Topic 4 -gaseous exchange systems Flashcards
name 7 layers of a plant leaf:
- waxy cuticle
- upper epidermis
- paliside mesophyll layer
- spongey mesophyll layer
- lower epidermis layer
- guard cells
- stomata
layers of a plant leaf
waxy cuticle
what does it do?
- prevents water loss
layers of a plant leaf
upper epidermis
-characterisitcs?
- which does what?
- found where in leaf?
- transparent to allow maximum light through to cells w/ chloroplast
- below cuticle. The epidermis is the top layer
layers of a plant leaf
palisade mesophyll layer
- how ceels stacked?
- what do they contain? and why?
- whaere are they in the leaf?
- cells stacked vertically to fit in as many cells as possible.
- These cells contain the most chloroplast. To maximise the energy transfer in photosynthesis.
- below upper epidermis
- composed of cylindrically shaped cells oriented perpendicular to the leaf surface.
layers of a plant leaf
spongey mesophyll layer
- what does it have and what for?
- where is it located?
- air spaces provide increased surface area for gas exchange
- the center mesophyll, between the palisade mesophyll layer and the lower epidermis of the leaf
layers of a plant leaf
guard cells
- walls are thicker on side adjacent to stomata to enable opening + closing
layers of a plant leaf
stomata
guard cells open + close to prevent excessive water loss
plants
how do the stomata open
aside from guard cells
opens by ions (k+)by moving into guard cells by active transport, causing water to move by osmois bc the water potential decreased, which makes gaurd cells turgid. This causes guard cells to swell+ stomata open
What makes guard cells turgid
ions moving into guard cells by active transport, water moving by osmosis
what are lenticles
areas of loosely arranged cells whcih act as a pore to allow gas exchange in lignified (woody) plants
gaseous exchange in mammals happens where
lungs
mammals
Boyle’s law?
what does this mean?
Volume is inversley proportional to pressure
- means inhalation happens by contraction of the intercostal muscle and diaphram. This casues volume to increase, which causes pressure to decrease and air moves into lungs by diffusion down pressure grandient
mammals
what happens in exhalation
intercostal muscles + diaphram relax = decreased vol = increased pressure =mair diffuses out down the pressure gradient
mammals
what in the lungs provides a large S.A
alveoli
mammals
why to the capillaries have a short diffusion distance
not bc theyre one cel thick
- one layer of epithelial cells provides short diffusion distance
mammals
why is the conc. gradient steep in capillaries
bc the blood in capillaries is deoxygenated as the oxygenated blood is carried away, so conc. gradient is always steep
insects
insects have a ____?____ gas system bc they have an ___?__
whcih ___?__ thewm from taking gas via __?__ through the skin
insects have a specialised gas system bc they have an exoskeleton which prevents them from taking gas via diffusion through the skin
insects
what are the openings on insects called (pores)?
spiracles
how are spiracles closed and opened.and why do they?
by Sphincters to prevent water loss
insects
what is trachea lined with? and whats its purpose
rings of chitin. prevents it from collapsing
insects
why cant the trachea carry out gas exchange?
bc its lined with rings of chitin wehich make it impermeable
insects
what gas diffuses through the spiracles
O2
from the trachea where does O2 diffuse into?
the tracheoles bc theyre permeable
what happens when water builds up at the bottom of tracheoles, slowing diffusion.
water is removed in active insects bc lactic acid builds up in cells, whcih lowers water potential, so water moves into cells by osmosis, gas exchange to occur.
- some ative insects have to ventilate their repiratory systems via mechanical ventiliation (pumping abdomen) and/ or air reserves
fish
process of which gas echange happens in fish
- floor of mouth opens ( Buccal cavity)
- operculum (gill flaps) close s
- floor of mouth closes (increases pressure, valve stops water leaving)
- increased pressure forces operculum open = forces water over the gills
fish
why is gas exchange in water more difficult?
bc water is denser and more visous than air, only contains 5% of Oxygen
what law is used to pump water over the gills
Boyle’s law
“volume is inversley proportional to pressure.”
fish
gills are made of ? that are covered by folds called ?
made of fillaments, covered by lamellae
why is the constant movement of water over gills good?
- it keeps them spread out = increased S.A + prevents them sticking together
fish
how do you maintain the conc. gradient btwn water and rich blood supply in capillary network in the lamellae
with a counter current system
draw one out
what hapens in a counter current system?
this is where the water flowing over the gills and blood in gill fillaments flow in opposite directions, maintaining a steep conc. gradient over entire gill fillament
