HESI A2
Biology HESI A2 2024
1. Which part of a plant’s reproductive system is of a different “gender†than the others?
- A. Stamen
- B. Pistil
- C. Stigma
- D. Style
Correct answer: A
Rationale: The stamen is the male reproductive organ of a plant, producing pollen grains. The pistil, consisting of the stigma, style, and ovary, is the female reproductive organ. Therefore, the stamen is of a different 'gender' than the other parts of the plant's reproductive system. The pistil, stigma, and style are all part of the female reproductive system, involved in receiving pollen and supporting fertilization. Stamen is the correct answer as it is the male part of a plant's reproductive system, making it different 'gender-wise' from the female parts.
2. What type of cells possess a cell membrane?
- A. Prokaryotic cells only
- B. Eukaryotic cells only
- C. Both prokaryotic and eukaryotic cells
- D. None of the above
Correct answer: C
Rationale: Cell membranes are present in both prokaryotic and eukaryotic cells. The cell membrane serves as a barrier that encloses the cell contents and regulates the entry and exit of substances in and out of the cell. It is a fundamental structure found in all types of cells, regardless of whether they are prokaryotic (lacking a nucleus) or eukaryotic (containing a nucleus). Choice A is incorrect because eukaryotic cells also possess cell membranes. Choice B is incorrect as prokaryotic cells, such as bacteria, also have cell membranes. Choice D is incorrect as both prokaryotic and eukaryotic cells have cell membranes.
3. What propels the cell forward?
- A. Microfilaments
- B. Propulsion
- C. Cilia
- D. Flagella
Correct answer: B
Rationale: Propulsion, not microfilaments, cilia, or flagella, is what drives the cell forward. Propulsion is the force or process that propels the cell forward and allows it to move within its environment. Microfilaments are involved in cell structure, cilia are small hair-like structures for movement, and flagella are tail-like structures used for cell propulsion in some organisms.
4. A cell that does not contain membrane-bound organelles or a defined nucleus would be classified as:
- A. eukaryotic
- B. embryonic
- C. prokaryotic
- D. symbiotic
Correct answer: C
Rationale: A cell that does not contain membrane-bound organelles or a defined nucleus is classified as prokaryotic. Prokaryotic cells lack a true nucleus, and their genetic material is typically found in a region called the nucleoid. Examples of prokaryotic organisms include bacteria and archaea. Eukaryotic cells, on the other hand, contain membrane-bound organelles and a true nucleus, distinguishing them from prokaryotic cells. Embryonic and symbiotic classifications are not directly related to the presence of organelles or a nucleus in cells.
5. Which of the following is true of the Krebs cycle?
- A. It is a redox reaction involving proteins produced during glycolysis
- B. It is a redox reaction involving sugars produced during glycolysis
- C. Protons are passed along a gradient to produce ATP
- D. It is also known as the glycolic acid cycle
Correct answer: B
Rationale: The Krebs cycle, also known as the citric acid cycle, involves a series of redox reactions that occur in the mitochondria. The cycle begins with the oxidation of acetyl CoA, which is derived from the breakdown of sugars produced during glycolysis. These sugars are broken down further in the Krebs cycle to produce ATP and reduce electron carriers such as NADH and FADH2. The cycle does not involve proteins produced during glycolysis. Protons are not passed along a gradient to produce ATP directly in the Krebs cycle; rather, they are used in the electron transport chain to generate ATP. The Krebs cycle is not known as the glycolic acid cycle; glycolysis is the metabolic pathway that produces pyruvate from glucose.
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