Which of the following is an example of a biological macromolecule?

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. 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 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 B. When a volcano erupts, it releases built-up pressure and gases, similar to the fizzing of a can of soda when opened. Both involve the release of pressure and trapped substances, leading to an outward expulsion of materials.

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. 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 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 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 C. Biological macromolecules are large, complex molecules essential for life. Nucleic acids, such as DNA and RNA, are examples of biological macromolecules. They are composed of nucleotides and play a crucial role in genetic information storage and transfer.

Nucleic acid, is also an example of a biological macromolecule. Nucleic acids are large molecules made up of nucleotides, which consist of a nitrogenous base, a sugar molecule, and a phosphate group. DNA and RNA are examples of nucleic acids, and they play crucial roles in storing and transmitting genetic information within cells. Therefore, both Protein) and Nucleic acidare correct examples of biological macromolecules.

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.