Nokea
How does an unbalanced force affect an object at rest?
- A. It maintains the object's state of rest
- B. It does not affect the object's rest
- C. It moves the object into motion
- D. It decreases the object's mass
Correct Answer: C
Rationale: An unbalanced force acting on an object at rest will cause the object to move into motion. This is in accordance with Newton's first law of motion, which states that an object at rest will remain at rest unless acted upon by an external force. Therefore, option C, 'It moves the object into motion,' is the correct answer. Choices A and B are incorrect because an unbalanced force disrupts the object's state of rest. Choice D is incorrect as force does not affect the mass of an object.
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In endocrine regulation, the feedback loop is a critical concept. In a negative feedback loop, high levels of a hormone can result in:
- A. Further stimulating the release of the same hormone
- B. Inhibiting the release of the hormone or its production
- C. Having no effect on the hormone's regulation
- D. Increasing the need for another hormone entirely
Correct Answer: B
Rationale: In a negative feedback loop, high levels of a hormone will inhibit the release of the hormone or its production. This mechanism is crucial for maintaining homeostasis by preventing excessive levels of hormones in the body. When a hormone reaches a certain concentration, it triggers the body to decrease its production or release, thereby ensuring a balance within the system. Choice A is incorrect because a negative feedback loop aims to counteract high hormone levels, not further stimulate them. Choice C is incorrect as high hormone levels do have an effect by triggering the feedback loop. Choice D is incorrect as the negative feedback loop operates within the same hormone system rather than increasing the need for an entirely different hormone.
Through which part of the digestive system are nutrients absorbed into the bloodstream?
- A. Stomach
- B. Large intestine
- C. Small intestine
- D. Esophagus
Correct Answer: C
Rationale: The small intestine is the primary site of nutrient absorption in the digestive system. It is where the majority of digestion and absorption of nutrients such as carbohydrates, proteins, and fats occurs. The inner lining of the small intestine is covered in tiny finger-like projections called villi, which increase the surface area available for absorption. Nutrients are absorbed through the walls of the small intestine and into the bloodstream to be transported to cells throughout the body. The stomach's main role is to break down food through the action of stomach acids and enzymes but does not absorb nutrients. The large intestine primarily absorbs water and electrolytes from the remaining indigestible food matter, and the esophagus is a muscular tube that transports food from the mouth to the stomach, without being involved in nutrient absorption.
What functional group is present in ethers?
- A. Hydroxyl
- B. Carbonyl
- C. Ether
- D. Amine
Correct Answer: C
Rationale: The functional group present in ethers is -O-, representing an oxygen atom bonded to two alkyl or aryl groups. Therefore, choice C, 'Ether,' is the correct answer. Choices A, B, and D refer to different functional groups: hydroxyl (-OH), carbonyl (C=O), and amine (NH2), respectively, which are not present in ethers. Ethers are characterized by the oxygen atom bonded to two carbon groups, distinguishing them from the other functional groups mentioned in the choices.
Which property of matter refers to the force of gravity acting on an object?
- A. Mass
- B. Weight
- C. Density
- D. Volume
Correct Answer: B
Rationale: Weight is the property of matter that refers to the force of gravity acting on an object. Mass is the amount of matter in an object, not affected by gravity. Density is the mass per unit volume of a substance, not directly related to gravity. Volume is the amount of space that an object occupies, not a measure of gravity's force.
Which of the following is an example of a polymer?
- A. Methane
- B. Ethanol
- C. Polyethylene
- D. Acetic acid
Correct Answer: C
Rationale: The correct answer is C, Polyethylene. Polyethylene is a polymer composed of a large number of repeating ethylene units linked together, forming a long-chain molecule, characteristic of polymers. Methane, ethanol, and acetic acid are small organic molecules that do not demonstrate the repeating unit structure typical of polymers. Therefore, they are not examples of polymers.