Which of the following tissues lines the interior surfaces of the heart?

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.

Phosphates are found in both DNA and cell membranes. In DNA, they form part of the backbone structure, linking the nucleotides together. In cell membranes, phosphates are a component of phospholipids, which are critical to the membrane's structure and function.

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 experiment involves dissolving different substances in water and observing how these solutions cool. The primary variable being tested is how the type of solute (salt, sugar, baking soda) affects the cooling rate, rather than solubility or volume effects.

The correct answer is C. 9. The pH is determined by taking the negative logarithm (base 10) of the hydrogen ion concentration ([H+]). In this case, -log(10^(-9)) equals 9, so the pH of the solution is 9.

To find the pH of a solution with a hydrogen ion concentration ([H+]) of \(10^{-9}\) M using the equation \(pH = -\log[H^+]\):

\[ pH = -\log(10^{-9}) \]

Now, since \( \log(10^{-9}) = -9 \), the negative sign before the logarithm makes the value positive:

\[ pH = -(-9) = 9 \]

Therefore, the solution has a pH of 9

The correct answer is B. Electrons are much lighter than protons and neutrons and have a negligible mass compared to them. Therefore, when calculating the atomic mass number, electrons are typically not considered.

The correct answer is C. Helper T-cells play a crucial role in the immune system by coordinating and stimulating other immune cells, including cytotoxic T-cells, to attack and destroy foreign agents.

The hip bone (or pelvis) in adults is formed by the fusion of three separate bones: the ilium, ischium, and pubis. This fusion occurs during adolescence and results in a single, solid structure.

The correct answer is A. Melanocytes are responsible for producing the pigment melanin and transferring pigment granules to adjacent epidermal cells, particularly keratinocytes. This process contributes to the coloration of the skin.

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.