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A-level Biology > 6- Nervous Sytem And Homeostasis > Flashcards

6- Nervous Sytem And Homeostasis Flashcards

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1
Q

Why do we need a nervous repsone

A

Selection pressure favours orgaisms with the more appropriate response

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2
Q

What is a stimulus

A

A detectable chmage In the internal or external environment

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3
Q

What is the response

A

What an organism can do to react to the stimuli

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4
Q

What are cells sensitive to stimulus called

A

Receptors

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5
Q

T or f
Receptors are specific to stimuli they recieve

A

T

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6
Q

response produced by an effector can be at what 2 levels

A

At a molecular level ( hormones)
Behaviour of Whole organism

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7
Q

What is taxis

A

The moment of an animal towards or away form a stimulus in one direction
Eg, chemotaxis

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8
Q

What is kinesis

A

Orienting behaviour where an animal reduced or increases it rate of movement as the intensity of a stimuli increases

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9
Q

What is an example of kinesis

A

Woodlois start to move when they start to dry out

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10
Q

What is Tropism

A

The growth movement of part of a plant in response to a directional stimuli

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11
Q

What is the reflex escape response

A

Rapid automatic response to escape predators

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12
Q

Why do plants respond to external stimuli

A

Avoid stress
Avoid being eaten
Enhance survival
Improve chances of successful breeding

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13
Q

What is phototropism response to

A

Light

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14
Q

What is geotropism response to

A

Gravity

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15
Q

What is chemotropism response to

A

Chemicals

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16
Q

What is thigmotropism response to

A

Touch

17
Q

What controls the response of plants

A

hormones control / coordinate plant response

18
Q

What are the chemicals in plants still considered hormones eventhough they are not produced by the endocrine system

A

They are transported away from site of manufacture to a target cell

19
Q

Do hormones allways move from site of manufacture to target cell

A

No some hormones stay in the cell that makes them and exerts their effects within the cell

20
Q

Descirbe hormones in plants

A

Produced by a specific cell
Have a specific shape
Bind to reseptors on the target cell
Receptor complementary to the shape of the hormone

21
Q

How are hormones carried around the plant

A

Diffusion
Active transport
Mass flow ( phloem / xylem)

22
Q

What is it called when hormones amplify each other

A

Synergy

23
Q

What is it called when hormones cancel each other out

A

Antagonistic

24
Q

Where does growth in a plant occur

A

Meristem

25
Q

What are the 3 areas of the meristem ( and be able to label)

A

Apical meristems
Lateral bud meristems
Intercallary meristem

26
Q

What causes phototropism

A

All shoots bend towards the light
As the shaded side elongates faster as light causes auxins to be transported to shaded side which promotes growth

27
Q

What causes gravptropism

A

Auxin increases in side next to the stimulus and inhibits growth. So upper roots grow quicker and bend roots ( down ) towards stimuli

28
Q

What does IAA stand for

A

Indolaceticacid

29
Q

What is the commercial use of auxins

A

Promotes cell gworth so used in cuttings
Seedless fruits
Herbicides

30
Q

What is the commercial use of gibberellins

A

Seed germination and grows the stems
Delays senescence ( aging )
Imporves shapes

31
Q

What is the commercial use of cytokinins

A

Promotes cell division
Prevents yellowing
Mass production

32
Q

What is the commercial use of ethene

A

Promotes fruit ripening
Promotes fruit drop
Female sex expression in cucumbers
Promotes lateral growth

33
Q

What is the acid growth hyposthesis

A

The action of IAAs increases the plasticity of cell walls in young cells (mature cells are more rigid)
Active transport of H+ ions form cytoplasm to spaces in the cell wall causing cell to become more plastic and elongated by expansion

34
Q

Describe the plant repsonse experiment carried out by Charles Darwin;

A

He observed young grass shoots growing towards the light
He proposed stimuli of the light was detected by the tip of the shoot
He cut of the tip in one
One with a tip bent towards the light , one with no tip had no response

35
Q

Desicbe the Peter boysen-jenson experiment

A

He tried to prove weather chemical substances produced in the top and transported down the stem and cause a repsonse or an electrical signal
He put a thin impermeable barrier of mica on light side# movement of chemical down shaded side caused stem to bend toward slight

The put the mica on the shaded side - the chemical was blocked by the mica so no response

Then he put a block of gelatin across whole stem- an electrical signal would be blocked by a chemical can still move , the stem bent towards the light so chemicalnot electrical

36
Q

Desicbe paal plant response experiments

A

He investigated how chemical messagers worked - he removed tops of shoots and put them in darkness
The tips bent towards side where no tips where present

37
Q

Describe the Winslow brings plant response experiment

A

How Light caused uneven distribution of IAA
1- two tips , one had light and bent - the total IAA is each was approx the same

2- then 1 tip with a thin glass plate separating the side of the shoot
Amount of iaa collected is apr. The same

3- half glass plate
Bent - 30% collected in light side amd 70% on shaded elongated side

A-level Biology (8 decks)

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