Nokea
What controls muscles by sending electrical impulses to the muscles?
- A. Blood vessels
- B. Nerves
- C. Hormones
- D. Neurons
Correct Answer: B
Rationale: Nerves control muscles by transmitting electrical impulses that initiate muscle contractions. Blood vessels are responsible for transporting blood, not controlling muscles. Hormones are chemical messengers produced by glands to regulate bodily functions, not specifically controlling muscles. Neurons are the basic building blocks of the nervous system that transmit signals, but nerves are the specific structures that control muscles by sending electrical impulses.
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Find the lowest coefficients that will balance the following combustion equation: __C H + __O2 → __CO2 + __H2O
- A. 1:5:5:2
- B. 4:10:20:8
- C. 2:9:10:4
- D. 2:5:10:4
Correct Answer: C
Rationale: To balance the combustion equation CxHy + O2 → xCO2 + y/2 H2O, we need to balance the carbon and hydrogen atoms. The balanced equation for the given combustion is: 2C H4 + 9O2 → 2CO2 + 4H2O. This means that the correct coefficients are 2:9:10:4, which corresponds to choice C. Choice A (1:5:5:2) does not balance the equation correctly, choice B (4:10:20:8) has excessive oxygen and does not balance the equation, and choice D (2:5:10:4) does not provide the correct ratio of oxygen to balance the equation.
What is the muscular tube that connects the outer surface to the cervix in a woman's birth canal referred to as?
- A. The uterus
- B. The cervix
- C. The vagina
- D. The ovaries
Correct Answer: C
Rationale: The correct answer is C, 'The vagina.' The muscular tube that connects the outer surface to the cervix in a woman's birth canal is called the vagina. The vagina serves as the passageway for menstrual flow, sexual intercourse, and childbirth. The cervix, not the uterus, connects the vagina to the uterus. The ovaries, on the other hand, are the organs responsible for producing eggs and female hormones, but they are not the muscular tube connecting the outer surface to the cervix in the birth canal.
Which two types of elements are most likely to form an ionic bond?
- A. Two elements that are in the same period.
- B. Two elements that are non-metals and have p orbitals.
- C. One element that is a transition metal with d orbitals and one element that is a metal with s orbitals.
- D. One element that is a metal with s orbitals and one element that is a nonmetal with p orbitals.
Correct Answer: D
Rationale: Ionic bonds typically form between a metal, which donates electrons from its s orbital, and a nonmetal, which accepts electrons into its p orbital. This transfer of electrons leads to the formation of an ionic bond. Choice A is incorrect as elements in the same period may vary significantly in their properties. Choice B is incorrect because ionic bonds are usually formed between a metal and a nonmetal, not two nonmetals. Choice C is incorrect because transition metals generally form complex ions through the sharing of electrons, not typical ionic bonds.
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.
Through which aspect do afferent fibers enter 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: B
Rationale: Afferent fibers, responsible for carrying sensory information, enter the spinal cord through the posterior (dorsal) aspect. Specifically, they enter through the dorsal roots, located on the back (posterior) side of the spinal cord. This route allows sensory information to be transmitted to the central nervous system for processing and integration. Choices A, C, and D are incorrect because afferent fibers do not enter the spinal cord through the anterior, ventral, or lateral aspects.