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.
The Correct Answer is C
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.
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Correct Answer is B
Explanation
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.
Correct Answer is D
Explanation
Genes are segments of DNA that encode the information for making proteins.
The sequence of nucleotides (As, Ts, Cs, and Gs) in a gene determines the amino acid sequence of the protein. DNA sequencing is the process of determining the sequence of nucleotides in a piece of DNA.
Choice A is incorrect because enzymes are proteins that catalyze chemical reactions, not DNA sequences. Choice B is incorrect because blood types are determined by the presence or absence of certain antigens on the surface of red blood cells, not by DNA sequences. Choice C is incorrect because hormones are chemical messengers that regulate various body functions, not DNA sequences.
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