5.5 Plant and animal responses Flashcards
What must a communication system enable when responding to the environment? (3)
detect changes in environment
cell signalling between all parts of body
coordinate effectors to carry out responses
suitable responses
What 2 parts does the CNS divide into ? (2)
brain
spinal chord
What does the peripheral nervous system divide into? (4)
sensory and motor system
motor system divides into autonomic and somatic
What does the autonomic nervous system divide into?
sympathetic
parasympathetic
What does the sympathetic nervous system do?
increase heart rate increase breathing rate dilate pupils inhibit digestion inhibit saliva production
What does the parasympathetic nervous system do?
decrease heart rate decrease breathing rate constrict pupils increase digestion increase saliva production
Role of the cerebrum?
higher thought processes
role of cerebellum?
movement and balance
role of hypothalamus?
coordinates homeostatic responses
role of medulla oblongata?
controls physiological processes- heart rate, circulation/blood pressure, rate/depth breathing
role of pituitary gland?
release hormones made by hypothalamus
what two things does the hypothalamus pituitary complex do? (2)
Osmoregulation- hypothalamus contains osmoreceptors monitoring water potential in blood
temperature regulation- hypothalamus detects changes in core body temperature, changes are mediated by pituitary gland
describe the corneal reflex (4)
sensory neuron from cornea enters pons
connects to relay neuron
passes action potential to motor neuron
back out of brain to facial muscles
what is the cornial reflex?
a CRANIAL blinking reflex to protect eye from damage
what is the optical reflex?
protects retinas light sensitive cells
stimulus is detected and mediated by cerebral cortex optical centre
what type of reflex is the knee jerk reflex?
its a spinal reflex -passes through spinal chord rather than brain
describe the knee jerk reflex
front of thigh muscle (quadriceps) contract to straighten leg
when this muscle is stretched, muscle spindles detect change in length
if stretching unexpected the reflex causes causes contraction of the same muscle
Describe the mechanism of adrenaline action (3)
- adrenaline binds to adrenaline receptor on plasma membrane thats associated with a G protein on inner surface membrane that activates adenyl cyclase
- adenyl cyclase converts ATP to cAMP which is the second messenger
- cAMP activates enzyme action
What two nerves link the cardiovascular centre in the brain to the SA node of the heart?
Sympathetic nerve (accelerans nerve) Vagus nerve
What neurotransmitter is released at the SAN when an action potential is sent down the sympathetic/accelerans nerve?
Noradrenaline
What neurotransmitter is released at the SAN when an action potential is sent down the vagus nerve?
Acetylcholine
What do noradrenaline (accelerans nerve) and acetylcholine (vagus nerve) do to heart rate?
Noradrenaline increases HR
Acetylcholine reduces HR
How and what do chemoreceptors detect?
pH of blood
Detects C02, more Co2=higher pH because of carbonic acid
What are the three types of muscle
Which are voluntary /involuntary
Smooth (involuntary)
Cardiac
Skeletal (voluntary)
Which type of muscle is structured into individual cells?
Smooth
Which type of muscle cells are joined by intercalated discs, and briefly state what these do
Cardiac
Free diffusion of ions between cells
What is the name of the junction between nerve and muscle?
Neuromuscular junction
What is the difference between a cholinergic synapse and a neuromuscular junction?(I.e. the last stage)
The wave of depolarisation passes zlong the sarcooemma and down transverse tubules
What at the contractile units of skeletal muscle?
Myofibrils
What 2 types of protein filament do myofibrils contain?
Thin filaments (actin) Thick filaments (myosin)
Describe the structure of thin filaments (3)
2 chains of actin twisted around each other
Wound around this is a molecule of tropomyosin
With troponin attached
Describe the structure of thick filaments
A bundle of myosin molecules
Each has 2 protruding heada
That bind to actin when binding sites are exposed
Explain the mechanism of muscle contraction. (8)
- Action potential along sarcolemma and down transverse tubule
- AP to sarcoplasmic reticulum which stores calcium ions
- Calcium ions are released into sarcoplasm
- Calcium ions bind to troponin altering shape (conformational change) pulling tropomyesin aside
- This exposes actin binding sites
- myosin heads bind to the actin forming cross bridges between filaments
- Myosin heads move pulling the actin filllament past the myosin filament
- Myosin heads detach from the actin and can bind again further up the actin filament
Explain the 3 roles of ATP in muscle contraction.
(1) Its hydrolysis by an ATPase activates the myosin head so it can bind to actin and rotate;
(2) Its binding to myosin causes detachment from actin after the power stroke
(3) It powers the pumps that transport calcium ions back into the sarcoplasmic reticulem.
What are cytokinins effects? (2)
cell division
delay leaf senescence
overcome apical dominance
cell expansion
What are abscisic acid effects?
inhibit germination, seed growth
stomatal closure in low water availability
What are the effects of auxins?
cell elongation
inhibit sie shoots growth
inhibit leaf fall
Effects of gibberellins?
promote seed germination
promote seed growth
Effect of ethene?
promote fruit ripening
What plant hormone exerts apical dominance?
Auxins
What plant hormone promotes seed germination?
Gibberellins
How do gibberellins promote seed germination? (3)
when seed absorbs water, embroyo releases gibberelin, enabling production of amylase
which breaks starch into glucose.
Glucose for respiration and protein synthesis.
Where in a plant does growth occur?/ name the four meristems, and state where they are located. (4)
apical meristem- tips of roots/shoots
lateral bud meristem- buds
lateral meristem- cylinder near outside of shoot
intercalary meristem- between nodes
What did Darwin prove about soot tips?
They are responsible for phototropic responses
What did Boysen-Jensen confirm about water and solutes?
they need to be able to move backwards from the shoot tip for phototropism to happen
How does auxin work?
Travels to zones of elongation, causing them to elongate, making shoot grow
increases stretchiness of cell wall by promoting active transport of H+ in, low pH breaks cellulose bonds, cell less rigid and takes on more water
state one commercial use of auxins
rooting powder
weed killer
cuttings
state one commercial use for cytokinins
promote bud and shoot growth
mass produce plants
state one commercial use for gibberellins
brewing sugar production plant breeding fruit production delay senescence
state one commercial use for ethene
speed fruit ripening
promote fruit drop
promote lateral growth
What would happen to the heart if the autonomic nerve supply was cut?
would continue to contract (myogenic)
wouldn’t beat at same rate
