HESI A2
HESI A2 Biology Practice Test
1. When the genotype consists of a dominant and a recessive allele, the phenotype will be like the _ allele.
- A. Dominant
- B. Recessive
- C. Both
- D. Neither
Correct answer: A
Rationale: When the genotype consists of a dominant and a recessive allele, the phenotype will be like the dominant allele. This is because dominant alleles typically mask the expression of recessive alleles. Therefore, the dominant allele will be expressed in the phenotype in most basic cases. The recessive allele will only be expressed phenotypically if the individual is homozygous recessive. Choice B, 'Recessive,' is incorrect because the phenotype will not be like the recessive allele in this case. Choice C, 'Both,' is incorrect because in simple dominant-recessive inheritance, the dominant allele will overshadow the recessive allele. Choice D, 'Neither,' is incorrect as the phenotype will resemble the dominant allele.
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. Tundra, savannas, grasslands, deserts, and rainforests are examples of what?
- A. Biomasses
- B. Biospheres
- C. Biodiversity
- D. Biomes
Correct answer: D
Rationale: Tundra, savannas, grasslands, deserts, and rainforests are examples of biomes. A biome is a large geographical area with similar climatic conditions and distinct flora and fauna. Each biome has its unique characteristics, such as temperature, precipitation levels, and types of vegetation, which define the ecosystem within that region. Biomasses refer to the total mass of living organisms in a given area, biospheres are the global ecological system integrating all living beings and their relationships, and biodiversity represents the variety of life forms in a specific habitat.
4. Where can epithelial tissue be found?
- A. Organ lining
- B. Heart muscle
- C. Tendons
- D. Spinal cord
Correct answer: A
Rationale: Epithelial tissue is primarily found lining the surfaces of organs, such as the skin and the linings of various internal organs like the digestive tract, respiratory tract, and blood vessels. It serves as a protective barrier and helps with absorption and secretion. Heart muscle is made up of cardiac muscle tissue, tendons are primarily composed of dense connective tissue, and the spinal cord is composed of nervous tissue, none of which are classified as epithelial tissue.
5. Which of the following is necessary for cell diffusion?
- A. water
- B. membrane
- C. ATP
- D. gradient
Correct answer: D
Rationale: The correct answer is 'gradient.' In cell diffusion, substances move from an area of high concentration to an area of low concentration, driven by the concentration gradient. This process does not require water, membrane, or ATP specifically. Water can aid in the movement of substances, but it is not necessary for diffusion itself. The membrane is involved in regulating diffusion but is not a requirement for the process. ATP is not directly involved in simple diffusion processes; instead, it is more related to active transport mechanisms. Therefore, the concentration gradient is essential for cell diffusion to occur.
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