Nokea
Dendrites are finger-like extensions found on
- A. Muscle cells
- B. Connective tissue cells
- C. Neurons
- D. Epithelial cells
Correct Answer: C
Rationale: Dendrites are the branched extensions of neurons that receive signals from other neurons and transmit those signals to the cell body. They play a crucial role in the communication process within the nervous system, allowing neurons to communicate with each other and integrate incoming signals to generate responses. The other choices are incorrect because dendrites specifically belong to neurons, not muscle cells, connective tissue cells, or epithelial cells.
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A 10 kg box rests on a frictionless surface. A horizontal force of 20 N is applied to the box. What is the box's acceleration?
- A. 0.5 m/s²
- B. 1 m/s²
- C. 2 m/s²
- D. 10 m/s²
Correct Answer: B
Rationale: The acceleration of an object is given by the formula \(a = \frac{F}{m}\), where \(F\) is the net force acting on the object and \(m\) is the mass of the object. In this case, the net force acting on the box is 20 N, and the mass of the box is 10 kg. Plugging these values into the formula, we get \(a = \frac{20}{10} = 2\) m/s².
Which of the following structures is responsible for preventing the backflow of blood from the left ventricle into the left atrium?
- A. Aortic valve
- B. Pulmonary valve
- C. Tricuspid valve
- D. Mitral valve
Correct Answer: D
Rationale: The correct answer is D, the Mitral valve. The mitral valve, also known as the bicuspid valve, is situated between the left atrium and the left ventricle. Its primary function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. The other choices are incorrect because: A) The aortic valve prevents backflow from the aorta into the left ventricle. B) The pulmonary valve prevents backflow from the pulmonary artery into the right ventricle. C) The tricuspid valve prevents backflow from the right ventricle into the right atrium.
Which gland produces the hormone responsible for the 'fight-or-flight' response in stressful situations?
- A. Thyroid gland
- B. Pituitary gland
- C. Adrenal gland
- D. Pancreas
Correct Answer: C
Rationale: The correct answer is C: Adrenal gland. The hormone responsible for the 'fight-or-flight' response in stressful situations is produced by the adrenal gland. This hormone is called adrenaline (epinephrine) and is released in response to stress, preparing the body to either fight the stressor or flee from it. The other choices are incorrect because the thyroid gland primarily produces hormones that regulate metabolism, the pituitary gland produces various hormones that control other endocrine glands, and the pancreas produces insulin and glucagon to regulate blood sugar levels.
Scoliosis is a condition characterized by abnormal lateral curvature of the spine. Which part of the spine is most commonly affected?
- A. Cervical spine (neck)
- B. Thoracic spine (upper back)
- C. Lumbar spine (lower back)
- D. All of the above
Correct Answer: B
Rationale: Scoliosis most commonly affects the thoracic spine, which is the upper back region. While scoliosis can potentially affect any part of the spine, the thoracic spine is the most frequently involved area. This region is more commonly affected due to the natural structural curves of the spine and the biomechanics of the thoracic area. The cervical spine (neck) and lumbar spine (lower back) can also be affected by scoliosis, but the thoracic spine is the primary area of involvement in most cases. Therefore, the correct answer is B, as it is the part of the spine most commonly affected by scoliosis.
Which property of a substance describes its ability to conduct heat or electricity?
- A. Reactivity
- B. Conductivity
- C. Density
- D. Viscosity
Correct Answer: B
Rationale: Conductivity is the correct property that describes a substance's ability to conduct heat or electricity. Reactivity is related to how readily a substance undergoes chemical reactions, not its ability to conduct heat or electricity. Density refers to the mass per unit volume of a substance, which is different from its ability to conduct heat or electricity. Viscosity measures a substance's resistance to flow, not its ability to conduct heat or electricity.