Nokea
A car brakes to a stop on a level road. Which of the following forces does NOT do work on the car?
- A. The braking force applied by the wheels
- B. The normal force from the road
- C. The gravitational force on the car
- D. The friction force between the tires and the road
Correct Answer: B
Rationale: The normal force from the road does not do work on the car because it is perpendicular to the direction of motion. Work is defined as force applied in the direction of motion, so the normal force, which acts perpendicular to the motion of the car, does not contribute to the work done on the car. The braking force applied by the wheels, the gravitational force on the car, and the friction force between the tires and the road all act in the direction of motion and contribute to the work done on the car. In this scenario, the normal force is supporting the weight of the car and keeping it from sinking into the road, but it does not transfer energy to the car as it moves.
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Which hormone, produced by the adrenal glands, prepares the body for a 'fight or flight' response by increasing heart rate, dilating airways, and mobilizing energy stores?
- A. Cortisol
- B. Aldosterone
- C. Epinephrine
- D. Insulin
Correct Answer: C
Rationale: Epinephrine, also known as adrenaline, is the hormone produced by the adrenal glands that prepares the body for a 'fight or flight' response. It increases heart rate, dilates airways, and mobilizes energy stores to provide the body with the necessary resources to respond to a perceived threat or stressor. Cortisol, although produced by the adrenal glands, is not responsible for the 'fight or flight' response; it is involved in regulating metabolism, immune response, and stress. Aldosterone, another hormone produced by the adrenal glands, primarily regulates electrolyte and fluid balance. Insulin, produced by the pancreas, is responsible for regulating blood sugar levels and is not directly involved in the 'fight or flight' response.
What is kwashiorkor, a protein deficiency disease, characterized by?
- A. Muscle wasting
- B. Night blindness
- C. Scurvy
- D. Rickets
Correct Answer: A
Rationale: Kwashiorkor is a severe acute malnutrition condition resulting from insufficient dietary protein intake. It is characterized by symptoms such as edema, skin lesions, an enlarged liver with fatty infiltrates, and notably, muscle wasting. Muscle wasting occurs as the body breaks down muscle tissue to obtain essential amino acids for vital functions. Night blindness (option B) is associated with vitamin A deficiency, scurvy (option C) results from a lack of vitamin C, and rickets (option D) is caused by a deficiency in vitamin D, calcium, or phosphate.
Which of the following is an example of a chemical change?
- A. Dissolving sugar in water
- B. Boiling water
- C. Rusting iron
- D. Crushing ice
Correct Answer: C
Rationale: Rusting iron is an example of a chemical change because it involves a chemical reaction where iron reacts with oxygen in the presence of water to form iron oxide (rust). This reaction results in a change in the chemical composition of the iron, unlike dissolving sugar in water, boiling water, or crushing ice, which are physical changes. Dissolving sugar in water is a physical change as sugar molecules remain unchanged but disperse in water. Boiling water is also a physical change as water changes its state from liquid to gas due to heat. Crushing ice is a physical change as the solid ice changes its physical form without altering its chemical composition.
What is the term for a hydrocarbon chain with no double or triple bonds between carbon atoms?
- A. Saturated
- B. Unsaturated
- C. Aromatic
- D. Alkene
Correct Answer: A
Rationale: A saturated hydrocarbon chain contains only single bonds between carbon atoms, making it 'saturated' with hydrogen atoms. Therefore, the correct answer is choice A, 'Saturated.' Choice B, 'Unsaturated,' is incorrect because it refers to hydrocarbon chains with double or triple bonds. Choice C, 'Aromatic,' is not the correct term for a hydrocarbon chain without double or triple bonds; it describes a specific type of cyclic and conjugated hydrocarbon structure. Choice D, 'Alkene,' is also incorrect as it specifically indicates a hydrocarbon chain with at least one double bond between carbon atoms.
What is the external body covering, providing protection and contributing to temperature regulation, composed of?
- A. Muscle tissue
- B. Epithelial tissue (skin)
- C. Bone marrow
- D. Cartilage
Correct Answer: B
Rationale: The external body covering, which is the skin, is composed of epithelial tissue. Epithelial tissue serves as a protective barrier against pathogens, chemicals, and physical damage. It also helps regulate body temperature through processes like sweating. Choice A (Muscle tissue) is incorrect as muscles are responsible for movement and not the external body covering. Choice C (Bone marrow) is incorrect as it is a component of the skeletal system and not the external body covering. Choice D (Cartilage) is incorrect as cartilage is a type of connective tissue found in joints and the structure of some body parts, not the external body covering.