HESI A2
Biology HESI A2 Practice Test
1. The fur color in a population of dogs is controlled by two alleles: black (B) and tan (b). The black allele exhibits complete dominance. If the phenotype of the dog is tan fur, what is its genotype?
- A. BB
- B. Bb
- C. bb
- D. Not enough information
Correct answer: C
Rationale: The correct answer is C: "bb." Since tan fur is the recessive trait controlled by the allele 'b,' the only possible genotype for a dog with tan fur is 'bb.' If a dog had the genotype 'BB' or 'Bb,' the dominant trait (black fur) would be expressed, not tan fur. Choice D, 'Not enough information,' is incorrect because based on the information provided, we can deduce the genotype of a dog with tan fur.
2. Which statement regarding energy content is true?
- A. Decomposers < secondary consumers
- B. Primary consumers < producers
- C. Producers > secondary consumers
- D. Secondary consumers < primary consumers
Correct answer: C
Rationale: The correct answer is C: "Producers > secondary consumers." Producers, like plants, are the foundation of the energy pyramid, containing the highest energy content in an ecosystem. They convert solar energy into chemical energy through photosynthesis. Secondary consumers, being organisms that feed on other organisms, have lower energy content compared to producers. This hierarchy in energy content is due to the transfer of energy through trophic levels. Choice A is incorrect because decomposers, though essential for nutrient recycling, typically have lower energy content than secondary consumers. Choice B is incorrect because primary consumers, which feed directly on producers, have lower energy content than producers. Choice D is incorrect because secondary consumers have lower energy content compared to primary consumers.
3. Which organelle provides storage space for the cell?
- A. Mitochondrion
- B. Vacuole
- C. Cell membrane
- D. Ribosome
Correct answer: B
Rationale: The correct answer is B: Vacuole. The vacuole is the organelle responsible for providing storage space in the cell. It stores water, nutrients, waste products, and other essential materials required by the cell. Vacuoles are crucial for maintaining cell structure and regulating cellular processes. Mitochondrion (choice A) is known as the powerhouse of the cell, responsible for producing energy. The cell membrane (choice C) is a protective barrier around the cell, regulating what enters and exits the cell. Ribosomes (choice D) are involved in protein synthesis, not storage.
4. Which of the following shows how information is transformed to make a protein?
- A. DNA-RNA-protein
- B. gene-chromosome-protein
- C. ATP-amino acid-protein
- D. RNA-DNA-protein
Correct answer: A
Rationale: The correct sequence of events for protein synthesis is that DNA is transcribed into RNA, which is then translated into a protein. This process is known as the central dogma of molecular biology. In this sequence, DNA serves as the template for RNA synthesis (transcription), and the RNA serves as the template for protein synthesis (translation). Choice B is incorrect as genes are segments of DNA that code for proteins, and chromosomes are structures that contain DNA. Choice C is incorrect as ATP is an energy molecule and amino acids are the building blocks of proteins, but they are not directly involved in the synthesis process. Choice D is incorrect because RNA is first transcribed from DNA and then used as a template to produce proteins.
5. How is mitosis different from meiosis?
- A. Mitosis is the process by which body cells are formed.
- B. Meiosis creates cells with half the chromosomes of the parent cell.
- C. Telophase occurs in both mitosis and meiosis.
- D. Spermatogenesis and oogenesis occur via meiosis.
Correct answer: B
Rationale: Meiosis is the type of cell division that creates cells with half the number of chromosomes compared to the parent cell. This is essential for sexual reproduction as it ensures that when the sex cells (sperm and egg) combine during fertilization, the resulting offspring has the correct number of chromosomes. In contrast, mitosis results in two identical daughter cells with the same number of chromosomes as the parent cell. Choice A is incorrect because mitosis is responsible for the division of body cells, not sex cells. Choice C is incorrect because telophase is a phase that occurs in both mitosis and meiosis. Choice D is incorrect because spermatogenesis and oogenesis involve meiosis, not mitosis.
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