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unit 4 Flashcards

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1
Q

What is a tropism

A

A directional growth response in which the direction of the response is determined by the direction of the external stimulus

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2
Q

What are the 4 types of tropisms

A

Photo tropism
Geotropism
Chemotropism
Thigmotropism

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3
Q

What is phototropism

A

When shoots grow towards the light which enables them to photosynthesis. They’re positively phototrophic

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4
Q

What is Geotropism

A

Roots grow towards the pull of gravity
Anchors them in the soil and helps them to take up water need for support, for a raw material of photosynthesis and to help cool the plant.

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5
Q

What is Chemotropism

A

On a flower when pollen tubes grow down the style attracted by chemicals, towards the ovary where fertilisation can take place

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6
Q

What is Thigmotropism

A

Shoots of climbing plants such as ivy wind around other plants or solid structures and gain support

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7
Q

What are hormones

A

Coordinate plant responses yo environmental stimuli

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8
Q

What are plant hormones referred to and why

A

Plant growth hormones

Unlike animal hormones they are no produced in endocrine glands, but by cells in a variety of tissues in the plant

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9
Q

Some hormones can have different effects on different tissues

Term when they amplify each others effects. Term when they cancel out each others effects

A

Synergy

Antagonism

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10
Q

If a plant responds towards a stimulus it’s a positive tropic response

If it’s away it’s still a tropic (directional) response but negative

A

Just saying

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11
Q

What limits the cells ability to divide

Consequence

A

The cell wall around a plant cell

Growth only. Happens in particular places in the plant

Meristems

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12
Q

4 types of Meristems

A

Apical
Lateral bud
Lateral
Intercalary

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13
Q

Apical Meristems

A

Found at tips or spices (apex) of roots and shoot and are responsible for the roots and shoots getting longer

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14
Q

Lateral bud Meristems

A

Found in buds

Could give rise to side shoots

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15
Q

Lateral

A

Found in a cylinder near the outside of the roots and shoots and are responsible for the roots and shoots getting wider

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16
Q

Intercalary Meristems

A

Found between the nodes

Growth between the ndes is responsible for the shoot getting longer

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17
Q

Where does cell division happen

What about elongation

A

Closest to the apex

Just behind the apex

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18
Q

Where are auxin produced

A

Apex

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19
Q

How does auxin travel to the cells in the zone of elongation

A

Diffusion or active transport

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20
Q

What happens when auxin reach the cells I the zone of elongation

A

Cells elongate making the shoot grow

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21
Q

Role of auxin

A

Stimulate shoot growth by causing elongation

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22
Q

How do auxin increase the stretchiness of the cell wall

A

By promoting the active transport of hydrogen ions by an atpase enzyme on the plasma membrane into the cell wall
The resulting low pH provides optimum conditions for wall loosening enzymes (expansins) to work which break the hinds within the cellulose
Hydrogen ions also disrupt hydrogen bonds within the cellulose so the walls become less rigid and can expand as the cell takes in water.

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23
Q

Why does a shoot bend

A

Cz shaded side elongates faster than illuminated side

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24
Q

Evidence

A

Light shining on one side of the shoot causes the auxin to be transported to the shaded side, where they promote an increase in the rate of elongation making the shoot bend towards the light

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25
How does the light cause redistribution
2 enzymes Phototropin 1 and 2 Activity is promoted by blue light So There's a lot of Phototropin 1 activity on the light side, but less on dark The gradient is the cause
26
Role of cytokinins
Stop the leaves of deciduous trees senescing by making sure leaf acts as a sink for phloem transport so it's got a good supply of nutrients
27
What happens if cytokinins production drops
Supply of nutrients fall Senescence begins Followed by leaves being shed or abscission
28
Role if auxin in shedding leaves
Inhibit abscission by acting on cells in the abscission zone
29
What is the cerebrum
Largest and most recognisable part of the brain.
30
What is the cerebrum responsible for
The laments of the nervous system that are associated with being human including thought imaginations and reasoning and judgement
31
How many hemispheres is the cerebrum divided into Whatvare they connected via
2 | Corpus callosum
32
What are cerebral cortex made of
Outermost layer of the cerebrum folded into thin layer of Nerve cell bodies
33
What does the cerebral cortex control | 3
Conscious thought and emotional responses Ability to override some reflexes Features associated with intelligence, judgement and reasoning
34
3 things cerebral cortex is subdivided into
Sensory areas Association areas Motor areas
35
Sensory areas
Receives impulses indirectly from the receptors
36
Association areas
Compare input with previous xps in order to interpret what the input means and judge an appropriate response
37
Motor areas
Send impulses to effectors
38
Motor area on right side of cerebral cortex control the muscular movements on the left side of the body and vice versa
Just saying
39
The fine control of muscular movements requires a significant level of non conscious operation
Just saying
40
4 examples of non conscious operation
Muscular activities associated with responding to changes in body positions to remain. Balanced and upright Sensory activities such as judging the positions of objects and limbs Feedback info on muscle position tension and fine movements Operation. Of antagonistic muscles to coordinate contraction and relaxation
41
Neurones from the cerebellum carry impulses to the motor areas so that motor output to the effectors can be adjusted appropriately in relation to these requirements (level if non conscious operation)
Explains why we go into autopilot, they're programmed into the cerebellum
42
Role of cerebellum
Controls coordination of balance and fine motor movement
43
Where does the cerebellum process it's sensory info from to coordinate balance and fine movemen
The retina Balance organs in the inner ear Spindle fibres in muscles which give info about muscle tension Joints
44
What's the hypothalamus
Controls the autonomic nervous system and the endocrine glands
45
Medulla oblongata
Controls the action of smooth muscle in gut wall, and controls breathing movements and heart rate.
46
Why do animals need to coordinate a vast set of responses | example
To stay alive Coordinated voluntary muscle actions to rub away from predator Fine control of balance posture and temperature regulation
47
What do coordinated responses use
Nerves and hormones
48
What does the nervous system do
Coordinates the actions of the body through electrical impulses
49
What does it work in conjunction with
Endocrine system
50
Whys the nervous system divided
Helps us describe nervous action and understand coordination processes
51
What is the nervous system divided into
Cns | Peripheral nervous system
52
What is the cns made up of
Grey matter non myelinated White matter Myelinated
53
What is the peripheral nervous system made up of
Neurones that carry impulses into and out of the cns
54
What are sensory neurones do Motor
Carry impulses from the receptors to the cns Carry impulses from cns to effector organs
55
What is the motor system divided into
2 Somatic Autonomic
56
Somatic motor neurones
Carry impulses from the cns to skeletal muscles | Under voluntary or conscious control
57
Autonomic motor neurones
Carry impulses from the cns to cardiac muscle to smooth muscle in the gut wall and to glands Non under voluntary control
58
What does autonomic mean
Self governing
59
What's the autonomic nervous system responsible for
Controlling the majority of homeostatic mechanisms
60
Autonomic nervous system involved in responses associated with the stress response too
Just saying
61
3 differences of autonomic nervous system to somatic
Most autonomic neurones are nonmyelinated Autonomic connections to effectors always consist of atleast 2 neurones unlike somatic 2 neurones connect at ganglion Autonomic motor neurones occur in 2 types. Sympathetic and parasympathetic
62
Why are the sympathetic and parasympathetic nervous systems referred to as antagonistic
Cz when one works 5 he other opposes the action of the other
63
Stimulation of the stress response EADS to ab altered balance of stimulation between the 2 systems which leads to an appropriate response.
Just saying
64
What is the cns
Consists of the brain and spinal cord
65
What is the peripheral nervous system
Consists of all of the sensory and motor neurones that are outside the central nervous system -connecting the receptor and effector to the cns
66
Parasympathetic ans sympathetic stimulation occurs all the time it's just balance of stimulation is altered
Just saying
67
Coordinated movements require the action of the brain in sending impulses along motor neurones to voluntary muscles
Just saying
68
What attached bones and voluntary muscles together
Tendons
69
Whatvare tendons made of
Inelastic collagen which is continuous with the muscle and the periosteum
70
Why does the movement of a bone at a joint require the coordinated action of atleast 2 muscles
Cz muscles are only capable of producing a force when they contract
71
What are antagonistic muscles
Muscles that work in pairs opposite to each other
72
What type of joint is the elbow joint What does it need
Synovial A large degree of movement
73
What us synovial fluid
A lubricant that eases movement
74
How do the biceps and triceps act
Antagonistically
75
Nervous system controls muscle action s because motor neurones are connected to muscle cells at a neuromuscular junction
Just saying and check stages
76
What controls the strength of contraction why
Brain | Cz many motor neurones stimulate a single muscle
77
Wach motor neurone branches to neuromuscular junctions, causing the contractions of a cluster of muscle cells (motor unit) The more motor units stimulated, the greater the force of contraction. This is known as gradation of response
What is a motor unit cluster of muscle cells
78
What are muscles composed of
Cells that are elongated to form fibres | They contact and relax
79
What do muscle cells contain How does this produce a force on contraction
Actin and myosin Basically filaments
80
What are the types of muscle
Involuntary - smooth Cardiac muscle Voluntary - skeletal muscle
81
Smooth muscle is innervated by neurones of the ans so contraction is non voluntary
Just saying
82
``` They don't appear streaked Look spindle shaped Single nucleus Contraction slow But muscle tires slowly ```
Just saying
83
What are the 3 types of cardiac muscle
Ventricular Atrial Excitatory and conductive muscle fibre
84
What do atrial and ventricular muscles contract similar to | How are they different
Skeletal muscles | Longer duration of contraction
85
What do the excitatory and conductive fibres do
Contact feebly | Conduct electrical impulses and control the thymic heartbeat
86
What is myogenic contraction
Fibres stimulating contraction without a nerve impulse
87
Where do neurones of the autonomic system carry impulses to
Heart to regulate rate of contraction and smooth
88
What does the action of voluntary muscles do
Leads to movement of the skeleton at the joints which miles the limbs
89
How much nuclei do voluntary muscles have
Several
90
What's the cell surface membrane surrounding each fibre in voluntary muscles Cytoplasm
Sarcolemma | Sarcoplasm
91
What is a sarcomere
The smallest contractile unit of a muscle cell
92
What organelles found in voluntary muscle cells
Mitochondria Sarcoplasmic reticulum Myofibrils - there are contractile elements which consist of of sarcomeres. Within length of protein myofillaments are actin and myosin
93
Under microscope voluntary look like what? How do they contract
Striped/streaked Quickly and powerfully but fatigue quickly
94
Span from one z line ti the next is known as the sarcomere
Just saying
95
Z lines are close together during contraction I band and h Zone are reduced A band doesn't change
Just saying
96
How many protein filaments are involved in contraction
2
97
What are the protein filaments involved in contraction
Thin filaments 2 strands Made mainly of f actin Each strand is composed of g actin subunits Tropomyosin molecules coil around f actin to reinforce it Troponin complex is attached to each tropomyosin Troponin consists of 3 polypeptides One binds to actin One to tropomyosin One to calcium ions

Biology unit 4 (2 decks)

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