Nursing Elites

1. A ball is rolling across the floor and comes to a stop on its own. What force caused the ball to stop?

• A. Gravitational force
• B. Normal force from the floor
• C. Air resistance
• D. None of the above

Correct answer: C

Rationale: The force that caused the ball to stop rolling across the floor is air resistance. As the ball moves through the air, air resistance acts in the opposite direction of its motion, gradually slowing it down until it comes to a stop. In this scenario, the ball is not in contact with the floor, so the normal force from the floor does not play a role in stopping the ball. Gravitational force acts to pull objects towards the center of the Earth and would not directly stop the ball in this situation. Therefore, air resistance is the force that opposes the motion of the rolling ball and causes it to come to a stop.

2. Which enzyme found in saliva is responsible for breaking down carbohydrates into smaller molecules like sugars?

• A. Pepsin
• B. Amylase
• C. Lipase
• D. Trypsin

Correct answer: B

Rationale: The correct answer is B. Saliva contains an enzyme called amylase, which specifically targets carbohydrates and breaks them down into smaller molecules like sugars. Pepsin, choice A, is an enzyme found in the stomach that breaks down proteins, not carbohydrates. Lipase, choice C, is responsible for breaking down fats, not carbohydrates. Trypsin, choice D, is an enzyme that breaks down proteins in the small intestine, not carbohydrates. Therefore, choices A, C, and D are incorrect for this question.

3. Which of the following is directly transcribed from DNA and represents the first step in protein synthesis?

• A. siRNA
• B. rRNA
• C. mRNA
• D. tRNA

Correct answer: C

Rationale: mRNA (messenger RNA) is directly transcribed from DNA in the nucleus during the process of transcription. It serves as a template for protein synthesis during translation in the cytoplasm. mRNA carries genetic information from the DNA to the ribosomes, where it determines the sequence of amino acids in a protein. Thus, mRNA represents the first step in protein synthesis as it carries the code from the DNA to be translated into a protein. Choice A, siRNA (small interfering RNA), is involved in post-transcriptional gene silencing and does not play a role in protein synthesis. Choice B, rRNA (ribosomal RNA), is a component of the ribosome and plays a structural and functional role in protein synthesis but is not directly transcribed from DNA. Choice D, tRNA (transfer RNA), is responsible for bringing amino acids to the ribosome during protein synthesis but is not directly transcribed from DNA.

4. In a study evaluating which type of road salt deices a road most quickly, what is the independent variable?

• A. Deicing time period
• B. Road used for deicing
• C. Type of road salt used
• D. Amount of road salt used

Correct answer: C

Rationale: The correct answer is C, 'Type of road salt used.' In an experiment, the independent variable is the one manipulated by the researcher to observe its impact on the dependent variable. In this study, the researchers are altering the type of road salt used to determine its influence on the deicing speed, thus making it the independent variable. The other choices are not the independent variable as they are not deliberately manipulated in the experiment: A - 'Deicing time period' is an outcome measure dependent on the type of salt used; B - 'Road used for deicing' is not controlled or manipulated; D - 'Amount of road salt used' would be a potential confounding variable rather than the independent variable as it could affect the outcome along with the type of salt.

5. Which of the following is LEAST likely to be found in a human cell's genes?

• A. Sequences of amino acids to be transcribed into mRNA
• B. Lethal recessive traits like sickle cell anemia
• C. Mutated DNA
• D. DNA that codes for proteins the cell doesn't use

Correct answer: D

Rationale: Human cells typically contain genes that code for proteins necessary for the cell's functions. DNA that codes for proteins the cell doesn't use would be an inefficient use of the cell's resources. Therefore, it is less likely to be found in a human cell's genes. Options A, B, and C are more commonly associated with genes found in human cells. Choice A refers to the genetic information needed for protein synthesis, while choice B involves traits that can be present in the gene pool. Mutated DNA (choice C) can also be found in human cells as a result of genetic alterations. However, DNA that codes for proteins not utilized by the cell would be redundant and not typically retained in the genome.

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