Nokea
Which blood vessels carry deoxygenated blood from the body back to the right atrium of the heart?
- A. Arteries
- B. Veins
- C. Capillaries
- D. Venules
Correct Answer: B
Rationale: Veins are the blood vessels that carry deoxygenated blood from the body back to the heart. Arteries transport oxygenated blood away from the heart. Capillaries are the smallest blood vessels where gas exchange occurs between blood and tissues. Venules are small veins that connect capillaries to larger veins, but they do not directly carry deoxygenated blood back to the heart.
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Which vitamin deficiency can lead to kidney stones?
- A. Vitamin A
- B. Vitamin B12
- C. Vitamin D
- D. Vitamin K
Correct Answer: C
Rationale: The correct answer is Vitamin D. Vitamin D deficiency can lead to kidney stones because Vitamin D helps regulate calcium levels in the body. Low levels of Vitamin D can result in increased calcium absorption from the intestines, leading to higher levels of calcium in the urine, which can form kidney stones. Choices A, B, and D are incorrect as deficiencies in these vitamins are not directly associated with kidney stone formation.
What enzyme plays a key role in breaking down carbohydrates in the small intestine?
- A. Pepsin
- B. Lipase
- C. Amylase
- D. Trypsin
Correct Answer: C
Rationale: Amylase is the enzyme responsible for breaking down carbohydrates in the small intestine. It specifically targets starches and sugars, breaking them down into smaller molecules like maltose and glucose that can be absorbed by the body. Pepsin is an enzyme that breaks down proteins in the stomach, not the small intestine. Lipase is responsible for breaking down fats, not carbohydrates. Trypsin is an enzyme that breaks down proteins in the small intestine, not carbohydrates.
What is the primary function of the myelin sheath that surrounds some axons in the nervous system?
- A. To initiate nerve impulses
- B. To transmit sensory information
- C. To speed up the transmission of nerve impulses
- D. To connect neurons at synapses
Correct Answer: C
Rationale: The primary function of the myelin sheath is to speed up the transmission of nerve impulses. The myelin sheath acts as an insulating layer around the axon, allowing for faster conduction of electrical impulses along the nerve fiber. This insulation prevents the electrical signal from dissipating or 'leaking' out, which helps in the rapid and efficient transmission of nerve impulses along the axon. Choice A is incorrect because the myelin sheath does not initiate nerve impulses; it helps in conducting them. Choice B is incorrect as the myelin sheath's main role is not in transmitting sensory information but rather in facilitating the transmission of nerve impulses. Choice D is incorrect because the myelin sheath's function is not to connect neurons at synapses; instead, it is primarily involved in enhancing the speed of nerve impulse transmission.
Which type of waves require a medium (solid, liquid, or gas) to propagate?
- A. Transverse waves
- B. Longitudinal waves
- C. Electromagnetic waves
- D. Surface waves
Correct Answer: B
Rationale: Longitudinal waves require a medium (solid, liquid, or gas) to propagate because the particles in the medium move parallel to the direction of the wave. As a result, they rely on the medium for transmission. Transverse waves, on the contrary, do not need a medium and can travel through a vacuum, making choice A incorrect. Electromagnetic waves, represented by choice C, do not require a medium as they consist of oscillating electric and magnetic fields that can propagate through a vacuum. Surface waves, the option in D, involve a combination of both longitudinal and transverse motion and do require a medium to travel, but longitudinal waves are the ones that strictly depend on a medium for propagation.
How are sister chromatids distinguished from homologous chromosomes in meiosis I?
- A. Sister chromatids share the same centromere, while homologous chromosomes have different centromeres.
- B. Sister chromatids have identical DNA sequences, while homologous chromosomes have slightly different sequences due to crossing over.
- C. Sister chromatids repel each other, while homologous chromosomes attract each other during synapsis.
- D. Sister chromatids separate during anaphase I, while homologous chromosomes separate during anaphase II.
Correct Answer: B
Rationale: In meiosis I, sister chromatids are exact copies of each other, containing identical DNA sequences. On the other hand, homologous chromosomes are pairs of chromosomes, with one inherited from each parent, and they can have different versions of genes due to genetic recombination during crossing over in prophase I. Choice A is incorrect because homologous chromosomes naturally have different centromeres. Choice C is incorrect as sister chromatids and homologous chromosomes do not exhibit repulsion or attraction during synapsis. Choice D is incorrect as sister chromatids separate during anaphase II, not anaphase I, while homologous chromosomes separate during anaphase I.