Nokea
Which statement is TRUE about valence electrons?
- A. They are located in the innermost electron shell.
- B. They have the highest binding energy to the nucleus.
- C. They are most likely to participate in chemical bonding.
- D. They have no influence on the element's chemical properties.
Correct Answer: C
Rationale: Valence electrons are the outermost electrons in an atom's electron cloud and are crucial in forming chemical bonds with other atoms. These electrons determine the reactivity and chemical properties of an element, making option C the correct statement. Option A is incorrect as valence electrons are found in the outer shell, not the innermost shell. Option B is incorrect because valence electrons have lower binding energy compared to inner electrons. Option D is incorrect since valence electrons play a significant role in an element's chemical behavior.
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Which of the following describes the difference between prokaryotic and eukaryotic cells?
- A. Prokaryotic cells have a nucleus, while eukaryotic cells don't.
- B. Eukaryotic cells are simpler in structure than prokaryotic cells.
- C. Prokaryotic cells have membrane-bound organelles, while eukaryotic cells don't.
- D. Eukaryotic cells have a true nucleus and membrane-bound organelles, while prokaryotic cells lack these.
Correct Answer: D
Rationale: Eukaryotic cells have a true nucleus that contains the genetic material, while prokaryotic cells lack a true nucleus. Eukaryotic cells also have membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus, which are absent in prokaryotic cells.
Which of the following is a strong acid?
- A. Acetic acid (CH₃COOH)
- B. Hydrochloric acid (HCl)
- C. Citric acid
- D. Carbonic acid (H₂CO₃)
Correct Answer: B
Rationale: Hydrochloric acid (HCl) is a strong acid because it completely ionizes in water to produce hydrogen ions, leading to a high concentration of H⺠ions in solution. This characteristic makes it a strong acid. Acetic acid (CH₃COOH), citric acid, and carbonic acid (H₂CO₃) are weak acids as they only partially ionize in water, resulting in a lower concentration of H⺠ions compared to strong acids. Therefore, hydrochloric acid is the correct choice as a strong acid.
Which blood vessels carry deoxygenated blood from the body back to the right atrium of the heart?
- A. Arteries
- B. Veins
- C. Capillaries
- D. Venules
Correct Answer: B
Rationale: Veins are the blood vessels that carry deoxygenated blood from the body back to the heart. Arteries transport oxygenated blood away from the heart. Capillaries are the smallest blood vessels where gas exchange occurs between blood and tissues. Venules are small veins that connect capillaries to larger veins, but they do not directly carry deoxygenated blood back to the heart.
Which term refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint?
- A. Isometric contraction
- B. Eccentric contraction
- C. Isotonic contraction
- D. Concentric contraction
Correct Answer: D
Rationale: Concentric contraction refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint. This type of contraction is commonly associated with the lifting phase of an exercise where the muscle is actively shortening against resistance. Isometric contraction (Choice A) involves muscle contraction without a change in muscle length, Eccentric contraction (Choice B) involves the muscle lengthening while generating force, and Isotonic contraction (Choice C) refers to muscle contraction against a constant load with a change in muscle length.
What is the scientific term for the monthly cycle in females that prepares the body for potential pregnancy?
- A. Ovulation cycle
- B. Menstrual cycle
- C. Implantation cycle
- D. Gestation cycle
Correct Answer: B
Rationale: The correct answer is B: Menstrual cycle. The menstrual cycle is the scientific term for the monthly cycle in females that prepares the body for potential pregnancy. This cycle involves various phases, including the release of an egg from the ovary (ovulation), thickening of the uterine lining in preparation for a fertilized egg, and shedding of the uterine lining if pregnancy does not occur (menstruation). Choices A, C, and D are incorrect. Option A, Ovulation cycle, only refers to the specific phase of egg release from the ovary. Option C, Implantation cycle, pertains to the process of the fertilized egg attaching to the uterine wall. Option D, Gestation cycle, denotes the period of fetal development during pregnancy, which is distinct from the monthly cycle preparing the body for potential pregnancy.