Nokea
Which of the following is not true about enzymes?
- A. They catalyze reactions
- B. They lower the activation energy needed
- C. They have an active site
- D. They are typically proteins
Correct Answer: B
Rationale: Enzymes lower the activation energy needed for a reaction to occur, not raise it. By lowering the activation energy, enzymes facilitate reactions, making them occur more easily and rapidly. Choice A is correct as enzymes indeed catalyze reactions. Choice C is correct as enzymes have specific active sites where substrates bind. Choice D is correct as enzymes are commonly proteins, although some RNA molecules also exhibit catalytic properties.
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Cells that line the inner or outer surfaces of organs or body cavities are often linked together by intimate physical connections. These connections are referred to as ______.
- A. Separate desmosomes
- B. Ronofilaments
- C. Tight junctions
- D. Fascia adherens
Correct Answer: C
Rationale: The correct answer is C: Tight junctions. Tight junctions, also known as zonula occludens, are the intimate physical connections between cells that line the inner or outer surfaces of organs or body cavities. These junctions form a virtually impermeable barrier to fluid, creating a tight seal between the cells. This helps in maintaining the integrity and function of the tissue as well as regulating the movement of substances across the cell layer. Choice A, Separate desmosomes, are cell structures that provide strong adhesion between cells but do not create a barrier to fluid. Choice B, Ronofilaments, is not a term used to describe the connections between cells. Choice D, Fascia adherens, are another type of cell junction involved in cell adhesion, but they are different from tight junctions in terms of their structure and function.
The force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere is the ______.
- A. Atmospheric pressure
- B. Barometric density
- C. Aneroid pressure
- D. Barometric pressure
Correct Answer: A
Rationale: Atmospheric pressure is the correct term for the force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere. It is commonly measured in units such as pascals, millibars, or inches of mercury. Barometric density and aneroid pressure are not accurate descriptions for this phenomenon. Barometric density refers to the density of the atmosphere at a particular location, while aneroid pressure is linked to a type of barometer but not a comprehensive term for the force exerted by the weight of air.
Why doesn't an antibiotic work for treating the flu?
- A. The antibiotic is for a different type of infection
- B. The antibiotic is not effective against viruses
- C. The antibiotic is not prescribed in a high enough dosage
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B. Antibiotics are used to treat bacterial infections, not viral infections like the flu. The flu is caused by a virus, and antibiotics are ineffective against viruses. Choice A is incorrect because it does not address the fact that antibiotics do not work on viruses. Choice C is incorrect as the issue is not related to the dosage amount, but rather the nature of the infection. Choice D is incorrect as there is a specific reason why antibiotics do not work for the flu.
72 chromosomes undergo meiosis. How many chromosomes will be in each gamete?
- A. 18
- B. 36
- C. 72
- D. 144
Correct Answer: A
Rationale: During meiosis, the number of chromosomes is halved in each gamete. Since 72 chromosomes undergo meiosis, each gamete will contain half of that number, which is 36 chromosomes. Therefore, the correct answer is 18 chromosomes in each gamete. Choice B (36 chromosomes) is incorrect because it represents the total number of chromosomes that undergo meiosis, not the number in each gamete. Choice C (72 chromosomes) is incorrect as it represents the initial number of chromosomes, not the number in each gamete after meiosis. Choice D (144 chromosomes) is incorrect as it doubles the initial number of chromosomes, which is not the outcome of meiosis.
The phases of mitosis include:
- A. Prophase, interphase, metaphase, anaphase, and telophase
- B. Prophase, prophase, metaphase, anaphase, and cytokinesis
- C. Prophase, prometaphase, metaphase, anaphase, and telophase
- D. Prophase, interphase, prophase, anaphase, and telophase
Correct Answer: C
Rationale: The correct phases of mitosis are prophase, prometaphase, metaphase, anaphase, and telophase. Prophase is the first phase where chromatin condenses into chromosomes, the nuclear envelope breaks down, and the mitotic spindle forms. Prometaphase follows prophase, involving the full disintegration of the nuclear envelope and the attachment of spindle fibers to the kinetochores of the chromosomes. Metaphase is where chromosomes align along the metaphase plate. Anaphase is the phase where sister chromatids separate and move towards opposite poles. Telophase marks the final stage of mitosis, involving the decondensation of chromosomes and the reformation of the nuclear envelope. Choice A is incorrect because it includes interphase, which is not a phase of mitosis. Choice B is incorrect as it repeats prophase, which is the initial phase. Choice D is incorrect because it includes interphase and repeats prophase.