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Biology Section 3 - Organisms Exchange Substances with their Environment (Section 3) > Mass Transport (Chapter 7) > Flashcards

Mass Transport (Chapter 7) Flashcards

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1
Q

Describe haemoglobin

A

A protein with 4 polypeptides, each associated with a haem group and each being able to carry an oxygen molecule.

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2
Q

Describe the role of haemoglobin and how it carries oxygen

A

1) Haemoglobin has a high affinity for oxygen - forms oxyhemoglobin in red blood cells.
2) Loading happens in lungs at a high partial pressure of oxygen.
3) Unloads/dissociates to respiring tissue at a low partial pressure of oxygen.
4) Unloading linked to higher carbon dioxide concentration.

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3
Q

Why does carbon dioxide cause a disassociation of oxygen?

A

(More respiration) more CO2 lowers the pH which reduces the affinity for oxygen by changing shape of haemoglobin so shifts curve to the right.

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4
Q

Why is the dissociation curve an s-shape?

A

1) Oxygen binds (to Hb causing a change in shape).

2) (Shape change of Hb) allows more O2 to bind easily/greater saturation with O2.

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5
Q

What is shown when a dissociation curve is shifted to the right?

A

1) Haemoglobin has a lower affinity for oxygen.
2) Dissociates to respiring tissue more readily at higher partial pressure of oxygen.
(3) Link to animal e.g. more oxygen for more respiration to generate heat.

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6
Q

What is shown when a dissociation curve is shifted to the left?

A

1) Haemoglobin has a higher affinity for oxygen.
2) Haemoglobin saturated and dissociates at lower partial pressure of oxygen.
(3) Link to animal

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7
Q

Describe the structure of the heart

A

Has 4 chamber - 2 atria and 2 ventricles and 4 vessels

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8
Q

How is pressure maintained in the heart?

A

Blood goes back to heart after lungs

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9
Q

What is the purpose of valves?

A

Stops blood from flowing backwards.

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10
Q

What are coronary arteries?

A

Arteries around the outside of the heart to provide oxygen to the heart muscle fibres.

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11
Q

Define myogenic

A

Beats by itself

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12
Q

Where does the aorta transport blood to and from?

A

Heart to body (oxygenated)

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13
Q

Where does the pulmonary artery transport blood to and from?

A

Heart to lungs (de-oxygenated)

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14
Q

Where does the pulmonary vein transport blood to and from?

A

Lungs to heart (oxygenated)

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15
Q

Where does the vena cava transport blood to and from?

A

Body to heart (de-oxygenated)

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16
Q

Describe the cardiac cycle

A

1) Diastole - relaxation. Blood in atria forces atria-ventricular valves to open. Semi-lunar valves close as pressure is lower in ventricles that arteries.
2) Atrial Systole - SAN transmits impulses to atria. Atria muscles contract and blood forced into ventricles.
3) Ventricular Systole - Wave of electrical activity passes from Atrioventricular Node (AVN) to atrial muscle.
4) Passes impulse to Bundle of His then to smaller muscle fibres at the bottom of ventricles.
5) Ventricles contract from bottom (apex of heart) upwards and blood is forced out through aorta.

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17
Q

What is the role of the SAN?

A
  • Sends out electrical impulses

* Initiates the heartbeat/acts as a pacemaker/stimulates atria to contract

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18
Q

Why is there a short delay between electrical wave entering the AVN and leaving?

A

It allows the atria to empty and the ventricles to fill before the ventricles contract. This happens as there is a layer of non-conductive tissue between the atria and the ventricles.

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19
Q

Why is pressure higher in ventricles than atria?

A

Has more muscle so contractions are stronger.

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20
Q

What are arteries and their properties?

A

Vessels which carry blood away from the heart.

Thickest elastic, quite thick muscle layer, thin endothelium, no valves.

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21
Q

What are arterioles and their properties?

A

Carry blood under low pressure to tissues.

Quite thick elastic layer, thickest muscle layer (proportionally), thin endothelium, no valves

22
Q

What are capillaries and their properties?

A

Exchange metabolic material with cells.

Numerous and branched, no valves, narrow lumen, walls consist mainly of lining layer, narrow diameter.

23
Q

Why do blood vessels have muscular walls?

A

Can change the blood flow/pressure. The muscles can contract, which reduces diameter of lumen (vasoconstriction). They can then relax to increase diameter of lumen (vasodilation).

24
Q

Why do blood vessels have elastic tissue?

A

Allows stretching/recoil/smoothes out flow of blood/maintains pressure. When ventricles contract the elastic tissue is stretched, this can recoil back when ventricle relaxes.

25
Q

Why do blood vessels have an endothelium?

A

Causes reduced friction as it is smooth

26
Q

Why do large organisms need a mass transport system?

A

Have too small SA:Volume ratio

27
Q

What is blood plasma?

A

Fluid that bathes blood cells in capillaries. Same as tissue fluid but with large proteins.

28
Q

What is tissue fluid?

A

Fluid that has left the capillary and bathes cells. Contains glucose, amino acids and fatty acids. Allows materials to be exchanged with cells. The ventricles contract and this produces high hydrostatic pressure which forces water out of blood capillaries.

29
Q

What is the hepatic artery/vein?

A

Carry blood to/from the liver

30
Q

What is the renal artery/vein?

A

Carry blood to/from the kidney

31
Q

What is the hepatic portal vein?

A

Carry blood from stomach and intestines to liver

32
Q

What is tissue?

A

Several types of cells working together.

33
Q

What is an organ?

A

Several types of tissue working together.

34
Q

What is an organ system?

A

Different Organs working together

35
Q

What is the xylem?

A

Hollow tubes that transport water. Dead hollow cells which form a continuous column.

36
Q

What is transpiration?

A

Water evaporating out of the stomata on the leaves of a plant. Transpiration pull helps to transport materials in a plant.

37
Q

What is the cohesion-tension theory?

A

Explains the tension caused by water loss from the top (stomata) and water moving at the bottom (root pressure`)
.

38
Q

Describe the process of transpiration

A

1) Water evaporates out of the stomata on the leaves of the plant.
2) Lowers water potential in the spongy mesophyll.
3) Water pulled up the xylem.
4) Water molecules stick together by cohesion due to hydrogen bonds.
5) Form a continuous water column as the adhesion of water to walls of xylem.

39
Q

What factors affect the rate of transpiration?

A

Increase (positive correlation):

  • Light Intensity - Stomata open to allow CO2 in for photosynthesis.
  • Temperature - The kinetic energy of water molecules increase so the molecules move faster.
  • Air Movement - Removing the moist air surrounding the leaf lowering water potential.

Decrease (negative correlation):

• Air humidity - Affects the water potential gradient

40
Q

What are potometers used for?

A

Measure water uptake

41
Q

Why does a potometer not measure the true transpiration rate?

A
  • Water is lost through other processes such as respiration/photosynthesis
  • Used to provide support
  • Maybe a leak in apparatus
42
Q

How is the rate of transpiration calculated using a potometer?

A

𝛑r^2 x distance moved by the air bubble in set time

𝛑r^2 = area of the capillary tube

43
Q

Describe how to set up a potometer

A

1) Must be airtight
2) Cut shoot at slant underwater
3) Insert apparatus underwater so there are no bubble at the start.
4) Note where the bubble starts.

44
Q

How is water loss calculated per mm^2 of SA of leaves?

A

1) Draw around leaves on graph paper and count square.
2) Repeat on both sides of leaves.
3) Divide rate by total surface area.

45
Q

What is some evidence for cohesion-tension theory?

A
  • Tree trunks have a wider diameter at night when transpiration is at its lowest.
  • If xylem is broken water doesn’t leak out and air enters so water can no longer enter the plant.
46
Q

What is the phloem?

A

Tissue which transports biological molecules in either direction. Made of sieve tube elements arranged end to end. Walls perforated to form sieve plates. Companion cells often associated with sieve tube elements.

47
Q

What is translocation?

A

How organic molecules and minerals ions are transported around a plant.

48
Q

What are sources?

A

Where sugars are made during photosynthesis.

49
Q

What are sinks?

A

Where sugars are used or stored

50
Q

What is Mass Flow Hypothesis?

A

1) Sugars are actively transported into phloem by companion cells.
2) Lowers water potential of sieve cells/tube and water enters by osmosis.
3) Increase in pressure causes mass movement (towards sink/root).
4) Sugars used/converted in root for respiration for storage.

51
Q

What are ringer and tracer experiments used for?

A

Can be used as evidence for translocation in the phloem.

52
Q

What are phloem sap feeders used for?

A

Used to show that the phloem carries sugar. They feed without jaw muscles as there is a high hydrostatic pressure in the phloem.

Biology Section 3 - Organisms Exchange Substances with their Environment (Section 3) (2 decks)

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