Nokea
Which of the following is the positively charged subatomic particle found in the nucleus of an atom?
- A. Electron
- B. Proton
- C. Neutron
- D. Quark
Correct Answer: B
Rationale: The correct answer is B: Proton. Protons are positively charged subatomic particles found in the nucleus of an atom. They have a mass of approximately 1 atomic mass unit (amu) and a charge of +1. The number of protons in an atom's nucleus determines the atomic number of the element, which is a unique identifier for each element. Choice A, Electron, is incorrect as electrons are negatively charged particles found outside the nucleus. Choice C, Neutron, is incorrect as neutrons are neutral particles found in the nucleus. Choice D, Quark, is incorrect as quarks are elementary particles that combine to form protons and neutrons, but they are not the positively charged particle found in the nucleus of an atom.
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Which of the following is NOT a recognized mode of natural selection?
- A. Directional selection (favoring one extreme trait value on a spectrum)
- B. Disruptive selection (favoring both extreme trait values on a spectrum)
- C. Stabilizing selection (favoring the average trait value on a spectrum)
- D. Sexual selection (selection based on mate choice that influences reproductive success)
Correct Answer: D
Rationale: A) Directional selection is a recognized mode of natural selection where one extreme trait value on a spectrum is favored over others, leading to a shift in the average trait value over time. B) Disruptive selection is a recognized mode of natural selection where both extreme trait values on a spectrum are favored over the average trait value, potentially causing the population to split into distinct groups. C) Stabilizing selection is a recognized mode of natural selection favoring the average trait value on a spectrum over extreme values, resulting in reduced genetic diversity. D) Sexual selection differs from traditional natural selection modes as it involves mate choice and competition for mates, not direct selection pressure on traits affecting survival and reproduction in the environment. Sexual selection can drive the evolution of traits enhancing an individual's attractiveness for mating purposes.
Identify the INCORRECT function of the liver.
- A. Bile production to aid digestion.
- B. Synthesis of blood proteins, such as albumin.
- C. Storage of glucose for energy regulation.
- D. Filtration of waste products from the blood.
Correct Answer: D
Rationale: A) Correct - The liver produces bile, which aids in the digestion and absorption of fats in the small intestine.
B) Correct - The liver is responsible for synthesizing blood proteins, including albumin, which helps maintain osmotic pressure in the blood.
C) Correct - The liver stores glucose in the form of glycogen and helps regulate blood sugar levels by releasing glucose when needed.
D) Incorrect - The liver does not filter waste products from the blood. Instead, the kidneys are responsible for filtering waste products from the blood and excreting them in the form of urine.
What is the product of the complete combustion of propane (C3H8)?
- A. CO2
- B. CO
- C. CH4
- D. C
Correct Answer: A
Rationale: The complete combustion of propane (C3H8) results in the production of carbon dioxide (CO2) and water. When a hydrocarbon such as propane undergoes complete combustion, the carbon atoms combine with oxygen to form CO2. This makes choice A, CO2, the correct answer. Choices B, C, and D are incorrect as CO is carbon monoxide, CH4 is methane, and C is elemental carbon, none of which are the primary product of the complete combustion of propane.
Identify the spectator ions in the reaction: 2KCl + Pb(NO3)2 → 2KNO3 + PbCl2.
- A. K+ and NO3-
- B. K+ and Cl-
- C. Pb2+ and NO3-
- D. Pb2+ and Cl-
Correct Answer: B
Rationale: - In the reaction, potassium ions (K+) and chloride ions (Cl-) are present on both sides of the equation. They are not involved in the formation of the products and remain unchanged.
- Lead ions (Pb2+) and nitrate ions (NO3-) are involved in the formation of the products potassium nitrate (KNO3) and lead(II) chloride (PbCl2).
- Therefore, the spectator ions in this reaction are K+ and Cl-.
Which hormone, produced by the pancreas, regulates blood sugar levels by promoting the uptake of glucose into cells?
- A. Insulin
- B. Glucagon
- C. Cortisol
- D. Thyroxine
Correct Answer: A
Rationale: Insulin is the correct answer. It is produced by the pancreas and plays a crucial role in regulating blood sugar levels by facilitating the absorption of glucose into cells. When blood sugar levels are elevated, insulin is released to help cells utilize glucose for energy or store it for future use. Glucagon, choice B, is produced by the pancreas as well but has the opposite effect of raising blood sugar levels by releasing stored glucose into the bloodstream. Cortisol, choice C, is a hormone produced by the adrenal glands that is involved in the stress response and metabolism, not specifically in regulating blood sugar levels. Thyroxine, choice D, is a hormone produced by the thyroid gland that regulates metabolism but is not directly involved in the uptake of glucose into cells.