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Which of the following correctly describes mitosis?
- A. Mitosis occurs in germ cells.
- B. Mitosis occurs in somatic cells.
- C. Mitosis involves the reduction of chromosome number by half.
- D. Mitosis produces four genetically different cells.
Correct Answer: B
Rationale: The correct answer is B. Mitosis occurs in somatic cells where a single cell divides to produce two identical daughter cells. Germ cells undergo meiosis, not mitosis. Choice C is incorrect as mitosis results in the preservation of the same chromosome number in daughter cells. Choice D is inaccurate as mitosis produces genetically identical cells, not genetically different ones.
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Which muscle is voluntary, striated, and found attached to bones?
- A. Smooth muscle
- B. Skeletal muscle
- C. Cardiac muscle
- D. Epithelial muscle
Correct Answer: B
Rationale: The correct answer is B, Skeletal muscle. Skeletal muscle is both voluntary and striated, as well as attached to bones, allowing for movement. Smooth muscle, on the other hand, is involuntary and typically found in the walls of internal organs, controlling functions like digestion. Cardiac muscle is also striated, but it is involuntary and specifically found in the heart, responsible for cardiac contractions to pump blood. 'Epithelial muscle' is an incorrect term; epithelial tissue is a type of tissue that forms the linings of various body surfaces and structures, not a muscle type.
What macromolecules are proteins that speed up chemical reactions and act as biological catalysts?
- A. Lipids
- B. Enzymes
- C. Carbohydrates
- D. Nucleic acids
Correct Answer: B
Rationale: Enzymes are proteins that act as biological catalysts, speeding up chemical reactions without being consumed in the process. Lipids, carbohydrates, and nucleic acids do not serve as proteins that function as catalysts; they have different biological roles. Lipids are primarily used for energy storage, structural components, and signaling molecules. Carbohydrates are mainly for energy storage and providing structural support. Nucleic acids are involved in genetic information storage and transfer. Therefore, the correct answer is B: Enzymes.
Most catalysts found in biological systems are which of the following?
- A. Special lipids called cofactors.
- B. Special proteins called enzymes.
- C. Special lipids called enzymes.
- D. Special proteins called cofactors.
Correct Answer: B
Rationale: Enzymes are special proteins that act as catalysts in biological systems. They accelerate chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes play a critical role in the regulation of metabolic pathways and are essential for various biological processes. While some enzymes may require cofactors for activity, the enzymes themselves are the catalysts in biological systems. Therefore, choice B, special proteins called enzymes, is the most suitable answer. Choices A, C, and D are incorrect because enzymes, not lipids, are the primary catalysts in biological systems.
What is an electrically charged atom called?
- A. Ion
- B. Isotope
- C. Molecule
- D. Compound
Correct Answer: A
Rationale: An ion is an atom that has gained or lost electrons, resulting in a positive or negative charge, making it electrically charged. This term specifically refers to atoms with a net electrical charge. Isotopes are atoms of the same element with different numbers of neutrons, not electrically charged. Molecules are formed when atoms bond together, but they are not necessarily charged. Compounds are substances composed of different elements bonded together, but they may not be electrically charged.
What is the role of enzymes in the body?
- A. To transport oxygen
- B. To speed up chemical reactions
- C. To regulate body temperature
- D. To store energy
Correct Answer: B
Rationale: Enzymes act as biological catalysts that speed up chemical reactions in the body. They lower the activation energy required for reactions to occur, thus facilitating processes like digestion, metabolism, and other essential functions. Choice A is incorrect as the transportation of oxygen is primarily carried out by red blood cells. Choice C is incorrect as the regulation of body temperature involves mechanisms such as sweating and shivering. Choice D is incorrect as energy storage is mainly performed by molecules like glycogen and triglycerides.