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Example Questions
Example Question #901 : Biology
Which of the following gases can bind to hemoglobin?
Oxygen (O2)
Carbon dioxide (CO2)
Carbon monoxide (CO)
Hemoglobin can bind to all of these gases
Hemoglobin can bind to all of these gases
Hemoglobin can bind to all three of these gases, however, it binds to each of them with a different affinity. Hemoglobin's affinity for the three gases, from highest to lowest, is listed below.
carbon monoxide (CO) > oxygen (O2) > carbon dioxide (CO2).
Note that cabron monoxide has the highest affininty; this is why is can be dangerous to inhale too much carbon monoxide, as it will displace onxygen that would otherwise bind to hemoglobin.
Example Question #82 : Circulatory System
Carbonic anhydrase serves to convert carbon dioxide wastes, produced from cellular respiration, into bicarbonate. This bicarbonate buffers blood pH and allows for the transport of more carbon dioxide equivalents in the blood to the kidneys for excretion. The reaction catalyzed by carbonic anhydrase is:
How would running, as compared to walking, change the pH of the blood if breathing rate remains constant?
The change cannot be determined without knowing more about the runner
Decreased blood pH
Increased blood pH
Blood pH will remain the same
Decreased blood pH
Cellular respiration is more active during running than during walking, producing more carbon dioxide. The carbon dioxide will enter the carbonic anhydrase reaction, producing more protons in the blood and lowering the pH. To counter this drop in pH, runners will naturally increase their breathing rate. This serves to deliver more oxygen to the muscles, as well as to remove more carbon dioxide wastes and prevent acid from building in the blood.
Example Question #892 : Systems Biology And Tissue Types
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be optimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin is given below.
H+ + HbO2 ←→ H+Hb + O2
Considering the described oxygen affinity pattern for hemoglobin, which curve is likely to depict fetal hemoglobin?
Curve 1, as it shows less affinity for oxygen
Curve 1, as it shows greater affinity for oxygen
Cannot be determined from the information given
Curve 2, as it shows greater affinity for oxygen
Curve 2, as it shows less affinity for oxygen
Curve 1, as it shows greater affinity for oxygen
Curve 1 shows greater affinity for oxygen than curve 2, as it is higher up the y-axis at any single point on the x-axis. We would expect this finding for fetal hemoglobin, which would need to extract oxygen from maternal blood.
Example Question #931 : Mcat Biological Sciences
Hemoglobin is the principal oxygen-carrying protein in humans. It exists within erythrocytes, and binds up to four diatomic oxygen molecules simultaneously. Hemoglobin functions to maximize oxygen delivery to tissues, while simultaneously maximizing oxygen absorption in the lungs. Hemoglobin thus has a fundamentally contradictory set of goals. It must at once be optimized to absorb oxygen, and to offload oxygen. Natural selection has overcome this apparent contradiction by making hemoglobin exquisitely sensitive to conditions in its microenvironment.
One way in which hemoglobin accomplishes its goals is through the phenomenon of cooperativity. Cooperativity refers to the ability of hemoglobin to change its oxygen binding behavior as a function of how many other oxygen atoms are bound to the molecule.
Fetal hemoglobin shows a similar pattern of cooperativity, but has unique binding characteristics relative to adult hemoglobin. Fetal hemoglobin reaches higher saturation at lower oxygen partial pressure.
Because of cooperativity, adult and fetal oxygen-hemoglobin dissociation curves appear as follows.
Beyond its ability to carry oxygen, hemoglobin is also effective as a blood buffer. The general reaction for the blood buffer system of hemoglobin given below.
H+ + HbO2 ←→ H+Hb + O2
Hemoglobin is the most important component of red blood cells. How are red blood cells different from other cells of the body?
They are produced in the thymus
They are larger than all other cells
They contain protein support for their membranes
They lack a nucleus
They lack a cell membrane
They lack a nucleus
Red blood cells are unique in that they lack a nucleus and are functionally just "bags of hemoglobin." They are among the most specialized cells, doing little else but transporting oxygen in the blood.
The choice indicating protein support for the membrane may have also been tempting, and is true. This characteristic, however, is shared by other cells of the body. Also remember that red blood cells are produced by red bone marrow (and sometimes the liver), while certain white blood cells mature in the thymus.
Example Question #893 : Systems Biology And Tissue Types
Which of the following is a cause of alkalosis?
Hyperventilation
Renal dysfunction leading to a buildup of urea and creatinine
High levels of in the blood
Strenuous exercise leading to a buildup of lactate
Increased parietal cell activity
Hyperventilation
Hyperventilation is a classic example of a process that can cause alkalosis, or basicity of the bloodstream. Hyperventilation can cause a net loss of CO2. Low levels of CO2 can cause respiratory alkalosis via reduction of carbonate in the blood. Lactate—also known as lactic acid—is a product of anaerobic respiration, and decreases blood pH. Increased levels of urea and creatinine indicate renal acidosis, a form of metabolic acidosis, which occurs when the kidney does not remove enough acid from the body.
Example Question #11 : Hemoglobin, Blood Cells, And Blood Proteins
A scientist takes a group of erythrocytes (red blood cells) and places them in a beaker containing a solution. The cells begin to shrink and eventually lyse. What can be concluded about the solution?
The solution was hypertonic to the erythrocytes
The solution was isotonic to the erythrocytes
The solution contained albumin
The solution was hypotonic to the erythrocytes
The solution contained bicarbonate
The solution was hypertonic to the erythrocytes
Placing erythrocytes in a hypertonic solution would cause them to shrink and burst, becuase water from the erythrocytes would move from high to low concenration (inside the cells to the outside hypertonic environment). Albumin and bicarbonate would have no effect, because they are normal components of blood. Placing them in a hypotonic solution would cause them to swell up.
Example Question #21 : Hemoglobin, Blood Cells, And Blood Proteins
What could the blood pH of a person who has blood acidosis (more acidic blood than normal) possibly be?
7.2
7.5
6.8
Either 7.5 or 7.2
Either 7.2 or 6.8
Either 7.2 or 6.8
The normal pH of blood is around 7.3, which means blood is normally slightly basic. A truly neutral pH is 7.0. Whenever the pH of blood is under 7.3 (not 7.0) it is considered acidosis, and so our answer is either 7.2 or 6.8.
Example Question #901 : Systems Biology And Tissue Types
Which statement regarding blood typing is correct?
A person with O- blood can receive a blood donation from someone with O+ blood.
A person with AB- blood can donate to a person whose blood type is O-.
A person with B- blood can donate to a person whose blood type is AB+.
A woman with Rh- blood is at risk for developing erythroblastosis fetalis during her first pregnancy if the fetus is Rh+.
The presence of the Rh factor is coded for by a recessive allele.
A person with B- blood can donate to a person whose blood type is AB+.
The AB+ blood type is known as the "universal recipient" type, therefore, people with any blood type can donate to an AB+ individual.
As for the incorrect answers, a person with O- blood has the "universal donor" type, and can only receive blood from other O- individuals. Erythroblastosis fetalis, also known as hemolytic disease of the newborn, cannot occur during a woman's first pregnancy because her body has not yet produced anti-Rh antibodies. Finally, Rh factor presence is a genetically dominant condition.
Example Question #85 : Circulatory System
Which of the following accurately represents the entire composition of blood?
Erythrocytes, leukocytes, platelets
Serum, erythrocytes, leukocytes, platelets
Serum, plasma, erythrocytes, leukocytes, platelets
Plasma, erythrocytes, leukocytes, platelets
Plasma, erythrocytes, leukocytes, platelets
Human blood contains 55% plasma and 45% cells. The cells include erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets). Plasma is largely composed of water, protein (albumin), and clotting factors.
Note that blood serum is simply blood plasma with the clotting factor elements (fibrinogen) removed.
Example Question #91 : Circulatory System
Which of the following most accurately depicts the process of clotting?
Thromboplastin aggregates platelets to form a clot; fibrin and fibrinogen are structural elements of cells that are not related to clotting
Thromboplastin is released and converts prothrombin to thrombin. Thrombin converts fibrinogen to fibrin, which recruits elements of the blood to form a clot.
Thromboplastin is released and converts fibrinogen to fibrin, which recruits elements of the blood to form a clot.
Prothrombin is released and activates thrombin. Thrombin converts fibrinogen to fibrin, which stimulates the secretion of thromboplastin. Thromboplastin recruits elements of the blood to form a clot.
Thromboplastin is released and converts prothrombin to thrombin. Thrombin converts fibrinogen to fibrin, which recruits elements of the blood to form a clot.
Thromboplastin is released when damage occurs to a tissue. Prothrombin and fibrinogen are both present in the blood. When thromboplastin interacts with the blood, it converts prothrombin to its active state, thrombin. Thrombin then cleaves fibrinogen, converting it to its active state, fibrin. Fibrin is exceptional at forming cross-linked mesh-like interactions, and in doing so traps passing blood cells and plasma proteins. This blockage and accumulation of blood elements becomes the clot.
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