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. Which part of the plant produces pollen?
- A. Anther
- B. Style
- C. Stigma
- D. Pistil
Correct answer: A
Rationale: The anther is the part of the flower that produces pollen. It is located at the tip of the stamen, the male reproductive organ of a flower. The anther contains pollen sacs where pollen grains are produced. The style is the part of the pistil that connects the stigma to the ovary, playing a role in pollen tube growth. The stigma is the part of the pistil that receives pollen during fertilization. The pistil is the female reproductive organ of a flower, consisting of the stigma, style, and ovary, and does not produce pollen.
3. Within the biological hierarchical system of organization, which of the following is least inclusive?
- A. phylum
- B. order
- C. kingdom
- D. species
Correct answer: D
Rationale: The correct answer is 'D: species.' In the biological hierarchical system of organization, a species is the least inclusive level. A species consists of organisms that share similar characteristics and can interbreed to produce fertile offspring. On the other hand, a phylum, order, and kingdom are more inclusive classifications that encompass multiple species. Phylum groups together related classes, order groups together related families, and kingdom groups together related phyla. Therefore, species is the least inclusive category within the biological hierarchical system.
4. During which phase of mitosis do the chromosomes align in the center of the cell?
- A. Prophase
- B. Metaphase
- C. Telophase
- D. Anaphase
Correct answer: B
Rationale: The correct answer is Metaphase. During Metaphase, the chromosomes line up along the center of the cell's equator, forming the metaphase plate. This alignment ensures that during the subsequent phase, Anaphase, the sister chromatids can separate and move towards opposite poles. Prophase is the initial phase of mitosis where chromosomes condense and the nuclear envelope breaks down. Telophase is the final phase of mitosis where two new nuclei form.
5. What is DNA made of?
- A. Proteins
- B. Nucleotides
- C. Lipids
- D. Carbohydrates
Correct answer: B
Rationale: DNA is made up of nucleotides, which are the building blocks of genetic material. Choice A (Proteins) is incorrect because while proteins play a crucial role in the body, they are not the building blocks of DNA. Choice C (Lipids) and Choice D (Carbohydrates) are also incorrect as they are not the primary components of DNA.
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