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What is glucagon, where is it produced, and what is its function?
- A. Produced in the liver, releases glucose
- B. Produced in the pancreas, raises blood sugar
- C. Produced in the pancreas, lowers blood sugar
- D. Produced in the adrenal glands, regulates stress response
Correct Answer: B
Rationale: Glucagon is a hormone produced in the pancreas and functions to raise blood sugar levels. It does so by signaling the liver to release stored glucose into the bloodstream. Therefore, the correct answer is B, 'Produced in the pancreas, raises blood sugar.' Choices A, C, and D describe functions or locations of other hormones, not glucagon. Glucagon is specifically released by alpha cells in the pancreas, making option B the correct choice.
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What is the basic structure of an atom?
- A. Protons, neutrons, electrons
- B. Protons, electrons, ions
- C. Neutrons, electrons, ions
- D. Protons, ions, molecules
Correct Answer: A
Rationale: The basic structure of an atom consists of protons and neutrons located in the nucleus, with electrons orbiting around the nucleus in specific energy levels or shells. Protons carry a positive charge, neutrons carry no charge, and electrons carry a negative charge. This arrangement maintains the overall neutrality of the atom, with the number of protons equaling the number of electrons. Therefore, the correct answer is 'Protons, neutrons, electrons.' Choices B, C, and D are incorrect as they do not accurately represent the fundamental components of an atom. Choice B includes 'ions,' which are charged particles, not fundamental components of an atom. Choice C includes 'ions' and lacks protons. Choice D includes 'ions' and 'molecules,' which are not part of the basic structure of an atom.
Which of the following best describes eosinophils?
- A. A type of granulocyte that secretes histamine to stimulate the inflammatory response.
- B. The most abundant type of white blood cell that secretes substances toxic to pathogens.
- C. A type of granulocyte found under mucous membranes that defends against multicellular parasites.
- D. A circulating granulocyte with high phagocytic activity and aggressiveness.
Correct Answer: C
Rationale: Eosinophils are best described as a type of granulocyte found under mucous membranes that defends against multicellular parasites. They release toxic substances to combat parasitic infections and play a significant role in allergic reactions and asthma. Histamine secretion to stimulate inflammation is more characteristic of basophils, while high phagocytic activity and aggressiveness are features of neutrophils, not eosinophils. Describing eosinophils as the most abundant type of white blood cell that secretes toxic substances to pathogens is inaccurate since eosinophils specifically target multicellular parasites, not a broad range of pathogens.
Which of the following is unique to covalent bonds?
- A. Most covalent bonds are formed between the elements H, F, N, and O.
- B. Covalent bonds are dependent on forming dipoles.
- C. Bonding electrons are shared between two or more atoms.
- D. Molecules with covalent bonds tend to have a crystalline solid structure.
Correct Answer: C
Rationale: The correct answer is C: 'Bonding electrons are shared between two or more atoms.' This statement is unique to covalent bonds. In covalent bonds, atoms share electrons to achieve a stable electron configuration, which leads to the formation of a bond. This sharing of electrons is a fundamental characteristic of covalent bonds and distinguishes them from other types of chemical bonds, such as ionic bonds, where electrons are transferred rather than shared. Choices A, B, and D do not represent unique characteristics of covalent bonds. Choice A describes some common elements involved in covalent bonds, choice B refers to the concept of dipoles, which can also exist in other types of bonds, and choice D describes a property of molecules (crystalline solid structure) that is not exclusive to covalent bonds.
Which of the following is LEAST likely to be found in a human cell's genes?
- A. Sequences of amino acids to be transcribed into mRNA
- B. Lethal recessive traits like sickle cell anemia
- C. Mutated DNA
- D. DNA that codes for proteins the cell doesn't use
Correct Answer: D
Rationale: Human cells typically contain genes that code for proteins necessary for the cell's functions. DNA that codes for proteins the cell doesn't use would be an inefficient use of the cell's resources. Therefore, it is less likely to be found in a human cell's genes. Options A, B, and C are more commonly associated with genes found in human cells. Choice A refers to the genetic information needed for protein synthesis, while choice B involves traits that can be present in the gene pool. Mutated DNA (choice C) can also be found in human cells as a result of genetic alterations. However, DNA that codes for proteins not utilized by the cell would be redundant and not typically retained in the genome.
Which muscle has involuntary cells that are branched and striated and connected by intercalated discs with gap junctions?
- A. Smooth muscle
- B. Cardiac muscle
- C. Skeletal muscle
- D. Epithelial muscle
Correct Answer: B
Rationale: The correct answer is B: Cardiac muscle. Cardiac muscle cells fit the description provided in the question; they are involuntary, striated, and branched, with intercalated discs containing gap junctions that allow for synchronized contractions of the heart. Smooth muscle (choice A) lacks striations and is found in the walls of internal organs. Skeletal muscle (choice C) is voluntary and attaches to bones for movement. 'Epithelial muscle' (choice D) is not a valid muscle type, making it an incorrect choice.