HESI A2
HESI A2 Biology 2024
1. What happens to glucose during glycolysis?
- A. Its energy is entirely lost.
- B. It splits into molecules of pyruvic acid.
- C. It is stored in NADH.
- D. It joins with molecules of citric acid.
Correct answer: B
Rationale: During glycolysis, glucose undergoes a series of enzymatic reactions in the cytoplasm of the cell, resulting in its breakdown into two molecules of pyruvic acid. This process also generates ATP and NADH as energy carriers. Choice A is incorrect because glucose is not entirely lost, but rather converted into other molecules. Choice C is incorrect because NADH is a product of glycolysis, not a storage form for glucose. Choice D is incorrect as glucose does not join with molecules of citric acid during glycolysis, but rather in subsequent stages of cellular respiration.
2. What is the composition of the plasma membrane?
- A. Proteins
- B. Lipids
- C. Carbohydrates
- D. Nucleotides
Correct answer: B
Rationale: The plasma membrane is composed of lipids, proteins, and carbohydrates. While proteins are an essential component of the plasma membrane, it is not the only constituent. Carbohydrates and lipids also play crucial roles in the structure and function of the plasma membrane. Nucleotides are not part of the primary structural components of the plasma membrane, making this choice incorrect.
3. Beeswax is an example of what kind of molecule?
- A. Lipid
- B. Carbohydrate
- C. Protein
- D. Nucleic acid
Correct answer: A
Rationale: Beeswax is primarily composed of esters of long-chain aliphatic alcohols and fatty acids, making it a type of lipid. Lipids are a diverse group of molecules that are hydrophobic in nature and have important functions in energy storage, signaling, and forming cellular membranes. Beeswax's chemical composition and properties categorize it as a lipid rather than a carbohydrate, protein, or nucleic acid. Carbohydrates are composed of sugars, proteins are made up of amino acids, and nucleic acids consist of nucleotides; none of which match the chemical composition of beeswax.
4. Which of the following arrangement is seen in the plasma membrane?
- A. Lipids with embedded proteins
- B. An outer lipid layer and an inner lipid layer
- C. Proteins embedded in lipid bilayer
- D. Altering protein and lipid layers
Correct answer: C
Rationale: The correct arrangement seen in the plasma membrane is proteins embedded in the lipid bilayer. The plasma membrane is composed of a lipid bilayer with embedded proteins. These proteins perform various functions such as transport, signaling, and structural support within the cell membrane. This arrangement allows for the selective permeability of the membrane and facilitates communication between the cell and its environment. Choices A, B, and D are incorrect because the primary arrangement in the plasma membrane involves proteins being embedded in the lipid bilayer, not lipids with embedded proteins, an outer and inner lipid layer, or altering protein and lipid layers.
5. The difference between diploid and haploid is as follows:
- A. Diploid organisms are multicellular
- B. Diploid cells are somatic
- C. Diploid cells have two sets of homologous chromosomes
- D. More than one of the above is true
Correct answer: D
Rationale: Option B correctly states that diploid cells are somatic cells that make up the body tissues and organs in an organism, while haploid cells are gametes involved in sexual reproduction. Option C accurately differentiates diploid and haploid cells based on their chromosome sets – diploid cells have two sets of homologous chromosomes (one from each parent), whereas haploid cells have one set of unpaired chromosomes. Therefore, the correct choice is D, as both statements in options B and C are accurate descriptions of the differences between diploid and haploid cells. Option A is incorrect because diploid and haploid refer to the number of sets of chromosomes in a cell, not whether the organism is multicellular or not.
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