Nokea
Which of the following is an example of an organ?
- A. Skin
- B. Neuron
- C. Brainstem
- D. DNA
Correct Answer: A
Rationale: The correct answer is A, 'Skin.' The skin is the largest organ in the human body and consists of multiple tissue types working together to perform various functions such as protection, sensation, and temperature regulation. Choice B, 'Neuron,' is a specialized cell in the nervous system and not an organ. Choice C, 'Brainstem,' is a part of the central nervous system composed of nerve tissues but is not an organ on its own. Choice D, 'DNA,' is a molecule that carries genetic instructions, not an organ.
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What does the P-wave in an ECG correspond to?
- A. Atrial repolarization
- B. Depolarization of SA node
- C. Ventricular depolarization
- D. Ventricular repolarization
Correct Answer: B
Rationale: The P-wave in an ECG represents the depolarization of the SA node and the atria, not atrial repolarization. Choice C, ventricular depolarization, is incorrect because the P-wave does not correspond to ventricular activity. Choice D, ventricular repolarization, is also incorrect as the P-wave does not depict ventricular repolarization. The correct interpretation is that the P-wave signifies the initiation of the electrical impulse at the SA node and subsequent atrial depolarization, making option B the correct answer.
Which element is essential for the formation of hemoglobin?
- A. Calcium
- B. Iron
- C. Potassium
- D. Sodium
Correct Answer: B
Rationale: The correct answer is Iron. Iron is essential for the formation of hemoglobin, the protein in red blood cells that binds and transports oxygen throughout the body. Calcium (Choice A), Potassium (Choice C), and Sodium (Choice D) are not directly involved in the formation of hemoglobin and its oxygen-carrying function.
Which of the following antibodies can cross the placenta?
- A. IgA
- B. IgD
- C. IgG
- D. IgM
Correct Answer: C
Rationale: The correct answer is IgG. IgG is the only antibody that can cross the placenta, providing passive immunity to the developing fetus. IgA, IgD, and IgM do not cross the placenta. IgA is mainly found in mucosal secretions, IgD is involved in the activation of B cells, and IgM is the first antibody produced in response to an infection, but it does not cross the placental barrier.
Which organelle is responsible for storing genetic material?
- A. Mitochondria
- B. Nucleus
- C. Ribosome
- D. Endoplasmic reticulum
Correct Answer: B
Rationale: The correct answer is the Nucleus. The nucleus is responsible for storing genetic material (DNA) and controlling cell functions. Mitochondria are known for energy production, not genetic storage. Ribosomes are involved in protein synthesis, not genetic material storage. The endoplasmic reticulum is involved in protein and lipid synthesis, not genetic material storage. Therefore, the nucleus is the organelle primarily responsible for housing the genetic material within a cell.
Which part of the brain controls breathing and heart rate?
- A. Cerebrum
- B. Medulla oblongata
- C. Thalamus
- D. Cerebellum
Correct Answer: B
Rationale: The medulla oblongata is the correct answer because it is responsible for controlling involuntary functions such as breathing and heart rate. The cerebrum (Choice A) is primarily associated with higher brain functions like thinking and voluntary movements, not with regulating basic bodily functions like breathing and heart rate. The thalamus (Choice C) serves as a relay station for sensory information but is not directly involved in controlling breathing and heart rate. The cerebellum (Choice D) plays a role in coordination and balance, not in regulating respiratory and cardiac functions.