Which of the following nucleotides is only found in RNA?

The correct answer is B. Objects A and B have the same mass, but B falls faster because it has less air resistance. Objects C and D have different masses, but C falls faster because it has a higher mass-to-surface-area ratio, which reduces the effect of air resistance.

The correct answer is C. The complementary strand of DNA will have bases that pair with the original strand according to the base-pairing rules. In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Therefore, the complementary strand reads 3’ TCGATCGCA5’.

The pharynx is primarily composed of muscle tissue. It plays a role in swallowing and is part of both the respiratory and digestive systems, which requires coordinated muscular activity.

The correct answer is B. Facilitated diffusion is the passive movement of molecules, including water, across a membrane with the help of specific transport proteins. Water moves through specialized channels called aquaporins during facilitated diffusion.

The correct answer is B. Parathyroid hormone (PTH) regulates blood calcium levels by stimulating the release of calcium from bones, reabsorption of calcium in the kidneys, and absorption of calcium in the intestines. Norepinephrine, growth hormone, and melatonin do not play a primary role in calcium regulation.

The correct answer is D. Water's high specific heat capacity allows it to absorb and store large amounts of heat energy without a significant increase in temperature. Coastal areas, being near large bodies of water, experience less dramatic temperature changes because the water helps moderate temperature fluctuations by absorbing and releasing heat slowly.

The correct answer is A. Browning of an apple is often caused by enzymes such as polyphenol oxidase. Lemon juice has a low pH, creating an acidic environment that inhibits the activity of these enzymes and prevents browning.

When a proton is emitted from the nucleus of an atom, the atomic number (Z) decreases by 1 because a proton has a positive charge, and it's effectively removing one positive charge from the nucleus. However, the atomic mass (A) remains the same because protons and neutrons contribute to the atomic mass, and the emission of a proton does not affect the number of neutrons.

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 choice B. This is the plate that represents the highest number of bacteria. The bacteria that grow on this plate are the most resistant to the antibiotic because they can survive in a high concentration of the substance. In the other plates, the antibiotic inhibits the growth of the bacteria to a greater or lesser extent, depending on their sensitivity.