Correct Answer: B

Rationale: The CRISPR-Cas9 system is a powerful tool used in gene editing to precisely target and cut DNA at specific locations within the genome. This system consists of a guide RNA that directs the Cas9 enzyme to the desired DNA sequence, where it creates a double-strand break. This break can then be repaired by the cell's natural DNA repair mechanisms, allowing for the introduction of specific genetic modifications. Options A, C, and D are incorrect as they do not accurately describe the primary function of the CRISPR-Cas9 system in gene editing. Amplifying DNA sequences, delivering genes into cells, and sequencing entire genomes are not the main functions of the CRISPR-Cas9 system, which is primarily focused on precise DNA cutting for targeted genetic modifications.

Correct Answer: A

Rationale: The rusting of iron is an endothermic reaction. This means that it absorbs heat from its surroundings to occur. Rusting involves the slow oxidation of iron in the presence of oxygen and water. As energy is absorbed during this process, it is classified as an endothermic reaction.
Choice B, an exothermic reaction, releases heat instead of absorbing it, which is not the case in rusting.

Choices C and D are unrelated to the process of rusting and do not involve the absorption of heat from the surroundings.

Correct Answer: B

Rationale: As a water wave approaches a shallow beach, the speed of the wave decreases due to the change in medium from deep to shallow water. According to the wave equation (speed = frequency x wavelength), if the speed decreases and the frequency remains the same, the wavelength must also decrease to maintain the equation balanced. This phenomenon occurs due to the wavefronts being slowed down by the shallower water, causing the wavelength to decrease while the frequency remains constant.
Choice A is incorrect as the speed of the wave decreases in shallow water.
Choice C is incorrect because the speed increases in deep water, not in shallow water.
Choice D is incorrect as all the wave characteristics change when moving from deep to shallow water.

Correct Answer: D

Rationale: The Golgi apparatus is responsible for the final stages of protein modification and packaging for secretion in animal cells. After proteins are synthesized in the rough endoplasmic reticulum (RER), they are transported to the Golgi apparatus for further processing, sorting, and packaging before being sent to their final destination within or outside the cell. The smooth endoplasmic reticulum (SER) is mainly involved in lipid metabolism and detoxification processes, not protein modification. Ribosomes are the cellular organelles responsible for protein synthesis, not the final stages of protein modification and packaging for secretion, which is the role of the Golgi apparatus.

Correct Answer: A

Rationale:
A) Multicellularity and heterotrophy: This is the correct answer because all organisms in the kingdom Animalia are multicellular (composed of multiple cells) and exhibit heterotrophy (obtain nutrients by consuming other organisms).

B) Unicellular nature: This is incorrect because organisms in the kingdom Animalia are multicellular, not unicellular.

C) Photosynthesis: This is incorrect because organisms in the kingdom Animalia do not perform photosynthesis; they are heterotrophs that obtain nutrients by consuming other organisms.

D) Cell walls made of chitin: This is incorrect because organisms in the kingdom Animalia do not have cell walls made of chitin. Chitin is a structural polysaccharide found in the cell walls of fungi, not animals.