Survival and Response Flashcards

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1
Q

Taxis

A

directional response to stimulus

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2
Q

Kinesis

A
  • random, non-directional response
  • to non-directional stimulus
  • changes in speed and rate of change of direction
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3
Q

Explain how organisms increase their chance of survival by detecting changes in their environment

A
  • detect and move away from harmful stimuli

- increase chance of moving into favourable environment towards food etc.

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4
Q

Tropism

A
  • growth of plant

- in response to directional stimulus

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5
Q

Auxin

A
  • growth hormones
  • made continually in shoots and roots
  • indoleacetic acid (IAA)
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6
Q

Explain how IAA causes cell elongation in shoots

A
  • 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
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7
Q

Explain how IAA results in phototropic response in shoots

A
  • 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
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8
Q

Explain how IAA results in gravitropic response in roots

A
  • IAA accumulates in underside of root
  • due to gravity
  • IAA inhibits cell elongation
  • bending downwards
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9
Q

Suggest what experiment cutting off shoot tip proves

A
  • shoot does not bend towards light

- tip produces response (contains IAA auxin)

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10
Q

Suggest what experiment placing lightproof cover over shoot tip proves

A
  • shoot does not bend towards light

- light stimulus must be detected by shoot tip

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11
Q

Suggest what experiment removing shoot tip and inserting gelatin block between tip and rest of shoot proves

A
  • shoot bends towards light

- chemical response not electrical

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12
Q

Suggest what experiment removing shoot tip and displaced to one side of shoot in darkness proves

A
  • shoots bend towards sides without shoot tip
  • bending is result of uneven distribution of hormone
  • not light alone
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13
Q

Suggest what experiments placing glass plate between shoot to prevent and allow lateral transfer of IAA prove

A
  • 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
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14
Q

Suggest how movement of maggots keep them moving rapidly out of unfavourable areas

A
  • move faster
  • change direction less often
  • so keeps them moving in one direction
  • stops them going around in circles
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15
Q

Central Nervous System

A

consists of brain and spinal cord

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16
Q

Peripheral Nervous System

A

pairs of nerves originating from brain or spinal cord

17
Q

Name types of neurones and their functions

A

Sensory Neurone - receptors to CNS
Interneurone - sensory to motor neurone
Motor Neurone - CNS to effector (muscle or gland)

18
Q

Autonomic

A
  • subconscious/ involuntary response
  • bypasses brain
  • carried to smooth muscles, glands and cardiac muscle
19
Q

Reflex Arc

A
  • pathway of neurones in an involuntary response to a sensory stimulus
  • stimulus > receptor > sensory neurone > interneurone > motor neurone > effector
20
Q

State the purpose of the reflex arc in providing a survival advantage

A
  • protection against damage to body tissue
  • help escape predators
  • rapid
  • enable homeostatic control
  • (brain free for more complex cognitive responses)
21
Q

State reasons why the reflex arc produces a rapid response

A
  • few neurones involved

- bypasses brain

22
Q

Sympathetic (Autonomic Nervous System)

A
  • fight or flight
  • stimulates effectors
  • controls conditions under stress/ activity
  • accelerates heart rate, constricts blood vessels, raises blood pressure
23
Q

Parasympathetic (Autonomic Nervous System)

A
  • rest and digest
  • inhibits effectors
  • controls conditions at rest
  • slows heart rate, increases intestinal and glandular activity
24
Q

Medulla oblongata

A
  • located in brainstem (continuation of spinal cord)
  • contains cardiovascular centre
  • one part linked to SAN by SNS and the other by PNS
25
Q

Describe how the body detects and responds to a decrease in pH

A
  • detected by chemoreceptors in wall of aorta/carotid
  • increased frequency of impulses sent to medulla oblongata
  • impulses sent via SNS to SAN to increase frequency of impulses
  • cardiac muscle contracts more frequently
  • increased heart rate removes excess carbon dioxide
26
Q

Describe how the body detects and responds to an increase/decrease in pressure

A
  • detected by baroreceptors in wall of aorta/carotid
  • increased frequency of impulses sent to medulla oblongata
  • impulses sent via PNS/SNS to SAN to decrease/increase frequency of impulses
  • cardiac muscle decreases/increases heart rate