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Osteoporosis is a condition that leads to weakened bones and an increased risk of fractures. Which hormone plays a key role in bone health and is often affected in osteoporosis?
- A. Estrogen
- B. Testosterone
- C. Thyroid hormone
- D. Insulin
Correct Answer: A
Rationale: Estrogen plays a crucial role in maintaining bone health by inhibiting bone resorption and promoting bone formation. In postmenopausal women, estrogen levels decrease, leading to an increased risk of osteoporosis due to accelerated bone loss. This hormonal imbalance contributes to weakened bones and an increased risk of fractures in individuals with osteoporosis. Testosterone and thyroid hormone do play roles in bone health, but estrogen has a more significant impact. Testosterone is more commonly associated with muscle mass and strength, while thyroid hormone regulates metabolism. Insulin is not directly involved in bone health and is not typically affected in osteoporosis.
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Which organelle is responsible for the final stages of protein modification and packaging for secretion in animal cells?
- A. Rough endoplasmic reticulum (RER)
- B. Smooth endoplasmic reticulum (SER)
- C. Ribosomes
- D. Golgi apparatus
Correct Answer: D
Rationale: The Golgi apparatus is responsible for the final stages of protein modification and packaging for secretion in animal cells. After proteins are synthesized in the rough endoplasmic reticulum (RER), they are transported to the Golgi apparatus for further processing, sorting, and packaging before being sent to their final destination within or outside the cell. The smooth endoplasmic reticulum (SER) is mainly involved in lipid metabolism and detoxification processes, not protein modification. Ribosomes are the cellular organelles responsible for protein synthesis, not the final stages of protein modification and packaging for secretion, which is the role of the Golgi apparatus.
What is the term used to describe the inability of the kidneys to effectively filter waste products from the blood?
- A. Dehydration
- B. Kidney failure
- C. Incontinence
- D. Nephritis
Correct Answer: B
Rationale: Kidney failure is the term used to describe the inability of the kidneys to effectively filter waste products from the blood. Dehydration refers to insufficient fluid intake and not the kidney's filtering function. Incontinence is the loss of bladder control, not related to kidney filtration. Nephritis is the inflammation of the kidneys, not specifically related to the kidneys' inability to filter waste products.
Which of the following is NOT an example of an intermolecular force?
- A. Hydrogen bonding
- B. Dipole-dipole interactions
- C. Ionic bonding
- D. London dispersion forces
Correct Answer: C
Rationale: Ionic bonding is not considered an intermolecular force but an intramolecular force. Intermolecular forces occur between different molecules, while intramolecular forces act within a molecule. Hydrogen bonding, dipole-dipole interactions, and London dispersion forces are intermolecular forces. Hydrogen bonding involves a hydrogen atom bonded to a highly electronegative atom, dipole-dipole interactions occur between polar molecules, and London dispersion forces are temporary attractions between nonpolar molecules.
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
Which type of muscle is characterized by involuntary contractions, is striated, and is primarily found in the heart?
- A. Skeletal muscle
- B. Smooth muscle
- C. Cardiac muscle
- D. Elastic muscle
Correct Answer: C
Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle fits the description provided in the question as it exhibits involuntary contractions, striations, and is predominantly located in the heart. Skeletal muscle, while also striated, is voluntary and not involuntary like cardiac muscle. Smooth muscle lacks striations and is typically found in the walls of internal organs. Elastic muscle is not a recognized type of muscle tissue in human anatomy, making it an incorrect choice.