3.1.2 Features of Exchange Surfaces

Question 1

How are fish adapted for gas exchange?

Answer 1

• Counter current flow (capillaries covering gills ensure blood flow is opposite direction to water flow)
• Concentration gradient always maintained along whole length of capillary
• Lamellae increase SA

Question 2

Ventilation

Answer 2

• maintains concentration gradient
• always higher concentration of oxygen in alveoli than in blood

Question 3

What are the features of effective exchange surfaces?

Answer 3

• Large Surface Area
• Short Diffusion Distance (thin)
• Good blood supply
• Ventilation Mechanism

Question 4

Root Hair Cells

Answer 4

• Absorb mineral ions and water from soil
• Have a root hair which increase SA
• Water uptake by osmosis is greater

Question 5

Alveoli Adaptations

Answer 5

• Thin (one cell thick) walls made of 1 layer of flattened squamous epithelium
• Short diffusion distance for exchange O2 and CO2 into and out of the blood
  .
• Lots of alveoli
• Large SA for exchange of O2 and CO2
  .
• Lots of capillaries
• Capillaries are 1 cell thick, short diffusion distance
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• Constant blood flow
• Maintains concentration gradient