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Communication and
-Describe the need for communication
systems within multicellular organisms
Define the terms negative feedback,
positive feedback and homeostasis
Q: What do cells need to keep active and
alive?…read more

Slide 2

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To describe responses that maintain a
constant core temperature in ectotherms
and endotherms
Q: Why does the temperature of an organism need to
be kept to an optimum?
What is meant by physiological and behavioural
responses?…read more

Slide 3

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All animals except mammals and birds
E.g. snakes, lizards
Temp fluctuates with external temp
Cannot increase respiration rate to
generate heat internally
Rely on external sources of heat
But can still regulate their body temp
under most conditions…read more

Slide 4

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Frilled lizard
Horned lizard…read more

Slide 5

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Ectotherms: advantages
Use less food in respiration
So need less food
Can survive long periods (weeks)
without eating
More energy from food can be used for
growth…read more

Slide 6

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Ectotherms: disadvantages
Less active in cooler temps
(need to warm up before they can be
So risk of predation
May be incapable of activity in winter
So must have enough energy stores to
survive without eating…read more

Slide 7

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Slide 8

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Slide 9

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Slide 10

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