5.1.5 Plant And Animal Responses Flashcards
What are the two sections of the mammalian nervous system?
Central and Peripheral Nervous system
What is the difference between the somatic and autonomic nervous system?
- Somatic = Conscious control from sense organs
- Autonomic= Subconscious control
What is a ganglion?
Collection of nerves outside of central nervous system
What is the function of the brain?
Processes information from receptor cells and hormonal system
What is the cerebrum used for?
Voluntary actions
How is the cerebrum adapted for its role?
Highly folded: Large surface area so more neurones
Cerebral cortex contains three layers for sensory,association and motor
what is the role of the cerebellum?
Unconscious actions
What is the role of medulla oblongata?
Autonomic functions e.g. heart rate
What is the role of the hypothalamus?
Regulates temperature water and patterns of behaviour
What is the role of the anterior pituitary gland?
FSH and growth hormone
What is the role of the posterior pituitary gland?
Stores and releases hormone made by hypothalamus
What are the features of the sympathetic nervous system?
Fight or flight
Increases activity
What is the structural organisation of the sympathetic neurones?
Pre ganglionic- Short,lightly myelinated and secrete acetyl choline
Posy ganglionic- long, unmyelinated and secrete noradrenaline
What are the features of the parasympathetic nervous system?
Rest and digest
So decrease activity
What are the features of the parasympathetic structural organisation?
Pre ganglionic neurone- Lightly myelinated and long
Post ganglionic neurone- Unmyelinated and short
Both secret acetylcholine
Why are reflexes important for survival?
- Avoids harm/ damage to the body
- Prevents overloading of brain when response is always the same
What is the difference between the knee jerk and blinking reflex?
Knee Jerk goes through only spinal cord
Blinking reflex only goes through brain not through spinal cord s
What is the nervous system process during the fight of flight response?
- Involves sympathetic nervous system
- Impulses activate smooth muscles and glands including adrenal medulla
What is the hormonal system process during fight or flight?
Adrenal cortisol system is activated ny releasing CRF
Release of ACTH by pituitary gland
ACTH binds too cells of adrenal cortex and stimulates release of hormones
What is the process of glycogenolysis triggered by adrenaline?
- Adrenaline binds to receptor activating adenyl cyclase enzyme
- Converts ATP to cAMP on inner surface of membrane
- Increased cAMP activates protein kinases which phosphorylase and activate other enzymes
- Enzymes added convert glycogen to glucose
How is the need for a change in heart rate detected?
Baroreceptors- detect changes of blood pressure in aorta,vena cava and carotid arteries
Chemoreceptors- Detect chemical changes in blood
How is heart rate increased via the sympathetic nervous system?
Via accelerator nerve which increases generation of SAN in heart
How is heart rate decreased by the parasympathetic nervous system?
Via the vagus nerve
What is a neuromuscular junction?
The connector between motor neurones and muscle cells
How does an action potential travel across a neuromuscular junction to stimulate a response?
- Action potential arrives at end of neurone and neurotransmitter is released
- Neurotransmitter binds to receptors on sarcolemma depolarising membrane
- Depolarisation travels along t tubules
- Ca2+ released from sarcoplasmic reticulum
- Ca2+ bind to muscle leading to contraction
What are three key features of muscle cells?
- Elongated cells which form fibres
- Conduct action potentials
- Contractile properties
What are the features of involuntary muscle?
Non striated
Autonomic
No regular cell arrangement so can contract in different directions
Spindle shaped fibres
Slow contractions but remain contracted for a longer period of time than normal
What are the features of cardiac muscle?
Specialised striated muscle
Cells branch and interconnect resulting in simultaneous contraction
Intermediate contraction speed
What are the features of skeletal muscle?
Striated
Conscious movement so somatic nervous system
Rapid contraction
Regularly arranged so muscles only contract in one direction
What is the definition of a sarcomere?
Basic functional unit of a skeletal muscle cell
What is the definition of a myofibril?
Units within a muscle cell
Which areas of a sarcomere give information on the contraction?
I band and the H zone
What happens to the H zone during contraction?
It disappears
What are the components of thin filaments?
- Mainly actin
- Have tropomyosin and troponin
What are the three binding sites of troponin?
1 to actin
1 to tropomyosin
1 to Ca2+
What are the features of thick filaments?
Myosin
Elastic and contractile properties
Have 2 components: a head and a tail
What are the steps of sliding filament theory?
- Myosin heads in starting position with ADP + Pi bound to myosin
- Ca2+ bind to troponin expressing binding site on actin, myosin heads ind
- ADP and Pi are released causing head to tilt and pull actin towards centre of sarcomere
- ATP binds to myosin head releasing energy which is used to separate myosin head from actin
- Myosin heads return to starting position
What are examples of physical response to herbivory?
- Stinging
- Spiny leaves
- Hairy leaves
- Inedible tissue
- Barbs and thorns
- Leaves folding in response to touch
What is the definition of synergism in hormones?
Different hormones working together to create an amplified response
What is the definition of antagonism between hormones?
The balance between two hormones will determine the response
What are the three types of chemical response to herbivory?
Tannins- Very bitter and toxic to insects
Alkaloids- Bitter tasting and affect metabolism
Terpenoids- Toxins to insects and fungi
What is the definition of a pheromone?
Chemical made by organism which affects social behaviour
What is positive chemotropism?
Growth due to chemical stimuli
What is positive thigmotropism?
Growth in response to touch
What is photoropism?
Growth in relation to light
What is gravitropism?
Growth in response to gravity
What is the definition of a tropism?
Response to external stimuli
What is a nastic response?
A response independent of stimulus direction
How does growth occur in unilateral light?
- Auxins move away from the light shining on one side to the shaded size
- This stimulate cell elongation and growth on shaded side
- Shaded side then grows faster causing it to bend
How does geotropism occur?
- Auxins collect on lower side inhibiting growth on lower side
- Leads to downward growth
What are the steps of apical shoot growth?
Auxins bind to receptors on cell membrane
Activate transport of H+ into cell wall lowering pH
Optimum pH for wall loosening enzymes which reduce ridgidity of cell wall
Cell expands
pH rises again and enzymes deactivated
What is apical dominance?
That high concentration of auxin in tip restricts plants from widening as high conc of auxins suppresses lateral growth
What are the steps of seed germination?
- Seed absorbs water and embryo is activated
- Embryo produces gibberellins
- Enzymes produced that break down food stores
- Food stores used to generate ATP for growth
What is the experimental evidence?
Seeds that lack gibberellin gene do not germinate
If inhibitors are applied germination does not occur
What does stem elongation do?
Uses giberrellins to affect the length of internodes
What is the experimental evidence for stem elongation?
Gibberellins produced by a rice fungus cause the rice seedings to grow taller
These can be isolated to make other plants taller
Why does leaf loss occur?
- Glucose required to maintain leaves greater than what is being produced
- Trees with leaves more likely to be damaged
What are the steps of leaf loss?
- Decreased light intensity lowers the levels of auxin
- this triggers production of gaseous ethene
- Cells in abcision zone are sensitive to ethene so enzymes digest cell wall
- Vascular bundles seal off preventing pathogens from entering
- Leaf separates and falls
What hormone controls stomatic control and where is it released?
Hormone ABA released from leaf cells under abiotic stress
What are the steps in stomatic control?
- ABA binds to receptors on guard cells causing ions to leave
- Changes ionic concentration in guard cells
- Increases water potential of guard cells so water follows ions
- Reduced turgor pressure so cells close
What measures are in place in plants to prevent freezing?
Cytoplasm and cell sap contain chemicals which decrease freezing point
Plants produce poly saccharides ,amino acids and proteins which act as an antifreeze
What is the term for a plant being sensitive to light?
Photoperiodism
What is the commercial use of ethene in plants?
Promoting of ripening when plants have been transported unripe
Reduces wastage and damage of plants in transport
What are the commercial uses of auxins?
- In rooting powders to promote root growth
- Also in weed killers to kill broad leaved weeds
What are the commercial uses of cytokinins?
Prevent ageing of ripened fruit
What are the commercial uses of giberrellins?
Delay ripening
Improve size/shape of fruit
