HESI A2
Biology HESI A2 Practice Test
1. What is the effect of the Earth's rotation on the atmosphere and on all objects on the Earth's surface?
- A. The Coriolis effect
- B. The Corona effect
- C. The Archimedes effect
- D. The tidal effect
Correct answer: A
Rationale: The Coriolis effect is the effect of the Earth's rotation on the atmosphere and on all objects on the Earth's surface. It causes moving objects and currents to be deflected to the right in the northern hemisphere and to the left in the southern hemisphere. This deflection is a result of the rotation of the Earth and plays a crucial role in influencing weather patterns and ocean currents around the globe. The other choices provided are incorrect. The Corona effect is related to the Sun's atmosphere, the Archimedes effect involves buoyancy in fluids, and the tidal effect is associated with the gravitational forces between the Earth, the Moon, and the Sun.
2. 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.
3. During which phase is the chromosome number reduced from diploid to haploid?
- A. S phase
- B. interphase
- C. mitosis
- D. meiosis I
Correct answer: D
Rationale: The correct answer is 'meiosis I.' During meiosis I, the chromosome number is reduced from diploid to haploid through two rounds of division. Choice A ('S phase') is incorrect as the S phase is part of the cell cycle where DNA is replicated. Choice B ('interphase') is also incorrect as interphase is the phase where the cell prepares for division. Choice C ('mitosis') is incorrect as mitosis is a process where a diploid cell divides to produce two identical diploid daughter cells, maintaining the chromosome number.
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. What happens to messenger RNA when it reaches the cytoplasm?
- A. It attaches to a ribosome.
- B. It unzips, exposing nitrogen bases.
- C. It pairs with the DNA bases.
- D. It pulls free of the DNA strand.
Correct answer: A
Rationale: Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm. When mRNA reaches the cytoplasm, it attaches to a ribosome. The ribosome functions as the site for protein synthesis through translation, where the genetic code carried by mRNA is read and translated into a specific sequence of amino acids. Choices B, C, and D are incorrect because mRNA does not unzip, expose nitrogen bases, pair with DNA bases, or pull free of the DNA strand in the cytoplasm. The primary function of mRNA in the cytoplasm is to serve as a template for protein synthesis by binding to ribosomes.
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