Nokea
What happens when an atom loses an electron?
- A. It forms a molecule.
- B. It gains a positive charge and becomes an ion.
- C. It alters its elemental identity.
- D. No change occurs; it remains neutral.
Correct Answer: B
Rationale: When an atom loses an electron, it gains a positive charge and becomes an ion. This occurs because the number of protons in the atom exceeds the number of electrons, leading to a positive charge. Therefore, the atom undergoes a transformation into an ion by losing an electron. Choice A is incorrect because losing an electron does not result in the formation of a molecule, as molecules are made up of bonded atoms. Choice C is incorrect because losing an electron does not change the fundamental identity of the atom; it only changes its charge. Choice D is incorrect because losing an electron causes the atom to become positively charged, altering its neutrality.
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What is a temporary loss of consciousness due to insufficient blood flow to the brain called?
- A. Stroke
- B. Seizure
- C. Syncope (fainting)
- D. Coma
Correct Answer: C
Rationale: Syncope, also known as fainting, is a temporary loss of consciousness caused by insufficient blood flow to the brain. It results from a brief interruption in the brain's blood supply, leading to a temporary loss of consciousness. The correct answer is C. A stroke, option A, is caused by a blockage or rupture of blood vessels in the brain, not insufficient blood flow. Seizure, option B, involves a sudden surge of electrical brain activity, not reduced blood flow. Coma, option D, is characterized by prolonged unconsciousness, not a temporary loss of consciousness due to insufficient blood flow.
What is the term for the distance between the center of a lens or curved mirror and its focal point?
- A. Aperture
- B. Focal length
- C. Refractive index
- D. Lens thickness
Correct Answer: B
Rationale: The correct answer is B: Focal length. Focal length is the distance between the center of a lens or curved mirror and its focal point. It determines how strongly the lens converges or diverges light, affecting the image formation. Aperture, choice A, refers to the opening through which light enters the lens, controlling the amount of light passing through. Refractive index, choice C, measures how much light bends when passing through a medium, affecting the speed of light. Lens thickness, choice D, is the physical dimension of the lens, influencing optical properties and compatibility with frames.
Which component of the nervous system is responsible for controlling voluntary movements, such as the contraction of skeletal muscles?
- A. Autonomic nervous system
- B. Peripheral nervous system
- C. Somatic nervous system
- D. Sympathetic nervous system
Correct Answer: C
Rationale: The correct answer is C: Somatic nervous system. The somatic nervous system is responsible for controlling voluntary movements, such as the contraction of skeletal muscles. This system consists of motor neurons that send signals from the central nervous system to the skeletal muscles, allowing for conscious control over movement. The autonomic nervous system (A) controls involuntary functions like heart rate and digestion, the peripheral nervous system (B) includes all nerves outside the central nervous system, and the sympathetic nervous system (D) is a division of the autonomic nervous system responsible for the fight-or-flight response. Therefore, choices A, B, and D are incorrect as they do not specifically regulate voluntary movements of skeletal muscles, which is a function of the somatic nervous system.
What is the final stage of both mitosis and meiosis?
- A. Interphase
- B. Telophase
- C. Cytokinesis
- D. G1 phase
Correct Answer: B
Rationale: - Interphase (option A) is not the final stage of mitosis or meiosis; it is the phase before cell division where the cell prepares for division by growing and replicating its DNA.
- Telophase (option B) is the final stage of both mitosis and meiosis. During telophase, the separated chromosomes reach opposite poles of the cell, the nuclear membrane reforms around each set of chromosomes, and the chromosomes begin to decondense.
- Cytokinesis (option C) is the process of dividing the cytoplasm to form two separate daughter cells. While it occurs after telophase, it is not considered the final stage of mitosis or meiosis.
- G1 phase (option D) is the first gap phase in the cell cycle, occurring before DNA replication. It is not the final stage of mitosis or meiosis.
What is the largest lymphatic vessel in the body?
- A. Jugular vein
- B. Thoracic duct
- C. Subclavian vein
- D. Aorta
Correct Answer: B
Rationale: The thoracic duct is the largest lymphatic vessel in the body, responsible for draining lymph from most parts of the body except for the right upper quadrant. The jugular vein, subclavian vein, and aorta are not part of the lymphatic system; they are blood vessels and do not serve as lymphatic vessels. Therefore, choices A, C, and D are incorrect as they are not associated with the lymphatic system's transport of lymph.