HESI RN
Biology Practice Test
1. The Punnett square shows that one parent carries the recessive gene for a cleft chin (c) while the other parent does not. What percentage of the parents' offspring is predicted to have a cleft chin?
- A. 25%
- B. 50%
- C. 0%
- D. 75%
Correct answer: C
Rationale: The correct answer is 0%. If one parent carries the recessive gene for a cleft chin while the other parent does not, none of the offspring will express the recessive phenotype. This is because in order for a child to have a cleft chin, they would need to inherit the recessive gene from both parents. Therefore, although the offspring could be carriers of the gene, none are predicted to have a cleft chin. Choices A, B, and D are incorrect because the presence of the recessive gene in one parent and its absence in the other would not result in any offspring showing the cleft chin trait.
2. The bilayer of the cellular membrane consists of phospholipids with all except which of the following scattered throughout?
- A. Nucleic acids
- B. Cholesterol
- C. Proteins
- D. Glycoproteins
Correct answer: A
Rationale: The cellular membrane is composed of a phospholipid bilayer with cholesterol, proteins, and glycoproteins distributed throughout. Nucleic acids are not found within the cellular membrane. Cholesterol helps maintain membrane fluidity, while proteins and glycoproteins play important roles in cell signaling, transport, and structural support.
3. What is the difference between saturated and unsaturated fatty acids?
- A. There is no difference between saturated and unsaturated fatty acids.
- B. Saturated fatty acids contain double bonds, unlike unsaturated fatty acids.
- C. Saturated fatty acids often contain two or more pairs of double bonds, unlike unsaturated fatty acids.
- D. Saturated fatty acids contain no double bonds, unlike unsaturated fatty acids.
Correct answer: D
Rationale: The correct answer is D. Saturated fatty acids contain no double bonds between the carbon atoms in their hydrocarbon chains, making them more solid at room temperature. Choice A is incorrect because there is a significant difference between saturated and unsaturated fatty acids. Choice B is incorrect as it inaccurately states that saturated fatty acids contain double bonds, which is a property of unsaturated fatty acids. Choice C is also incorrect as saturated fatty acids do not contain double bonds, let alone two or more pairs of double bonds.
4. Which of the following is responsible for the synthesis of carbohydrates, lipids, and steroid hormones?
- A. Smooth endoplasmic reticulum (ER)
- B. Rough endoplasmic reticulum (ER)
- C. Golgi apparatus
- D. Ribosomes
Correct answer: A
Rationale: The smooth endoplasmic reticulum (ER) is the correct answer. It is responsible for the synthesis of lipids, including steroids, and also plays a role in carbohydrate metabolism. The rough endoplasmic reticulum (ER) is involved in protein synthesis and processing, not lipid or carbohydrate synthesis. The Golgi apparatus is responsible for modifying, sorting, and packaging of proteins and lipids, but not for their synthesis. Ribosomes are the cellular organelles responsible for protein synthesis, not lipid or carbohydrate synthesis.
5. A water molecule contains two types of atoms that are covalently bonded. Which of the following makes up a water molecule?
- A. One hydrogen atom and one oxygen atom
- B. One hydrogen atom and two oxygen atoms
- C. Two hydrogen atoms and two oxygen atoms
- D. Two hydrogen atoms and one oxygen atom
Correct answer: D
Rationale: The correct answer is D: Two hydrogen atoms and one oxygen atom. A water molecule consists of two hydrogen atoms covalently bonded to one oxygen atom. This forms a stable structure known as H2O. Choice A is incorrect as water molecule contains two hydrogen atoms. Choices B and C are incorrect as they do not reflect the correct composition of a water molecule.
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