Which of the following is the structure through which blood exits the glomerulus? 

 

Melanin.

Melanin is a pigment produced by cells called melanocytes in the skin.

It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.

This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.

Choice B.

Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.

Choice C.

Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.

Choice D.

Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.

Plasma B cells.

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells).

When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

The mature B cells, called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system.

Choice A, Natural killer cells, is not the correct answer because natural killer cells are a type of white blood cell that play a major role in the host-rejection of both tumors and virally infected cells.

Choice B, Cytotoxic T-cells, is not the correct answer because cytotoxic T-cells are a type of white blood cell that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.

Choice D, Helper T-cells, is not the correct answer because helper T-cells are a type of white blood cell that play an important role in the immune system by helping other white blood cells fight infections.

The pleura is a double-layered serous membrane that covers each lung and lines the thoracic cage

The pleura is a vital part of the respiratory tract.

Its role is to cushion the lung and reduce any friction that may develop between the lung, rib cage, and chest cavity.

Each pleura (there are two) consists of a two-layered membrane that covers each lung.

The layers are separated by a small amount of viscous (thick) lubricant known as pleural fluid.

The pleura is comprised of two distinct layers: the visceral pleura and the parietal pleura.

The visceral pleura is the thin, slippery membrane that covers the surface of the lungs and dips into the areas separating the different lobes of the lungs (called the hilum).

Amino acids have a unique structure consisting of an amino group (-NH3⁺) and a carboxyl group (-COO⁻) attached to a central carbon (called the α-carbon). At physiological pH (around 7.4), these functional groups often exist in their ionized forms:

• The amino group (-NH3⁺) is positively charged, acting as a proton acceptor (a base).
• The carboxyl group (-COO⁻) is negatively charged, acting as a proton donor (an acid).

This results in a zwitterion — a molecule with both a positive and a negative charge. Because amino acids can accept or donate protons depending on the pH of their environment, they have buffering capacity. This means they can resist changes in pH by stabilizing the concentration of hydrogen ions (H⁺).

Why Other Options Are Incorrect:

• A. Monosaccharides: These are simple sugars without ionizable functional groups, so they cannot act as buffers.
• B. Ribonucleotides and D. Deoxyribonucleotides: While nucleotides have phosphate groups that can donate protons, they lack the dual positive and negative functional groups necessary for the strong buffering effect seen in amino acids.

Therefore, amino acids are the correct choice because their zwitterionic nature provides them with excellent buffering capacity.

The atomic number of an atom is equal to the number of protons in its nucleus.

In this case, the atom has 12 protons, so its atomic number is 12.

Choice A, 24, is not the correct answer because it represents the sum of the number of protons and neutrons in the atom’s nucleus, which is known as the mass number.

Choice C, 1, is not the correct answer because it does not represent the number of protons in the atom’s nucleus.

Choice D, 144, is not the correct answer because it represents the square of the mass number and does not represent any property of the atom.

A decline in osteoblast activity while osteoclast activity continues at expected levels results in osteoporosis.

Osteoporosis is caused by an imbalance between the functioning of osteoclast and osteoblast cells.

Osteoblasts are responsible for forming new bone, while osteoclasts break down old bone.

If osteoblast activity declines while osteoclast activity continues at expected levels, this means that more bone is being broken down than is being formed, leading to a loss of bone density and an increased risk of osteoporosis.

Choice A is incorrect because an increase in osteocyte activity would not result in osteoporosis.

Osteocytes are mature bone cells that maintain the mineral concentration of the bone matrix.

Choice B is incorrect because a decline in osteoclast activity would not result in osteoporosis.

Osteoclasts break down old bone, so a decline in their activity would mean that less bone is being broken down.

Choice C is incorrect because an increase in osteocyte activity would not result in osteoporosis.

As mentioned earlier, osteocytes are mature bone cells that maintain the mineral concentration of the bone matrix.

Carbonic acid.

In the human body, maintaining the pH of the blood within a narrow range is critical for proper physiological functioning.

One of the buffering systems that helps to regulate blood pH involves the conversion of carbon dioxide (CO2) and water (H2O) into carbonic acid (H2CO3), which then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-).

Carbonic acid (H2CO3) is responsible for donating H+ ions to act as a buffer when blood pH rises.

When blood pH rises (becomes more alkaline), carbonic acid dissociates, and the H+ ions combine with bicarbonate ions to form more carbonic acid.

This helps to remove excess H+ ions from the blood and prevent the pH from rising too much.

Option A, carbon dioxide, is involved in the buffering system through its conversion to carbonic acid.

However, it does not directly donate H+ ions to act as a buffer when blood pH rises.

Option B, carbon monoxide, is a toxic gas that binds to hemoglobin in red blood cells, preventing them from carrying oxygen.

It is not involved in the buffering system and does not donate H+ ions.

Option D, oxygen, is carried by hemoglobin in red blood cells and is essential for respiration.

It is not involved in the buffering system and does not donate H+ ions.

A tsunami is a catastrophic ocean wave that is usually caused by a submarine earthquake.

It can also be caused by an underwater or coastal landslide, the eruption of a volcano, or the impact of a meteor or comet in a body of water.

Choice A is not correct because sunspot activity does not cause tsunamis.

Choice B is not correct because lightning strikes do not cause tsunamis.

Choice D is not correct because flooding does not cause tsunamis.

Urea is a substance that is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia.

When proteins are broken down, they produce ammonia, which is a highly toxic compound for the body.

Ammonia is then converted into urea and released out of the body through sweat glands.

Choice B.

Sebum is not correct because it is an oily substance secreted by sebaceous glands to lubricate and protect the skin, but it is not related to the breakdown of proteins or the formation of ammonia.

Choice C.

Water is not correct because while it is a component of sweat, it is not specifically related to the breakdown of proteins or the formation of ammonia.

Choice D.

Lysozymes are not correct because they are enzymes found in tears, saliva and other body fluids that have antibacterial properties, but they are not related to the breakdown of proteins or the formation of ammonia.

As a solid turns to a liquid, the particles become less ordered and more free to move around.

Choice B is not correct because particles have an increase in mobility as a solid turns to a liquid.

Choice C is not correct because particles move further apart as a solid turns to a liquid.

Choice D is not correct because intermolecular forces between particles become weaker as a solid turns to a liquid.