5.1.5 Plant and animal responses Flashcards
What is the need for plant responses?
to avoid abiotic stress;
to avoid herbivory;
to maximise photosynthesis;
help ensure germination;
What is phototropism?
plants growth response to light
positive (stem) = towards light
negative (roots) = away from light
What is geotropism?
plants response to the earths gravitational field
roots exhibit positive geotropism = nutrients from soil/water
shoots exhibit negative geotropism = light
What is thigmotropism?
plants response to touch
What is the Mimosa Pudica plant?
respond to touch by folding
- scare herbivores
- protect leaves
What are alkaloids?
bitter tasting
toxic to organisms
nicotine and caffiene
What are tannins?
very bitter taste
toxic to insects
What are pheromones?
chemicals made by organisms that affect the behaviour of other members of the same species
What are the 3 chemical defences in plants?
alkaloids
tannins
pheromones
What is the function of cytokinins?
promote cell division in roots and shoots
cytokinins = more mitosis = more cells = plant growth
What is the function of gibberellins?
seed germination;
stem elongation;
the seed absorbs water;
gibberellins synthesised in the embryo;
gibberellins act as a transcription factor turning on sections of the DNA allowing it to be transcribed into RNA;
then translated into amylase and proteases;
amylase is going to break down polysachharides into glucose;
protease going to break down protein stores into amino acids;
glucose is used in aerobic respiration = develop into seedling
What is the function of abscisic acid (ABA)?
stimulates stomatal opening and closure;
water becomes limiting;
root hair cells synthesise and release ABA;
ABA is transported to the leaves;
ABA bind to the receptors on the cell plasma membrane of guard cells;
ions leave the guard cells and water potential increases;
water moves out the cell via osmosis;
reduction in turgor pressure = stomata close
What is the general functions of auxin?
stem elongation;
prevent fruit fall by inhibiting ethene;
apical dominance;
inhibit root growth at high conc;
In the shoots, how does auxin enable phototropism?
auxins are made in the shoot tip;
diffuse down the shoot tip;
sunlight breaks down auxins;
shaded area has higher conc of auxins;
causing more cell division on shaded side of shoot;
this leads to the shoot bending towards the light
What does auxin do in plant root tips?
auxin inhibits cell division in root tips;
auxin is moved to the side with the most gravitational pull;
the opposite side with the least gravitational pull will undergo mitosis more;
plant tip grows downwards;
What is the function of ethene?
promotes fruit ripening;
promotes leaf abscission;
Describe the process of abscission of leaves?
- leaves are lost as there is a need for more energy/glucose in winter;
- increase in darkness results in less auxin being made;
- this allows ethene to be produced;
- stimulates the cells in the abscission zone to produce enzymes which digest and weaken the end of the lead petiole;
- fatty deposits prevent pathogens from entering;
AUXIN PLANT EXPTS
GIBBERELLIN experimental evidence
What is the commercial use of ethene?
control of fruit ripening
preserves cut flowers/green vegetables
What is the commercial use of auxin?
rooting powders;
produce seedless plants;
weed killers;
What is the commercial use of gibberellins?
to produce malt;
used to delay ripening;
What does the mammalian nervous system consist of?
central nervous system;
peripheral nervous system
What does the peripheral nervous system consist of?
somatic nervous system;
autonomic nervous system;
What does the CNS consist of?
brain and the spinal cord;
relay neurones;
many synapses;
What does the autonomic nervous system consist of?
sympathetic nervous system;
parasympathetic nervous system;
Describe the peripheral nervous system?
includes the somatic NS and autonomic NS;
nerves go from sense organs to glands;
contains sensory and motor neurones;
detects stimuli;
control effectors;
Describe the function of the somatic nervous system?
conscious control e.g move arm
Describe the function of the autonomic nervous system?
works constantly;
subconscious control;
e.g heart beat
Describe the function of the sympathetic nervous system?
flight and fight response;
noradrenaline
IN MORE DETAIL
Describe the function of the parasympathetic nervous system?
acetylcholine NT
IN MORE DETAIL
What is the function of the cerebrum?
controls voluntary actions;
learning, memory, personality and conscious thought
What is the function of cerebellum?
controls unconscious functions such as posture, balance, and non-voluntary movment
What is the function of the medulla oblongata?
used in the autonomic control
controls heart rate and breathing rate
What is the function of the pituitary gland?
stores and releases hormones that regulate body functions e.g LH
What is the function of the hypothalamus?
regulatory centre;
for temperature and water potential
contains thermoreceptors and osmoreceptors
Describe the reflex action of a knee jerk?
when the leg is tapped beneath the knee cap it stretches the patellar tendon
this stimulus causes the quadriceps to contract and the hamstring to relax causing the leg to extend
LOOK for survival value
Describe the action of the blinking reflex?
this reflex occurs when the cornea is stimulated (sound, touch, light)
and the eyelid closes to prevent anything from entering the eye
What is the survival important of reflexes?
involuntary responses - the decision making parts of the brain are not involved
not having to be learnt; they are present in birth and provide immediate protection
extremely fast; the reflex arc is short and only involves one or two synapses
What is involved in the fight or flight response in terms of symtptoms?
increases breathing rate;
increases the diameter of airways;
increases blood flow to skeletal muscle;
dilate pupils;
liver releases glucose
How do hormones and nervous mechanisms increase heart rate?
low blood pressure is detected by BARORECEPTORS in the aorta/vena cava/muscles
OR
low blood pH is detected by chemoreceptors in the carotid artery/aorta/brain
both receptors send signal to medulla oblongata in the cardiovascular centre
CC will activate the sympathetic nervous system
allows impulses to be sent down the accelerator nerve to the SAN
an increase in the frequency of waves of excitation from SAN
hormones:
adrenal medulla: adrenaline
adrenal cortex: cortisol
= increase in heart rate
How do hormones and nervous mechanisms decrease heart rate?
OPPOSITE to other
different PARAsympathetic system!!!!!!!
What is standard deviation?
spread of data around the mean
excludes extreme values
What is a t-test used?
compare two means from two different data sets;
to see if there is a sig difference;
What is the unpaired t test used for?
between two sets of data that are unrelated
What is the paired t test used for?
between two sets of data that are related
For a unpaired t-test what is the formula for the degrees of freedom?
df = (n1 - 1) + (n2 - 1)
For a paired t-test what is the formula for the degrees of freedom?
df = n - 1
What are the three types if mammalian muscle tissue?
skeletal muscle
cardiac muscle
smooth muscle
What is the structure and function of skeletal muscle?
responsible for movement under conscious control
multinucleated cell;
striated due to bands of actin and myosin;
cylindrical cells;
short and rapid contraction;
What is the structure and function of cardiac muscle?
involuntary/myogenic; contracts without nervous stimulation;
striated (fainter than skeletal);
contains branched cells; (simulataneous contractions);
interlocking junctions;
uninucleate;
immediate contraction length and speed
What is the structure and function of smooth muscle?
involved in peristalsis/controlling diameter of bronchi and pupil size and arteries
non striated;
uninucleate;
spindle shaped cells;
contract more slowly;
no regular arrangement contraction can occur in different directions
Draw a venn diagram comparing all three muscle fibres:
screenshot on iPad
Look at the structure of a myofibril
including sarcolemma, sarcoplasmic reticulum, T tubule, etc
What is the name of the membrane around the muscle fibre?
sarcolemma
What does a sarcomere consist of?
actin and myosin filaments
What is the structure of actin?
2 strands twisted around each other
What is the structure of myosin?
rod shaped will bulbous heads
What is the M-line made of?
middle of sarcomere = contains myosin
What is the Z line made of?
end of the sarcomere = contains actin
What is the A band made of?
myosin and some overlapping actin
What is the H band made of?
myosin only (dark)
What is the I band made of?
actin only (light)
Draw a microscope image of a muscle fibre:
screenshot on iPad
Describe the process of the sliding filament model?
- at rest tropomyosin and troponin are sitting in a position in the actin filament that prevents myosin from binding
- nerve impulse causes calcium ions to be released from the sacroplasmic reticulum
- calcium ions bind to troponin causing it to change shape and move the tropomyosin out of the actin binding sites
- binding sites for myosin are exposed on the actin
- myosin binds to actin forming a crossbridge
- myosin head tilts = = pulling the actin filaments towards the centre of the sarcomere/sacromere shortening
- ATP is needed to break the crossbridge/hydrolysed = mysosin head returns to its original position and bind into the next point of actin
- calcium ions are actively transported back into the sarcoplasmic reticulum = stored until they are needed again
What are the two uses for ATP during the sliding filament model?
breaking of the corssbridge between actin and myosin;
actively transport calcium ions back into the sarcoplasmic reticulum
Draw an image of a neuromuscular junction:
image on iPad
How does a nerve impulse cause muscle contraction?
1) action potential arrives at the presynaptic membrane causing the calcium ion channels to open
2) calcium ions flood into the pre synaptic knob
3) causes vesicles containing NT to fuse with pre-synaptic membrane
4) the NT diffuses across the synapse and binds to the receptors (sodium voltage gated channels) on the sarcolemma
5) channels open and sodium ions move in along electrochemical gradient = depolarosation of the sarcolemma = AP spreads along the sarcolemma through T tubules
6) calcium ions channels open and diffuse out of the sarcoplasmic reticulum
What are the 3 mechanisms by which ATP supply is maintained in muscular contraction?
aerobic
anaerobic
creatine phosphate
How is creatine phosphate used in ATP supply for muscle contractionn?
occurs in the sarcoplasm
phosphate group from creatine phosphate is transffered to ADP to form ATP
sufficient to support muscle contraction for 2-4 seconds
