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What is a temporary loss of consciousness due to insufficient blood flow to the brain called?
- A. Stroke
- B. Seizure
- C. Syncope (fainting)
- D. Coma
Correct Answer: C
Rationale: Syncope, also known as fainting, is a temporary loss of consciousness caused by insufficient blood flow to the brain. It results from a brief interruption in the brain's blood supply, leading to a temporary loss of consciousness. The correct answer is C. A stroke, option A, is caused by a blockage or rupture of blood vessels in the brain, not insufficient blood flow. Seizure, option B, involves a sudden surge of electrical brain activity, not reduced blood flow. Coma, option D, is characterized by prolonged unconsciousness, not a temporary loss of consciousness due to insufficient blood flow.
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What is the significance of studying pedigrees in human genetics?
- A. Predicting the exact outcome of genetic crosses in humans.
- B. Tracing the inheritance of complex traits with multiple contributing genes.
- C. Identifying carriers of dominant genetic disorders.
- D. Determining the risk of acquiring a specific mutation de novo.
Correct Answer: B
Rationale: Pedigrees are diagrams that show the relationships within a family and can be used to track the inheritance patterns of specific traits or diseases. While pedigrees can provide information on the inheritance of single gene disorders (such as identifying carriers of dominant genetic disorders, as mentioned in option C), their primary significance lies in studying complex traits with multiple contributing genes. These traits do not follow simple Mendelian inheritance patterns and are influenced by both genetic and environmental factors. By analyzing pedigrees, researchers can identify patterns of inheritance for complex traits, such as polygenic diseases or traits influenced by gene-environment interactions. Therefore, option B is the most appropriate choice as it captures the main significance of studying pedigrees in human genetics.
Which of the following is the neutral subatomic particle found in the nucleus of an atom?
- A. Electron
- B. Proton
- C. Neutron
- D. Positron
Correct Answer: C
Rationale: The correct answer is C, Neutron. Neutrons are subatomic particles found in the nucleus of an atom that have no charge. They have a mass of approximately 1 atomic mass unit (amu). The number of neutrons in an atom's nucleus contributes to the mass number of the atom, which is the total number of protons and neutrons in the nucleus. Choice A, Electron, is incorrect as electrons are negatively charged particles found outside the nucleus. Choice B, Proton, is incorrect as protons are positively charged particles found in the nucleus. Choice D, Positron, is incorrect as positrons are positively charged antiparticles of electrons and are not typically found in the nucleus of an atom.
What is the process of removing waste products from the cell called?
- A. Exocytosis
- B. Endocytosis
- C. Phagocytosis
- D. Pinocytosis
Correct Answer: A
Rationale: A) Exocytosis is the process by which cells expel waste products or other substances by fusing a vesicle containing the waste with the cell membrane, releasing its contents outside the cell. This process is essential for maintaining cellular homeostasis by removing waste products from the cell.
B) Endocytosis is the process by which cells take in substances by engulfing them in a vesicle formed from the cell membrane. This process is the opposite of exocytosis and is used to bring substances into the cell.
C) Phagocytosis is a type of endocytosis where cells engulf solid particles or other cells to form a vesicle called a phagosome. This process is used by immune cells to engulf and destroy pathogens.
D) Pinocytosis is a type of endocytosis where cells engulf fluids and dissolved solutes. This process allows cells to take in nutrients.
What is the function of ribosomal RNA (rRNA)?
- A. Carries amino acids to the ribosomes
- B. Reads the genetic code on mRNA
- C. Forms the structural framework of ribosomes
- D. Controls the rate of protein synthesis
Correct Answer: C
Rationale: Ribosomal RNA (rRNA) plays a crucial role in forming the structural framework of ribosomes. Ribosomes are the cellular organelles responsible for protein synthesis and consist of both protein and rRNA components. The primary function of rRNA is to provide the structural support necessary for ribosomes to function properly. This structural framework allows the ribosome to interact with messenger RNA (mRNA) and transfer RNA (tRNA) during translation, where genetic information encoded in mRNA is used to assemble proteins from amino acids. Therefore, rRNA's main role is in contributing to the structure and function of ribosomes, rather than directly carrying amino acids, reading the genetic code, or controlling the rate of protein synthesis. Choices A, B, and D are incorrect because rRNA does not carry amino acids to the ribosomes (tRNA does this), read the genetic code (this is the role of ribosomes and tRNA), or control the rate of protein synthesis (this is regulated by various factors but not directly by rRNA).
What is the balanced chemical equation for the reaction between sodium and chlorine to form sodium chloride?
- A. Na + Cl2 -> NaCl
- B. 2Na + Cl2 -> 2NaCl
- C. Na2 + Cl -> 2NaCl
- D. Na + 2Cl -> NaCl2
Correct Answer: B
Rationale: In a balanced chemical equation, the number of atoms of each element must be the same on both sides of the equation. When sodium (Na) reacts with chlorine (Cl2) to form sodium chloride (NaCl), we need to ensure the equation is balanced. There are 2 chlorine atoms in Cl2; hence, we need 2 sodium atoms on the left side to balance it. Therefore, the balanced chemical equation is 2Na + Cl2 -> 2NaCl. Choice A is incorrect because it does not have the correct coefficients to balance the equation. Choice C is incorrect as it incorrectly represents the formula of sodium. Choice D is incorrect as it forms NaCl2, which is not the correct compound formed in this reaction.