HESI A2
HESI A2 Practice Test Biology
1. How are molecules of water bonded to each other?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct answer: C
Rationale: Water molecules are bonded to each other by 'hydrogen' bonds. These bonds are not as strong as covalent bonds, which hold the atoms within each water molecule together (Choice B). Ionic bonds (Choice A) involve the transfer of electrons between atoms, which is not the case in water molecules. The term 'molecular' (Choice D) is too general and doesn't specifically describe the type of bond between water molecules.
2. What is the second part of an organism’s scientific name?
- A. species
- B. phylum
- C. population
- D. kingdom
Correct answer: A
Rationale: The correct answer is 'species.' In binomial nomenclature, the second part of an organism's scientific name represents its species. The species name is a unique identifier within the genus and helps differentiate between different organisms within the same genus. Choices B, C, and D are incorrect. Phylum is a taxonomic rank higher than species, population refers to a group of organisms of the same species living in the same area, and kingdom is a taxonomic rank higher than genus.
3. In the scientific process, which of the following is a statement or explanation of certain events or happenings?
- A. hypothesis
- B. observation
- C. experiment
- D. conclusion
Correct answer: A
Rationale: A hypothesis is a statement or explanation of certain events or phenomena based on observations and prior knowledge. It is a testable prediction that guides the scientific investigation process. By formulating a hypothesis, scientists can make predictions and design experiments to gather data and test the validity of the hypothesis. Observations (choice B) involve gathering information through the senses. Experiments (choice C) are procedures carried out to support or refute a hypothesis. Conclusions (choice D) are deductions made based on the results of experiments and observations, but they are not the initial statement or explanation of events or happenings.
4. What molecule is primarily responsible for providing energy to the cell?
- A. ATP
- B. DNA
- C. ADP
- D. Glycogen
Correct answer: A
Rationale: Correct! ATP (Adenosine Triphosphate) is the main molecule that stores and provides energy for cellular activities. ATP is known as the energy currency of the cell, where energy released from the breakdown of nutrients is stored in the high-energy phosphate bonds of ATP. Choices B, C, and D are incorrect because DNA carries genetic information, ADP is the precursor of ATP, and glycogen is a polysaccharide used for energy storage, not direct energy provision.
5. What is the role of tRNA during protein synthesis?
- A. Carries amino acids to the ribosome
- B. Links nucleotides together
- C. Copies DNA sequences
- D. Replicates genetic material
Correct answer: A
Rationale: During protein synthesis, tRNA plays the crucial role of carrying amino acids to the ribosome. This process ensures that the correct amino acids are brought to the ribosome according to the mRNA sequence. Choice B, linking nucleotides together, refers to the role of RNA polymerase in transcription, not tRNA. Choice C, copying DNA sequences, is the function of DNA polymerase during DNA replication, while choice D, replicating genetic material, is an overarching function of DNA replication, not specific to tRNA's role in protein synthesis.
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