Correct Answer: A

Rationale: Microtubules are fundamental components of the cytoskeleton in a cell, playing a crucial role in providing structural support and maintaining the cell's shape. They are composed of tubulin protein subunits and are involved in various cellular processes like cell division, intracellular transport, and cell motility. Microfilaments, on the other hand, are involved in cell movement and maintaining cell shape but are not primarily responsible for supporting the cell's overall structure. Cilia and microvilli are cellular projections that aid in movement and absorption, respectively, but they do not play a significant role in providing structural support to the cell.

Correct Answer: D

Rationale: The correct answer is D, Steroids. Steroids are a type of lipid that function as essential components of cell membranes and serve as precursors for significant hormones like estrogen and testosterone. Nucleic acids (choice A) are not lipids but are molecules like DNA and RNA that store genetic information. Proteins (choice B) and carbohydrates (choice C) are biomolecules but are not lipids and do not serve as precursors for hormones or membrane components.

Correct Answer: A

Rationale: The correct answer is A, Punnett square. A Punnett square is a tool specifically designed to predict the genotype and phenotype combinations of offspring resulting from a particular cross or breeding experiment. It helps in understanding the probability of different genotypes and phenotypes appearing in the offspring. Choice B, Chi-square, is a statistical test used to determine if there is a significant difference between the expected frequencies and the observed frequencies in a study. Choice C, Microscope, is used for viewing tiny structures and organisms, not for predicting genetic outcomes. Choice D, None of these, is incorrect as Punnett square is a valid tool for predicting genetic outcomes in offspring.

Correct Answer: A

Rationale: The correct answer is A: To produce amino acids. During the translation stage of protein synthesis, the mRNA is decoded to assemble a specific sequence of amino acids. These amino acids then fold into a functional protein. Choices B, C, and D are incorrect because the translation stage specifically deals with the production of amino acids, not nucleotides, fatty acids, or nucleic acids.

Correct Answer: A

Rationale: The correct answer is A: Proteins. Proteins are the most significant contributor to cellular function as they play crucial roles in almost all biological processes. They act as enzymes that catalyze reactions, are involved in cell signaling pathways, and provide structural support to cells. Phospholipids (Choice B), while important for cell membrane structure, do not have the same diverse functions as proteins in cellular processes. Carbohydrates (Choice C) primarily serve as an energy source and structural components but are not as versatile in cellular functions as proteins. Fatty acids (Choice D) are essential components of cell membranes and energy storage molecules but do not have the same broad range of functions as proteins in cellular processes.