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Biology Year 2 > Chapter 14 - Stimuli and response > Flashcards

Chapter 14 - Stimuli and response Flashcards

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1
Q

What is meant by tropism

A

The response of a plant to a directional stimulus

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2
Q

What is the impact of IAA on shoot cells and root cells

A

Shoot cells elongate

Growth of root cells is inhibited

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4
Q

Explain the process of positive phototropism

A
  • Only in shoots
  • IAA (type of auxin) moves to shaded side of shoot
  • Causing cell elongation in these cells
  • Shoots bend and so grow towards light
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5
Q

Explain the process of negative phototropism

A
  • Only in roots
  • IAA moves to shaded side
  • Inhibits cell growth
  • Roots grow away from light
    Ask sir about this
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6
Q

Explain the process of positive geotropism

A
  • IAA moves to underside of root
  • Inhibits cell growth
  • Roots grows towards gravity
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7
Q

What is meant by taxes

A

When a mobile organism moves towards or away from a directional stimulus
Can be positive or negative, positive towards negative away from

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8
Q

What is meant by kinesis

A

When a mobile organism changes their rate of movement in response to a non-directional stimulus

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9
Q

Explain the choice chamber practical

A

Woodlice

Record rate of movement and final position

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10
Q

What is meant by a reflex

A

A rapid response to a stimulus without conscious control

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11
Q

Draw diagram of a reflex from stimulus to response

A

In folder

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12
Q

What are advantages of reflexes

A
  • Help organisms avoid damage
  • Very fast reaction
  • Doesn’t need to be learned (protect infants)
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13
Q

What is a pacinian capuscle

A

The receptor that detects pressure, touch and vibration in the skin

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14
Q

Explain how the pacinian corpuscle detects pressure

A
  • Pressure causes the lamellae to stretch and deform
  • Stretch mediated sodium ions channels open
  • Sodium ions diffuse into neurone
  • A large stimulus will open more sodium ion channels
  • If threshold is reached then action potential is initiated
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15
Q

Draw and label the human eye

A

Folder

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16
Q

What is the forea

A

The area behind the retina that has lots of photoreceptors, which are mostly cones

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17
Q

What is the blind spot

A

The area behind the retina that has no photoreceptors

18
Q

How does the eye detect light

A
  • Light is focused on retina by the lens
  • Light is absorbed by pigments in the photoreceptors
  • Causes some of the sodium ions channels to open creating a generator potential
  • If this reaches threshold, action potential, bipolar neurone, optic nerve, central nervous system
19
Q

Explain the role of rods

A
  • Monochromatic so only detect one pigment (black and white)
  • More sensitive time low intensity of light
  • Low visual acuity (resolution/detail)
  • Mostly in peripheral part of retina (edges)
20
Q

Explain what cones do

A
  • They’re trichromatic, so have red, green and blue optical pigments, allowing colour vision
  • Less sensitive to low intensity light
  • Higher visual acuity
21
Q

Why do cones have higher visual acuity and are less sensitive to low light than rods

A

Each cone has its own bipolar neurone so need a stronger stimulus to reach threshold, whereas many rods join to a single bipolar neurone so the opposite

22
Q

Explain the order of the heart beat

A
  • Sinoatrial node (SAN) initiates the heart beat
  • Sends an electrical impulse across the atria
  • Atria contract
  • Non-conductive tissue prevents the electrical impulse reaching the ventricles
  • Atrioventricular nose delays electrical impulse, allowing atria to contract and empty before ventricles contract
  • AVN sends the electrical impulse down the bundle of His and along the purkyne fibres
  • Ventricles contract from the base upwards
23
Q

What is different about the left ventricle

A
  • Has highest blood pressure
  • Most cardiac muscle
  • Contracts with a greater force
  • Pumps blood to the whole body
24
Q

Explain how heart rate is slowed down in the body

A
  • Chemoreceptors detect high blood oxygen, low blood CO2 and high pH, or baroreceptors detect high blood pressure
  • Receptors send nerve impulses to medulla oblongata in brain
  • Medulla oblongata sends nerve impulses along parasympathetic neurone
  • Parasympathetic neurones secrete acetylcholine
  • Heart rate slows down
25
Q

Explain how heart rate is sped up in the body

A
  • Chemoreceptors detect low blood oxygen, high blood CO2 and low pH, or baroreceptors detect low blood pressure
  • Receptors send nerve impulses to medulla oblongata
  • Medulla oblongata sends nerve impulses along sympathetic neurones
  • sympathetic neurones secrete noradrenaline
  • Heart rate speeds up
26
Q

Explain the process of negative geotropism

A
  • IAA moves to underside of shoot
  • Causes cell elongation
  • Shoot grows away from gravity
27
Q

What is the photosynthetic pigment in cones called

A

Iodopsin

28
Q

What is the photosynthetic pigment in rods called

A

Rhodopsin

Biology Year 2 (10 decks)

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