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biology year 13 IRIS > 5.5 plant & animal responses > Flashcards

5.5 plant & animal responses Flashcards

(64 cards)

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1
Q

What are the two plant responses?

A

Response to abiotic stress
Response to herbivor attact

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2
Q

What are the responses to abiotic stress?

A

Extra wax deposition
Hyper-lignification
Folding to touch
Geotropisms
Phototropism

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3
Q

Why do plants deposit additional wax?

A

Resist evaporation in hotter environments

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4
Q

Why do plants have additional lignin deposits?

A

To aid plants in windy conditions

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5
Q

What is a tropism?

A

Directional growth in response to a stimulus

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6
Q

What is a positive tropism?

A

Growth towards a stimulus

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7
Q

What is a negative tropism?

A

Growth away from a stimulus

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8
Q

What is a nastic response?

A

A non-directional response

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9
Q

What are plant hormones?

A

Chemical messengers that are transported from a tissue of origin to act on a target tissue

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10
Q

What are the plant responses to herbivores?

A

Alkaloid production: bitter tasting shoots, roots, flowers and stems
Tannin production: bitter tasting leaves, antimicrobial properties prevent entry of pathogens
Pheremone production: Repel feeding insects and attracts their predators

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11
Q

What do you call the buds on the side of the plant?

A

Lateral buds

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12
Q

What do you call the buds on top of the plant?

A

Apical buds

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13
Q

What is a plant bud?

A

Cluster of young developing leaves

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14
Q

Describe apical dominance

A

High concentrations of auxins in the shoot tips keeps abscisic acid levels in lateral buds high and cytokinin levels low- this restircts growth (of lateral buds)

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15
Q

How do you override apcal dominance?

A

Cut the tip
If no auxins are produced in the tip, abscisic acid levels in lateral buds decrease and cytokinin concentrations increase- promoting growth

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16
Q

What do gibberellins stimulate?

A

Germination and cell elongation

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17
Q

What is germination?

A

The sprouting of a seed spore

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18
Q

How do gibberellins stimulate cell elongation?

A

ent-kauerne -. intermediate giberellins -> GA1 -> cell elongation

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19
Q

Explain the mechanism of seed germination

A
  1. Water absorbed by seed reaches embryo
  2. Giberellins released by embryo
  3. Giberellins absorbed by aleurone layer of seed
  4. Aleurone stimulated to secrete amylase enzyme
  5. Amylase digests starch to maltose. Maltase digests maltose to glucose
  6. Glucosed used for respiration and protein synthesis
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20
Q

Describe the role of abscisic acid

A

Inhibits seed germination and growth
Causes stomatal closure

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21
Q

Describe the role of cytokinin

A

Delays plant cell senescence
Overcomes apical dominance

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22
Q

What are the roles of the (3 that we need to know) hormones in plants?

A

Auxin: leaf loss in deciduous plants
Gibberellins: promote cell elongation and germination
Abscicic acid: stomatal closure

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23
Q

What is primary growth in plants?

A

Lengthening

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24
Q

What is secondary growth in plants?

A

Widening

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25
What type of meristem tissue controls primary growth?
Root and shoot apical meristem Lateral bud meristem: found in bud gives rise to side shoots
26
What type of meristem tissue controls secondary growth?
lateral meristem (form a cylinder around the shoots and roots)
27
Describe how IAA (auxin) works in shoots
IAA transported to side of shoot without sunlight Promotes cell elongation on the side without sunlight (with auxin) so that the shoot grows towards the sunlight (positive phototropism)
28
Describe how IAA works in the roots
IAA transported to lower side of flat root and inhibits cell elongation so that the root grows down towards the ground (positive geotropism)
29
How does auxin work?
Increases A.T of H+, increasing H+ conc. Lower pH allows wall-loosening enzymes to work at optimum.
30
What is the use of auxin commercially?
-Added to rooting powder to encourage growth of roots in cuttings -Promotes seedless fruit growth when added to unpollinated flowers -Herbicide: causes uncontrollable growth which can lead to stem breakage
31
What is the use of gibberellins commercially?
Delays ripening
32
What is the use of ethene commercially?
Speeds up ripening and fruit drop
33
Role of medulla oblongata in the brain?
- Regulates heart rate - Vasoconstriction and vasodilation - Breathing rate and depth
34
Role of cerebrum in brain?
Higher thought processes: - thought - speech - consciousness - memories - language
35
Role of cerebellum in the brain?
Movement and balance including fine precise movements
36
What part of the brain would you find the pituitary gland and hypothalamus?
The medulla oblongata
37
What is the role of the hypothalamus?
Produces hormones that are transferred into the blood in the posterior pituitary gland Releasing factors from the pituitary gland stimulate the anterior pituitary gland to release its own hormones
38
What is a reflex?
Rapid autonomic response that protects body from harm. Has 'survival value' Not coordinated by cerebrum to increase speed
39
What is the general pathway of a reflex action?
sensory, relay, motor
40
What is the nervous pathway of a knee reflex? Why is this special?
sensory, motor Because there is no relay neurone, the motor neurone is directly stimulated by the sensory neurone, this doesn't give the brain enough time to override this process
41
How can reflexes be overridden?
When a reflex occurs, higher centres in the brain are informed that the stimulus has occurred. Cerebral cortex sends inhibitory signals to motor center. (This process uses myelinated neurones whereas relay neurones are unmyelinated so it's faster and occurs before the action has occurred)
42
How is the fight or flight response coordinated?
1. Hypothalamus secretes releasing hormones CRH and TRH 2. CRH triggers the secretion of ACTH from the pituitary gland which stimulates the adrenal cortex to secrete corticoid hormones 3. TRH triggers the secretion of TSH from the pituitary gland, stimulating the secretion of thyroxine from the thyroid gland 4. These hormones are secreted into the bloodstream 5. At the same time, the hypothalamus also stimulates a sympathetic response 6. This causes the adrenal medulla to secrete adrenaline into the blood and the activation of glands and smooth muscles 7. This neural activity combines with the hormones in the blood to coordinate the fight or flight response.
43
Describe the action of hormones in cell signalling
1. Adrenaline = first messenger 2. Binds to receptor on cell surface membrane 3. This activates G protein 4. This activates adenyl cyclase 5. This activates cAMP (second messenger) 6. Leads to the activation of enzymes involved in the fight or flight response
44
Describe how processes in the stretch receptors in the muscles control the heart rate
1. Stretch receptors in muscles detect movement 2. This triggers a response in which information is relayed to the cardiac centre of the medulla oblongata 3. The medulla oblongata then relays information to the SAN and causes the heart rate to increase This is a sympathetic response
45
Describe how the processes in the Chemoreceptors of the blood vessels control the heart rate
1. Chemoreceptors detect an increase in blood pH 2. A response occurs in which information is relayed to the cardiac centre of the medulla oblongata 3. Medulla oblongata sends impulses to the SAN and causes the heart rate to increase This is a sympathetic response
46
Describe how the process in baroreceptors of the blood vessels control heart rate
1. Baroreceptors detect an increase in blood pressure 2. A response occurs in which information is relayed to the cardiac centre of the medulla oblongata 3. The medulla oblongata coordinates the SAN to decrease the heart rate This is a parasympathetic response
47
What is muscle tissue?
Specialist tissue that contracts and shortens to produce a force
48
Describe smooth muscles
- Individual cells with tapered ends - Each has its own nucleus
49
Describe cardiac muscle
- Each cell is fused together with intercalated discs, forming long fibres with cross-bridges
50
Describe skeletal muscle
Long, multinucleate cells joined end to end- known as muscle fibres Fibres bunch to form bundles
51
What is the 'hierarchy' of muscle structure?
cells, bundles, fibres, myofibril
52
How are muscles caused to contract?
1. Action potential reaches end of motor neurone 2. Cause Ca2+ ion channels to open and Ca2+ to diffuse into the motor neurone 3. This causes vesicles containing ACh to fuse to the CSM and release the ACh into the neuromuscular junction 4. ACh binds to Na+ ion channels on the sarcomere, causing them to open, allowing Na+ to diffuse into the sarcoplasm, depolarising the sarcomere 5. Waves of depolarisation travel down t-tubules to the sarcoplasmic reticulum 6. This stimulates the sarcoplasmic reticulum to release Ca2+, initiating muscle contraction.
53
What is the region called where motor neurones interact with muscle fibres
Neuromuscular junction
54
When the muscles contract, what happens to the z lines?
They get closer together
55
When the muscles contract, what happens to the sarcomere?
It gets narrower
56
When the muscles contract, what happens to the A band?
Nothing
57
When the muscles contract, what happens to the I band?
It gets narrower
58
When the muscles contract, what happens to the H zone?
It gets narrower
59
How do muscles contract?
1. Myosin head attaches to myosin binding site on actin filaments forming a cross bridge 2. ADP and Pi release from myosin head, causing it to tilt (known as a power stroke) 3. The actin filament is dragged towards the centre of the sarcomere 4. The myosin head will remain in the forward power stroke position until ATP binds and breaks cross bridge 5. ATP is hydrolysed to ADP and Pi, resetting the myosin head position
60
How is contraction controlled?
Ca2+ ions will bind to troponin which moves the tropomyosin out of the way so that the myosin binding site is revealed.
61
How is the provision of ATP maintained in the muscles
Creatine phosphate is hydrolysed into creatine and Pi. The phosphate can then be combined with ADP to form ATP.
62
What is primary growth in plants?
The increase in length of the roots and shoots
63
What is secondary growth in plants?
The widening of the plant/ increased girth of plant
64

biology year 13 IRIS (16 decks)

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