Topic 3
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Alveolar wpithiliul
Falttened/squashed layer of single cells so short diffusion distance
Explain principle of counter current flow
Blood and water flow in opp directions Diffusion conc gradient maintained along the whole length of the gill lamellae
The smaller an organism
=bigger SA:V -which means loose heat faster as cells are closer to surface
The bigger the SA:V
The more heat loss per unit of body mass, the more heat loss that means there needs to be a higher metabolic rate to counteract the more heat loss
Link of SA:V with metabolic rate
-Smaller so larger SA:V -More heat loss per gram/in relation to size -faster rate of respiration/metabolism releases heat
Explain adv for larger animals of having a specialised system that facilitates oxygen uptake
-larger organisms so smaller SA:V -overcomes the long diffusion
Insects gas exchange
Spiracles—->trachea———>tracheoles
Trachea
Has rings of kitin(impermeable) provides strength and prevents inward collapse during venitikaykon
Tracheoles
Site of gas exchange in insect as are permeable, things can pass through it
Features of gas exchange in insects
-tracheoles in direct contact with insects body cells -insects are small maintaining an overall short DD pathway from soiracles to repairing tissues -tracheoles walls r thin
Large SA
Tracheoles branched
Preventing water loss
-coated in an exoskeleton-made out of chitin- impermeable so reduces water loss by evap from insects tissue -exoskeleton also covered in a waxy cuticle-imperanle/ waterproof -spiralclea are lined with hairs to trap water vapour around the spiracles
Gills short dd
Single layer of epithelial cells and cap within the gills have a single layer of endothelial cells
Large SA
Gills—-gill filaments—-gill lamellaw
Potomoter rate of trans: Why is xylem cut under water
As due to cohesion tension theory xylem has a negative pressure meaning it’s always pulling water up so if it was cut in air it would be pulling air up instead sirupiting the continuous coloumn of water flowing preventing transp
Why is an air bubble introduced?
When sir bubble reaches 0 on the capillary tube, start a stopwatch and see how far that bubble travels in a certain period of time
How to workout rate of transp
Vol of a cylinder/time it took water to travel Vol of a cylinder is PIEXR^2L
Why must all the joints in the apparatus be covered in petroleum jelly?
Why must all the joints in apparatus be covered in petrouelm jelly?
Petroleum jelly is waterproof Therefore prevents any water leaking out and ensure all water can leave by evap out stomata of a plant
What variables would have to be controlled if I were to preform this experiment on two different plant species?
-SA of leaves (n.o and size of leaves)
Insect adaptations of gas exahnge surface in tracheal sys
Tracheoles one cell thick- short FD Tracheoles supply muscles fibres/ tissue directly- short Dd Tracheoles-high branched providing large SA
Explain importance of cycles being kept open in a continuous tube
-so water can flow in a continuous coloumn -cohesion can form H bonds between water molecules -transp creates tension
Student wanted to determine the rate of water loss per mm2 of SA of the leaves of the shoot Outline a method she could have used to find this rate.
-method for measuring area e.g draw around each leaf on graph paper and count count square of both sides of leaf -divide rate of water loss/uptake from potomoter bu total surface area
The rate of water movement through a shoot in a potomoter may not the the ale as the rate of water movement through a whole plant Suggest one reason why
-as plant has roots -xylem vessels r very narrow