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Bio Module 5 > Plant and animal responses 5.5 > Flashcards

Plant and animal responses 5.5 Flashcards

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Biology 101 flashcards
1
Q

What is leaf senessence?

A

It is the colour change in leaves caused by the breakdown of chlorophyll

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2
Q

What is leaf abscission?

A

It is the shedding of leaves, fruits and flowers to reduce transpiration to survive harsher conditions

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3
Q

Why does leaf abscission and senessence happen?

A

It is the plants responses to stress

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4
Q

What is tropism?

A

Directional growth towards an external stimulus

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5
Q

What are the 5 types of tropism?

A
  • phototropism
  • geotropism
  • hydrotropism
  • chemotropism
  • thigmotropism
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6
Q

What happens during phototropism?

A

It is the growth response of a plant in response to light, causing positive tropism in the shoots and negative phototropism in the roots

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7
Q

What happens during geotropism?

A

It is the growth response of a plant in response to gravity, causing positive geotropism in the roots and negative tropism in the stem

The stem grows against gravity

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8
Q

What happens during hydrotropism?

A

It is the growth response of a plant in response to water, causing positive tropism in the roots

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9
Q

What happens during thigmotropism?

A

It is the growth response of a plant in response to physical contact, causing positive tropism

Plants cling to physical structures

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10
Q

What happens during chemotropism?

A

It is the growth response of a plant in response to chemicals, causing positive or negative tropism in the roots

They can either grow towards minerals or away from acids

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11
Q

What is a nastic response?

A

A non directional response to an external stimulus

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12
Q

What is an example of a nastic response?

A

Thigmonasty

mimosa plants fold their leaves in response to touch

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13
Q

Why are plant growth regulators considered hormones?

A
  • transported from site of manufacture to target tissues
  • bind to receptors on plasma membrance of specific tissue
  • complimentary shape
  • molecules that influence development in plants
    ***
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14
Q

What is synergism?

A

When 2 or more plant hormones act together to rienforce and amplify the effects

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15
Q

What is antagonism?

A

When 2 or more plant hormones have opposing actions that diminish each others effects

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16
Q

What do plant hormones usually influence?

A

Cell elongation, differentation and division

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17
Q

What are the 5 plant hormones?

A
  • auxin
  • gibberellin
  • cytokinins
  • ethene
  • abscisic acid
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18
Q

What are the effects of auxin?

A
  • promotes cell elongation
  • inhibits lateral growth
  • inhibits leaf absission
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19
Q

What are the effects of gibberellins?

A
  • promotes seed germination
  • promotes growth of stems/ cell elongation
  • stimulates cell division

loosens cell walls
stimulates cell cycle protein

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20
Q

What are the effects of abscisic acid?

A
  • inhibits seed germination and growth
  • causes stomatal closure when the plant is stressed by low water availibility
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21
Q

What are the effects of ethene?

A

Promotes fruit ripening

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22
Q

What are the effects of cytokinins?

A
  • promotes cell division
  • delays leaf abscission and senescence
  • overcomes apical dominance
  • promotes cell expansion
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23
Q

What does the removal of the apical bud cause?

A

lateral growth

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24
Q

What is the apical bud and what does it do?

A
  • top bud on a plant
  • causes apical dominance which promotes vertical growth and inhibits lateral growth

contains lots of auxin, causing cytokinins to accumulate

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25
Q

What causes apical dominance?

A
  • there is a lot of auxin in the bud
  • this causes cytokinins to accumulate near the shoot
  • it increases the ABA in the rest of the plant which inhibits lateral growth
  • this causes apical dominance
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26
Q

What happens when you remove the top bud?

A
  • remove the top bud
  • cytokinins then spread out more evenly along the plant
  • it decreases the ABA so lateral bud growth is stimulated
  • which leads to no apical dominance
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27
Q

What is the role of abscisic acid during apical dominance?

A

Inhibit lateral bud growth

High levels of auxins keep abscisic acid levels high

28
Q

What is the role of cytokinins during apical dminance?

A

Stimulates growth

High levels of auxin cause cytokinins to move to the shoot apex

29
Q

What is the chemical needed to create tall plants?

A

GA1 as it directly causes stem growth

Gibberellin

30
Q

What is the Le gene?

A

It is the gene needed to create the enzyme that converts GA20 into GA1

31
Q

Why are dwarf plants short?

A

They lack the Le gene to convert GA20 into GA1

Contain recessive le allele instead

32
Q

Why is the plant without the na allele short?

A

it cannot turn nt-kaurene into GA12-aldehyde to create GA1

33
Q

What happens when you graft a dwarf plant with one that does not contain the na allele?

A

It lead to the tall plant as the dwarf plant has the na allele and the other plant has the Le allele so together they can creat GA1

34
Q

How are gibberellins used commercially?

A
  • used to develop bigger fruit
  • allows for stem elongation so fruit have more space to grow (grapes)
  • speeds up germination for brewing?
  • allows sugar cane stalks to grow more to increase production
  • lodging (shorter stems so plants don’t snap)
35
Q

How are auxins used commercially?

A
  • promotes rapid shoot growth so stem cannot support leaves and the plant dies (weed killer)
  • on flowers to promote ovule growth so fruit grows with no seeds
  • as a rooting powder to encourage root growth in plant cuttings
36
Q

How is ethene used commercially?

A
  • fruit ripening
  • stops fruit from ripening
37
Q

How does auxin cause cell elongation in the shoots?

A
  • promotes active transport of H+ ions into the cell wall which decreases pH
  • it enables optimum conditions for the enzymes (expansis)
  • this breaks the bonds in the cellulose cell wall as the H+ ions disrupt the H bonds in the cellulose
  • it becomes less rigid and expands as water moves in via osmosis
38
Q

How does auxin cause geotropism in the roots?

A
  • auxin accumulates on he bottom of the roots
  • it inhibits cell elongation so roots grow downwards
  • auxin conc. is much lower in the roots compared to the shoots
39
Q

What tropism experiment did Charles and Francis Darwin do and what did it discover?

A
  • they cut off/ covered he shoot tips
  • the tip is sensitive to light
40
Q

What tropism experiment did Boysen-Jensen do and what did it discover?

A
  • cut off te tip and replaced it with different materals separating it
  • chemical messenger has the ability to move
  • separating part of the shoot from the rest of the plant
  • chemical acts on shady side and encourages growth
41
Q

What tropism experiment did Paal do and what did it discover?

A
  • removing the tip and placing it to one side
  • chemical travels in a downward direction
42
Q

What tropism experiment did Went do and what did it discover?

A
  • cut the tip off and placed it onto agar and then placed the agar on the shoot with no tip
  • chemical messanger can diffuse and can be stimulated artificially
43
Q

How does seed germination happen?

A
  • when conditions are correct the seed begins to absorbe water
  • embryo releases gibberellin which stimulates production of amylase
  • amylase breaks starch down into glucose
  • glucose is used in respiration to release energy
  • energy is used for cellular recations to allow for germination
44
Q

What are examples of smooth muscle?

A
  • blood vessels
  • eyes
  • intestines
  • uterus
  • bladder
  • cardiac muscles
  • respiratory system
45
Q

What is peristalsis?

A

The unvoluntary and smooth contraction and relaxation of the intestines

46
Q

What are the two main divisions of the nervous system?

A

The central nervous system and the peripheral nervous system

47
Q

What is the PNS divided into?

A

The somatic nervous system and the autonomic nervous system

48
Q

What does the CNS consist of?

A

Brain and the spinal cord and relay neurones

49
Q

What is the role of the PNS?

A

To ensure rapid communication between sensory receptors, the CNS and the effectors

50
Q

What are the characteristics of the somatic nervous system?

A
  • effectors are skeletal muscles
  • 1 nerone
  • acetylcholine as neurotransmitter
  • heavily myelinated neurons
  • stimulatory responses
  • quick responses
50
Q

What are characteristics of the sympathetic nervous system?

A
  • prepares body for activity
  • ‘fight or flight’
  • ganglia just outside CNS
  • uses noradrenaline as a neurotransmitter
  • neurons are lightly myelinated
  • most active during times of stress
    Eg/ increases heart rate, dialates pupils
51
Q

What are the characteristics of the parasympathetic nervous system?

A
  • decreases activity/ conserves energy
  • ‘rest and digest’
  • ganglia in effector tissue
  • uses acetylcholine as neurotransmitter
  • neurons are lightly myelinated
  • most active during sleep or relaxation
    Eg/ increases digestive activity, decreases heart rate
52
Q

What are the characteristics of the autonomic nervous system?

A
  • effectors are involuntary muscles
  • 2 neurones
  • acetylcholine and noradrenaline as neurotransmitters
  • lightly myelinated
  • stimulatory or inhibitory responses
  • slower responses
  • splits into parasympathetic and sympathetic nervous systems
53
Q

What does the brain consist of?

A
  • medulla oblongata
  • cerebellum
  • cerebrum cortex
  • hypothalamous
54
Q

What is the role of the medulla oblongata?

A

It controls vital functions like heart and ventilation rates, peristalsis and blood pressure

55
Q

What is the role of the cerebellum?

A

Controls balance and muscle coordination

56
Q

What is the role of the cerebrum cortex?

A

It controls the bodies voluntary behaviour such as learning, personality, memory, decision making, intelligence and sensory input

57
Q

What is the role of the hypothalamus?

A

It recieves sensory information and contains centres that control factors such as temperature and blood solute concentration. It also produces ADH and stores it in the pituitary glands

58
Q

What are the clues that an action is a reflex?

A
  • involves only three neurones
  • coordinated by medulla oblangata
59
Q

What are the clues that an action is involuntary or autonomic?

A
  • does not use the cerebrum cortex
  • does not use decision making
60
Q

What are the characteristics of a reflex?

A
  • involuntary responses
  • very rapid
  • not learned
  • controls everyday actions
61
Q

What is the pathway of the knee jerk reflex?

A
  • receptors at the knee detect the stimulus of the touch
  • action potencial sent down sensory neurone
  • passes the relay neurone in the spinal chord
  • goes down the motor neurone to the effector which causes the quadriceps to contract
  • this reflex helps with balance whilst walking
62
Q

What is the pathways for a cranial reflex (blink reflex)?

A
  • receptors at the eye detect the stimulus of the touch
  • action potencial sent down sensory neurone
  • passes the relay neurone in the medulla oblongata
  • goes down the motor neurone to the effector which causes the eyelid muscles to contract
63
Q

Where are alkaloids found and what do they do?

A
  • growing tips and flowers
  • feeding deterrents as they taste bitter
  • derived from amino acids
64
Q

What do pheromones do?

A
  • secreted by the plant
  • affect the behaviour or physiology of another organism

Bio Module 5 (7 decks)

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