HESI A2
HESI A2 Biology Practice Test 2024
1. What is the primary function of the endoplasmic reticulum in a cell?
- A. Energy production
- B. Protein synthesis
- C. Waste removal
- D. Transport of materials
Correct answer: D
Rationale: The endoplasmic reticulum's primary function is the transport of materials within the cell. It acts as a network of membranes to assist in the transportation of proteins and other substances throughout the cell. Choice A, 'Energy production,' is incorrect because the endoplasmic reticulum is not directly involved in energy production. Choice B, 'Protein synthesis,' is incorrect as protein synthesis mainly occurs in ribosomes, although the endoplasmic reticulum is involved in modifying and transporting proteins. Choice C, 'Waste removal,' is also incorrect as waste removal is primarily handled by other organelles like lysosomes and peroxisomes.
2. Which of the following is not found within a bacterial cell?
- A. mitochondria
- B. DNA
- C. vesicles
- D. ribosome
Correct answer: A
Rationale: The correct answer is A: mitochondria. Mitochondria are not found in bacterial cells. Bacterial cells lack membrane-bound organelles like mitochondria, which are commonly found in eukaryotic cells. Choices B, C, and D are all components that can be found within a bacterial cell. Bacterial cells contain DNA as their genetic material, vesicles for various cellular functions, and ribosomes for protein synthesis. Therefore, the presence of mitochondria is the distinguishing factor that is not found in bacterial cells, making option A the correct answer.
3. 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.
4. How should a researcher test the hypothesis that a particular species of bird vocalizes most in the hours around dawn?
- A. Observe a flock of the birds in captivity and record them at two-hour intervals from predawn until sunset for a month.
- B. Observe a flock of the birds in the wild and record them at one-hour intervals from predawn until sunset in several seasons.
- C. Observe a flock of the birds in the wild and record them in predawn and postdawn hours every day for six months.
- D. Observe a flock of the birds in the wild, record them at one-hour intervals for a month, and compare that recording to recordings of other species.
Correct answer: C
Rationale: Observing a flock of the birds in the wild and recording them in predawn and postdawn hours every day for six months would be the best way to test the hypothesis that a particular species of bird vocalizes most in the hours around dawn. This method allows for consistent monitoring of the birds during specific times of interest over an extended period, providing a comprehensive dataset to accurately analyze the vocalization patterns. Options A and B do not focus specifically on dawn hours, making them less suitable for testing the hypothesis. Option D introduces a comparison with other species, which is unnecessary and distracts from the main objective of studying the vocalization pattern of the particular bird species around dawn.
5. If bacteria are placed in a strong solution of salt water, they will shrink as water moves out of the bacteria. What is this process called?
- A. Dehydration synthesis
- B. Hydrolysis
- C. Osmosis
- D. Isotonic transport
Correct answer: C
Rationale: Osmosis is the process by which water molecules move across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. In this case, when bacteria are placed in a strong solution of salt water, the high concentration of solutes outside the bacteria causes water to move out of the bacteria, leading to shrinkage. This process is known as osmosis. Dehydration synthesis (Choice A) is a process where molecules combine by removing water. Hydrolysis (Choice B) is the breakdown of molecules by the addition of water. Isotonic transport (Choice D) does not accurately describe the specific movement of water in or out of bacterial cells in a hypertonic solution.
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