Which type of mutation involves a change in the number of chromosomes?

Correct Answer: D

Rationale: A) Point mutation involves a change in a single nucleotide base pair within the DNA sequence. B) Frameshift mutation involves the insertion or deletion of nucleotides, causing a shift in the reading frame of the genetic code. C) Missense mutation involves a single nucleotide change that results in a codon that codes for a different amino acid. D) Aneuploidy involves a change in the number of chromosomes, where an individual may have an extra chromosome (trisomy) or a missing chromosome (monosomy). Aneuploidy can lead to genetic disorders such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X). Changing the number of chromosomes is a characteristic feature of aneuploidy, making it the correct answer. Point mutation, frameshift mutation, and missense mutation do not involve a change in the number of chromosomes and are focused on alterations at the nucleotide level within the DNA sequence.

Correct Answer: D

Rationale: A) Appendicitis is inflammation of the appendix, not the small intestine. B) Celiac disease is an autoimmune disorder triggered by gluten consumption that damages the small intestine, but it is not characterized by inflammation alone. C) Gastritis is inflammation of the stomach lining, not the small intestine. D) Crohn's disease is a chronic inflammatory condition that can affect any part of the gastrointestinal tract, but it commonly involves the small intestine. Symptoms of Crohn's disease include abdominal pain, diarrhea, weight loss, and fatigue.

Correct Answer: B

Rationale: When ice melts, it undergoes a physical change, transitioning from a solid state to a liquid state. This change does not involve altering the chemical composition of the ice, making it a physical change rather than a chemical change, nuclear change, or radioactive decay. Choice A, 'Chemical change,' is incorrect because a chemical change involves a rearrangement of atoms resulting in new substances. Choice C, 'Nuclear change,' is incorrect as it refers to changes in the nucleus of an atom, not the phase transition of ice. Choice D, 'Radioactive decay,' is incorrect as it involves the spontaneous disintegration of an unstable atomic nucleus, which is not the process occurring when ice melts.

Correct Answer: B

Rationale: Sublimation is the process by which a solid directly transforms into a gas without passing through the liquid phase. This occurs when the atmospheric pressure is lower than the vapor pressure of the solid, causing it to transition to a gas state. Choice A, evaporation, is the process where a liquid changes into a gas, not a solid. Choice C, condensation, is the opposite process where gas changes into a liquid. Choice D, melting, is the process where a solid changes into a liquid, not a gas.

Correct Answer: C

Rationale: The correct answer is 'Mixing.' When substances are combined, a heterogeneous mixture is formed where the components are physically distinguishable. 'Dissolving' (Choice A) is the process of a solute becoming uniformly dispersed in a solvent to form a solution, not a heterogeneous mixture. 'Diluting' (Choice B) refers to reducing the concentration of a solute in a solution. 'Reacting' (Choice D) involves a chemical change where substances interact to form new products, rather than just physically mixing to form a heterogeneous mixture.