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Adaptations
Chloroplasts
Chlorophyll embedded in a double membrane
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These structures hold the chloroplasts in the position where the
most light falls
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Excess glucose
is converted into starch and stored in starch grains to make sure water potential is unaffected
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Cellulose is held
together by (1,4) glycosidic bonds
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Small bundles of cellular molecules make microfibrils which re
very strong – can withstand stretching
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Cellulose also limits water intake
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Amylose – 1-4 glycosidic bonds
allows the molecule to coil
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Amylase breaks down starch into glucose but we build glycogen to store
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This allows glycogen to be really branched and quickly breaks down
when needed
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SA:V ratio
The larger the animal the smaller the surface area to volume ratio
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This
prevents them from drying out but also makes it impossible for gas exchange
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Air passes through the
spiracles into a system of tracheae and tracheoles
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In larger insects the spiracle close and muscles pull skeletal plates of abdomen which squeezes
tracheal system and pumps air in sacs deeper into tracheoles
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When wing muscles work really hard they respire partly anaerobically and
lactate is produced
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Fish
Each gill arch has two stacks of thin plates – filaments – that stick out and on top of each filament is
a row of thin lamellae
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Because they are delicate they are protected by

an operculum
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Counter-current system – blood flows in the opposite direction to the water and this maintains the
concentration gradient across the whole gill plate
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Stomata – on the underside of the leaf (open during sunlight hours)
Guard cells – surround the stomata
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Mesophyll – central tissue has many air spaces to allow gases to circulate
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Large syrface area exposed to
atmosphere
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Xerophytes
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thick waxy cuticle
small or needle-shaped leaves – reduce surface area exposed to atmosphere
few stomata
stomata sunken into pits
hairs around stomata – help to reduce air movement
leave can roll up – water vapour becomes trapped and kept near stomata
two sets of roots, set that grows sideways to take advantage of occasional heavy showers
and a set that grows straight down to obtain water from a low water table
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