Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
Carbon dioxide
Carbon monoxide
Carbonic acid
Oxygen
Correct Answer : C
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.
TEAS 7 Exam Quiz Bank
HESI A2 Exam Quiz Bank
Find More Questions 📚
Teas 7 Questions: We got the latest updated TEAS 7 questions
100% Money Refund: 100% money back guarantee if you take our full
assessment pass with 80% and fail the actual exam.
Live Tutoring: Fully customized live tutoring lessons.
Guaranteed A Grade: All students who use our services pass with 90%
guarantee.
Related Questions
Correct Answer is D
Explanation
The pulmonary veins are the vessels that carry oxygenated blood from the lungs to the left atrium of the heart.
Choice A is not correct because the superior vena cava carries deoxygenated blood from the upper body to the right atrium of the heart.
Choice B is not correct because the inferior vena cava carries deoxygenated blood from the lower body to the right atrium of the heart.
Choice C is not correct because the pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.
Correct Answer is C
Explanation
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.
Correct Answer is D
Explanation
Proteins.
Proteins are made up of amino acids which are organic molecules that contain both an amine functional group (–NH2) and a carboxylic acid functional group (– COOH).
![]() |
Choice A, Lipids, is not the correct answer because lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, phospholipids, and others.
They do not contain both an amine and carboxyl group.
Choice B, Chitin, is not the correct answer because chitin is a long-chain polymer of N-acetylglucosamine, a derivative of glucose.
It does not contain both an amine and carboxyl group.
Choice C, Cellulose, is not the correct answer because cellulose is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units.
It does not contain both an amine and carboxyl group.
Correct Answer is C
Explanation
The best reason for the prolonged preservation of the body is that it was frozen in the cold temperature of the Alps shortly after he died and remained frozen until it was found.
Freezing can preserve a body by slowing down or stopping the decomposition process.
Choice A is not correct because the food that the person ate would not have contained toxins that killed the bacteria that would have otherwise destroyed the body.
Choice B is not correct because the arrow wound would not have caused blood to flow out of the body in a way that would have cleared enzymes that break down tissue from the body.
Choice D is not correct because ultraviolet rays at high altitude would not have caused all of the body’s molecules to be preserved.
Correct Answer is D
Explanation
Testosterone is classified as an androgen hormone.
Androgens are a type of sex hormone that primarily regulates the development and maintenance of male characteristics, such as body hair growth, muscle mass, and deepening of the voice.
Testosterone is produced primarily in the testes in males and in smaller amounts in the ovaries and adrenal glands in females.
Option A, estrogen, is a female hormone that regulates the development of female sexual characteristics, such as breast growth and menstruation.
While estrogen and testosterone are both steroid hormones and can be converted to one another in the body, testosterone is not categorized as estrogen.
Option B, progestin, is a synthetic form of the hormone progesterone.
Progesterone is a female hormone that plays a role in the menstrual cycle and pregnancy.
Testosterone and progestin are not related, and testosterone is not categorized as progestin.
Option C, aldosterone, is a mineralocorticoid hormone that regulates salt and water balance in the body.
It is produced in the adrenal gland and plays a role in regulating blood pressure.
Testosterone and aldosterone are not related, and testosterone is not categorized as aldosterone.
Correct Answer is C
Explanation
Control.
A control group is a group in an experiment that does not receive the treatment or manipulation being tested and is used as a benchmark to measure how the other tested subjects do.
The control group is used to minimize the effects of all variables except the independent variable.
This allows researchers to determine if changes in the dependent variable are due to the manipulation of the independent variable or if they are due to some other factor.
Choice A.
Responding is not the correct answer because it refers to the dependent variable, which is the variable that is being measured in an experiment.
Choice B.
Manipulated is not the correct answer because it refers to the independent variable, which is the variable that is being manipulated in an experiment.
Choice D.
Variable is not the correct answer because it refers to any factor that can change in an experiment and can include both independent and dependent variables.
Correct Answer is C
Explanation
Heavier objects fall faster than lighter objects.
The data in the table shows that as the number of filters (and therefore the mass) increases, the terminal velocity also increases.
This means that the heavier objects (with more filters) are falling faster than the lighter objects (with fewer filters).
Choice A is not supported by the data in the table as much as it is true.
Terminal velocity is indeed when the force of gravity is equal to air resistance, but this definition does not provide any information about the relationship between mass and terminal velocity.
Choice B is also not supported by the data in the table.
The data does not provide any information about the time it takes for an object to reach terminal velocity.
Choice D is not supported by the data in the table.
The data shows that as the number of filters increases, the terminal velocity also increases.
This means that the greater the number of filters, the greater (not smaller) the terminal velocity.
Correct Answer is A
Explanation
The approximate threshold value for mammalian neurons is -55 mV.
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV
Â
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
Correct Answer is B
Explanation
Antidiuretic hormone (ADH), also known as vasopressin, is a hormone that helps regulate the amount of water in your body.
It works to control the amount of water your kidneys reabsorb as they filter out waste from your blood.
Choice A is not correct because an increase in the concentration of calcium in the glomerulus is not a physiological response caused by the release of antidiuretic hormone.
Choice C is not correct because a decrease in the concentration of calcium in the glomerulus is not a physiological response caused by the release of antidiuretic hormone.
Choice D is not correct because a decrease in water reabsorption in the collecting duct is not a physiological response caused by the release of antidiuretic hormone.
Correct Answer is A
Explanation
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.
Â
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.
This question was extracted from the actual TEAS Exam. Ace your TEAS exam with the actual TEAS 7 questions, Start your journey with us today
Visit Naxlex, the Most Trusted TEAS TEST Platform With Guaranteed Pass of 90%.
Money back guarantee if you use our service and fail the actual exam. Option of personalised live tutor on your area of weakness.