What is the primary function of ribosomes in the cell?

Correct Answer: D

Rationale: Ribosomes are cellular organelles responsible for protein synthesis. They read the genetic information encoded in messenger RNA (mRNA) and use this information to assemble amino acids into a specific sequence, forming a protein. This process is known as translation and is essential for the production of proteins that carry out various functions in the cell. Options A, B, and C are incorrect as they do not accurately describe the primary function of ribosomes. Choice A is incorrect because the synthesis of lipids and other cellular components is not the primary function of ribosomes. Choice B is incorrect as packaging and transporting proteins are functions typically associated with the endoplasmic reticulum and Golgi apparatus. Choice C is incorrect because ribosomes do not break down macromolecules; instead, they are involved in building proteins from amino acids.

Correct Answer: A

Rationale: Peroxisomes are membrane-bound organelles found in eukaryotic cells that contain enzymes involved in various metabolic processes. One of the main functions of peroxisomes is to break down hydrogen peroxide, a toxic byproduct of metabolism, into water and oxygen through the action of the enzyme catalase. This process helps protect the cell from oxidative damage caused by hydrogen peroxide. While peroxisomes are involved in other metabolic functions such as lipid metabolism and the synthesis of bile acids, their primary role is the breakdown of hydrogen peroxide. Choices B, C, and D are incorrect because peroxisomes are not primarily responsible for synthesizing lipids, packaging and transporting proteins, or storing genetic material within the cell.

Correct Answer: C

Rationale: Chromatography is the correct term for the process of separating the components of a solution based on their different rates of movement through a medium. In chromatography, the components move at different speeds due to their interactions with the medium, causing separation. Filtration involves using a barrier to separate solid particles from a liquid. Distillation separates components based on differences in boiling points to collect the vapor of the more volatile component. Precipitation refers to the formation of a solid from a solution by a chemical reaction or change in conditions.

Correct Answer: A

Rationale: Interphase is the phase of the cell cycle where the cell spends the majority of its time and is characterized by three subphases: G1 (Gap 1), S (Synthesis), and G2 (Gap 2). DNA replication specifically occurs during the S phase of interphase. This is a crucial step as it ensures that each daughter cell produced during cell division receives an exact copy of the genetic material. Mitosis is responsible for the equal distribution of the replicated DNA to the daughter cells during cell division. Meiosis is a specialized cell division process for gamete production in sexually reproducing organisms, involving two rounds of division to generate haploid cells. Cytokinesis is the final step of the cell cycle, where the cytoplasm divides to complete the formation of two separate daughter cells following nuclear division.

Correct Answer: A

Rationale: The correct answer is A: The centrioles. Centrioles are cylindrical structures found in animal cells that are crucial in organizing the spindle fibers during cell division (mitosis). They play a vital role in separating chromosomes during cell division, ensuring each daughter cell receives the correct number of chromosomes. Additionally, centrioles are involved in the formation of cilia and flagella, essential for cell motility and sensory functions. The nucleolus is responsible for ribosome production, the Golgi apparatus processes and packages proteins, and the endoplasmic reticulum is involved in protein synthesis and lipid metabolism. These structures do not have a direct role in controlling the cell cycle and preventing uncontrolled cell growth.