Nursing Elites

1. Which valve prevents the backflow of blood into the left ventricle as it leaves through the aorta?

• A. Pulmonary semilunar valve
• B. Aortic semilunar valve
• C. Tricuspid valve
• D. Mitral valve

Correct answer: B

Rationale: The aortic semilunar valve is the correct answer as it prevents the backflow of blood into the left ventricle once it has been pumped into the aorta. The pulmonary semilunar valve prevents backflow into the right ventricle, the tricuspid valve controls blood flow between the right atrium and ventricle, and the mitral valve regulates blood flow between the left atrium and ventricle. Therefore, option B is the correct choice for this question.

2. In ecology, what defines a closed system?

• A. Exchanges energy but not matter
• B. Exchanges both energy and matter
• C. Exchanges neither energy nor matter
• D. Recycles nutrients efficiently

Correct answer: A

Rationale: In ecology, a closed system is one that does not exchange matter with its surroundings but can exchange energy. This means that while energy can enter or leave the system, the amount of matter within the system remains constant. Option A correctly defines a closed system in ecology. Choices B and C are incorrect as a closed system does not exchange matter or energy. Option D is unrelated to the concept of a closed system in ecology.

3. What is the building block of RNA?

• A. Amino acid
• B. Nucleotide
• C. Protein
• D. Fatty acid

Correct answer: B

Rationale: Nucleotide: Nucleotides are the building blocks of RNA. A nucleotide consists of a nitrogenous base (adenine, guanine, cytosine, or uracil in RNA), a sugar (ribose in RNA), and a phosphate group. A) Amino acid: Amino acids are the building blocks of proteins, not RNA. C) Protein: Proteins are made up of amino acids, not nucleotides. D) Fatty acid: Fatty acids are components of lipids, not RNA.

4. What are the microscopic units responsible for muscle contraction called?

• A. Neurons
• B. Myofibrils
• C. Tendons
• D. Sarcomeres

Correct answer: D

Rationale: Sarcomeres are the fundamental contractile units of skeletal muscles and are responsible for muscle contraction. They consist of actin and myosin filaments that slide past each other during muscle contraction. Neurons are responsible for transmitting signals to and from muscles but are not directly involved in muscle contraction. Myofibrils are composed of sarcomeres and are the structures within muscle cells where muscle contractions take place. Tendons are connective tissues that attach muscles to bones and are not directly involved in muscle contraction.

5. What is a contraceptive method that uses hormones to prevent ovulation?

• A. Spermicide
• B. Barrier method (condom, diaphragm)
• C. Combined oral contraceptive pill
• D. Intrauterine device (IUD)

Correct answer: C

Rationale: The correct answer is the Combined oral contraceptive pill (C). This method contains hormones (estrogen and progestin) that prevent ovulation, making it an effective contraceptive. Spermicide (A) is a substance that kills sperm and does not use hormones to prevent ovulation. Barrier methods (B) like condoms and diaphragms physically block sperm but do not involve hormone-induced prevention of ovulation. Intrauterine devices (IUDs) (D) prevent pregnancy through different mechanisms, such as altering the uterine environment and preventing sperm from fertilizing the egg, not by hormone-induced prevention of ovulation.

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