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What is the difference between polygenic inheritance and pleiotropy?
- A. Polygenic inheritance involves multiple genes influencing one trait, while pleiotropy involves one gene affecting multiple traits.
- B. Polygenic inheritance is found in simple Mendelian traits, while pleiotropy is found in complex traits.
- C. Polygenic inheritance is always quantitative, while pleiotropy can be qualitative or quantitative.
- D. Both involve multiple genes and multiple traits, but the specific mechanisms differ
Correct Answer: A
Rationale: - Polygenic inheritance refers to the situation where a trait is influenced by multiple genes, each contributing a small effect to the phenotype. These traits often show continuous variation and are not easily categorized into discrete categories.
- Pleiotropy, on the other hand, occurs when a single gene influences multiple, seemingly unrelated traits. This means that a mutation in one gene can lead to multiple phenotypic effects across different traits or characteristics.
- Therefore, the key difference between polygenic inheritance and pleiotropy lies in the number of genes involved in influencing a trait (multiple genes in polygenic inheritance vs. one gene in pleiotropy) and the direction of influence (one trait affected by multiple genes in polygenic inheritance vs. multiple traits affected by one gene in pleiotropy).
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Which of the following properties is characteristic of water?
- A. Water has a neutral pH.
- B. Water has a low specific heat capacity.
- C. Water has polar covalent bonds.
- D. Water can dissolve almost any solid, liquid, or gas.
Correct Answer: D
Rationale: The correct answer is D because water's polarity enables it to dissolve a wide variety of substances, making it a versatile solvent. This property is due to water's ability to form hydrogen bonds with other molecules, allowing it to break them apart and surround the solute particles, facilitating dissolution. Choices A, B, and C are incorrect as water having a neutral pH, a high specific heat capacity, and polar covalent bonds are also true properties of water. However, the most relevant property related to its versatility as a solvent is its dissolving capability.
Which organelle is responsible for controlling the activities of the cell?
- A. Golgi apparatus
- B. Mitochondria
- C. Nucleus
- D. Ribosomes
Correct Answer: C
Rationale: The nucleus is the organelle responsible for controlling the activities of the cell. It contains the cell's genetic material (DNA) and serves as the command center of the cell, regulating gene expression and directing cellular activities. The nucleus plays a crucial role in cell growth, metabolism, and reproduction. While the Golgi apparatus is involved in processing and packaging proteins, the mitochondria are responsible for producing energy in the form of ATP, and ribosomes are involved in protein synthesis, none of these organelles have the primary function of controlling the activities of the cell like the nucleus does. Therefore, the correct answer is the nucleus.
Which of the following organs is responsible for detoxifying chemicals and metabolizing drugs?
- A. Kidneys
- B. Liver
- C. Heart
- D. Pancreas
Correct Answer: B
Rationale: The correct answer is B: Liver. The liver plays a crucial role in detoxifying chemicals and metabolizing drugs. It also produces bile for digestion. The liver contains enzymes that help metabolize drugs and toxins, making them easier for the body to eliminate. The kidneys are primarily responsible for filtering blood and regulating fluid balance, the heart's main function is to pump blood, and the pancreas produces digestive enzymes and hormones like insulin, but they do not have the primary function of detoxifying chemicals and metabolizing drugs.
What step of the scientific method must come before generating a hypothesis?
- A. Collecting and organizing data.
- B. Communicating the results in a scientific journal.
- C. Conducting an experiment.
- D. Researching previous studies for background.
Correct Answer: D
Rationale: The correct answer is D, 'Researching previous studies for background.' Before formulating a hypothesis, it is essential to review existing literature, studies, and information related to the topic to understand the context and identify gaps in knowledge. This step helps researchers build on existing knowledge and formulate a clear hypothesis based on the information gathered. Choices A, B, and C are incorrect because they come after the step of researching previous studies and developing a hypothesis. Collecting and organizing data, conducting an experiment, and communicating results typically follow the hypothesis generation step in the scientific method.
What is the fundamental unit of the nervous system?
- A. Neuron
- B. Nerve
- C. Ganglion
- D. Neuroglia
Correct Answer: A
Rationale: The correct answer is A: Neuron. Neurons are the fundamental building blocks of the nervous system. These specialized cells play a crucial role in transmitting information through electrical and chemical signals. While nerves are comprised of bundles of neurons and ganglia consist of clusters of nerve cell bodies located outside the central nervous system, neuroglia serve as support cells for neurons. Neurons are specifically responsible for processing and transmitting information within the nervous system, making them the essential unit of this complex system. Choices B, C, and D are incorrect as nerves are bundles of neurons, ganglia are clusters of nerve cell bodies outside the central nervous system, and neuroglia are support cells for neurons, not the fundamental units responsible for information processing and transmission.