Nursing Elites

1. What is the half-life of a radioactive isotope, and how does it relate to its decay rate?

• A. The time it takes for half of the initial sample to decay.
• B. The time it takes for all of the sample to decay.
• C. The rate at which new isotopes are created.
• D. The energy released during decay.

Correct answer: A

Rationale: The half-life of a radioactive isotope is the time it takes for half of the initial sample to decay. After one half-life, half of the radioactive atoms have decayed. The decay rate, however, refers to the rate at which radioactive atoms decay, which is not directly related to the half-life. Choice B is incorrect because it does not correctly define the half-life. Choice C is incorrect as it refers to the creation of new isotopes, not the decay process. Choice D is incorrect as it describes the energy released during decay, which is not the same as the concept of half-life.

2. What happens to the potential energy of an object when it is lifted higher above the ground?

• A. Potential energy decreases
• B. Potential energy remains the same
• C. Potential energy increases
• D. Potential energy becomes zero

Correct answer: C

Rationale: When an object is lifted higher above the ground, its potential energy increases. This is because the higher the object is lifted, the greater its potential energy due to the increased distance from the ground. The formula for gravitational potential energy is PE = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height above the reference point. Therefore, as the height (h) increases, the potential energy (PE) also increases, making choice C the correct answer. Choices A, B, and D are incorrect because when an object is lifted higher, it gains potential energy rather than losing it, keeping it the same, or becoming zero. Thus, the correct answer is that the potential energy of an object increases when it is lifted higher above the ground.

3. Muscle soreness after exercise is often caused by microscopic tears in muscle fibers. This is called

• A. Atrophy
• B. Hypertrophy
• C. DOMS (Delayed Onset Muscle Soreness)
• D. Spasm

Correct answer: C

Rationale: Muscle soreness after exercise is often caused by microscopic tears in muscle fibers, leading to Delayed Onset Muscle Soreness (DOMS). Atrophy refers to the wasting away of muscle tissue, hypertrophy is the increase in muscle size, and spasm is an involuntary contraction of a muscle. DOMS typically occurs 24 to 72 hours after intense exercise and is characterized by muscle stiffness, tenderness, and reduced range of motion. It is a normal response to unfamiliar or strenuous physical activity and indicates that the muscles are adapting to the workload. Therefore, the correct answer is C (DOMS) as it specifically describes the phenomenon of muscle soreness resulting from microscopic tears in muscle fibers, distinguishing it from the other choices which refer to different physiological processes or conditions.

4. Homologous structures are similar structures in different organisms that have a common evolutionary origin. An example is:

• A. Butterfly wings and bird wings (analogous structures with different origins)
• B. The arm of a human, the wing of a bat, and the flipper of a whale
• C. The eyes of an octopus and a human (convergent evolution with different origins)
• D. The stinger of a bee and the barb of a cactus (unrelated structures)

Correct answer: B

Rationale: Homologous structures are similar structures found in different organisms that share a common evolutionary origin. The arm of a human, the wing of a bat, and the flipper of a whale are all examples of homologous structures. Despite serving different functions, they share a common underlying structure due to their evolutionary relationship, evidencing a shared ancestry. These structures are modified over time to suit the specific needs of each species. Option A (Butterfly wings and bird wings) refers to analogous structures with different origins. Option C (The eyes of an octopus and a human) describes convergent evolution where traits evolve independently. Option D (The stinger of a bee and the barb of a cactus) are unrelated structures.

5. What is the function of ribosomal RNA (rRNA)?

• A. Carries amino acids to the ribosomes
• B. Reads the genetic code on mRNA
• C. Forms the structural framework of ribosomes
• D. Controls the rate of protein synthesis

Correct answer: C

Rationale: Ribosomal RNA (rRNA) plays a crucial role in forming the structural framework of ribosomes. Ribosomes are the cellular organelles responsible for protein synthesis and consist of both protein and rRNA components. The primary function of rRNA is to provide the structural support necessary for ribosomes to function properly. This structural framework allows the ribosome to interact with messenger RNA (mRNA) and transfer RNA (tRNA) during translation, where genetic information encoded in mRNA is used to assemble proteins from amino acids. Therefore, rRNA's main role is in contributing to the structure and function of ribosomes, rather than directly carrying amino acids, reading the genetic code, or controlling the rate of protein synthesis. Choices A, B, and D are incorrect because rRNA does not carry amino acids to the ribosomes (tRNA does this), read the genetic code (this is the role of ribosomes and tRNA), or control the rate of protein synthesis (this is regulated by various factors but not directly by rRNA).

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