Nokea
Melanin, the pigment responsible for skin color, is produced by
- A. Keratinocytes (These cells produce keratin)
- B. Melanocytes
- C. Sebocytes (These cells produce sebum)
- D. Langerhans cells (These cells are part of the immune system)
Correct Answer: B
Rationale: Melanocytes are the cells responsible for producing melanin, the pigment that determines skin color. Melanin gives skin its color and protects it from the harmful effects of UV radiation. Keratinocytes produce keratin, a tough protein that forms the outer layer of the skin, hair, and nails. Sebocytes produce sebum, an oily substance that helps moisturize and protect the skin. Langerhans cells are a type of immune cell found in the skin that play a role in protecting against infections and foreign substances but do not produce melanin.
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Certain medications can suppress the immune system to treat autoimmune diseases or prevent organ rejection after transplants. What is a potential risk associated with immunosuppressive drugs?
- A. Increased risk of developing allergies
- B. Increased susceptibility to infections
- C. Both A and B
- D. Neither A nor B
Correct Answer: B
Rationale: Immunosuppressive drugs work by suppressing the immune system's activity, which can increase the risk of infections as the body's ability to fight off pathogens is compromised. While allergies can be a side effect of some medications, the primary concern with immunosuppressive drugs is the increased susceptibility to infections. Therefore, the correct answer is B, increased susceptibility to infections. Choice A, 'Increased risk of developing allergies,' is incorrect as the primary risk associated with immunosuppressive drugs is not related to allergies. Choice C, 'Both A and B,' is incorrect as the main concern is the increased susceptibility to infections rather than developing allergies. Choice D, 'Neither A nor B,' is incorrect as there is a known risk of increased susceptibility to infections when using immunosuppressive drugs.
Adipose tissue, commonly known as fat, primarily functions in:
- A. Support
- B. Insulation
- C. Energy storage
- D. All of the above
Correct Answer: D
Rationale: Adipose tissue, also known as fat, serves multiple essential functions in the body. It provides support by cushioning and protecting organs, acts as an insulator to help regulate body temperature, and serves as a major energy storage site by storing excess energy in the form of triglycerides. Therefore, all the options (support, insulation, and energy storage) are correct functions of adipose tissue, making 'All of the above' the correct answer. Choices A, B, and C are all individually valid functions of adipose tissue, but to encompass the comprehensive role of adipose tissue, 'All of the above' is the most accurate option.
Which statement accurately describes cytokinesis in animal cells?
- A. Which statement accurately describes cytokinesis in animal cells?
- B. A cell plate forms in the center of the dividing cell, eventually separating the cytoplasm into two daughter cells.
- C. A cell plate forms in the center of the dividing cell, eventually separating the cytoplasm into two daughter cells.
- D. The nucleus elongates and pulls apart, physically dividing the cytoplasm into two.
Correct Answer: B
Rationale: A) This statement is a duplicate of option C and does not accurately describe cytokinesis in animal cells.
B) In animal cells, during cytokinesis, a cleavage furrow forms in the center of the dividing cell. This furrow deepens and eventually pinches the cytoplasm into two daughter cells. This process is distinct from plant cells, where a cell plate forms.
C) This statement is a duplicate of option A and does not accurately describe cytokinesis in animal cells.
D) This statement describes the process of nuclear division (mitosis) rather than cytokinesis, which is the division of the cytoplasm.
Why does a prism separate white light into its constituent spectral components?
- A. It absorbs certain colors
- B. Different colors experience varying speeds within the prism
- C. It bends all colors with the same magnitude
- D. It reflects specific colors
Correct Answer: B
Rationale: A prism separates white light into its constituent spectral components because different colors experience varying speeds within the prism due to their different wavelengths. This causes the light to refract at different angles, resulting in the separation of colors. When light enters the prism, it undergoes dispersion, where different colors are refracted at different angles due to their unique wavelengths. This phenomenon is known as chromatic dispersion. Choice A is incorrect because a prism does not absorb colors but refracts and disperses them. Choice C is incorrect because a prism refracts different colors at different angles, not with the same magnitude. Choice D is incorrect because a prism does not reflect colors but refracts and disperses them based on their wavelengths.
How do vaccines primarily function within the body?
- A. Creating a physical barrier against pathogens
- B. Triggering an inflammatory response
- C. Developing immunological memory to a specific pathogen
- D. Activating phagocytes to engulf pathogens
Correct Answer: C
Rationale: Vaccines primarily function by stimulating the immune system to develop immunological memory to a specific pathogen. When a vaccine is administered, it exposes the immune system to a harmless version of a pathogen or a piece of it. This exposure triggers the immune response, leading to the production of antibodies and memory cells specific to that pathogen. Choice A is incorrect because vaccines do not create a physical barrier; rather, they prepare the immune system to recognize and fight specific pathogens. Choice B is incorrect as vaccines do trigger an immune response, but the primary goal is to create memory rather than inflammation. Choice D is incorrect as vaccines do not directly activate phagocytes; instead, they stimulate the immune system to generate a targeted response against a particular pathogen.