Organisms Exchange Substances With Their Environment (6) Flashcards
All cells and organisms exchange material between what?
Themselves and the enviornment
To enter or leave an organism, substances must do what to get across the plasma membrane?
Pass across
The amoeba acmmcan exchange materials across its entire body surface by diffusion. True or False
True
How do we calculate volume?
Length × width ×height
How do we calculate surface area?
(Length × width) × number of faces
Diffusion is directly proportional to what?
(Surface area × difference in concentration) ÷ length of diffusion path
The tracheae are supported by strengthened rings to prevent them from what?
Collapsing
The tracheae divide into smaller dead end tubes called what?
Tracheoles
What are the 3 ways respiratory gases move in and out of the tracheal system?
1) Along a diffusion gradient
2) mass transport
3) the ends of tracheoles are filled with water
Along the diffusion gradient: how is a diffusion gradient formed?
When all of the oxygen is used up and so it’s concentration towards of the tracheoles falls.
In mass transport, contraction of the muscles in insects can squeeze the trachea, enabling what?
Mass movements of air in and out
When an insect is very active, the muscle cells around the tracheoles maybe have to use what?
Anaerobic respiration
The ends of the tracheoles are filled with water: In anaerobic respiration, lactate is produced and lowers the water potential in the muscles cells causing what to happen?
Water at the end of the tracheoles have more water in them
With less water in the the tracheoles, the diffusion of oxygen into cells and carbon dioxide out into the tracheoles is more what?
Rapid
Increasing gas exchange leads to what?
Greater water evaporation
What are spiracles?
Tiny holes on the side of the abdomen
Spiracles can be opened and closed by what?
A valve
Why do spiracles open and close?
To prevent water loss
Insects have waterproof covering, how?
They have a chitin protein and a waxy cutie substance forming an exoskeleton
What is a limitation of insect gas exchange?
Relies mostly on diffusion so short diffusion pathway needed and restricts the size of insects
What is a limitation of insect gas exchange?
Relies mostly on diffusion so short diffusion pathway needed and restricts the size of insects
What is the flao above the gills in a fish called?
Operculum
What does the Gill lamelle do?
Increases the surface area of the gills
What is counter current flow?
When blood and water flow in opposite directions at a constant rate of diffusion across the entire length of the Gill lamelle of which 80% of oxygen from the water is absorbed into the blood
What is parallel flow?
When blood and water flow in the same direction when the diffusion gradient only maintainee across a part of the Gill lamelle of which 50% of oxygen from the water is absorbed into the blood
How might the gills of an active fish be different to the gills of a flat fish which spends most of its time on the sea bed?
- would need more oxygen in the blood
- so Gill lamelle needs to have a larger surface area and more filaments
- because it needs to efficiently absorb oxygen into the blood as they are using more oxygen when contracting their muscles
When the rate of photosynthesis is the same as the rate of respiration what happens?
There is no diffusion of oxygen or carbon dioxide out of or into the leaf
When it Is dark, oxygen is diffusing into the leaf as what is diffusing out of the leaf?
Carbon dioxide
When it is light, carbon dioxide diffused only if the factors that enable photosynthesis are high enough. What arte these 2 factors?
Light intensity and temperature
When it is light, oxygen only diffuses out if the rate of photosynthesis is what?
Greater than the rate of respiration
Where is the stomata located?
Underside of a leaf
Guard cells can do what to the stomata pores?
Change the stomata shape, which can open and close the stomata pores
What are mesophytes?
A plant needing a moderate amount of water
What are hydrophytes?
A plant that grows in or out water
What is a halophyte?
A plant growing in saltmarsh
What is a xerophyte?
A plant which needs very little water and has adaptations to prevent excessive water loss
How does a thick cuticle minimise water loss?
As the cuticle gets thicker and thicker, the less the water can escape as it is a waterproofing layer made of lipid-wax
How does the rolling up of the leaves minimise water loss?
It protects the lower epidermis from the outside and helps to trap still air that is In the rolled lead so no water potential is between the inside and outside of the leaf.
How do hairy leaves and stomata in pits minimise water loss?
The hairs trap still air next to the leafs surface. The water potential between inside and outside is reduced so less water lost by evaporation.
How is a reduced SA:V of the leaves prevent or minimise water loss?
The rate of diffusion is slower as the leaves cross section are circular
