Nokea
Which neurotransmitter is involved in muscle movement?
- A. Dopamine
- B. Acetylcholine
- C. Serotonin
- D. GABA
Correct Answer: B
Rationale: Acetylcholine is the neurotransmitter responsible for muscle movement. It is released from motor neurons at the neuromuscular junction and binds to receptors on muscle fibers, initiating muscle contraction. Dopamine, serotonin, and GABA serve different functions in the brain and body, such as regulating mood, sleep, and inhibitory signaling, respectively. Therefore, choices A, C, and D are incorrect in the context of muscle movement.
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Which of the following is NOT a mechanism that can directly cause evolution by natural selection?
- A. Mutations in genes
- B. Differential survival and reproduction based on traits
- C. Inheritance of acquired characteristics (like strong muscles from working out)
- D. Competition for resources in an environment
Correct Answer: C
Rationale: A) Mutations in genes can introduce new genetic variations into a population, which can be acted upon by natural selection.
B) Differential survival and reproduction based on traits is a key component of natural selection, as individuals with advantageous traits are more likely to survive and pass on their genes to the next generation.
C) Inheritance of acquired characteristics, also known as Lamarckism, is not a mechanism of evolution by natural selection. Traits acquired during an individual's lifetime (such as strong muscles from working out) are not passed on to offspring.
D) Competition for resources in an environment can drive natural selection by favoring individuals with traits that help them better compete for limited resources.
Therefore, the correct answer is C) Inheritance of acquired characteristics (like strong muscles from working out), as it is not a mechanism that can directly cause evolution by natural selection.
Which of the following blood vessels carries oxygenated blood away from the heart?
- A. Pulmonary artery
- B. Aorta
- C. Superior vena cava
- D. Inferior vena cava
Correct Answer: B
Rationale: The aorta is the correct answer because it is the main artery in the body that carries oxygenated blood away from the heart to the rest of the body. The pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. The superior and inferior vena cava are veins that carry deoxygenated blood from the body back to the heart. Therefore, choices A, C, and D are incorrect as they do not carry oxygenated blood away from the heart.
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.
The endocrine system communicates through chemical messengers called:
- A. Enzymes
- B. Hormones
- C. Antibodies
- D. Neurons
Correct Answer: B
Rationale: The correct answer is B: Hormones. The endocrine system communicates through hormones, which are chemical messengers produced by glands and released into the bloodstream to target specific cells or organs in the body. Enzymes are biological molecules that catalyze biochemical reactions, antibodies are part of the immune system, and neurons are cells that transmit nerve impulses. In this context, enzymes, antibodies, and neurons do not play roles in the endocrine system's communication process, making them incorrect choices.
Which structure connects the two hemispheres of the brain, allowing communication and coordination between them?
- A. Corpus callosum
- B. Thalamus
- C. Hypothalamus
- D. Medulla oblongata
Correct Answer: A
Rationale: The correct answer is the corpus callosum. It is a thick band of nerve fibers that connects the two hemispheres of the brain, facilitating communication and coordination between them. The thalamus acts as a relay station for sensory information, the hypothalamus regulates basic functions like hunger and thirst, and the medulla oblongata controls vital functions such as breathing and heart rate. Therefore, choices B, C, and D are incorrect as they do not specifically connect the two hemispheres of the brain as the corpus callosum does.