Nokea
What is the primary function of the respiratory system?
- A. Maintain body temperature
- B. Deliver oxygen to the bloodstream and remove carbon dioxide
- C. Produce antibodies for the immune system
- D. Break down food molecules for energy
Correct Answer: B
Rationale: The primary function of the respiratory system is to deliver oxygen to the bloodstream and remove carbon dioxide. This process occurs through breathing, where oxygen is inhaled into the lungs and then transferred to the bloodstream, while carbon dioxide is removed from the bloodstream and exhaled out of the body. Maintaining body temperature (A), producing antibodies for the immune system (C), and breaking down food molecules for energy (D) are functions of other systems in the body, not the respiratory system. Therefore, the correct answer is B.
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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 structure helps regulate body temperature by constricting or dilating in response to temperature changes?
- A. Sebaceous glands
- B. Hair follicles
- C. Sweat glands
- D. Langerhans cells
Correct Answer: C
Rationale: Sweat glands play a crucial role in regulating body temperature by producing sweat that evaporates from the skin surface. This evaporation cools the body when it is hot and helps to maintain a stable internal temperature. Sebaceous glands produce oil to lubricate the skin, hair follicles are responsible for hair growth, and Langerhans cells are a type of immune cell in the skin. Therefore, the correct answer is 'Sweat glands' as they are specifically designed to respond to temperature changes by constricting or dilating to help regulate body temperature.
In the reaction 4Al + 3O2 → 2Al2O3, what is the mole ratio of aluminum to oxygen?
- A. 4:3
- B. 2:3
- C. 3:2
- D. 3:4
Correct Answer: A
Rationale: The balanced chemical equation shows that 4 moles of aluminum react with 3 moles of oxygen to produce 2 moles of aluminum oxide. Therefore, the mole ratio of aluminum to oxygen is 4:3. Choice B (2:3) is incorrect because it does not reflect the correct ratio based on the balanced equation. Choice C (3:2) and Choice D (3:4) are also incorrect as they do not represent the correct mole ratio of aluminum to oxygen according to the balanced chemical equation.
A 10 kg box rests on a frictionless surface. A horizontal force of 20 N is applied to the box. What is the box's acceleration?
- A. 0.5 m/s²
- B. 1 m/s²
- C. 2 m/s²
- D. 10 m/s²
Correct Answer: B
Rationale: The acceleration of an object is given by the formula \(a = \frac{F}{m}\), where \(F\) is the net force acting on the object and \(m\) is the mass of the object. In this case, the net force acting on the box is 20 N, and the mass of the box is 10 kg. Plugging these values into the formula, we get \(a = \frac{20}{10} = 2\) m/s².
What is the role of the appendix, a small pouch attached to the large intestine?
- A. To store waste products
- B. To produce immune cells
- C. To secrete digestive enzymes
- D. To regulate blood sugar levels
Correct Answer: B
Rationale: The appendix is a small pouch attached to the large intestine and is part of the lymphatic system. Its main function is to produce immune cells, particularly lymphocytes, which play a crucial role in fighting infections and maintaining gut health. Therefore, the correct answer is B. The appendix does not serve to store waste products (option A), secrete digestive enzymes (option C), or regulate blood sugar levels (option D).