Nokea
What is the cellular function of cilia and flagella?
- A. Cilia and flagella are responsible for cell movement.
- B. Cilia and flagella synthesize proteins.
- C. Cilia and flagella help protect the cell from its environment.
- D. Cilia and flagella have enzymes that help with digestion.
Correct Answer: A
Rationale: The correct answer is A: Cilia and flagella are responsible for cell movement. Cilia and flagella are specialized structures found on the surface of many types of cells. They are involved in the movement of the cell itself or in moving substances around the cell. This movement helps in various functions such as propulsion, moving fluids, and sensing the environment. Choices B, C, and D are incorrect. Cilia and flagella are not involved in synthesizing proteins, protecting the cell from its environment, or aiding in digestion. Their primary function is related to cell movement and cellular transport.
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Two isotopes of the same element have different numbers of:
- A. Electrons
- B. Protons
- C. Neutrons
- D. Nuclei
Correct Answer: C
Rationale: The correct answer is C: 'Neutrons.' Isotopes are variants of an element that have the same number of protons and electrons but differ in the number of neutrons they contain. This difference in neutron count is what distinguishes isotopes from each other while maintaining the same chemical properties. Choice A, 'Electrons,' is incorrect because isotopes of the same element have the same number of electrons. Choice B, 'Protons,' is incorrect because isotopes of the same element have the same number of protons. Choice D, 'Nuclei,' is incorrect as nuclei refer to the central part of an atom containing protons and neutrons, and the question specifically asks about differences between isotopes of the same element.
Which of the following best describes one of the roles of RNA?
- A. Manufacturing the proteins needed from DNA
- B. Creating the bonds between the elements that make up DNA
- C. Sending messages about the correct sequence of proteins in DNA
- D. Forming the identifiable double helix shape of DNA
Correct Answer: C
Rationale: The correct answer is C. RNA serves as a messenger that carries instructions from DNA for protein synthesis. It does not manufacture proteins directly from DNA (choice A), create bonds within DNA (choice B), or form the double helix structure of DNA (choice D). Therefore, the primary role of RNA is to convey information about the correct sequence of proteins to be synthesized based on the DNA sequences it receives.
Which statement most accurately compares and contrasts the structures of DNA and RNA?
- A. Both DNA and RNA have 4 nucleotide bases. Three of the bases are the same, but the fourth base is thymine in DNA and uracil in RNA.
- B. Both DNA and RNA have the same 4 nucleotide bases. However, the nucleotides bond differently in DNA compared to RNA.
- C. Both DNA and RNA have different numbers of nucleotide bases. DNA is a double helix while RNA is a single strand.
- D. Both DNA and RNA have a double helix structure. However, DNA contains 6 nucleotide bases and RNA contains 4 nucleotide bases.
Correct Answer: A
Rationale: The correct answer is A because DNA and RNA both consist of 4 nucleotide bases, namely adenine, cytosine, and guanine, which are common in both. The key difference lies in the fourth base, which is thymine in DNA and uracil in RNA. This distinction is fundamental in understanding the structural variances between DNA and RNA. Choice B is incorrect as it incorrectly states that the nucleotides bond differently in DNA compared to RNA without specifying the crucial base differences. Choice C is inaccurate as it misrepresents the numbers of nucleotide bases in DNA and RNA, and incorrectly describes DNA as a double helix and RNA as a single strand, which is not related to the difference in bases. Choice D is incorrect as it inaccurately portrays DNA with 6 nucleotide bases and RNA with 4, which is not true; both DNA and RNA have 4 nucleotide bases, but with differences in one of the bases.
Which structure controls the hormones secreted by the pituitary gland?
- A. Hypothalamus
- B. Adrenal gland
- C. Testes
- D. Pancreas
Correct Answer: A
Rationale: The correct answer is A: Hypothalamus. The hypothalamus controls the release of hormones from the pituitary gland. It acts as a master regulator of the endocrine system by producing releasing and inhibiting hormones that influence the secretion of hormones from the pituitary gland. Choice B, the Adrenal gland, is incorrect because while it plays a role in hormone production, it is not responsible for controlling the pituitary gland's hormones. Choice C, the Testes, and Choice D, the Pancreas, are also incorrect as they are not directly involved in controlling the hormones secreted by the pituitary gland.
Based on the following evidence, what is the most likely reason that spoiled food left out in the open often contains fly larvae?
- A. The spoiled food evolves into fly larvae.
- B. Since the food is left out in the open, flies lay eggs in the food.
- C. Fly larvae are spontaneously generated by the spoiled food.
- D. People only imagine they see fly larvae in the spoiled food.
Correct Answer: B
Rationale: The correct answer is B. Flies laying eggs in the food when it is left exposed to the air is a common occurrence and a logical explanation for the presence of fly larvae in spoiled food. Choice A is incorrect as food cannot evolve into fly larvae; fly larvae come from eggs laid by flies. Choice C is incorrect as fly larvae do not spontaneously generate from spoiled food but rather develop from eggs laid by flies. Choice D is incorrect as the presence of fly larvae in spoiled food is a real phenomenon, not merely imagined by people.