gcse biology paper 2
what is a stimulus
change in the enviroment
what is homeostasis
maintenance of a constant internal enviroment to perform at optimum
name the relay arc in order
stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector
what is a receptor
detects a stimuli
what is a coordination centre
process information from the receptors
what is an effector
brings about a response
what does the cerebellum control in the brain
movement of muscles
what do effectors typically come in the form of
muscles and glands
what does the cerebral cortex control
controls conciousness and intelligence such as language
what does the medulla control
unconcious activity such as breathing rate
what is the pituary gland
the master gland
what does the hypothalmus do
controls body temperature and water levels
what is accomodation
the adjustment of the eye over various distances
state 3 things that happen when focusing on a near object
cilliary muscles contract
suspensory ligaments loosen
the lens get thicker and more curved
state 3 things that happen when focused on a distant object
cilliary muscles relax
suspensory ligaments tighten
lens becomes thinner
what is short sightedness called
myopia
what is long sightdness called
hyperopia
what is the general optimum human body temperature
37.5 degrees
what happens if temp becomes to high
sweating
vasodilation (widening of the blood vessels to lose heat)
what happens when temp becomes to low
shivering (respiration releases energy)
vasoconstriction (vessels narrow)
hairs stand to create an insulating layer
what is a community
two or more populations of organisms
what is an abiotic factor
a non living factor that affects the enviroment
what is a biotic factor
a living factor that affects the enviroment
state 3 abiotic factors
light intensity, water levels, Ph
state 2 biotic factors
producers and consumers
what does interdependence mean
it means all organisms in a food chain rely on each other
what is the optimum temp for photosynthesis
20 degrees celsius
what is the maximum efficiency of aerobic respiration
40-50 percent
what is produced when a plant respires anaerobically
ethanol and carbon dioxide
what is a trophic level
each of several heirachal levels in an ecosystem
what gases make up biogas
methane and carbon dioxide