Nokea
Why is homeostasis necessary?
- A. It maintains temperature.
- B. It maintains pH.
- C. It maintains glucose levels.
- D. All of the above.
Correct Answer: D
Rationale: Homeostasis is essential for maintaining the internal balance and stability of the body. It regulates various factors, such as temperature, pH levels, and glucose levels, to ensure optimal physiological function. Therefore, all the choices (temperature, pH, and glucose levels) are correct as they are all essential components of homeostasis, working together to keep the body's internal environment stable and functioning properly.
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Which characteristic is typically found in prokaryotic cells?
- A. Have a nucleus
- B. Have a capsule
- C. Have membrane-bound organelles
- D. Cannot move on their own
Correct Answer: B
Rationale: Prokaryotic cells are characterized by the absence of a nucleus and membrane-bound organelles. One common feature of prokaryotic cells is the presence of a capsule, which is a protective layer outside the cell wall. This capsule helps protect the cell and can also assist in adherence to surfaces. Therefore, the correct characteristic typically found in prokaryotic cells is that they have a capsule.
What is the first step in the process of respiration?
- A. Fermentation
- B. Krebs cycle
- C. Electron transport chain
- D. Glycolysis
Correct Answer: D
Rationale: The correct answer is Glycolysis. Glycolysis is the initial step in cellular respiration where glucose is broken down into pyruvate, producing a small amount of ATP and NADH in the cytoplasm. This step is crucial as it initiates the breakdown of glucose, setting the stage for further energy production in subsequent stages like the Krebs cycle and electron transport chain.
Which of the following cell types lacks a nucleus?
- A. platelet
- B. red blood cell
- C. white blood cell
- D. phagocyte
Correct Answer: B
Rationale: The correct answer is red blood cell (choice B). Red blood cells, also known as erythrocytes, lack a nucleus at maturity in humans. The absence of a nucleus allows these cells to carry oxygen more efficiently by maximizing space for hemoglobin, the oxygen-carrying protein. Platelets (choice A), white blood cells (choice C), and phagocytes (choice D) all have nuclei. Platelets are involved in blood clotting, white blood cells are part of the immune system, and phagocytes specialize in engulfing and digesting cellular debris and pathogens.
The cellular membrane consists of a bilayer of which substances?
- A. Nucleic acids
- B. Phospholipids.
- C. Proteins.
- D. Carbohydrates.
Correct Answer: B
Rationale:
Which combination of cell cycle phase and descriptor is correct?
- A. S phase - the cell synthesizes DNA and doubles its cytoplasm
- B. G� phase - the amount of chromosomes is doubled
- C. GÄ‚‚ phase - the phase prior to the start of mitosis in which the cell continues to grow in size and make proteins
- D. Interphase - the cell increases in mass and number of organelles to prepare for cell division
Correct Answer: C
Rationale: The correct answer is C. The GÄ‚‚ phase is the phase before mitosis within interphase where the cell grows in size and synthesizes proteins needed for cell division. Option A incorrectly describes the S phase, which is primarily for DNA synthesis. Option B is incorrect as the doubling of chromosomes does not occur in GÄ‚� phase. Option D is inaccurate because interphase encompasses GÄ‚�, S, and GÄ‚‚ phases, during which the cell prepares for division by increasing its mass and organelles, rather than specifically focusing on mitosis preparation.