Nokea
What is the first event to occur in a primary immune response?
- A. Macrophages phagocytose pathogens and present their antigens.
- B. Neutrophils aggregate and act as cytotoxic, nonspecific killers of pathogens.
- C. B lymphocytes make pathogen-specific antibodies.
- D. Helper T cells secrete interleukins to activate pathogen-fighting cells.
Correct Answer: A
Rationale: The correct answer is A. The initial event in a primary immune response is the phagocytosis of pathogens by macrophages and the subsequent presentation of their antigens, which is crucial for initiating the adaptive immune response. Neutrophils (Choice B) are also involved in the innate immune response, but they typically respond after macrophages. B lymphocytes (Choice C) produce antibodies later in the adaptive immune response, and Helper T cells (Choice D) help in coordinating the immune response but are not the first cells to act in a primary immune response.
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What is the final phase of mitosis?
- A. Prophase
- B. Telophase
- C. Anaphase
- D. Metaphase
Correct Answer: B
Rationale: Telophase is indeed the final phase of mitosis. During telophase, the chromosomes have reached opposite poles of the cell, the nuclear envelope is re-forming around the separated sister chromatids, and cytokinesis may also occur, leading to the division of the cell into two daughter cells. Choice A, Prophase, is incorrect as it is the initial phase of mitosis where chromatin condenses into chromosomes. Choice C, Anaphase, is incorrect as it is the phase where sister chromatids separate and move towards opposite poles. Choice D, Metaphase, is incorrect as it is the phase where chromosomes align at the cell's equator before separating.
Where does visual processing begin in the eye?
- A. Cornea
- B. Optic nerve
- C. Retina
- D. Eyelid
Correct Answer: C
Rationale: Visual processing begins in the retina, not the cornea, optic nerve, or eyelid. The retina is a layer of tissue at the back of the eye that contains photoreceptor cells responsible for converting light into neural signals that are then sent to the brain for processing. The cornea is the transparent outer layer of the eye that helps focus light, but it does not process visual information. The optic nerve transmits visual information from the retina to the brain, it does not initiate visual processing. The eyelid is a protective covering for the eye and is not involved in visual processing.
What is an alteration in the normal gene sequence called?
- A. DNA mutation
- B. Gene migration
- C. Polygenic inheritance
- D. Incomplete dominance
Correct Answer: A
Rationale: A DNA mutation is the correct term used to describe an alteration in the normal gene sequence. It refers to changes in the DNA sequence that can result in different traits or characteristics. Gene migration involves the movement of genes between populations, polygenic inheritance refers to the inheritance of traits controlled by multiple genes, and incomplete dominance is a pattern of inheritance where neither allele is dominant.
When testing how quickly a rat dies based on the amount of poison it eats, which of the following is the independent variable and which is the dependent variable?
- A. How quickly the rat dies is the independent variable; the amount of poison is the dependent variable.
- B. The amount of poison is the independent variable; how quickly the rat dies is the dependent variable.
- C. Whether the rat eats the poison is the independent variable; how quickly the rat dies is the dependent variable.
- D. The cage the rat is kept in is the independent variable; the amount of poison is the dependent variable.
Correct Answer: B
Rationale: The correct answer is B. In this experiment, the independent variable is the amount of poison because it is what is being manipulated by the researcher. The dependent variable is how quickly the rat dies, as it is the outcome that is being measured based on the different amounts of poison administered. Choice A is incorrect because the independent variable should be what is being manipulated or changed, which is the amount of poison in this case. Choice C is incorrect because whether the rat eats the poison is not being varied or controlled by the researcher. Choice D is incorrect because the cage the rat is kept in is not relevant to the relationship being studied between the amount of poison and the rat's survival time.
Where does sperm maturation take place in the male reproductive system?
- A. Seminal vesicles
- B. Prostate gland
- C. Epididymis
- D. Vas Deferens
Correct Answer: C
Rationale: Sperm maturation occurs in the epididymis, a coiled tube located on the back of each testicle. In the epididymis, sperm gain motility and the ability to fertilize an egg. It serves as a storage site for mature sperm until ejaculation. The seminal vesicles and the prostate gland contribute fluids to semen, enhancing sperm viability and motility. The vas deferens is responsible for transporting mature sperm from the epididymis to the urethra during ejaculation, but it is not where sperm maturation takes place. Therefore, the correct answer is the epididymis.