51. Inspiration in humans is regulated by: A. Oxygen levels in the blood B. The

Question

51. Inspiration in humans is regulated by: A. Oxygen levels in the blood B. The concentration of red blood cells C. Hemoglobin levels in the blood. D. Carbon dioxide and pH level sensors 52. Oxygen moves from the lungs into the blood because There is a higher partial pressure of O, in the blood compared with the alveolus 8. A. There is a higher partial pressure of O, in the alveolus compared with the Ther C. re is a higher partial pressure of CO2 in the alveolus compared with the blood. There is a higher partial pressure of CO; in the blood compared with the alveolus. 53. Oxygen is transported in the blood by: A. Binding to the iron ion in hemoglobin B. Converting to bicarbonate ion C. Dissolving in the plasma D. Combining with water and forming carbon dioxide -54. A specialized function shared by many cells lining the lungs and lumen of the small intestine is A. B. C. D. decreased oxygen demand due to the lack of oxygen in foods. increased exchange surface area provided by their membranes. greater protection due to increased cellular mass. lowered metabolic rate due to cooperation between cells. -55, which of the following is TRUE with regard to B cells in the immune response? A. They are co-stimulated by Helper T cells. B. They differentiate into plasma cells C. B cell receptors contain an antigen binding region D. All of the above 56. MHC II (major histacompatibility complex) is found on A. Body cells B. Red blood cells C. White blood cells such as B cell and macrophages D. All of the above 57. Artificially acquired active immunity involves: A. Injection of a vaccine containing antibodies B. Transfer of antibodies through breast milk. C. Succumbing to a disease such as chicken pox. D. Injection of a vaccine containing a weakened pathogen

Explanation / Answer

51. Option D. Carbon dioxide and pH level sensors

Explanation: Chemoreceptors and Baroreceptors present in the aorta, carotid arteries and brain detect changes in pH and partial pressure of carbon dioxide, oxygen. Input from these sensors triggers the respiratory center and regulate the inspiration rate and depth. Hence, the correct answer is Option D

52. B. There is a higher partial pressure of O2 in the alveolus compared with the blood.

Explanation: The partial pressure in the alveoli is 104 mmHg and it is 40 mmHg in the pulmonary capillary (blood). This difference of 64mmHg pressure gradient facilitates the diffusion of oxygen from alveoli into the blood. Hence, the correct answer is B

53. A. Binding to the iron ion in the hemoglobin

Explanation: The transport of oxygen via hemoglobin accounts 97% (remaining 3% is by simple physical solution in plasma). Oxygen combines with the iron in heme part of hemoglobin. Since there are 4 iron atoms in Hemoglobin molecule, each molecule can carry 4 molecules of oxygen. Hence, option A is correct answer

54. B. Increased exchange surface area provided by their membranes

Explanation: The cells lining lungs and lumen of the gut provide more exchange surface area which makes respiration and absorption more efficient in the given unit space and increase the productivity of the cells

55. D. All of the above

All the given options are true and fit the description of B cells

56. C. White blood cells such as B cells and macrophages

MHC II cells are usually found on antigen presenting cells like B cells, macrophages, dendritic cells. So the correct answer is C

57. D. Injection of a vaccine containing a weakened pathogen

Active immunity infers that there is production of antibodies in the body and since there is production of antibodies which is induced from weakened (attenuated) pathogen it refers to artificial and since it is not produced on own terms but induced, it is acquired. So the correct answer is option D

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