Nursing Elites

1. What happens to the density of a substance if its mass increases while its volume remains constant?

• A. Density increases
• B. Density decreases
• C. Density remains constant
• D. Density becomes zero

Correct answer: A

Rationale: When the mass of a substance increases while its volume remains constant, the density, which is calculated by dividing mass by volume, will increase. This is because with a higher mass and the volume staying the same, the ratio of mass to volume (density) will be greater, resulting in an overall increase in density. Choice B, 'Density decreases,' is incorrect because an increase in mass with constant volume leads to a higher density. Choice C, 'Density remains constant,' is incorrect as an increase in mass will cause the density to increase. Choice D, 'Density becomes zero,' is incorrect because even with an increase in mass, as long as volume remains constant, density will not reach zero; it will increase instead.

2. Which level of protein structure is defined by the folds and coils of the protein's polypeptide backbone?

• A. Primary
• B. Secondary
• C. Tertiary
• D. Quaternary

Correct answer: B

Rationale: The correct answer is B: Secondary. The secondary structure of a protein is defined by the folding and coiling of the polypeptide backbone into structures like alpha helices and beta sheets. Secondary structure primarily involves interactions such as hydrogen bonding within the backbone. This level of protein structure is distinct from primary structure (A) which refers to the linear sequence of amino acids, tertiary structure (C) which involves the overall 3D arrangement of a single polypeptide chain, and quaternary structure (D) which pertains to the interaction between multiple polypeptide chains in a protein complex.

3. Which of the following processes breaks down cellular components for recycling or waste removal?

• A. Photosynthesis
• B. Cellular respiration
• C. Cell division
• D. Phagocytosis

Correct answer: D

Rationale: The correct answer is D: Phagocytosis. Phagocytosis is the process by which cells engulf and break down cellular components or foreign particles for recycling or waste removal. It is a vital mechanism used by cells to maintain homeostasis and remove waste materials. Photosynthesis (A) is the process by which plants convert light energy into chemical energy to produce food, not for breaking down cellular components. Cellular respiration (B) is the process by which cells generate energy from nutrients, not for waste removal. Cell division (C) is the process by which cells replicate and divide to form new cells during growth, repair, or development, not for breaking down cellular components.

4. What is the energy required to break a chemical bond called?

• A. Kinetic energy
• B. Potential energy
• C. Activation energy
• D. Bond energy

Correct answer: C

Rationale: Activation energy is the energy required to break a chemical bond and initiate a chemical reaction. It is the minimum amount of energy needed to start a chemical reaction by breaking bonds in the reactant molecules. Kinetic energy (option A) is the energy of motion and is not directly related to breaking chemical bonds. Potential energy (option B) is stored energy that can be converted into other forms of energy but is not specifically about breaking chemical bonds. Bond energy (option D) refers to the energy required to break a particular chemical bond in a molecule and is not the general term for the energy needed to break any chemical bond. Activation energy is crucial in determining the rate of a chemical reaction as it affects the probability of reactant molecules colliding with sufficient energy to surpass the energy barrier and form products.

5. Which element's neutral atom has 2 electrons in the first shell and 6 electrons in the second shell of the electron cloud?

• A. Beryllium
• B. Carbon
• C. Helium
• D. Oxygen

Correct answer: D

Rationale: The correct answer is Oxygen. Oxygen has a total of 8 electrons, with 2 in the first shell and 6 in the second shell. This configuration matches the description provided in the question. Choice A, Beryllium, has 2 electrons in total, so it cannot have 2 in the first shell and 6 in the second. Choice B, Carbon, has 6 electrons in total, so it also does not match the given electron distribution. Choice C, Helium, has only 2 electrons in total and therefore does not fit the electron configuration described in the question.

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