Nursing Elites

1. What is the primary source of energy entering most ecosystems?

• A. Chemical energy stored in bonds
• B. Thermal energy from the Earth's core
• C. Light energy from the sun
• D. Kinetic energy from wind and water

Correct answer: C

Rationale: In most ecosystems, the primary source of energy is sunlight. This energy is captured by plants and other photosynthetic organisms through the process of photosynthesis. These organisms convert light energy into chemical energy stored in the bonds of organic molecules, such as glucose. This stored chemical energy is then passed on to other organisms in the ecosystem through the food chain, making sunlight the fundamental source of energy for most ecosystems. Thermal energy from the Earth's core (option B) is not a primary source of energy for ecosystems, as it is not readily accessible to most organisms. Kinetic energy from wind and water (option D) can play a role in some ecosystems, but it is not the primary source of energy. Chemical energy stored in bonds (option A) is a form of energy that is ultimately derived from the sun through photosynthesis, making it a product of the primary energy source rather than the primary source itself.

2. What are substances that stimulate adaptive immunity called?

• A. Peptides
• B. Phagocytes
• C. Prions
• D. Platelets

Correct answer: A

Rationale: Substances that stimulate adaptive immunity are called peptides. Peptides are short chains of amino acids that play a crucial role in activating the immune response by interacting with immune cells such as T cells and B cells. Peptides are important in antigen presentation and recognition, leading to the development of specific immune responses against pathogens. Choice B, phagocytes, are cells that engulf and digest pathogens but are not substances that stimulate adaptive immunity. Choice C, prions, are infectious agents made of misfolded proteins and are not related to stimulating adaptive immunity. Choice D, platelets, are cell fragments involved in blood clotting and have no direct role in stimulating adaptive immunity.

3. DNA has both a 'sense' and 'antisense' strand. What is true about the antisense strand?

• A. It runs 5' to 3'.
• B. It runs 3' to 5'.
• C. It is used in replication.
• D. It is the direction DNA is stored.

Correct answer: B

Rationale: The correct answer is B: 'It runs 3' to 5'. The antisense strand runs in the 3' to 5' direction, complementing the sense strand. Choice A is incorrect as the antisense strand runs in the opposite direction, which is 3' to 5'. Choice C is incorrect because the antisense strand is not directly involved in replication. Choice D is incorrect as the direction DNA is stored is not determined by the antisense strand.

4. Which organelle provides energy for cellular functions?

• A. Nucleus
• B. Cell membrane
• C. Mitochondria
• D. Cytoplasm

Correct answer: C

Rationale: The correct answer is C, Mitochondria. Mitochondria are often referred to as the powerhouse of the cell as they produce energy in the form of ATP through cellular respiration. This process is essential for various cellular functions, making mitochondria crucial for energy production within the cell. Choice A, Nucleus, is incorrect as the nucleus is responsible for housing the cell's genetic material and controlling cellular activities but not for energy production. Choice B, Cell membrane, is incorrect as it is primarily involved in maintaining cell integrity and regulating the passage of substances in and out of the cell, not in energy production. Choice D, Cytoplasm, is incorrect as it is the jelly-like substance that fills the cell and is the site of many metabolic pathways, but it is not the specific organelle responsible for energy production.

5. How does the developing fetus primarily eliminate metabolic wastes?

• A. The developing fetus does not produce metabolic wastes.
• B. Fetal waste is excreted as feces, which pass into the mother's anus.
• C. Fetal waste is passed down the umbilical cord to the mother's circulatory system.
• D. Fetal waste is passed down the umbilical cord and leaves the mother's body via the vagina.

Correct answer: C

Rationale: Metabolic wastes produced by the developing fetus are eliminated primarily by being passed down the umbilical cord to the mother's circulatory system. Once in the mother's blood, these wastes are then filtered and excreted by the mother's kidneys. Choice A is incorrect because the developing fetus does produce metabolic wastes. Choice B is incorrect as fetal waste does not pass into the mother's anus. Choice D is incorrect as fetal waste does not leave the mother's body via the vagina.

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