Reasons for a Transport System (OCR A-Level Biology A): Flashcards
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Practise the cards
10 cards from this deck
What cells need from surroundings
What cells need from surroundings
Nutrients and oxygen
How small organisms obtain O₂ & nutrients
How small organisms obtain O₂ & nutrients
Diffusion across body surface
Problem 1 for large organisms (distance)
Problem 1 for large organisms (distance)
Increasing distances - diffusion too slow
Problem 2 for large organisms (surface)
Problem 2 for large organisms (surface)
Decreasing surface area:volume ratio
Problem 3 for large organisms (activity)
Problem 3 for large organisms (activity)
Higher activity levels need more O₂
Definition: mass flow
Definition: mass flow
Directed movement by mechanical force
What drives mass flow in animals
What drives mass flow in animals
Heart/muscular contractions
Surface area represents (SA:V ratio)
Surface area represents (SA:V ratio)
Supply of oxygen
Volume represents (SA:V ratio)
Volume represents (SA:V ratio)
Demand for oxygen/number of cells
Examples of specialized exchange surfaces
Examples of specialized exchange surfaces
Lungs and intestines