Nokea
What is the process of cell division in somatic (most body) cells called?
- A. Mitosis
- B. Meiosis
- C. Respiration
- D. Cytogenesis
Correct Answer: A
Rationale: Mitosis is the correct answer. It is the process of cell division in somatic cells, leading to the formation of two identical daughter cells with the same number of chromosomes as the parent cell. Meiosis, on the other hand, is the type of cell division that occurs in sex cells, leading to the formation of gametes with half the number of chromosomes. Respiration is a completely different biological process related to energy production, and cytogenesis is not a recognized term for cell division.
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Which level of protein structure is defined by the folds and coils of the protein's polypeptide backbone?
- A. Primary
- B. Secondary
- C. Tertiary
- D. Quaternary
Correct Answer: B
Rationale: The correct answer is B: Secondary. The secondary structure of a protein is defined by the folds and coils of the protein's polypeptide backbone. This level of structure is characterized by the formation of alpha helices and beta sheets, which are stabilized by hydrogen bonds between amino acids along the polypeptide chain. Choice A, Primary, refers to the linear sequence of amino acids in the protein. Choice C, Tertiary, involves the 3D folding of the entire polypeptide chain. Choice D, Quaternary, pertains to the arrangement of multiple polypeptide subunits in a protein complex.
Which of the following best defines the term amphoteric?
- A. A substance that conducts electricity due to ionization when dissolved in a solvent
- B. A substance that can act as an acid or a base depending on the properties of the solute
- C. A substance that, according to the Br¸nsted-Lowry Acid-Base Theory, is a proton-donor
- D. A substance that donates its proton and forms its conjugate base in a neutralization reaction
Correct Answer: B
Rationale: An amphoteric substance can act as both an acid or a base depending on the environment. It can donate a proton (act as an acid) or accept a proton (act as a base), showing versatility in its behavior. Choice A is incorrect as it describes an electrolyte rather than an amphoteric substance. Choice C is incorrect as it defines an acid based on the Br¸nsted-Lowry Acid-Base Theory. Choice D is incorrect as it specifically refers to a substance donating a proton in a neutralization reaction, not capturing the dual behavior of an amphoteric substance.
Which types of molecules can move through a cell membrane by passive transport?
- A. Complex sugars
- B. Non-lipid soluble molecules
- C. Oxygen
- D. Molecules moving from areas of low concentration to areas of high concentration
Correct Answer: C
Rationale: The correct answer is C: Oxygen. Small, non-polar molecules like oxygen can easily pass through the cell membrane by passive transport as they move down their concentration gradient without the need for energy input. Complex sugars (choice A) are typically too large to pass through the membrane by passive transport. Non-lipid soluble molecules (choice B) may require active transport mechanisms. Choice D describes active transport, where molecules move against their concentration gradient, requiring energy input.
Which of the following correctly lists the four properties that all types of muscle tissue share?
- A. Contractile, excitable, elastic, extensible
- B. Contractile, voluntary, elastic, extensible
- C. Contractile, excitable, voluntary, extensible
- D. Contractile, excitable, elastic, voluntary
Correct Answer: A
Rationale: The correct answer is A: 'Contractile, excitable, elastic, extensible.' All types of muscle tissue share these four properties. Muscle tissue can contract, respond to stimuli, stretch and return to its original shape (elastic), and extend or stretch (extensible). Choice B is incorrect because not all muscle tissues are voluntary (some are involuntary). Choice C is incorrect because not all muscle tissues are voluntary. Choice D is incorrect because not all muscle tissues are voluntary and lack the elastic property.
The acceleration of a falling object due to gravity has been proven to be 9.8 m/s^2. A scientist drops a cactus four times and measures the acceleration with an accelerometer and gets the following results: 9.79 m/s^2, 9.81 m/s^2, 9.80 m/s^2, and 9.78 m/s^2. Which of the following accurately describes the measurements?
- A. They're both accurate and precise.
- B. They're accurate but not precise.
- C. They're precise but not accurate.
- D. They're neither accurate nor precise.
Correct Answer: A
Rationale: The measurements are close to the true value of 9.8 m/s^2 and are also close to each other, indicating both accuracy and precision. Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other. In this case, the measurements are accurate because they are close to the accepted value of 9.8 m/s^2, and they are precise because they are clustered closely around each other. Therefore, choice A, 'They're both accurate and precise,' is the correct answer. Choice B is incorrect because the measurements are precise as they are close to each other, but they are also accurate as they are close to the true value. Choice C is incorrect because the measurements are accurate as they are close to the true value, and choice D is incorrect because the measurements exhibit both accuracy and precision in this scenario.