HESI A2
Biology HESI A2 2024
1. Why are bacteria and blue-green algae often classified together?
- A. Both are gymnosperms.
- B. Both are prokaryotes.
- C. Both are autotrophs.
- D. Both are pathogens.
Correct answer: B
Rationale: Bacteria and blue-green algae (cyanobacteria) are often classified together because they are both prokaryotes. Prokaryotes are unicellular organisms that lack a membrane-bound nucleus and other membrane-bound organelles. This characteristic distinguishes them from eukaryotic organisms, which have these membrane-bound structures. Choice A is incorrect because gymnosperms are seed-producing plants with naked seeds, not bacteria or blue-green algae. Choice C is incorrect because being an autotroph (able to produce its own food) is not a reason for classifying them together. Choice D is incorrect because not all bacteria and blue-green algae are pathogens; many of them are beneficial or neutral to other organisms.
2. Why does cytokinesis happen?
- A. DNA can duplicate
- B. Organelles can convert energy
- C. Bacteria can be killed
- D. Daughter cells can divide
Correct answer: D
Rationale: Cytokinesis happens at the end of mitosis to physically separate the newly formed daughter cells. This allows the cell to divide into two separate daughter cells, each containing a complete set of genetic material (DNA) and organelles. The purpose of cytokinesis is to ensure that each daughter cell receives the necessary components to function independently. Choices A, B, and C are incorrect because cytokinesis does not directly involve DNA duplication, organelles converting energy, or killing bacteria.
3. When the genotype consists of a dominant and a recessive allele, the phenotype will be like the _ allele.
- A. Dominant
- B. Recessive
- C. Both
- D. Neither
Correct answer: A
Rationale: When the genotype consists of a dominant and a recessive allele, the phenotype will be like the dominant allele. This is because dominant alleles typically mask the expression of recessive alleles. Therefore, the dominant allele will be expressed in the phenotype in most basic cases. The recessive allele will only be expressed phenotypically if the individual is homozygous recessive. Choice B, 'Recessive,' is incorrect because the phenotype will not be like the recessive allele in this case. Choice C, 'Both,' is incorrect because in simple dominant-recessive inheritance, the dominant allele will overshadow the recessive allele. Choice D, 'Neither,' is incorrect as the phenotype will resemble the dominant allele.
4. In nature, water vapor becomes liquid water through the process of ___________.
- A. condensation
- B. sublimation
- C. precipitation
- D. absorption
Correct answer: A
Rationale: In nature, water vapor becomes liquid water through the process of condensation. Condensation occurs when water vapor cools and changes its state from a gas to a liquid, forming droplets that we commonly see as water droplets on surfaces or clouds in the sky. Sublimation refers to the transition from a solid to a gas without passing through the liquid phase. Precipitation is the process where water in the atmosphere falls to the ground as rain, snow, sleet, or hail. Absorption is the process of one substance being taken in by another.
5. The procedure to focus an image using a compound microscope involves
- A. Adjusting the coarse adjustment each time a new magnification is selected
- B. Adjusting the fine adjustment each time a new magnification is selected
- C. Adjusting the stage each time a new magnification is selected
- D. All of the above
Correct answer: B
Rationale: When using a compound microscope, it is essential to adjust the fine adjustment knob each time you switch to a new magnification level. The fine adjustment knob allows for precise focusing on the specimen at different magnifications, ensuring a clear and sharp image. The coarse adjustment knob is typically used only at the lower magnification settings to bring the image into view roughly. Adjusting the stage may be necessary based on the size and thickness of the specimen, but it does not need to be done every time a new magnification is selected. Therefore, option B is the correct choice as it focuses on the key aspect of precise focusing during magnification changes.
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