The tricuspid valve is located between the right atrium and right ventricle, the pulmonary valve is between the right ventricle and the pulmonary artery, and the aortic valve is situated between the left ventricle and the aorta. Therefore, choices A, B, and D are incorrect as they are not related to preventing blood from entering the left atrium during ventricular contraction.
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Which term refers to a position farther from the midline of the body? For example, the little toe is lateral to the big toe on the same foot.
- A. Lateral
- B. Medial
- C. Proximal
- D. Distal
Correct Answer: A
Rationale: The correct answer is A: Lateral. Lateral refers to a position farther away from the midline of the body. In the example provided, the little toe is indeed lateral to the big toe on the same foot. This is in contrast to 'medial,' which means closer to the midline. 'Proximal' refers to a position closer to the point of attachment or the trunk of the body, while 'distal' refers to a position farther from the point of attachment or the trunk of the body.
What is the length of DNA that can code for a particular protein?
- A. Chromosome
- B. Nucleotide
- C. Gene
- D. Ribosome
Correct Answer: C
Rationale: The correct answer is C: Gene. A gene is a specific segment of DNA that contains the information necessary to produce a particular protein. Genes are responsible for coding proteins, and each gene carries the instructions for a specific protein. Chromosomes consist of many genes and are not a specific length that codes for a protein. Nucleotides are the building blocks of DNA and are not a length that codes for a protein. Ribosomes are cellular organelles involved in protein synthesis and do not directly code for proteins.
Smooth muscle is the only ____________ muscle in the body.
- A. Voluntary, striated
- B. Involuntary, non-striated
- C. Involuntary, striated
- D. Voluntary, non-striated
Correct Answer: B
Rationale: Smooth muscle is the only involuntary, non-striated muscle type in the body. It is found in organs like the intestines and blood vessels, where it controls movements without conscious effort. Choice A is incorrect because voluntary muscles are under conscious control, while smooth muscle is involuntary. Choice C is incorrect because striations are not present in smooth muscle, unlike skeletal muscle. Choice D is incorrect because smooth muscle is not voluntary and lacks striations, making it different from skeletal muscle.
Which type of capillary is the most permeable?
- A. Continuous capillaries
- B. Sinusoidal capillaries
- C. Fenestrated capillaries
- D. Vascular capillaries
Correct Answer: B
Rationale: Sinusoidal capillaries are indeed the most permeable type. They are characterized by large gaps between endothelial cells, allowing for the passage of large molecules and cells. These capillaries are commonly found in organs like the liver, bone marrow, and spleen where high permeability is required for specialized functions such as filtration and exchange of substances.
Continuous capillaries have tight junctions and are the least permeable, found in muscles, lungs, and the central nervous system where strict control over permeability is needed. Fenestrated capillaries, on the other hand, have small pores or fenestrations and are intermediate in permeability, found in organs like the kidneys, endocrine glands, and intestines where selective permeability is necessary. Vascular capillaries is not a specific type of capillary and is not a valid choice.
What is the fatty substance that coats axons to insulate, protect, and speed up impulses?
- A. Myelin
- B. Dendrite
- C. Neuron
- D. Synapse
Correct Answer: A
Rationale: The correct answer is 'Myelin.' Myelin is a fatty substance that functions as an insulator for axons, providing protection and enhancing the speed of electrical impulses along neurons. This insulation is essential for ensuring efficient and rapid communication within the nervous system. Choices B, C, and D are incorrect. Dendrites are branched extensions of a neuron that receive signals, neurons are the basic building blocks of the nervous system that transmit information, and synapses are the junctions between neurons where communication occurs.