Escherichia coli is plated on nutrient agar plates that each contain a different type of antibiotic. The shaded area represents the growth of the bacteria. Which of the following plates contains bacteria that were most resistant to the antibiotic?

A.

B.

C.

D.

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 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 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. Emphysema is a disease that primarily affects the alveoli, which are tiny air sacs in the lungs responsible for gas exchange. The destruction of alveoli walls in emphysema reduces the surface area available for oxygen and carbon dioxide exchange.

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 B. The vermiform appendix is a small, tube-like structure that extends from the cecum, which is the first part of the large intestine. It is not associated with the jejunum, rectum, or ischium.

Independent assortment occurs during metaphase I when homologous chromosome pairs line up randomly at the cell’s equator. This randomness contributes to genetic variation because the distribution of maternal and paternal chromosomes into gametes is different each time meiosis occurs.

The correct answer is B. Atoms become cations by losing electrons. Potassium has one electron in its outermost shell, and it is more likely to lose that electron to achieve a stable, cationic state. Fluorine, helium, and oxygen are more likely to gain electrons and form anions.

The correct answer is D. Mitochondria are the cellular organelles responsible for the production of ATP (adenosine triphosphate) through the process of cellular respiration.

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.