HESI RN
Biology Practice Test
1. Which of the following statements is true if a molecule exhibits adhesion?
- A. Two molecules of the same substance have the ability to stay bonded to one another
- B. The molecule has the ability to bond to or attract other molecules
- C. A molecule has the ability to increase its heat when necessary
- D. The molecule has the ability to form hydrogen bonds
Correct answer: B
Rationale: The correct statement is that if a molecule exhibits adhesion, it has the ability to bond to or attract other molecules. Adhesion refers to the ability of a molecule to bind to or attract different types of molecules. Choice A is incorrect because adhesion is about bonding to different molecules, not the same substance. Choice C is incorrect as adhesion does not relate to the ability of a molecule to increase its heat. Choice D is incorrect because forming hydrogen bonds is a specific type of interaction and not a general characteristic of molecules exhibiting adhesion.
2. Which of the following molecules contains the code required for replication?
- A. Deoxyribonucleic acid (DNA)
- B. Transfer RNA (tRNA)
- C. Messenger RNA (mRNA)
- D. Ribonucleic acid (RNA)
Correct answer: A
Rationale: The correct answer is A: Deoxyribonucleic acid (DNA). DNA contains the genetic information essential for replication, ensuring the accurate transmission of genetic material from one generation to the next. Choice B, Transfer RNA (tRNA), is involved in protein synthesis, not replication. Choice C, Messenger RNA (mRNA), carries genetic information from DNA to the ribosome but does not contain the code for replication. Choice D, Ribonucleic acid (RNA), is a broader category that includes both mRNA and tRNA, but the specific molecule containing the code required for replication is DNA.
3. In DNA, the nucleotide base adenine always binds with which of the following?
- A. Guanine
- B. Uracil
- C. Thymine
- D. Cytosine
Correct answer: C
Rationale: The correct answer is C: Thymine. In DNA, adenine always pairs with thymine, forming a base pair held together by hydrogen bonds. Guanine pairs with cytosine. Uracil is found in RNA, not DNA. Cytosine pairs with guanine. Therefore, option C is the correct pairing for adenine in DNA.
4. Water is held together by which of the following bonds?
- A. Electrostatic attraction
- B. Van der Waals forces
- C. Hydrogen
- D. Oxygen
Correct answer: C
Rationale: Water molecules are held together by hydrogen bonds, which are weak bonds formed between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another. Choice A, electrostatic attraction, is a general term for the attraction between opposite charges but does not specifically describe the bonds in water. Choice B, Van der Waals forces, are weak intermolecular forces that arise from temporary fluctuations in electron distribution, not the primary bonds in water. Choice D, oxygen, is incorrect as oxygen is part of the water molecule but not the bond holding water molecules together.
5. Which of the following best describes phenotype?
- A. The hereditary potentials and limitations of an individual
- B. The genetic makeup of an individual organism
- C. The entire complex of genes inherited from both parents
- D. All the observable characteristics of an organism
Correct answer: D
Rationale: The correct answer is D: 'All the observable characteristics of an organism.' Phenotype refers to all the observable characteristics of an organism, such as physical appearance, behavior, and other traits, which result from the interaction of its genotype with the environment. Choice A is incorrect because it describes genotype. Choice B is incorrect as it defines genotype, not phenotype. Choice C is incorrect as it refers to the genotype, the genetic information inherited from both parents, rather than the observable traits.
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