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Which part of the brain is responsible for coordinating muscle movements, maintaining balance, and posture?
- A. Cerebrum
- B. Cerebellum
- C. Medulla oblongata
- D. Thalamus
Correct Answer: B
Rationale: The correct answer is B, the cerebellum. The cerebellum plays a crucial role in coordinating muscle movements, maintaining balance, and posture. It receives inputs from sensory systems, the spinal cord, and other brain regions to fine-tune motor movements. The cerebrum, choice A, is primarily involved in higher brain functions like thinking and decision-making. The medulla oblongata, choice C, controls essential functions such as breathing and heart rate. The thalamus, choice D, serves as a relay center for sensory information but is not directly responsible for coordinating muscle movements, balance, or posture.
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What is the main function of calcitonin, a hormone produced by the thyroid gland?
- A. Stimulate metabolism and heat production
- B. Increase calcium absorption from the intestines
- C. Enhance bone growth and development
- D. Lower blood calcium levels
Correct Answer: D
Rationale: Calcitonin is a hormone produced by the thyroid gland that primarily functions to lower blood calcium levels. It achieves this by inhibiting bone breakdown and promoting calcium excretion by the kidneys. Therefore, the correct answer is D as it reflects the main role of calcitonin in calcium homeostasis. Choices A, B, and C are incorrect as they do not align with the primary function of calcitonin. Calcitonin does not stimulate metabolism and heat production (Choice A), increase calcium absorption from the intestines (Choice B), or enhance bone growth and development (Choice C).
What is the difference between mitosis and meiosis?
- A. Mitosis produces haploid cells, while meiosis produces diploid cells
- B. Mitosis involves crossing over, while meiosis does not.
- C. Mitosis results in four daughter cells, while meiosis results in two
- D. Mitosis is responsible for sexual reproduction, while meiosis is responsible for asexual reproduction.
Correct Answer: C
Rationale: - Mitosis is a type of cell division that results in two identical daughter cells with the same number of chromosomes as the parent cell. Therefore, mitosis results in two daughter cells.
- Meiosis is a type of cell division that results in four daughter cells, each with half the number of chromosomes as the parent cell. This reduction in chromosome number is essential for sexual reproduction.
- Option A is incorrect because mitosis produces diploid cells (cells with the same number of chromosomes as the parent cell), while meiosis produces haploid cells (cells with half the number of chromosomes as the parent cell).
- Option B is incorrect because crossing over, the exchange of genetic material between homologous chromosomes, occurs during meiosis and not during mitosis.
- Option D is incorrect because mitosis is not responsible for sexual reproduction; it is a process of asexual reproduction and
What are the white blood cells responsible for coordinating the immune response called?
- A. Red blood cells
- B. Platelets
- C. Lymphocytes
- D. Neutrophils
Correct Answer: C
Rationale: Lymphocytes, which include B cells, T cells, and natural killer cells, are responsible for coordinating the immune response. They play a crucial role in recognizing and fighting against pathogens and foreign substances in the body. Red blood cells are responsible for oxygen transport, platelets aid in blood clotting, and neutrophils are white blood cells primarily involved in combating infections. Therefore, the correct answer is C, lymphocytes, as they are specifically involved in coordinating immune responses.
Where is the energy for most cellular processes produced?
- A. Nucleus
- B. Cytoplasm
- C. Mitochondria
- D. Ribosomes
Correct Answer: C
Rationale: The correct answer is C: Mitochondria. The energy for most cellular processes is produced in the mitochondria through the process of cellular respiration. Mitochondria are often referred to as the powerhouse of the cell because they generate ATP, the energy currency of the cell. This process involves the breakdown of glucose molecules to produce ATP, which fuels various cellular activities. Choices A, B, and D are incorrect. The nucleus is responsible for storing genetic material and controlling cell activities, not energy production. The cytoplasm is where various cellular activities take place, but it is not the primary site for energy production. Ribosomes are involved in protein synthesis and do not generate energy for cellular processes.
In a neutral atom, the number of electrons is:
- A. Must be equal to the number of protons.
- B. Must be less than the number of protons.
- C. Must be greater than the number of neutrons.
- D. Can vary depending on the atom's temperature.
Correct Answer: A
Rationale: In a neutral atom, the number of electrons must be equal to the number of protons to maintain electrical neutrality. Electrons carry a negative charge while protons carry a positive charge. By having an equal number of electrons and protons, the positive and negative charges balance each other out, resulting in an electrically neutral atom. Choice B is incorrect because in a neutral atom, the number of electrons and protons must be equal. Choice C is incorrect as it compares electrons to neutrons, which are not directly related in determining an atom's charge. Choice D is incorrect as the number of electrons in a neutral atom is not dependent on the atom's temperature but rather on the atom's balance of positive and negative charges.