Nokea
What is the term for a genetic disorder caused by a mutation on the X chromosome?
- A. Autosomal dominant disorder
- B. Autosomal recessive disorder
- C. Sex-linked recessive disorder
- D. Sex-linked dominant disorder
Correct Answer: C
Rationale: A genetic disorder caused by a mutation on the X chromosome is termed a sex-linked recessive disorder (Option C). This type of disorder is more commonly seen in males due to their single X chromosome, making them more vulnerable to X-linked mutations. Females have two X chromosomes, providing a protective effect against X-linked disorders.\n- Autosomal dominant disorders (Option A) result from a mutation in one copy of a gene on non-sex chromosomes (autosomes) and are not specifically related to the X chromosome.\n- Autosomal recessive disorders (Option B) occur due to mutations in both copies of a gene on autosomes, not on the X chromosome.\n- Sex-linked dominant disorders (Option D) are rare and lead to more severe symptoms in males as they only require one copy of the mutated gene on the X chromosome to express the disorder. However, this is not the term for a genetic disorder caused by an X chromosome mutation.
You may also like to solve these questions
What happens to the kinetic energy of an object when its velocity is doubled?
- A. Kinetic energy remains the same
- B. Kinetic energy is halved
- C. Kinetic energy doubles
- D. Kinetic energy quadruples
Correct Answer: C
Rationale: Kinetic energy is directly proportional to the square of the velocity of an object according to the kinetic energy formula (KE = 0.5 * m * v^2). When the velocity is doubled, the kinetic energy increases by a factor of four (2^2), which means it doubles. Therefore, when the velocity of an object is doubled, its kinetic energy also doubles. Choice A is incorrect because kinetic energy is not constant but dependent on velocity. Choice B is incorrect because halving the velocity would result in 1/4 of the original kinetic energy. Choice D is incorrect as quadrupling the kinetic energy would occur if the velocity is squared, not the kinetic energy.
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.
What is the main function of the kidneys?
- A. To filter waste products from the blood
- B. To produce urine
- C. To regulate blood pressure
- D. To produce hormones that help control blood sugar levels
Correct Answer: A
Rationale: The main function of the kidneys is to filter waste products, excess ions, and water from the bloodstream to form urine, which is then excreted from the body. This process helps maintain the body's internal environment by regulating the balance of electrolytes, fluid volume, and pH levels. While the kidneys do produce urine as a result of filtering the blood, their primary function is to filter waste products rather than solely producing urine. Although the kidneys play a role in regulating blood pressure by controlling blood volume and electrolyte concentration, their main function is waste filtration. While the kidneys do produce hormones like erythropoietin and renin that regulate physiological processes, such as red blood cell production and blood pressure, the main role of the kidneys is waste filtration.
Which term best describes the gradual change in a species over time in response to environmental pressures?
- A. Punctuated equilibrium (rapid bursts of evolution)
- B. Gradualism (slow and continuous change)
- C. Founder effect (genetic drift in a small population)
- D. Adaptive radiation (rapid diversification of a species)
Correct Answer: B
Rationale: A) Punctuated equilibrium refers to rapid bursts of evolution followed by long periods of stability, rather than gradual change over time in response to environmental pressures. B) Gradualism is the process by which species evolve through slow and continuous changes over time in response to environmental pressures. This gradual change can lead to the development of new traits and adaptations. C) Founder effect is a type of genetic drift that occurs when a small group of individuals establishes a new population, leading to a loss of genetic variation compared to the original population. It does not specifically describe the gradual change in a species over time. D) Adaptive radiation is the rapid diversification of a species into a variety of forms to exploit different ecological niches, but it does not specifically refer to the gradual change in response to environmental pressures. Therefore, the term that best describes the gradual change in a species over time in response to environmental pressures is 'Gradualism.'
What is the difference between a prokaryotic cell and a eukaryotic cell?
- A. Prokaryotic cells have a nucleus, while eukaryotic cells do not
- B. Eukaryotic cells have a nucleus, while prokaryotic cells do not.
- C. Prokaryotic cells have membrane-bound organelles, while eukaryotic cells do not.
- D. Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not.
Correct Answer: B
Rationale: - Prokaryotic cells are simpler and do not have a true nucleus. Their genetic material is located in the nucleoid region, which is not enclosed by a membrane.
- Eukaryotic cells are more complex and have a true nucleus that houses the genetic material, enclosed within a nuclear membrane.
- Both prokaryotic and eukaryotic cells have organelles, but eukaryotic cells have membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus, while prokaryotic cells lack these membrane-bound organelles.