Survival and Response Flashcards
(26 cards)
Taxis
directional response to stimulus
Kinesis
- random, non-directional response
- to non-directional stimulus
- changes in speed and rate of change of direction
Explain how organisms increase their chance of survival by detecting changes in their environment
- detect and move away from harmful stimuli
- increase chance of moving into favourable environment towards food etc.
Tropism
- growth of plant
- in response to directional stimulus
Auxin
- growth hormones
- made continually in shoots and roots
- indoleacetic acid (IAA)
Explain how IAA causes cell elongation in shoots
- acid growth hypothesis
- IAA causes H+ to be actively transported out of cytoplasm to spaces in cell wall
- acidification causes cell wall to be more plastic and elongate
Explain how IAA results in phototropic response in shoots
- light cause uneven distribution of IAA
- IAA moves from light side to accumulate on shady side of shoot
- IAA causes cell elongation
- bending towards light
Explain how IAA results in gravitropic response in roots
- IAA accumulates in underside of root
- due to gravity
- IAA inhibits cell elongation
- bending downwards
Suggest what experiment cutting off shoot tip proves
- shoot does not bend towards light
- tip produces response (contains IAA auxin)
Suggest what experiment placing lightproof cover over shoot tip proves
- shoot does not bend towards light
- light stimulus must be detected by shoot tip
Suggest what experiment removing shoot tip and inserting gelatin block between tip and rest of shoot proves
- shoot bends towards light
- chemical response not electrical
Suggest what experiment removing shoot tip and displaced to one side of shoot in darkness proves
- shoots bend towards sides without shoot tip
- bending is result of uneven distribution of hormone
- not light alone
Suggest what experiments placing glass plate between shoot to prevent and allow lateral transfer of IAA prove
- when glass plate prevents lateral transfer of IAA shoot does not bend towards light
- when glass plate allows lateral transfer of IAA shoot bends towards light
- IAA transported from light to shady side
- uneven distribution of IAA causes bending
- light does not inhibit or destroy IAA
Suggest how movement of maggots keep them moving rapidly out of unfavourable areas
- move faster
- change direction less often
- so keeps them moving in one direction
- stops them going around in circles
Central Nervous System
consists of brain and spinal cord
Peripheral Nervous System
pairs of nerves originating from brain or spinal cord
Name types of neurones and their functions
Sensory Neurone - receptors to CNS
Interneurone - sensory to motor neurone
Motor Neurone - CNS to effector (muscle or gland)
Autonomic
- subconscious/ involuntary response
- bypasses brain
- carried to smooth muscles, glands and cardiac muscle
Reflex Arc
- pathway of neurones in an involuntary response to a sensory stimulus
- stimulus > receptor > sensory neurone > interneurone > motor neurone > effector
State the purpose of the reflex arc in providing a survival advantage
- protection against damage to body tissue
- help escape predators
- rapid
- enable homeostatic control
- (brain free for more complex cognitive responses)
State reasons why the reflex arc produces a rapid response
- few neurones involved
- bypasses brain
Sympathetic (Autonomic Nervous System)
- fight or flight
- stimulates effectors
- controls conditions under stress/ activity
- accelerates heart rate, constricts blood vessels, raises blood pressure
Parasympathetic (Autonomic Nervous System)
- rest and digest
- inhibits effectors
- controls conditions at rest
- slows heart rate, increases intestinal and glandular activity
Medulla oblongata
- located in brainstem (continuation of spinal cord)
- contains cardiovascular centre
- one part linked to SAN by SNS and the other by PNS
