Which of the following nucleotides is only found in RNA?

The correct answer is A. This option describes a chemical reaction known as the reaction of water with sodium, producing hydrogen gas. Chemical reactions involve the breaking and forming of chemical bonds, and in this case, sodium reacts with water to produce hydrogen gas and sodium hydroxide.

The correct answer is C. A spectrophotometer measures the amount of light absorbed or transmitted by a substance in a liquid. Turbidity, caused by suspended particles, can be assessed by measuring the reduction in light transmission through the sample. The other tools listed are not specifically designed for measuring turbidity.

The correct answer is C. Chlorine molecule (Cl2) has only one covalent bond between the two chlorine atoms, which share one pair of electrons. The other molecules have more covalent bonds: water has two, methane has four, and ammonia has three.

The correct answer is A. Endocrine glands secrete hormones directly into the bloodstream without ducts, while exocrine glands have ducts through which their secretions are transported to specific locations. This fundamental difference in the mode of secretion distinguishes endocrine from exocrine glands.

The correct answer is B. The phenotypic ratio of 50% green pods and 50% yellow pods indicates that the genotype of the parent with green pods is heterozygous (Gg), and the genotype of the parent with yellow pods is homozygous recessive (gg). The cross would be Gg x gg.

The correct answer is D. The scientific purpose would be to analyze the factors that led to the failure of the 1924 expedition, providing insights into mountaineering challenges and safety considerations, rather than demonstrating modern technology or exploring new routes.

The correct answer is A. The endocardium is the innermost layer of tissue that lines the interior surfaces of the heart, providing a smooth surface for blood flow. The myocardium is the middle muscular layer, the pericardium is the outer protective sac, and the epicardium is the outermost layer covering the heart.

The correct answer is B. This option involves a control group (water) and an experimental group (energy drink) to compare the effects. By having a group that does not consume the energy drink, researchers can better attribute any observed differences in running speed to the energy drink itself.

The correct answer is D. The typical pathway of blood flow involves arteries branching into arterioles, which further branch into capillaries, facilitating the exchange of nutrients and gases with the organ's tissues.

The correct answer is A. Increasing the surface area of a solid reactant by grinding it to a powder exposes more particles to the reactants, enhancing their chances of colliding and increasing the reaction rate. The other options would generally decrease the rate of the reaction.