HESI A2
HESI A2 Practice Test Biology
1. Which of the following organelles are responsible for producing cell energy?
- A. Mitochondrion and chloroplast
- B. Mitochondrion and nucleus
- C. Chloroplast and nucleus
- D. Chloroplast and lysosome
Correct answer: A
Rationale: The correct answer is A: Mitochondrion and chloroplast. Mitochondria and chloroplasts are the organelles responsible for producing cell energy through cellular respiration and photosynthesis, respectively. Choice B is incorrect because the nucleus is not involved in energy production. Choice C is incorrect as the nucleus is not an organelle that produces energy. Choice D is incorrect as lysosomes function in digesting waste materials, not in energy production.
2. Most enzymes are made up of what?
- A. proteins
- B. lipids
- C. starches
- D. simple sugars
Correct answer: A
Rationale: Most enzymes are made up of proteins. Proteins are large biomolecules composed of amino acids that are vital for the structure and function of enzymes. Enzymes act as catalysts in biochemical reactions, speeding up the rate of chemical reactions in living organisms. They exhibit high specificity and efficiency due to their unique protein structures. Lipids, starches, and simple sugars are not typically the primary components of enzymes, making them incorrect choices.
3. Which statement is untrue?
- A. RNA is single-stranded.
- B. RNA contains uracil.
- C. DNA codes for proteins.
- D. DNA cannot be altered.
Correct answer: D
Rationale: DNA can be altered through various processes such as mutations, genetic engineering, and epigenetic modifications. Changes in DNA can occur naturally or through external influences, leading to variations in the genetic code. Therefore, the statement that DNA cannot be altered is untrue. Choices A, B, and C are true statements. RNA is indeed single-stranded, RNA contains uracil instead of thymine, and DNA serves as a template for protein synthesis.
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. Why is it important for cells to undergo mitosis?
- A. mitosis allows for reproduction with male and female gametes
- B. mitosis increases variation within the species
- C. mitosis produces cells that are different from the parent cell
- D. mitosis produces cells for growth and repair of body tissue
Correct answer: D
Rationale: It is important for cells to undergo mitosis because it produces cells for the growth and repair of body tissues. Mitosis allows for the formation of genetically identical daughter cells, ensuring proper function and maintenance of the organism's body. By producing new cells, mitosis helps in the replenishment of damaged or worn-out tissue and supports overall growth and development. Choices A, B, and C are incorrect because mitosis is not directly related to reproduction with male and female gametes, increasing variation within the species, or producing cells different from the parent cell. These functions are more associated with meiosis, which is specifically for sexual reproduction and genetic diversity.
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