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Biology Unit 2 > Exchange and Transport > Flashcards

Exchange and Transport Flashcards

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1
Q

What maintains the diffusion gradient of gases in + out of a cell?

A

Mitochondria have lowest conc of O2 + highest conc of CO2

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2
Q

Why do large organisms have internalized gas exchange systems?

A

They have small surface area to volume ratio

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3
Q

Why don’t small organisms have internal exchange systems?

A

Have a large surface area to volume ratio

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4
Q

What three ways do insects minimize water loss?

A
  1. Waterproof shell
  2. Small surface area
  3. Close spiracles
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5
Q

How does Oxygen reach the cells of an

Insect?

A
  • enter into spiracle
  • diffuses through trachea + tracheoles down conc gradient
  • abdominal muscles contract for ventilation of air to maintain conc gradient
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6
Q

How is diffusion kept efficient between the tracheoles + surrounding cells?

A

Every cell very short distance from tracheoles

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7
Q

Describe the two main structures in fish gills

A

Gill filaments + lamellae on them

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8
Q

What is countercurrent flow?

A

Water flows in opposite direction to blood in the gill lamellae

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9
Q

What is the purpose of the gill lamellae?

A

Increase surface area for gas exchange

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10
Q

How is a steep diffusion gradient maintained in fish?

A

Ventilation of oxygen

Mass transport of O2 carried away from gills by blood

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11
Q

Explain how the countercurrent flow creates a diffusion gradient across the whole length of the gill lamellae

A
  • O2 blood meets water that has max O2 = diffusion

- no O2 blood meets water that still has some O2 left = diffusion

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12
Q

What would happen if the blood + water flowed in the same direction across the gill lamellae?

A

Gas exchange reaches equilibrium + diffusion only occurs across part of gill lamellae

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13
Q

Why is countercurrent flow important in the gas exchange in fish?

A

Maintains a concentration gradient for diffusion across the whole length of gill lamellae

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14
Q

What is the purpose of the tracheoles?

A

Thin + permeable walls = short diffusion distance to surrounding cells

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15
Q

Oxygen still diffuses into the leaf when it is dark, why?

A

It’s constantly being used by cells in respiration

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16
Q

Why are the diffusion gradients maintained in the leaf?

A

Mitochondria respiring + chloroplasts photosynthesis

17
Q

How does the structure of the leaf allow for efficient gas exchange?

A
  • Cells close to external air, flat leaf

- diffusion in gas spaces = quicker than in water

18
Q

Why does the leaf have no specialized gas exchange system?

A

Large surface area to volume ratio

19
Q

What adaptations does a leaf have for rapid diffusion?

A
  • thin + flat = SA + cells not far from external air
  • stomata on underside of leaf
  • interconnecting air spaces in mesophyll
20
Q

What do plants do to control gaseous exchange and water loss?

A

Guard cells close stomata

21
Q

What two factors determines whether a large organism has an internalized gas exchange network?

A
  • if the SA:V ratio is small

- how active organism is

22
Q

What are 3 features of transport systems in large organisms?

A
  1. Blood to carry materials
  2. Tubular vessels that contain blood + distribute
  3. Valves to ensure movement in one direction
23
Q

Why does the oxygenated blood return back to the heart from the lungs instead of just circulating round the rest of the body?

A

Low pressure after lungs = too slow

24
Q

Why do the substances + gases in the blood need to be delivered to cells in mammals quickly?

A

Mammals have a high body temp => high metabolism

25
Q

What basic structure of layers do all arteries, arterioles and veins have + what is the purpose of each layer?

A
  • tough outer layer: pressure
  • muscle: contract
  • elastic: stretch/recoil, pressure
  • endothelium: friction
  • lumen: carries blood
26
Q

Which vessel carries out exchange of material?

A

Capillaries

27
Q

How do the proportions of an artery differ to veins and relate to its function?

A
  • thicker muscle layer than veins = constrict blood flow to arterioles
  • thicker elastic layer than veins = stretch + recoil + smooth/high pressure smooth
  • thick wall = pressure bursting
  • no valves = high pressure
28
Q

How does the structure of an arteriole differ to an artery + link to its function?

A
  • thicker muscle layer: vasoconstriction

- thinner elastic layer: pressure is lower

29
Q

How does the structure of a vein link to its function?

A
  • thin muscle layer: carrying blood away from tissues
  • thin elastic layer: pressure too low
  • thin wall: flattened easily = aid flow of blood
  • valves: prevent back flow
30
Q

How does the structure of the capillaries link to their function?

A
  • endothelium layer = short diffusion distance
  • branched = SA
  • narrow diameter = permeate tissues
  • narrow lumen = blood cells flat
  • spaces in endothelial = white blood cells escape
31
Q

Name 3 substances tissue fluid contains

A

Amino acids, glucose, oxygen

32
Q

What is hydrostatic pressure?

A
  • Pressure created by the blood moving from the arteries, arterioles, to capillaries
  • forces tissue fluid out of blood
33
Q

What two forces oppose the movement of tissue fluid out of the capillaries?

A
  • hydrostatic pressure of tissue fluid

- lower water potential of blood (few proteins)

34
Q

What type of filtration occurs at the arteriole end of the capillary?

A

Ultrafiltration (large molecules left in blood)

35
Q

Why does tissue fluid return to the venous end of the capillary?

A
  • lower hydrostatic pressure inside capillary than surrounding tissue fluid
  • low water potential because of many proteins in blood = gradient = osmosis
36
Q

How is the composition of the tissue fluid different when it returns to the capillaries?

A

CO2 + waste materials from cells

37
Q

What two forces move the tissue fluid through the lymphatic system to the heart?

A

Hydrostatic pressure + contraction body muscles

38
Q

Why don’t red blood cells + plasma proteins move out of the capillaries?

A

Too large

Biology Unit 2 (11 decks)

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