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Biology > 6.1 - Receptors, survival and response > Flashcards

6.1 - Receptors, survival and response Flashcards

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1
Q

Define tropism

A

Growth towards a directional stimulus

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2
Q

Name the two types of animal response

A
  • taxis (directional) - moves directly towards/away from stimulus
  • kinesis (non-directional) - change in speed of movement and rate it changes direction
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3
Q

What is IAA?

A

indoleacaetic acid - a type of auxin (growth factor), so broken down by light

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4
Q

Auxin effect in shoots and roots

A

Shoots - stimulate growth so causes cell elongation
Roots - inhibits (slows, not stops) growth so prevents cell elongation

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5
Q

Auxin effect (phototropism)

A

shoots - IAA diffuses from shoot tip to shaded side, so cell elongation, so bends towards light source (positive phototropism)
roots - IAA inhibits elongation so roots elongate more on lighter side and root bends away from light (negative phototropism)

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6
Q

Auxin effect (gravitropism)

A

shoots - IAA diffuses from upper side to lower side, causes cells to elongate and plant grows upwards (if on its side, shoot will bend upwards) = negative gravitropism
roots - IAA diffuses to lower side of roots so upper side elongates and root bends towards gravity = positive gravitropism

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7
Q

How is IAA transported?

A

usually by diffusion, /active transport for short distances e.g through phloem

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8
Q

Define energy transducer

A

converts one type of energy into another

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9
Q

Rods

A
  • found on retina except fovea
  • rhodopsin photopigment
  • three rods synapse to one bipolar neurone (convergence to produce summation)
  • high light sensitivity
  • low visual acuity
  • mitochondria, RER, nuclei
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10
Q

Why can rods detect light of very low intensity?

A

due to retinal convergence - 3 rods connect to one bipolar neurone, so there is a summation of generator potentials

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11
Q

Cones

A
  • found on fovea
  • iodopsin photopigment
  • monosynaptic so separate impulses sent to brain, so can distinguish light sources as separate
  • low light sensitivity so iodopsin requires high light intensity to be broken down and trigger action potential
  • high visual acuity
  • mitochondria, RER, nuclei
  • 3 types: sensitive to blue, green, red (each cone contains only one type to detect a certain wavelength of light)
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12
Q

How does colourblindness occur?

A

brain interprets wrong colour cone

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13
Q

Breakdown of rhodopsin by light energy into…

A

retinal and opsin
(can be resynthesised)

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14
Q

Suggest how muscles enable the pupil to constrict

A

radial muscle relaxes
circular muscle contracts

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15
Q

Describe how pressure affects a Pacinian Corpuscle

A
  • caused stretch mediated sodium ion channels to open due to being stretched and deformed
  • so sodium ions flood in down electrochemical gradient
  • produces generator potential
  • which causes action potential when reaches the threshold
  • once threshold reached, this is the maximum response no matter how much pressure is applied (either a response or no response)
  • greater pressure means more channels open
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16
Q

Movement of ions in and out of Pacinian Corpuscle

A

sodium potassium pump
- 3 sodium ions out
- 2 potassium ions in
cell is more permeable to K+ ions than Na+ ions

17
Q

Describe how the heart coordinates the regular contraction of the atria and ventricles

A
  • synoatrial node (SAN) sends wave of electrical activity across atria, causing atrial contraction
  • non-conducting tissue prevents immediate contraction of ventricles
  • atrioventricular node (AVN) delays impulse whilst blood leaves atria and ventricles fill
  • AVN sends wave of electrical activity down Bundle of His/Purkyne fibres
  • causing ventricular contraction from apex upwards
18
Q

Explain how the heart muscle and valves maintain a one-way flow of blood from left atrium to aorta

A
  • higher pressure in atrium than ventricle causing atrioventricular valves to open
  • ventricle has a higher pressure than atrium causing AV valves to close
  • ventricle has higher pressure than aorta causing semilunar valve to open
  • higher pressure in aorta than ventricle causing SLV to close
  • contraction causes increase in pressure
19
Q

Define myogenic

A

can initiate its own contractions without any nervous stimulation

20
Q

Describe the role of receptors and nervous system in detecting an increase in HR

A
  • chemoreceptors detect rise in CO2/H+/acidity/carbonic acid/fall in pH OR baroreceptors detect rise in blood pressure
  • impulses sent to medulla
  • more frequent impulses to SAN
  • by sympathetic NS (chemo) OR parasympathetic NS (baro)
21
Q

How does the heart coordinate both ventricles so they contract at the same time?

A
  • electrical activity only through Bundle of His
  • wave of electrical activity passes through both ventricles at the same time
22
Q

Examples of stimuli

A

(animals): light, pressure, moisture
(plants): light, gravity, water

23
Q

Two branches of nervous system

A

central - brain, spinal cord
peripheral - receptors, sensory neurones, motor neurones

24
Q

Typical threshold value for pacinian corpuscle

A

-55mV

25
Q

Suggest advantages of simple reflexes

A

quick response
do not have to be learnt
protect against damage to body tissues
help escape from predators
enable homeostatic control

26
Q

Two branches of peripheral NS

A
  • somatic (conscious)
  • autonomic (unconscious)
27
Q

Define cardiac impulse

A

impulse heart generates to contract

28
Q

Where is the sinoatrial node (pacemaker) found?

A

right atrium

29
Q

Two types of autonomic response (antagonistic), their neurotransmitters, neurone locations, and type of receptors

A

parasympathetic (rest and digest), acetylcholine, in middle/lower spinal cord, baroreceptors
sympathetic (fight or flight), noradrenaline, in brain and base of spinal cord, chemoreceptors

30
Q

Where are baroreceptors found?

A

walls of carotid arteries
aorta walls
medulla

31
Q

Parasympathetic or sympathetic to increase or decrease HR/blood pressure

A

HR/blood pressure too low: sympathetic
HR/blood pressure too high: parasympathetic

32
Q

Consequences of blood pressure

A

too high: artery wall damage
too low: insufficient supply of O2 blood to respiring cells and waste removal

33
Q

Consequences of pH

A

ph decreases when high respiratory rate due to CO2/lactic acid production
too low: enzymes denature
so HR is increased to make CO2 diffuse out of alveoli more rapidly to prevent denatured enzymes

34
Q

Describe the role of the SAN

A

initiates heartbeat, acts as a pacemaker, stimulates atrial contraction

Biology (37 decks)

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