Bio Module 8 Notes

Resource Description

Module 8 Notes by C.P

IQ1: How is an organism’s internal environment maintained in response to a changing external environment?

1.1 construct and interpret negative feedback loops that show homeostasis, including temperature and glucose

HOMEOSTASIS

● Homeostasis is the maintenance of a stable internal environment despite changes in the external environment.
● Stimulus (change) receptors (detect change and convert into nerve impulse) control centre (brain/spinal cord) messenger (communicates message from CNS to effector) effector (receives message and causes response) response (change in body).

● Malfunctions in homeostatic mechanisms can lead to disease.

o e.g. hyperglycaemia or hypoglycaemia diabetes
o e.g. hypothermia or hyperthermia heat stroke, pneumonia

1.2 investigate mechanisms used by organisms to maintain their internal environment, including:
− behavioural, structural and physiological adaptations in endotherms that assist homeostasis

ANIMAL ADAPTATIONS FOR HOMEOSTASIS
● Heat is exchanged with the environment through conduction, convection, radiation and evaporative cooling.
● Endotherms produce their own body heat through metabolism e.g. mammals and birds
● Ectotherms use the external environment to obtain heat energy e.g. fish, reptiles, invertebrates

● Structural adaptations relate to the size and shape of an organism and its body parts.

o e.g. kangaroos have network of veins under thin forelimb skin
o e.g. body proportions suited to climate

● Physiological adaptations relate to how an organism’s body works.

o e.g. temperature regulation – vasoconstriction, vasodilation, sweating
o e.g. hormonal control of water levels (see: kidneys)

● Behavioural adaptations relate to an organism’s behaviours.

o e.g. snakes seeking sun or shade
o e.g. kangaroos licking forelimbs to promote evaporative cooling
o e.g. penguins huddling for warmth
− mechanisms in plants that allow water balance to be maintained