HESI RN
Biology Test
1. Which of the following molecules acts as the genetic code's messenger?
- A. RNA
- B. Proteins
- C. DNA
- D. Carbohydrates
Correct answer: A
Rationale: The correct answer is RNA. RNA, particularly mRNA, serves as the messenger that carries genetic information from DNA to the ribosome, where proteins are synthesized. Proteins (choice B) are not the genetic code's messenger; they are synthesized based on the information carried by RNA. DNA (choice C) stores the genetic information but does not directly act as the messenger. Carbohydrates (choice D) are not involved in transmitting genetic information.
2. What is the most significant contributor to cellular function?
- A. Proteins
- B. Phospholipids
- C. Carbohydrates
- D. Fatty acids
Correct answer: A
Rationale: The correct answer is A: Proteins. Proteins are the most significant contributor to cellular function as they play crucial roles in almost all biological processes. They act as enzymes that catalyze reactions, are involved in cell signaling pathways, and provide structural support to cells. Phospholipids (Choice B), while important for cell membrane structure, do not have the same diverse functions as proteins in cellular processes. Carbohydrates (Choice C) primarily serve as an energy source and structural components but are not as versatile in cellular functions as proteins. Fatty acids (Choice D) are essential components of cell membranes and energy storage molecules but do not have the same broad range of functions as proteins in cellular processes.
3. DNA and RNA are both subunits of which biological molecule?
- A. Nucleic acids
- B. Proteins
- C. Carbohydrates
- D. Lipids
Correct answer: A
Rationale: The correct answer is A: Nucleic acids. DNA and RNA are both types of nucleic acids, which are fundamental biological molecules responsible for storing and transmitting genetic information. Choice B, Proteins, are not subunits of DNA and RNA but are composed of amino acids. Carbohydrates, choice C, are another type of biological molecule involved in energy storage and structural support, not subunits of DNA and RNA. Lipids, choice D, are a diverse group of molecules that include fats, oils, and steroids, but they are not subunits of DNA and RNA.
4. Which of the following makes it possible to predict the genotype and phenotype of the offspring of sexual reproduction?
- A. Punnett square
- B. Chi-square
- C. Microscope
- D. None of these
Correct answer: A
Rationale: The correct answer is A, Punnett square. A Punnett square is a tool specifically designed to predict the genotype and phenotype combinations of offspring resulting from a particular cross or breeding experiment. It helps in understanding the probability of different genotypes and phenotypes appearing in the offspring. Choice B, Chi-square, is a statistical test used to determine if there is a significant difference between the expected frequencies and the observed frequencies in a study. Choice C, Microscope, is used for viewing tiny structures and organisms, not for predicting genetic outcomes. Choice D, None of these, is incorrect as Punnett square is a valid tool for predicting genetic outcomes in offspring.
5. What is the primary method of asexual reproduction used by most bacteria?
- A. Meiosis
- B. Mitosis
- C. Binary fission
- D. Interphase
Correct answer: C
Rationale: The correct answer is C: Binary fission. This is the main process through which most bacteria reproduce asexually. During binary fission, a single cell divides into two identical cells, each containing a copy of the genetic material. Choices A and B, meiosis and mitosis, are processes involved in sexual reproduction and are not used by bacteria for asexual reproduction. Choice D, interphase, is a stage of the cell cycle where the cell prepares for division and is not a method of reproduction.
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