plant and animal responses🌳🐍 Flashcards
nicotine increases blood pressure and causes thrombosis, how does lead to neurone death
- increased blood pressure*
- capillaries burst
- O2 supply stops
- cells cannot respire
- thrombosis*
- clot reduces blood flow
- O2 supply reduces
- cells cannot respire
stroke can be caused by high blood pressure or thrombosis. why would a drug that stops thrombosis not be appropriate to use on someone with high bp
- high blood pressure causes a stroke by bleeding due to bursting capillaries
- this drug will thin blood and increase bleeding
possible effects of a stroke:
- Problems with coordination of movement
- Loss of memory and speech
- Paralysis of the body below the neck
With reference to named parts of the brain, explain how each of these specific effects is caused.
- disruption of O2 supply for aerobic respiration
- damage to cerebellum causes problems with coordination and movement
- damage to cerebrum causes speech and memory loss
- damage to medulla oblongata causes paralysis
how is nicotine production advantageous to a plant
- stops plant being eaten
- plant survives
explain nicotine effect on nervous system
- nicotine slows down rate of nervous impulses
- binds to ACh receptor
- causes depolarisation
- remains in receptor longer than ACh
- receptor in refractory period for longer preventing action potential
Describe how neonectinoids absorbed by root may be transported to the fruits of the maize plant
- in phloem by mass flow
- in xylem by cohesion tension
why are controls necessary when testing treatments
allows effect of treatment to be compared
what plant hormone inhibits development of lateral buds
auxin
what plant hormone causes growth of lateral buds
giberellin
A third source of ATP in muscle involves the transfer of a phosphate group to ADP from a substance called…
creatine phosphate
During the contraction of skeletal muscle, energy from ATP is used to break the ….. that hold the actin and ….. together
cross links
myosin
describe how the components of the elbow joint interact to bring about hinge
movement
- muscles contract in antagonistic pairs
- tendons pull on bone/connect muscle to bone
- ligaments hold bones together
- cartilage reduces friction
- synovial membrane secretes fluid
- synovial fluid is a lubricant
Outline the organisation and roles of the autonomic nervous system in mammals
- sympathetic and parasympathetic
- s has ganglia close to spinal cord, p has ganglia close to organ
- s noradrenaline p acetylcholine
- s stress p calm
- s increases heart rate p decreases
- s increases breathing rate p decreases
- s reduces digestion p allows digestion
- s increases blood flow to skeletal muscle p increases blood flow to gut
Give two reasons why both plants and animals need to be able to respond to changes in their environment
- to avoid abiotic stress
- to avoid being eaten
- to access resources
differences in plant and mammal hormones
- m made in endocrine glands p made in many plant tissues
- m move in blood p move in xylem/phloem
- m act on target tissues p act on most tissues
- m act more rapidly
lack of human growth hormone causes dwarfism explain why this is a genetic condition
- inherited
- caused by mutation
Describe an example of genes being switched on or being switched off by a molecule that binds directly to DNA other than steroid
repressor protein
- changes shape when bound to lactose
- with lactose it lifts off operator, allowing gene expression
- beta galactosidase
homeotic genes
- gene product binds to DNA
- gene product starts transcription
- many genes affected
Describe two ways in which hormones may alter a plant’s growth in response to overcrowding by other plants
auxin
- phototropism
- plant bends towards light
- thigmotropism
- roots grow towards water
Suggest how hormones alter a plant’s growth if the top of the plant shoot is eaten by an animal.
- less auxin
- apical dominance stopped
- lateral buds develop
- plant becomes bushy
Describe how you would measure the distribution and abundance of plants over a distance of 100 metres
- use transect
- use identification key
- sample every 10m for total of 10 samples
- ACFOR scale
- record percentage cover of plants
Suggest how the adrenaline molecule can cause different effects in different target tissues
- different target tissues have different second messengers
- different enzymes activated
Explain why glycogen granules are present in striated muscle.
- glycogen hydrolysed to glucose
- glucose needed for aerobic respiration to produce ATP
- for muscle contraction
high concentration of hydrogen ions reduces the ability of calcium ions to bind to proteins in the myofibrils
explain how an increased concentration of hydrogen ions leads to a reduction in the force of contraction of a muscle
- fewer ca2+ bind to troponin
- fewer troponin change shape
- fewer tropomyosin move aside
- fewer binding sites on actin available
- fewer actin myosin bridges form
- power stroke reduced
- actin filaments pulled past myosin with less force
cns vs pns
central
- brain and spinal cord
- intermediate neurones
- many synapses
peripheral
- nerves from sense organs to effectors
- sensory and motor neurones
- somatic and autonomic
- role in sensing stimuli
difference between prophase 1 and prophase 2
- homologous chromosomes in prophase 1
- crossing over in prophase 1
cellular structure and function of skeletal muscle
- striated bands of myosin and actin
- to move bones
cellular structures and function of smooth muscle
- unstriated
- peristalsis
cellular structure and function of cardiac muscle
- striated
- to pump blood
name example of skeletal, smooth and cardiac muscle in thorax
skeletal = intercoastal
smooth= arteries
cardiac=heart
Describe and explain how the activation of the ‘fight or flight’ response affects voluntary, involuntary and cardiac muscle.
- sympathetic nervous system
- noradrenaline
- adrenaline secreted
- from adrenal medulla
- sympathetic nerve increases heart rate
- cardiovascular centre in medulla oblongata
- greater blood flow to skeletal muscle
- less blood flow to smooth muscle
- heart beats more forcefully
- breathing faster
similarity in function between neuromuscular junction and synapse
changes potential difference
Explain why one individual can only have two of the different alleles of a gene.
- humans are diploid
- homologous chromosomes
explain how an allele becomes common in the population
- natural selection
- allele gives selective advantage
- more likely to survive
- allele passed to offspring
- over many generations frequency increases in population
commercial uses of plant growth substances
- seedless fruits
- weedkillers
- rooting powder
- control fruit ripening
how can injury to pituaitary and hypothalamus cause wide range of symptoms
- have many different functions
- affect other endocrine glands
where does knee jerk reflex go through
spinal cord
reflexes are fast because they only go through one or two…
synapses
what blood vessel would be shown in a pancrease cross section
arteriole
what does the PNS consist of
nerves in the body
what is a nerve
bundle of neurones
what is the somatic nervous system
voluntary
controls body movements
sensory and motor neurones
functions of medulla oblongata
- cardiovascular centre controls heart rate
- vasomotor centre controls blood pressure by controlling contraction of smooth muscle in arteriole walls
- respiratory centre controls breathing rate
functions of cerebrum
vision hearing speech thinking memory
functions of cerebellum
motor coordination including balance
is involuntary
functions of hypothalamus
- monitors the blood, either releases hormones in response or stimulates pituitary gland
- controls metabolic processes by stimulating PG
- ADH production
- osmoregulation
- thermoregulation
- controls secretion of enzymes in gut and peristalsis
where is hypothalamus in relation to pituitary gland
hypothalamus above pituitary gland
functions of pituitary gland
- produce hormones which directly influence processes
- produce hormones which stimulate other glands
anterior vs posterior pituitary gland
anterior: produces and releases hormones
posterior : stores and releases hormones produced by hypothalamus
cerebrum structural adaptation
- thin outer layer cerebral cortex
- highly folded so high SA so high number of neurones
- more neruones means more connections
- greater ability for complex behaviours
typical reflex sequence
- stimulus detected by receptor
- impulse to coordinator brain or spinal cord
- impulse to effector
describe the knee jerk reflex
- pressure on ligament from hammer
- detected by receptor
- impulse down sensory neurone
- to motor neurone in spinal cord
- to quadriceps muscle
- contraction so leg lifts
why are reflexes faster than usual nerve impulses
- nerve impulses usually delayed by synapses, if the impulse goes through brain then there are many synapses
- reflex either doesnt go through brain or does but doesnt go through decision making area
- minimal synapses so fast
how does nervous and endocrine system work together to secrete adrenaline in fight or flight
- threat detected
- sensory neurone
- hypothalamus
- sympathetic nerve to adrenal gland
- adrenaline secretion
how does the body increase heart rate for exercise
- chemoreceptors in aorta detect more CO2 in blood
- impulses to medulla oblongata
what is striated
made up of muscle fibres
describe structure of a muscle fibre
- cell like unit
- plasma membrane=sarcolemma
- ER= sarcoplasmic reticulum
- cytoplasm=sarcoplasm
- contains organised arrangement of contractile proteins
- many nuclei which is why it is not considered a cell
- sarcolemma has many deep tube like projections that fold from its outer surface called T tubules which are close to SR
- sarcoplasm contains mitochondria and myofibrils
what are myofibrils
bundles of actin and myosin filaments
what is the H band
only myosin
what is the I band
only actin
what is the A band
areas of only myosin and myosin/actin overlap
what is the Z line
attachment for actin filamenta
what is the M line
attachment for myosin filaments
what is a sacromere
section of myofibril between two Z lines
differences between slow and fast muscle fibres
- f contract rapidly s more slowly
- f has more Ca2+ present to stimulate contraction
- f relies on anaerobic respiration s on aerobic respiration
- f is good for short bursts of high intensity due to lactate build up, s for longer sustained activity
- f has fewer capillaries s has dense capillary network
- f has low amount of myoglobin, s has high amounts of myoglobin haemoglobin and mitochondria
describe structure of smooth muscle
unstriated
small elongated cells with one nucleus
describe structure of cardiac muscle
- muscle fibres form network that spreads through walls of atria/ventricles
- connected to each other via intercalated discs
- lots of mitochondria in muscle fibres
- one nucleus per cell
describe what happens at a neuromuscular junction which leads to sliding filaments
- impulse on motor neurone causes Ca2+ to diffuse in which causes Ach vesicles to fuse with plasma membrane and released
- Ach diffuses across synapse and binds to receptor on sarcolemma
- Na+ channels open, influx of Na+ depolarises sarcolemma
- generates action potential that passes down T tubules towards centre of muscle fibre
- action potential opens Ca2+ channels in SR membrane
- Ca2+ diffuse out of SR into sarcoplasm
- Ca2+ bind to troponin so it changes shape
- cause tropomyosin to move aside exposing binding sites on actin
myosin structure
- fibrous protein with globular head which point away from M line
- many myosin molecules make up thick filament
actin structure
- globular protein
- many actins joined together form chain
- 2 actin chains twist together to form thin filament
where is tropomyosin and troponin
- tropomyosin twisted around the 2 actin chains
- troponin attached to actin chain at regular intervals
describe sliding filament model
- once binding sites on actin exposed
- myosin heads bind forming cross bridges
- myosin heads pull actin filaments towards centre of sacromere
- ATP hydrolysis at myosin heads providing energy for myosin head to release actin filament
- myosin heads move back and bind to new binding site
- myosin head pull actin filaments even closer to centre of sarcomere, ATP hydrolysis to detach
- as long as binding sites are exposed this process repeats until muscle fully contracted
what happens after muscle contraction
- acetylcholinesterase breaks down Ach in synapse to prevent continuous contraction
- Ca2+ pumped back into SR once sarcolemma is repolarised
why is ATP needed for muscle contraction
- return movement of myosin heads
- return of Ca2+ into SR via active transport
function of creatine phosphate
-respiration takes long time to begin producing ATP
-creatine phosphate is stored by muscles for rapid ATP
creatine phosphate + ADP = ATP + creatine
-allows contraction for short period of time
what leads to muscle fatigue
- Ca2+ availability decreased
- lactate produced which lowers pH of muscles and affects comtraction of fibres
what is a tropism
growth movement responding to directional stimulus
what are the different tropisms
- phototropism= light
- geotropism= gravity (ensures shoot and root grow in right direction)
- hydrotropism= water
- thigmotropism= touch (curls around support )
- chemotropism
plant response to touch
- leaves rapidly fold in
- bioelectrical signals
- protects from herbivorous insects
- venus fly trap folds to eat insect
plant response to herbivory
- repellent chemicals
- tannins bitter toxic
- alkaloids bitter toxic
- pheromones toxic or trigger other defences
plant response to drought
close stomata to reduce transpiration
plant response to freezing temperatures
produce antifreeze chemical to decrease formation of ice crystals which can be deadly to cells
how do plants initiate leaf loss
- deciduous plants lose leaves in hot/dry temps to reduce water loss
- abscission layer develops at base of leeaf stalk
- made up of parenchyma cells with thin walls so weak and easy to break
- ethene stimulates breakdown of these parenchyma cells so leaf drops off
- auxin usually inhibits leaf loss but as leaf ages to auxin conc decreases
how does leaf use hormones to close stomata
- abscisic acid produced to close stomata when little water available
- guard cells have ABA receptors
- ABA binds and inhibits proton pumps and cause Ca2+ into cytoplasm
- Ca2+ cause ions to leave which increases WP
- water leaves by osmosis
- flaccid so stomata closes
