Which of the following processes causes most of the carbon dioxide from the blood to move into the alveoli?
A. Conversion to carbon monoxide.
B. Diffusion down a concentration gradient.
C. Passive transport using carrier proteins.
D. Active transport using energy.
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.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science
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Q #1: Parasitic worm infestation is hypothesized to be damaging to the host. However, scientists have recently discovered that worm infestation can relieve the effects of certain autoimmune disorders. In which of the following ways should the hypothesis be modified, given the new findings?
A. Worm infestation prevents the body from immune malfunction
B. Worm infestation reduces the severity of certain autoimmune disorders
C. Worm infestations exacerbate the body's immune reactions
D. Lack of worm infestations is the cause of some autoimmune disorders
Answer Explanation
The hypothesis should be modified to include the new findings that worm infestation can relieve the effects of certain autoimmune disorders.
A possible modification could be: “Parasitic worm infestation can have both damaging and beneficial effects on the host.
While it can cause harm, it has also been found to reduce the severity of certain autoimmune disorders.”
Choice A.
Worm infestation prevents the body from immune malfunction is not correct because it overstates the findings and implies that worm infestation completely prevents immune malfunction, which is not supported by the evidence.
Choice C.
Worm infestations exacerbate the body’s immune reactions is not correct because it contradicts the new findings that worm infestation can relieve the effects of certain autoimmune disorders.
Choice D.
Lack of worm infestations is the cause of some autoimmune disorders is not correct because it overstates the findings and implies a causal relationship between lack of worm infestations and autoimmune disorders, which is not supported by the evidence.
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Q #2: Which of the following represents the complementary strand of a DNA sequence 3' TCGATCGCA 5'?
A. 3' AGCTAGCGT 5'
B. 5’ AGCTAGCGT 3’
C. 5' UCGAUCGCA 3'
D. 3' TCGUTCGCU 3'
Answer Explanation
In DNA, the nitrogenous bases adenine (A) and thymine (T) pair together, while cytosine (C) and guanine (G) pair together.
Therefore, the complementary strand of the given DNA sequence 3' TCGATCGCA 5' would have the complementary nitrogenous bases as:
5’ AGCTAGCGT 3’
NOTE: The 5’ to 3’ direction of the complementary strand is opposite to that of the given strand.
Choice A.
3’ AGCTAGCGT 5’ is not correct because it is not complementary to the given strand.
Choice C.
5’ UCGAUCGCA 3’ is not correct because it contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Choice D.
3’ TCGUTCGCU 3’ is not correct because it also contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
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Q #3: Which of the following results in osteoporosis?
A. An increase in osteocyte activity while osteoclast activity continues at expected levels.
B. A decline in osteoclast activity while osteoblast activity continues at expected levels.
C. An increase in osteocyte activity while osteoblast activity reduces.
D. A decline in osteoblast activity while osteoclast activity continues at expected levels.
Answer Explanation
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.
