Nokea
How much sugar is in a 1 M solution of sugar water?
- A. 1 L of water
- B. 100 mL of solution
- C. Every 100 g of water
- D. It depends on the type of sugar
Correct Answer: B
Rationale: A 1 M solution of sugar water contains 1 mole of sugar in 1 liter of solution. Since 1 M (molar) solution means there is 1 mole of solute (sugar) dissolved in 1 liter of solvent (water), the correct answer is 100 mL of solution. Choice A, '1 L of water,' is incorrect because it does not specify the total volume of the solution. Choice C, 'Every 100 g of water,' is incorrect as it focuses on the weight of water, not the volume of the solution. Choice D, 'It depends on the type of sugar,' is incorrect since the concentration of a 1 M solution is standardized and does not vary based on the type of sugar used.
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Balance the chemical equation: C4H10 + O2 → CO2 + H2O. What is the coefficient for oxygen?
- A. 5
- B. 6
- C. 7
- D. 8
Correct Answer: B
Rationale: To balance the chemical equation, we need to ensure that the number of each type of atom is the same on both sides of the equation. In this case, there are 10 oxygen atoms on the right side (5 in CO2 and 5 in H2O). To balance this, we need to add a coefficient of 6 in front of O2 on the left side, resulting in 6 O2 molecules. This change will give us a total of 12 oxygen atoms on both sides, making the equation balanced. Choice A (5) is incorrect because it does not account for all the oxygen atoms present in the products. Choices C (7) and D (8) are incorrect as they would result in an imbalance in the number of oxygen atoms on both sides of the equation.
Which type of white blood cell directly attacks and destroys pathogens like bacteria and viruses?
- A. Neutrophils
- B. Lymphocytes
- C. Monocytes
- D. Eosinophils
Correct Answer: A
Rationale: Neutrophils are a type of white blood cell that plays a crucial role in the immune system's response to infections. They are phagocytes, meaning they engulf and destroy pathogens like bacteria and viruses. Neutrophils are the most abundant type of white blood cell and are known for their rapid response to infections, making them the primary cell type that directly attacks and destroys pathogens. Lymphocytes, although important in adaptive immunity, are not primarily responsible for directly attacking and destroying pathogens. Monocytes are involved in phagocytosis and immune response regulation but are not the primary cell type for direct pathogen destruction like neutrophils. Eosinophils are mainly involved in combating multicellular parasites and are not the primary cell type for targeting bacteria and viruses.
Which part of the respiratory system is responsible for gas exchange between the blood and inhaled air?
- A. Trachea
- B. Larynx
- C. Alveoli
- D. Pharynx
Correct Answer: C
Rationale: The correct answer is C, Alveoli. The alveoli are tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place between the air we breathe in and the blood. The trachea, larynx, and pharynx are all part of the airway passage but do not directly participate in gas exchange. The trachea serves as the windpipe, the larynx is involved in sound production and protecting the airway during swallowing, and the pharynx helps with swallowing and speech production. Therefore, the alveoli specifically facilitate the critical gas exchange process, making them the correct answer in this context.
What is the function of ribosomes?
- A. Packaging and transporting proteins
- B. Storing genetic material
- C. Controlling cell division
- D. Synthesizing proteins
Correct Answer: D
Rationale: The correct answer is D: Synthesizing proteins. Ribosomes are cellular organelles responsible for protein synthesis. They read the messenger RNA (mRNA) and utilize the information to assemble amino acids into proteins through a process known as translation. Choice A, packaging and transporting proteins, is incorrect as this function is typically performed by the Golgi apparatus and vesicles. Choice B, storing genetic material, is incorrect as genetic material is usually stored in the nucleus in the form of DNA. Choice C, controlling cell division, is incorrect as this function is primarily regulated by the cell cycle checkpoints and specific proteins involved in cell cycle regulation.
What is the primary function of the myelin sheath that surrounds some axons in the nervous system?
- A. To initiate nerve impulses
- B. To transmit sensory information
- C. To speed up the transmission of nerve impulses
- D. To connect neurons at synapses
Correct Answer: C
Rationale: The primary function of the myelin sheath is to speed up the transmission of nerve impulses. The myelin sheath acts as an insulating layer around the axon, allowing for faster conduction of electrical impulses along the nerve fiber. This insulation prevents the electrical signal from dissipating or 'leaking' out, which helps in the rapid and efficient transmission of nerve impulses along the axon. Choice A is incorrect because the myelin sheath does not initiate nerve impulses; it helps in conducting them. Choice B is incorrect as the myelin sheath's main role is not in transmitting sensory information but rather in facilitating the transmission of nerve impulses. Choice D is incorrect because the myelin sheath's function is not to connect neurons at synapses; instead, it is primarily involved in enhancing the speed of nerve impulse transmission.