HESI A2
Biology HESI A2 Practice Test
1. 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.
2. The scientific name for a house cat is Felis catus. This indicates the house cat’s ___________ and ___________.
- A. kingdom; family
- B. order; subspecies
- C. phylum; class
- D. genus; species
Correct answer: D
Rationale: The scientific name for an organism consists of its genus and species. In this case, 'Felis' refers to the genus, while 'catus' refers to the species, thus indicating the house cat's genus and species as Felis catus. Therefore, the correct answer is 'D.' Choices A, B, and C are incorrect because a scientific name does not include information about the kingdom, family, order, subspecies, phylum, or class of an organism.
3. Which molecules contain only carbon, hydrogen, and oxygen?
- A. Lipids and proteins
- B. Carbohydrates and lipids
- C. Proteins and carbohydrates
- D. Nucleic acids and proteins
Correct answer: B
Rationale: Carbohydrates and lipids are the molecules that contain only carbon, hydrogen, and oxygen. Carbohydrates such as sugars and starches are made up of carbon, hydrogen, and oxygen in a ratio of 1:2:1, while lipids such as fats and oils are composed of carbon, hydrogen, and oxygen as well. Lipids typically contain more carbon and hydrogen atoms compared to oxygen atoms. Proteins contain nitrogen in addition to carbon, hydrogen, and oxygen, while nucleic acids contain phosphorus in addition to carbon, hydrogen, and oxygen. Therefore, choices A, C, and D are incorrect as they include molecules that contain elements other than carbon, hydrogen, and oxygen.
4. Which structure might be described as a core of nucleic acid surrounded by a protein coat?
- A. RNA
- B. Virus
- C. Blue-green alga
- D. Saprophyte
Correct answer: B
Rationale: A virus can be described as a core of nucleic acid (either RNA or DNA) surrounded by a protein coat, known as a capsid. This structure distinguishes viruses from other microorganisms such as blue-green algae (Cyanobacteria), fungi known as saprophytes, or individual RNA molecules. Viruses depend on a host cell to replicate and are considered non-living entities due to their inability to carry out metabolic functions independently.
5. Which is not one of the raw materials needed for cellular respiration?
- A. ADP
- B. Phosphate
- C. Water
- D. Glucose
Correct answer: C
Rationale: Water is not one of the raw materials needed for cellular respiration. The essential raw materials for cellular respiration include glucose (which is broken down to produce energy), oxygen, and ADP (adenosine diphosphate) and phosphate (which are necessary for the formation of ATP, the energy currency of cells). While water is crucial for many cellular processes and makes up a significant portion of cells, it is not directly involved as a raw material in the cellular respiration process.
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