Nursing Elites

1. What is the main function of valence electrons in chemical bonding?

• A. They are responsible for holding the nucleus together.
• B. They are involved in forming bonds with other atoms.
• C. They determine the element's physical properties.
• D. They play no role in chemical reactions.

Correct answer: B

Rationale: Valence electrons are the electrons in the outermost energy level of an atom. These electrons are involved in forming bonds with other atoms, which is crucial for chemical bonding. By participating in bonding, valence electrons determine an atom's ability to form compounds and engage in chemical reactions. Therefore, the primary function of valence electrons is to facilitate the formation of bonds between atoms, making option B the correct answer. Choices A, C, and D are incorrect because valence electrons primarily influence chemical bonding by participating in the formation of bonds between atoms, rather than holding the nucleus together, determining physical properties, or having no role in chemical reactions.

2. Which technology allows scientists to directly edit the human genome?

• A. Polymerase Chain Reaction (PCR)
• B. Gel electrophoresis
• C. DNA sequencing
• D. CRISPR-Cas9

Correct answer: D

Rationale: CRISPR-Cas9 is the correct answer. A) Polymerase Chain Reaction (PCR) is used for amplifying specific DNA segments, not directly editing the human genome. B) Gel electrophoresis is for separating DNA fragments by size, not for genome editing. C) DNA sequencing determines DNA nucleotide order but does not directly edit the genome. D) CRISPR-Cas9 technology enables precise modifications in the DNA of organisms, including humans. It guides the Cas9 enzyme to specific genome locations for targeted edits, revolutionizing genetic research and offering various applications in gene editing and therapy. Unlike the other techniques mentioned, CRISPR-Cas9 is specifically designed to make changes in the genetic code itself, making it a powerful tool for genetic manipulation.

3. An atom has 17 protons, 20 neutrons, and 17 electrons. What is its mass, in amu?

• A. 17
• B. 20
• C. 37
• D. 54

Correct answer: C

Rationale: The atomic mass of an atom is the sum of the protons and neutrons in its nucleus. In this case, the atom has 17 protons and 20 neutrons, totaling 37 particles in the nucleus. Electrons are not considered in the atomic mass calculation as their mass is negligible compared to protons and neutrons. Therefore, the mass of the atom in atomic mass units (amu) is 37.

4. The pancreas secretes digestive enzymes into the small intestine. What enzyme breaks down proteins into amino acids?

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

Correct answer: D

Rationale: Trypsin is the correct enzyme that breaks down proteins into amino acids. It is produced by the pancreas and released into the small intestine to facilitate protein digestion. Pepsin is an enzyme from the stomach that also breaks down proteins, amylase targets carbohydrates, and lipase works on fats. In this context, since the question specifies the pancreas and small intestine, the correct answer is Trypsin as it is the pancreatic enzyme responsible for protein breakdown in the small intestine.

5. Which type of cell division is responsible for growth and repair?

• A. Meiosis
• B. Mitosis
• C. Binary fission
• D. Osmosis

Correct answer: B

Rationale: Mitosis is the correct type of cell division responsible for growth and repair. During mitosis, a cell divides to produce two identical daughter cells, contributing to growth and tissue repair in multicellular organisms. Meiosis, on the other hand, is involved in the formation of gametes (sperm and egg cells) for sexual reproduction. Binary fission is a form of asexual reproduction in single-celled organisms, and osmosis is the movement of water molecules across a selectively permeable membrane. Therefore, choices A, C, and D are incorrect as they are not directly related to growth and repair in multicellular organisms.

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