Chapter 1 - Principles Of Exchange And Transport Flashcards
What do animal tissues obtain?
Oxygen form the air
Glucose, fatty acids and amino acids from ingested food
Water
What do plant tissues obtain?
Oxygen form air
Carbon dioxide from air
Inorganic ions from soil solution
Water
What does a surface need to have to exchange substances?
It needs to be moist and permeable
Why do mammals and plants require specialised exchange surfaces?
It depends on the size and shape of an organism, because both these factors affect the surface area-to-volume ratio
What is surface area?
Represented as the total number of cells in direct contact with the surrounding environment
What is volume?
The total three dimensional space occupied by metabolically active tissues
Is it better to have a small or large surface area-to-volume ratio?
Large
What reasons would an organism need a specialised exchange/absorptive surface?
It has an impermeable surface,
Large,
Small SA-V ratio,
High metabolic rate
Methods of increasing absorptive surface
Evagination (outfolding) of the surface
Invagination (infolding) of the suface
Flattening if the organism
Where can the specialised surfaces be?
They can be internal exchange surfaces e.g. Fish gills and alveoli
They can be external exchange surfaces e.g. Folded external membranes of the external gills of young tadpoles
Why are exchange surfaces thin?
So that the rate of diffusion is maximised
Why does there need to be a large concentration gradient?
Diffusion will only occur across a surface if there is a concentration gradient.
What is mass flow?
It is brought about by pressure differences existing within the organism.
Materials are moved by the pressure differences between the area where pressure is generated(source) and the area where the pressure is much less(sink)
What are some examples of mass flow systems
Xylem tissue,
Phloem tissue,
Circulation in mammals,
Ventilation in mammals.
What does the xylem do?
Transports water and mineral ions fro the roots to the leaves
What does the phloem do?
Transport of sucrose(translocation) to roots and to growing regions.
What does circulation in mammals do?
Transport of substances including oxygen, carbon dioxide, glucose, amino acids, lipids, and urea in the blood system around the body
What happens during ventilation in mammals?
The bringing fresh air into the lungs and removing air with raised carbon dioxide levels and low oxygen levels,
It ensures that diffusion if respiratory gases can take place between the alveoli and the capillaries
How do you maximise the rate of exchange?
Have a large surface area, Have a moist surface, Have diffusion gradients for both oxygen and carbon dioxide, Must be permeable, Thin exchange surface.
What is Ficks law?
Surface area x difference in concentration
___________________________________________
Rate of diffusion=. thickness of membrane
Leaf adaptations for gas exchange
Leaves are thin,
Large and moist gas exchange surfaces of the spongy mesophyll,
Intercellular air spaces of the spongy mesophyll,
Stomata and two guard cells,
Waxy cuticle to reduce water loss
