Mass transport in animals Flashcards

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1
Q

Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs. (3)

A
  • through renal vein
  • into vena cava to right atrium
  • into right ventricle and up pulmonary artery
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2
Q

Describe the advantage of the Bohr effect during intense exercise. (2)

A
  1. Increases dissociation of oxygen; / unloading of O2
  2. For aerobic respiration at the tissues/muscles/cells
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3
Q

What is the consequence of having too high haematocrit in blood? (4)

(too many RBC’s)

A
  • thickens blood
  • slows blood flow
  • could cause clots
  • could block coronary arteries
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4
Q

Why is the O2 dissasociation curve an S shape?

A
  • It is difficult for the haemoglobin to pick up the first O2 molecule.
  • Binding of the first O2 changes the tertiary structure of the haemoglobin.
  • This uncovers another heam group for O2 to binding to.
  • So hemoglobin’s affinity for oxygen increases.
  • This makes it easier to pick up the next two oxygen molecules.
  • This is called cooperative binding.
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5
Q

Gas exchange for the fetus occurs in the placenta.
Describe how the composition of blood in the pulmonary artery of a fetus is different from the composition of blood in the pulmonary artery of its mother.
Give one reason for this difference. (2)

A
  1. Fetal blood has more oxygen
    ..
  2. (Because) gas exchange occurs in the placenta
    OR
    Gas exchange does not occur in (fetal) lungs;
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6
Q

Explain how water from tissue fluid is returned back to the circulatory system: (4)

A
  1. (Plasma) proteins remain;
  2. Reduces water potential (of blood);
  3. Water moves (to blood) by osmosis;
  4. Returns (to blood) by lymphatic system;
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7
Q

cardiac output

A

heart rate x stroke volume

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8
Q

The rise and fall in blood pressure in the aorta is greater than in the small arteries. Suggest why. (3)

A

(Aorta)
1. (is) close to the heart / ventricle / pressure is higher / is very high;
2. (Aorta has) elastic tissue;
3. (Aorta has) stretch / recoil.

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9
Q

Although the speed of blood flow in an arteriole is greater than speed of blood flow in a capillary, blood does not accumulate in the arterioles.
Explain why. (2)

A
  1. Many / more capillaries (than arterioles);
  2. (Cross-sectional) area of capillaries (much) greater (than of arterioles).
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10
Q

Other than causing slow blood flow, explain one advantage of capillaries being narrow. (3)

A
  1. Short pathway / short distance between blood and outside of capillary;
  2. Large surface area (of blood) in contact with walls of capillaries;
  3. Fast exchange / fast diffusion / fast osmosis.
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11
Q

Explain how blood in a vein in the leg is returned to the heart (6)

A
  1. Muscles (surrounding veins) contract and press on (walls of) vein and squeezes blood along veins;
  2. Valves prevent backflow
  3. contraction of heart pumps blood (through arteries) into veins
  4. Recoil of heart muscle during diastole / after contraction;
  5. Draws blood from veins into atria;
  6. Wide lumen little resistance / friction
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12
Q

Species A and B live in the same place but B is more active.
Suggest an advantage to B of having an oxygen haemoglobin dissociation curve to the right of that for A.

A
  • fish B has greater rate of respiration
  • so more o2 supplied
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13
Q
A
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