Nokea
Which hormone primarily triggers ovulation in the female menstrual cycle?
- A. Estrogen
- B. Progesterone
- C. Luteinizing hormone (LH)
- D. Follicle-stimulating hormone (FSH)
Correct Answer: C
Rationale: Luteinizing hormone (LH) is the hormone primarily responsible for triggering ovulation in the female menstrual cycle. LH surge occurs around the middle of the menstrual cycle, causing the mature follicle to release an egg from the ovary. Estrogen and progesterone play crucial roles in regulating the menstrual cycle and preparing the endometrium for potential implantation of a fertilized egg, but they do not trigger ovulation directly. Follicle-stimulating hormone (FSH) is essential for the development of ovarian follicles but is not the primary hormone responsible for ovulation. Therefore, the correct answer is Luteinizing hormone (LH) as it directly initiates the release of the egg during ovulation.
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Which part of the nervous system is responsible for transmitting signals from the sensory organs to the central nervous system?
- A. Autonomic nervous system
- B. Somatic nervous system
- C. Peripheral nervous system
- D. Central nervous system
Correct Answer: C
Rationale: The correct answer is C, the peripheral nervous system. The peripheral nervous system is responsible for transmitting signals from the sensory organs to the central nervous system. It consists of nerves that connect the central nervous system to the rest of the body, including sensory nerves that carry information from the sensory organs to the brain and spinal cord. Choices A, B, and D are incorrect. The autonomic nervous system is responsible for involuntary functions like heart rate and digestion, the somatic nervous system controls voluntary movements, and the central nervous system consists of the brain and spinal cord.
What is the term for a solution that has exactly the same concentration of solute as another solution?
- A. Saturated solution
- B. Unsaturated solution
- C. Isotonic solution
- D. Concentrated solution
Correct Answer: C
Rationale: An isotonic solution is a solution that has the same concentration of solute as another solution. When cells are placed in an isotonic solution, there is no net movement of water across the cell membrane, maintaining equilibrium. Choice A, a saturated solution, refers to a solution that contains the maximum amount of solute that can be dissolved at a given temperature. Choice B, an unsaturated solution, is a solution that contains less solute than a saturated solution under the same conditions. Choice D, a concentrated solution, is a solution with a high amount of solute compared to the solvent.
An element with atomic number 26 and mass number 56 is most likely to be:
- A. Iron (Fe)
- B. Cobalt (Co)
- C. Nickel (Ni)
- D. Manganese (Mn)
Correct Answer: A
Rationale: The element with atomic number 26 and mass number 56 corresponds to Iron (Fe). Iron has 26 protons, which aligns with the given atomic number, and Fe-56 has 26 neutrons, which aligns with the given mass number. This confirms that Iron (Fe) is the correct answer. Cobalt (Co), Nickel (Ni), and Manganese (Mn) have different atomic numbers and mass numbers, so they are not the correct choices in this scenario.
Which vitamin plays a vital role in immune function?
- A. Vitamin A
- B. Vitamin B12
- C. Vitamin D
- D. Vitamin E
Correct Answer: C
Rationale: Vitamin D is the correct answer. It plays a vital role in immune function by regulating the immune system and enhancing the pathogen-fighting effects of monocytes and macrophages. Deficiency in Vitamin D has been linked to increased susceptibility to infections and autoimmune diseases, highlighting its importance in maintaining a healthy immune response. Vitamin A (Choice A) is essential for vision and skin health but is not primarily known for its role in immune function. Vitamin B12 (Choice B) is important for red blood cell formation and neurological function, not specifically immune function. Vitamin E (Choice D) acts as an antioxidant and is beneficial for skin health and cell function, but it is not primarily associated with immune system support.
In a single displacement reaction, one element takes the place of another element in a compound. Which of the following is an example?
- A. 2H2 + O2 -> 2H2O
- B. Zn + 2HCl -> ZnCl2 + H2
- C. CaCO3 -> CaO + CO2
- D. CH4 + 2O2 -> CO2 + 2H2O
Correct Answer: B
Rationale: Option B demonstrates a single displacement reaction where zinc (Zn) displaces hydrogen (H) in hydrochloric acid (HCl) to produce zinc chloride (ZnCl2) and hydrogen gas (H2). This reaction exemplifies the concept of one element (Zn) replacing another element (H) in a compound (HCl), which is characteristic of single displacement reactions. Choices A, C, and D do not involve a single element displacing another in a compound, making them incorrect. In choice A, hydrogen and oxygen combine to form water, which is not a single displacement reaction. In choice C, calcium carbonate decomposes into calcium oxide and carbon dioxide, not involving displacement of elements. In choice D, methane reacts with oxygen to form carbon dioxide and water, which is a combustion reaction, not a single displacement reaction.