In a phase diagram, which of the following is the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously?

 

 

Diffusion down a concentration gradient causes most of the carbon dioxide from the blood to move into the alveoli.

The alveoli are tiny air sacs in the lungs where gas exchange occurs.

Carbon dioxide is a waste product of cellular respiration and is carried by the blood to the lungs to be exhaled.

In the lungs, carbon dioxide diffuses from the blood (where its concentration is high) into the alveoli (where its concentration is lower) down its concentration gradient.

Choice A is incorrect because carbon dioxide is not converted to carbon monoxide in the body.

Choice C is incorrect because passive transport using carrier proteins is not the primary mechanism by which carbon dioxide moves from the blood into the alveoli.

Choice D is incorrect because active transport using energy is not involved in the movement of carbon dioxide from the blood into the alveoli.

The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution.

A solution with a pH of 7 is neutral, while a solution with a pH less than 7 is acidic and a solution with a pH greater than 7 is alkaline.

Because the pH scale is logarithmic, each whole number change in pH represents a tenfold change in acidity or alkalinity.

Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.

Choice A.

A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline and also incorrectly states the magnitude of the difference in acidity or alkalinity.

Choice B.

A substance with a pH of 3 is two times more acidic than a substance with a pH of 4 is not correct because it correctly states that the substance with a lower pH is more acidic but incorrectly states the magnitude of the difference in acidity.

Choice D.

A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline.

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.

Ovulation is the process in which an ovarian follicle matures and releases a reproductive egg.

During ovulation, a mature egg is released from the female ovary, enabling it to be fertilized by male sperm cells 1.

Choice A is incorrect because menstruation is the process of shedding the uterine lining, which occurs when an egg is not fertilized.

Choice B is incorrect because fertilization is the process of a sperm cell joining with an egg cell to form a zygote.

Choice D is incorrect because oogenesis is the process of forming female gametes (eggs) in the ovaries.

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.

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.

The hypothalamus is a region of the brain that synthesizes antidiuretic hormone (ADH), also known as vasopressin.

ADH is then transported to the posterior pituitary gland via neurohypophysial capillaries, where it is stored until it is ready to be secreted into the circulation.

Choice A.

Pineal gland is not correct because it is a small endocrine gland located in the brain that secretes the hormone melatonin, which regulates sleep-wake cycles, but it does not synthesize ADH.

Choice B.

Thymus is not correct because it is a gland located in the chest that produces hormones involved in immune system development, but it does not synthesize ADH.

Choice D.

Pancreas is not correct because it is a gland located behind the stomach that secretes hormones such as insulin and glucagon, which regulate blood sugar levels, but it does not synthesize ADH.

Bag mass change is the dependent variable in this experiment.

In an experiment, the dependent variable is the variable that is being measured and is expected to change in response to changes in the independent variable(s).

In this case, the bag mass change is being measured and is expected to change in response to changes in the independent variable (sucrose concentration).

Choice A is incorrect because duration is not a variable in this experiment.

Choice B is incorrect because temperature is not a variable in this experiment.

Choice D is incorrect because sucrose concentration is an independent variable, not a dependent variable.

An independent variable is a variable that is manipulated by the experimenter to see how it affects the dependent

Reverse transcriptase, an enzyme encoded by the virus.

Reverse transcriptase is a virus-specific enzyme that transcribes an RNA template to DNA1.

This allows the AIDS virus, which contains RNA, to insert viral DNA into the DNA of a host cell after the AIDS virus enters the cell.

Choice A, The phospholipids found on the envelope of the virus, is not the correct answer because phospholipids are a major component of cell membranes and do not play a direct role in inserting viral DNA into the DNA of a host cell.

Choice C, Receptor proteins located on the surface of the virus, is not the correct answer because receptor proteins located on the surface of the virus play a role in attachment and fusion of HIV virons to host cells, but do not play a direct role in inserting viral DNA into the DNA of a host cell.

Choice D, The protein that makes up the capsid of the virus, is not the correct answer because capsid is the outer protein shell of a virus and does not play a direct role in inserting viral DNA into the DNA of a host cell.

The glomerulus is the main filtering unit of the kidney.

It is formed by a network of small blood vessels (capillaries) enclosed within a sac called the Bowman’s capsule.

The blood supply to the glomerulus is provided via the afferent arteriole.

The blood then flows through the capillary network, where it gets filtered, and then leaves the glomerulus via the efferent arteriole.

Choice B.

Proximal tubule is not correct because it is where the ultrafiltrate collected in the Bowman’s space drains directly into.

Choice C.

Distal tubule is not correct because it is not mentioned in relation to blood exiting the glomerulus.

Choice D.

Afferent arteriole is not correct because it provides blood supply to the glomerulus.