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What causes dandruff?
- A. Excessive sebum production (This can contribute to oily dandruff)
- B. Bacterial infection (This can cause scalp folliculitis, not dandruff)
- C. Overgrowth of a specific type of fungus on the scalp
- D. Lack of proper skin hydration
Correct Answer: C
Rationale: Dandruff is primarily caused by an overgrowth of a specific type of fungus called Malassezia on the scalp. This fungus feeds on the natural oils produced by the hair follicles, leading to irritation and flaking of the scalp skin. Choice A is incorrect because excessive sebum production can contribute to oily dandruff, but it is not the primary cause of dandruff. Choice B is incorrect as bacterial infection primarily causes scalp folliculitis, not dandruff. Choice D is incorrect as dandruff is not primarily caused by a lack of proper skin hydration.
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Which of Mendel's Laws states that alleles for a gene segregate during gamete formation?
- A. Law of Independent Assortment
- B. Law of Segregation
- C. Law of Dominance
- D. Law of Probability
Correct Answer: B
Rationale: The Law of Segregation, proposed by Gregor Mendel, states that alleles for a gene segregate during gamete formation. This means that each parent passes on only one allele for each gene to their offspring. This law explains how genetic diversity is maintained and how different combinations of alleles are generated in offspring. The Law of Independent Assortment (option A) is not the correct answer as it states that alleles of different genes assort independently of each other during gamete formation, not specifically alleles of a single gene. The Law of Dominance (option C) is incorrect as it pertains to the expression of alleles rather than their segregation during gamete formation. The Law of Probability (option D) is also incorrect as it is a general concept describing the likelihood of events, not specifically related to alleles segregating during gamete formation.
What type of reaction is represented by the following equation: Fe2O3 (s) + 3H2 (g) -> 2Fe (s) + 3H2O (g)?
- A. Combustion
- B. Decomposition
- C. Single displacement
- D. Redox reaction
Correct Answer: C
Rationale: The correct answer is C: Single displacement. This reaction is a single displacement reaction because the iron (Fe) in Fe2O3 is displaced by the hydrogen (H) in H2 to form Fe and H2O. In single displacement reactions, one element replaces another in a compound. Choice A, Combustion, involves a reaction with oxygen typically producing heat, light, and often a flame. Choice B, Decomposition, is when a compound breaks down into simpler substances. Choice D, Redox reaction, involves both reduction and oxidation reactions happening simultaneously, which is not the case in the provided equation.
Scientists compare the DNA of different organisms to understand evolutionary relationships. What is this type of evidence called?
- A. Morphological evidence (comparing body structures)
- B. Biochemical evidence (comparing molecules like proteins)
- C. Geographic distribution evidence (where organisms live)
- D. Genetic evidence (comparing DNA sequences)
Correct Answer: D
Rationale: A) Morphological evidence involves comparing body structures of organisms, which can provide information about evolutionary relationships based on physical similarities and differences. However, DNA comparison is a more direct and accurate method for understanding evolutionary relationships.
B) Biochemical evidence involves comparing molecules like proteins, which can also provide insights into evolutionary relationships. However, DNA comparison is considered more reliable due to the direct relationship between DNA sequences and genetic information.
C) Geographic distribution evidence refers to where organisms live and how their distribution may provide clues about evolutionary history. While this can be informative, it is not as direct or specific as comparing DNA sequences.
D) Genetic evidence involves comparing DNA sequences of different organisms to understand their evolutionary relationships. DNA comparison is a powerful tool in evolutionary biology because it provides direct information about genetic similarities and differences, offering precise insights into evolutionary relationships.
What is the relationship between work and energy?
- A. Work is the rate of energy transfer
- B. Work and energy are the same concepts
- C. Work is the result of energy
- D. Work changes an object's energy from one form to another
Correct Answer: A
Rationale: Work is defined as the transfer of energy from one system to another. It is the rate at which energy is transferred or converted. Therefore, work is the rate of energy transfer, making option A the correct choice. Work involves the transfer or conversion of energy, but it is not the same as energy itself, nor is it the result of energy. Additionally, work does not change an object's energy from one form to another; instead, it involves the transfer of energy.
What is the scientific term for the windpipe, a tube that carries air from the larynx to the bronchi?
- A. Pharynx
- B. Trachea
- C. Epiglottis
- D. Bronchiole
Correct Answer: B
Rationale: The trachea is the correct scientific term for the windpipe, a tube that carries air from the larynx to the bronchi. It is an essential part of the respiratory system, enabling the passage of air to and from the lungs. The pharynx is the region behind the mouth and nasal cavity, acting as a passageway for air and food. The epiglottis is a cartilage flap that shields the trachea during swallowing to prevent food from entering the airway. Bronchioles are smaller airways that branch off from the bronchi within the lungs, further dividing and distributing air within the lungs.