Nokea
Which property remains constant despite possible changes to the element?
- A. Atomic number
- B. Number of electrons
- C. Atomic mass
- D. Isotopic form
Correct Answer: A
Rationale: The correct answer is 'Atomic number' (A). The atomic number of an element remains constant as it defines the number of protons in the nucleus, which does not change despite various chemical reactions or physical processes affecting the element. The number of protons in the nucleus determines the identity of the element, and this fundamental property remains unchanged even if the element undergoes chemical reactions, forms ions, or changes its physical state. Choices B, C, and D are incorrect because the number of electrons (B) can change in chemical reactions, atomic mass (C) can vary with isotopes, and isotopic form (D) refers to variations in the number of neutrons in the nucleus, which can result in different isotopes of an element.
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Which type of tissue provides support and structure to the body?
- A. Muscle tissue
- B. Connective tissue
- C. Nervous tissue
- D. Epithelial tissue
Correct Answer: B
Rationale: Connective tissue is the correct answer as it provides support, structure, and strength to the body by holding tissues and organs in place. Muscle tissue is primarily responsible for movement, nervous tissue for communication, and epithelial tissue for covering and lining surfaces. While muscle tissue allows for voluntary and involuntary movement, nervous tissue transmits electrical signals, and epithelial tissue acts as a protective barrier and is involved in absorption and secretion. Therefore, in the context of providing support and structure, connective tissue is the most appropriate choice.
Which of the following is NOT a major function of the respiratory system in humans?
- A. It provides a large surface area for gas exchange of oxygen and carbon dioxide.
- B. It helps regulate the blood's pH.
- C. It helps cushion the heart against jarring motions.
- D. It is responsible for vocalization.
Correct Answer: C
Rationale: Option C, 'It helps cushion the heart against jarring motions,' is NOT a major function of the respiratory system in humans. The primary functions of the respiratory system include gas exchange, regulation of blood pH, and vocalization. The respiratory system does not play a role in cushioning the heart; that function is primarily carried out by the pericardium and other protective structures around the heart. Choices A, B, and D are major functions of the respiratory system in humans. Choice A refers to the respiratory system's role in gas exchange, Choice B highlights its involvement in regulating blood pH, and Choice D points out its responsibility for vocalization.
With which genotype would the recessive phenotype appear if the dominant allele is marked with 'A' and the recessive allele is marked with 'a'?
- A. AA
- B. aa
- C. Aa
- D. aA
Correct Answer: B
Rationale: The recessive phenotype appears when an individual has two copies of the recessive allele. In this case, the recessive allele is marked with 'a.' Therefore, the genotype 'aa' would display the recessive phenotype as both alleles are recessive. Choice A (AA) has two dominant alleles, choice C (Aa) has one dominant and one recessive allele, and choice D (aA) represents the same genotype as Aa due to the principle of allele dominance.
Which hormone is produced by the pancreas to lower blood sugar levels?
- A. Glucagon
- B. Insulin
- C. Adrenaline
- D. Melatonin
Correct Answer: B
Rationale: The correct answer is B: Insulin. Insulin is produced by the pancreas and plays a crucial role in lowering blood sugar levels by promoting the uptake of glucose into cells for energy production or storage. Glucagon, which is also produced by the pancreas, functions to increase blood sugar levels by stimulating the release of stored glucose. Adrenaline, produced by the adrenal glands, is involved in the fight-or-flight response and does not directly regulate blood sugar levels. Melatonin, produced by the pineal gland, primarily regulates the sleep-wake cycle and is not involved in blood sugar level control.
Which of the following best describes the relationship among density, volume, and mass?
- A. As volume increases, density decreases.
- B. As volume decreases, density increases.
- C. An object's mass does not affect its density.
- D. As volume decreases, mass increases.
Correct Answer: B
Rationale: The correct answer is B: 'As volume decreases, density increases.' This is because density is defined as mass divided by volume. When volume decreases and mass remains constant, the ratio of mass to volume increases, leading to higher density. Choice A is incorrect because as volume increases, density typically remains constant or increases due to the mass also increasing. Choice C is incorrect because an object's density is directly influenced by its mass. Choice D is incorrect as decreasing volume does not lead to an increase in mass.