Nursing Elites

1. Which of the following enzymes unwinds the double-stranded DNA during replication?

• A. Helicase
• B. Ligase
• C. Nuclease
• D. Polymerase

Correct answer: A

Rationale: Helicase is the enzyme responsible for unwinding the double-stranded DNA during replication by breaking the hydrogen bonds between the base pairs. This process creates the replication fork where DNA polymerase can then synthesize new DNA strands. Ligase functions to join Okazaki fragments on the lagging strand, not unwind DNA. Nuclease is involved in DNA repair by removing damaged DNA segments. Polymerase is responsible for synthesizing new DNA strands based on the existing template strands, not for unwinding the DNA.

2. Which blood vessels transport blood from the capillaries back to the heart?

• A. Arterioles
• B. Veins
• C. Venules
• D. Capillaries

Correct answer: B

Rationale: Veins are the correct answer as they are the blood vessels that carry blood from the capillaries back to the heart. Veins have thinner walls compared to arteries and contain valves to prevent blood from flowing backward. This transport of blood from the capillaries to the heart is essential for the circulatory system to maintain proper blood flow and oxygenation levels. Arterioles are small branches of arteries that lead to capillaries, not vessels that transport blood back to the heart. Venules are small vessels that collect blood from capillaries and lead to veins. Capillaries are the smallest blood vessels where the exchange of gases and nutrients occurs between blood and tissues, not vessels that transport blood back to the heart.

3. Which element is found in water and is crucial for biological functions like nerve impulses and muscle contraction?

• A. Sodium
• B. Potassium
• C. Calcium
• D. Magnesium

Correct answer: A

Rationale: The correct answer is Sodium. Sodium is found in water and is crucial for biological functions like nerve impulses and muscle contraction. It plays a key role in maintaining electrolyte balance and transmitting nerve impulses, affecting both muscles and nerves. Potassium (Choice B), although essential for nerve function and muscle control, is not typically found in water. Calcium (Choice C) is important for bone health and muscle function, but it is not the element found in water. Magnesium (Choice D) is also essential for various biological functions but is not the element commonly found in water.

4. What type of chemical bond connects the oxygen and hydrogen atoms in a molecule of water?

• A. Static bond
• B. Aquatic bond
• C. Ionic bond
• D. Covalent bond

Correct answer: D

Rationale: The correct answer is D, Covalent bond. Covalent bonds are formed between oxygen and hydrogen atoms in a water molecule. In a water molecule, each hydrogen atom forms a covalent bond with the oxygen atom, sharing electrons to achieve a stable configuration. Static bond (choice A) and Aquatic bond (choice B) are not valid types of chemical bonds. Ionic bond (choice C) involves the transfer of electrons between atoms of different electronegativities, which is not the case between oxygen and hydrogen in a water molecule.

5. What is the pathway of deoxygenated blood in our body?

• A. From the lungs to the left ventricle
• B. From the body to the right atrium, then to the right ventricle, and finally to the lungs
• C. From the left atrium to the body
• D. From the aorta to the right atrium

Correct answer: B

Rationale: The correct pathway of deoxygenated blood in our body involves blood returning from the body, entering the right atrium, then passing to the right ventricle, and eventually reaching the lungs for oxygenation. This sequence ensures that deoxygenated blood is pumped to the lungs, where it receives oxygen and releases carbon dioxide before circulating back to the body. Choices A, C, and D are incorrect because they do not follow the actual path of deoxygenated blood in the circulatory system.

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