Term | Definition |
enzyme | Highly specialized protein that reduces amount of energy required to initiate a chemical reaction, increasing the speed of the reaction |
metabolism | All of the biochemical reactions occurring in the cells of the body |
Enzyme models: Lock and Key; Induced Fit | Mechanisms for enzyme mechanisms- lock and key: instant fit; induced fit: enzyme changes shape when substrate binds |
pH | describes the acidity of a substance |
homeostasis | Tendency in organisms towards maintenance of physiological stability |
stimulus-response pathway | stimulus--> receptor --> control centre --> effector --> response |
nervous system | The system of nerves and nerve centres in an animal |
nervous system and feedback mechanism | sensory neurones- takes signal from the receptor to control center.
relaying neurones- takes signal around control center.
motor neurones- takes signal from control center to effector |
ectotherms | Organisms that change their body temperature by using heat from environment |
endotherms | Organisms that regulate their own body temperature using heat generated from their metabolism |
Australian endotherms | kangaroo, bandicoot |
Australian ectotherms | brown snake, blue tongue lizard |
optimum enzyme conditions | For optimal efficiency- specific temperatures, pH and amount of substrate are needed |
positive feedback mechanism | enhance or amplify changes e.g. contractions during birth |
negative feedback mechanism | conteracts changes to return to a stable, maintained level e.g. responding to temperature |
plant responses to temperature change | sunken stomata, leaf orientation, leaf fall |
structural adaptations | physical features of an organism e.g. feathers |
behavioural adaptations | behaviours of an organism e.g. hibernation |
physiological adaptations | permit an organism to perform special functions e.g. shivering |
denatured | structural change in proteins that cause destruction of the active site |
active site | a region on an enzyme that binds to a protein or other substance during a reaction |
evaporative cooling | removing heat from body by changing liquid water to water vapour using heat from skin (sweating) OR from respiratory surfaces (panting) |
metabolic pathway | Series of step-wise chemical reactions, each governed by an enzyme. e.g. Cellular Respiration; Photosynthesis are metabolic pathways |
rate of reaction | Speed at which a reaction proceeds. Measured by: amount of substrate used up or products formed in a given amount of time |
vasodilation | When we are too hot the blood vessels supplying warm blood to the skin become enlarged or dilated |
vasoconstriction | When we are too cold the blood vessels supplying warm blood to the skin become narrow or constrict |
ambient | environmental or surrounding (e.g. ambient temperature) |
Stimulus- response example | Stimulus: Increase temperature
Receptor: Thermoreceptor in skin
(via sensory neurones to)
Control center: Hypothalamus (in brain)
(via motor neurones to)
Effector: Sweat glands activated
Response: Sweat produced & evaporative cooling takes place |