5.5 Plant and Animal Respsones Flashcards
(136 cards)
1
Q
Give 4 types of tropisms.
A
- phototropism
- geotropism
- thigmotropism
- chemotropism
2
Q
Describe phototropism.
A
Shoots growing towards the light
3
Q
Describe geotropism.
A
Roots growing towards the pull of gravity.
4
Q
Describe thigmotropism.
A
Shoots winding around a structure or other plants to gain support.
5
Q
Describe chemotropism.
A
When pollen tubes grow downwards, attracted by chemicals in the ovary.
6
Q
What is a tropic response?
A
A directional growth response.
7
Q
What is a nastic response?
A
A non-directional growth response.
8
Q
What is the difference between a positive tropism and a negative tropism?
A
A positive tropism is when a plant responds towards the stimulus but in a negative tropism the plant responds away from the stimulus.
9
Q
What are 3 chemical plant responses?
A
- tannins
- pheromones
- alkaloids
10
Q
What are tannins?
A
Phenol compounds in the upper epidermis that are toxic to herbivores and microorganisms.
11
Q
What are alkaloids?
A
Chemicals derived from amino acids in the tips, stems and roots that make the plant taste bitter to animals.
12
Q
What are pheromones?
A
Chemicals released by one individual that can effect the behaviour of others.
13
Q
What are auxins?
A
A family of plant hormones responsible for growth.
14
Q
Describe apical dominance.
A
When growth from the apical (top) bud inhibits the growth of the lateral buds.
15
Q
Describe the effects of high auxin levels.
A
High rates of apical growth and low rates of lateral growth.
16
Q
Describe the effects of low auxin levels.
A
High rates of lateral growth and low rates of apical growth.
17
Q
What other hormone does high levels of auxins promote?
A
Abscisic acid.
18
Q
What is the function of abscisic acid?
A
To inhibit lateral growth.
19
Q
What hormone follows auxins around the plant?
A
Cytokinins
20
Q
What is the function of cytokinins?
A
To promote all bud growth.
21
Q
What following events occur when the plant tip stays intact?
A
- high auxin levels so auxins are in the apical bud
- high abscisic acid levels
- cytokinins follow auxin to the apical bud
- high apical bud growth and low lateral bud growth
22
Q
What following events occur when the plant tip is cut off
A
- lower auxin levels so auxins are spread out
- cytokinins are therefore also more spread out
- lower abscisic acid levels
- high lateral bud growth and low apical bud growth
23
Q
What are gibberellins?
A
Plant hormones that cause seed germination and stem elongation.
24
Q
What are the two subsystems of the human nervous system?
A
Central Nervous System
Peripheral Nervous System
25
What is the central nervous system made up of?
The brain and spinal cord
26
What is the peripheral nervous system made up of?
All of the other nerves in the body not in the brain or spinal cord
27
What are nerve cells also called?
Neurones
28
What are the 3 types of nerves?
Sensory
Relay
Motor
29
What two categories of nervous systems are there?
Somatic nervous system and Autonomic nervous system
30
What is the function of the somatic nervous system?
For the control of voluntary movements.
31
What is the function of the autonomic nervous system?
For involuntary functions and movements.
32
What are the two types of autonomic nervous system
Sympathetic and Parasympathetic
33
What does the sympathetic nervous system control?
The release of adrenaline during the 'fight or flight response'.
34
What is the cerebrum?
The largest part of the brain that controls voluntary actions, conscious thought, vision and speech (an others)
35
What connects the two cerebral hemispheres?
The corpus callosum.
36
What is the cerebellum?
Part at the back of the brain that controls muscle coordination and movement.
37
What is the medulla oblongata?
The part at the base of the brain that controls involuntary actions such as heart and breathing rates.
38
What is the hypothalamus?
Area in the middle of the brain just above the pituitary gland that monitors blood and helps maintain homeostasis.
39
What is the pituitary gland?
At the bottom of the brain below the hypothalamus. It releases a range of hormones. It is divided into the anterior and posterior pituitary.
40
What are the 4 lobes in the brain?
Frontal Lobe
Parietal Lobe
Occipital Lobe
Temporal Lobe
41
What is the sequence that causes a reflex action?
```
Stimulus
Receptor
Coordinator (either brain or spinal cord)
Effector
Response
```
42
What type of neurone detects the stimulus?
Sensory Neurone
43
What type of neurone carries an impulse to the effector?
Motor Neurone
44
Name a reflex that doesn't use relay neurones?
The knee jerk reflex
45
What is the coordinator of the knee jerk reflex?
The spinal cord
46
What causes the blinking reflex
Something travelling towards the eye or contacting the cornea?
47
What is the coordinator of the blinking reflex?
The brain
48
Why cant adrenaline enter a cell?
It is a peptide hormone so is not lipid soluble
49
Describe the mechanism of adrenaline action?
- adrenaline binds to the adrenaline receptors on the plasma membrane
- this stimulates the G protein which activates the enzyme adenyl cyclase
- adenyl cyclase converts ATP into cAMP (cyclic adenine monophosphate)
- cAMP is the second messenger which causes effects in the cell by releasing enzymes to initiate the fight or flight response
50
What is the contractile unit of skeletal muscle?
Myofibril
51
What are the two protein filaments in a myofibril?
Actin and Myosin
52
Which of the protein filaments in a myofibril is thinner?
Actin
53
Which of the protein filaments in a myofibril come in bundles?
Myosin
54
Which molecules are wound around actin
Tropomyosin
55
What molecules are attached to tropomyosin?
Troponin
56
How many polypeptides does a troponin complex have?
3
57
What do the 3 polypeptides of troponin bind to?
- one to tropomyosin
- one to actin
- one to calcium ions when available
58
What part of the myosin binds to actin
The myosin heads
59
What is the sarcomere
The distance between the two Z lines on a myofibril
60
What is the I band
The part of a sarcomere where there is no myosin
61
What is the H zone
The part of the sarcomere where there is no actin
62
What parts of the sarcomere shorten when the the myofibrils contracts
The I band and H zone
63
What describes the relationship between actin and myosin
They are agnostic so work opposite eachother.
64
Describe how an action potential reaches the muscle fibres
- following the action potential in the motor neurone, the acetylcholine will diffuse across the neuromuscular junction and bind to receptors on the sarcolemma
- this opens sodium ion channels on the sarcolemma membrane and allows for the depolarisation of the sarcolemma
- the depolarisation spreads across the sarcolemma and down the transverse tubules to the muscle fibres
65
What is a motor unit
When a motor neurone spreads an action potential to many muscle fibres causing greater contraction.
66
Which type of muscle cell is multinucleated
Skeletal muscle
67
What is the name of the membrane that surrounds skeletal muscle cells?
The sarcolemma
68
What is the name of the cytoplasm of skeletal muscle cells
Sarcoplasm
69
What are the sub-units of myofibrils
Sarcomeres
70
Where does the action potential travel once it has gone down the transverse tubules
Into the sarcoplasmic reticulum
71
What happens when the action potential reaches the sarcoplasmic reticulum
It releases calcium ions into the sarcoplasm
72
What happens when calcium ions enter the sarcoplasm
Calcium ions bind to the troponin. This alters the shape of the tropomyosin which pulls the tropomyosin aside and exposes the binding sites on the actin.
73
What happens when the binding site on actin is exposed.
Myosin heads bind with the actin and form cross bridge bonds. The myosin heads move backwards, pulling the actin along the myosin. The myosin heads then detach from actin and can form more bonds further up the actin. This causes the muscle to contract
74
What happens in the myofibrils once muscles have contracted
Calcium ions are pumped back into the sarcoplasmic reticulum and the muscles relax
75
What provides energy for muscle contraction
The hydrolysis of ATP to ADP and a phosphate group
76
What happens in the power stroke
When the myosin head tilts backwards and pulls the actin across the myosin
77
What is released from myosin during the power stroke
ADP and a phosphate group
78
What happens after the powerstroke
ATP attaches to the myosin head and breaks the cross bridge bonding
79
What happens to ATP when the myosin head returns to its original position
The ATP is hydrolysed to release energy
80
What is creatine phosphate
The reserve store of phosphate groups in the sarcoplasm to phosphorylate ADP into ATP to provide energy for additional contractions
81
What is the difference between voluntary and involuntary muscle
Voluntary muscle contracts under conscious control but involuntary muscle contraction is unconscious.
82
Which section of the nervous system controls voluntary muscle
The somatic nervous system
83
Which section of the nervous system controls involuntary muscle
The autonomic nervous system
84
What are the 3 types of muscle tissue
Cardiac
Smooth (AKA involuntary)
Skeletal
85
Describe the structure of smooth muscle
Tapered, spindle shaped cells that are uni-nucleated and arranged longitudinally.
86
Describe the function of smooth muscle
Smooth muscle contracts slowly and regularly in the walls of tubular structures such as blood vessels and the intestines.
87
Describe the structure of cardiac muscle
Long fibres that are branched and form cross bridges. The cells are joined by intercalated discs. This increases the speed of action potential contraction.
88
Describe the function of cardiac muscle
Myogenically conducting tissue that is controlled by the SAN in order to pump blood around the body
89
Describe the structure of skeletal muscle
Multinucleated fibres surrounded by a sarcolemma membrane. Fibres are divided into myofibrils with sarcomere subunits.
90
Describe the function of skeletal muscle
Found at joints in the skeleton and it's contraction allows for the movement of the skeleton. Skeletal muscles are arranged in agnostic pairs where when one contracts, the other relaxes
91
Why is cardiac muscle myogenic
It is self stimulating and initiates it's own heart beat
92
What are the 3 ways heart action can be modified
- heart rate
- stroke volume
- force of ventricular systole
93
How is the cardiac output calculated
Heart Rate X Stroke Volume
94
Which cardiac muscle has a higher myogenic frequency
Atrial muscle has a higher frequency than ventricular muscle
95
What initiates the action potential in the heart
The sinoatrial node
96
Where is the sinoatrial node
The wall of the right atrium
97
What controls the frequency of the waves of excitation in the heart
The cardiovascular centre
98
Where in the brain is the cardiovascular centre
Medulla Oblongata
99
Which type of neurones travel from the CVC to the SAN
Motor neurones
100
What two nerve are connected from the CVC to the SAN
Accelerans nerve and Vagus nerve
101
Which nerve is responsible for increasing the heart rate
The accelerans nerve
102
Which nerve is responsible for decreasing the heart rate
The vagus nerve
103
What is the neurotransmitter for sympathetic nerves such as the accelerans nerve
Noradrenaline
104
What is the neurotransmitter for parasympathetic nerves such as the vagus nerve
Acetylcholine
105
What decides when the CVC changes the heart rate
When sensory receptors detect a change in the environment and send impulses to the CVC
106
What are stretch receptors
Receptors in muscles that send impulses to the CVC when muscles stretch so that extra oxygen is needed
107
What are chemoreceptors
Receptors in the carotid arteries, aorta and blood that detect changes in pH.
108
Give 3 examples of the commercial use of auxin
- cuttings are placed in rooting powder with auxin in to encourage root growth
- treating unpollinated flowers with auxin promotes the growth of seedless fruit
- used as herbicides for weeds to promote uncontrolled shoot growth so that the stems buckle
109
Give 2 examples of the commercial use of cytokinins
- used in tissue culture to promote bud and shoot growth
| - cytokinins will delay leaf senescence
110
Give 3 examples of the commercial use of gibberellins
- used to promote the germination of barley grains in beer production
- spraying sugar canes with gibberellins will promote stem elongation, this is where the sugar is found so it will increase the yield
- gibberellin speeds up the formation of seeds in young trees in plant breeding
111
Why can ethene not be directly applied to plants
Because ethene is a gas
112
Give 2 examples of the commercial use of ethene
- ethene can promote fruit ripening and fruit drop
| - storing fruit in areas without ethene will delay ripening and keep the fruits for longer
113
Which hormones are secreted directly from the hypothalamus
Releasing hormones
114
What is the purpose of releasing hormones
To stimulate the release of hormones from the anterior pituitary gland
115
What does the corticotropin releasing hormone (CRH) from the hypothalamus cause the release of
Adrenocorticotropic hormone (ACTH)
116
What is the purpose of Adrenocorticotropic hormone (ACTH)
Stimulates the zona fasciculata to release glucocorticoid hormones such as cortisol which regulates the metabolism of carbohydrates.
117
What does the thyrotropin releasing hormone (TRH) from the hypothalamus cause the release of
Thyroid stimulating hormone (TSH)
118
What is the purpose of thyroid stimulating hormone (TSH)
It stimulates the thyroid gland to secrete thyroxine which increases metabolic rates and makes target cells more sensitive to adrenaline
119
What effect does auxin have on cell walls in the stem
It increases the stretchiness of the cell walls
120
Describe the mechanism of auxin action on cells in the shoot
Auxin promotes the active transport of H+ by ATPase enzymes in the plasma membrane into the cell wall. This will lower the pH in the cell wall which provides an optimum pH for expansin enzymes to loosen the cell wall. The expansins break bonds within the cellulose. This loosening of the cell wall allows the cell to elongate.
121
Describe the effect of auxin in geotropic responses
Auxin accumulates on the lower side of the root which inhibits cell elongation. Therefore the top of the root elongates at a greater rate than the bottom of the root so the root grows downwards.
122
Which type of stretch receptors detect changes in blood pressure
Stretch receptors in the carotid sinus of the carotid artery
123
Which area of the brain is the largest and organises higher thought processes
The cerebrum
124
Which layer of the cerebrum is unmyelinated
The cerebral cortex
125
Give some functions of the cerebrum
- vision
- thought
- hearing
- speech
- memory
126
What connects the cerebrum to the cerebellum
The pons
127
How does gibberellin promote stem elongation
By promoting cell division and cell elongation (by loosening cell walls by making them more stretchy).
128
How does gibberellin promote seed germination
When the seed absorbs water, the embryo releases gibberellin. This gibberellin travels to the aleurone layer in the endosperm region of the seed. It enables the production of amylase which can break down starch into glucose which can be used as a respiratory substrate to provide energy for growth and cell division.
129
Give the stimulus, receptor, coordinator, effector and response of the knee jerk reaction
Stimulus - a mallet is used to hit the knee ligament, causing the quadriceps muscle to stretch
Receptor - stretch receptors (called muscle spindles) in the quadriceps muscle detect the stretch
Coordinator - the stretch receptors send an impulse to the spinal cord down a sensory neurone
Effector - The quadriceps muscles then contract
Response - The leg straightens
130
Why is the knee jerk reaction important
Allows for balance when moving
131
Why is conscious control unable to override the knee jerk reaction
There is no relay neurone involved in the knee jerk reflex so it is rapid. Therefore there is not enough of a delay in the reflex for an inhibitory action potential to be generated.
132
What is most of the brain composed of
Non- myelinated relay neurones
133
What colour are non myelinated neurones and what colour are myelinated nuerones
Non Myelinated - Grey
| Myelinated - White
134
What is a reflex action
A response to a change in the environment that does not require any processing or voluntary brain coordination.
135
What is a reflex arc
A reflex action where the receptor and effector are in the same place
136
Describe 3 physiological changes following a fight or flight response and explain how each response aids survival
Heart Rate Increases - so nutrients and oxygen are delivered to cells at a greater rate so they can increase their rate of respiration to provide more energy
Blood Glucose Levels Increase - provides more respiratory substrates
Arterioles Connected to the Digestive system and skin Constrict - diverts blood away from the digestive system and skin and towards the muscles
