5.5-the longest (plant and animal responses) Flashcards
what are alkaloids?
organic nitrogen containing bases that have important physiological effects on animals eg nicotine, quinine, morphine
what are pheromones?
any chemical substance released by 1 living thing, which influences the behaviour or physiology of another living thing.
what are tannins?
phenolic compunds, located in cell vacuoles or in surface wax on plants.
what is tropism?
a directional growth response in which the direction of the response is determined by the direction of the external stimulus.
what might plants do in hotter conditions?
thicken their waxy cuticle
what might plants do in windy conditions?
have vascular tissue which is more heavily lignified.
how do plants respond to the threat of herbivores?
tannins
alkaloids
pheremones
what do tannins do?
- are toxic to microorganisms and herbivores.
- found in the upper epidermis of leaves and make them taste bad
- in roots they prevent infiltration of pathogens
what do alkaloids do?
feeding deterrent to animals-taste bitter
where are alkaloids found in plants?
growing tips and flowers, peripheral cell layers of stems and roots.
what are 5 types of tropism?
phototropism geotropism chemotropism thigmotropism hydrotropism
what is the purpose of geotropism?
anchors plants in soil+ helps them take up water+minerals.
what is an example of chemotropism?
on a flower, pollen tubes grow down the style, attracted to chemicals, towards the ovary where fertilisation can take place.
what is thigmotropism?
directional growth movement which occurs as a mechanosensory response to a touch stimulus.
what is an example of thigmotropism?
shoots of climbing plants like ivy wing around other plants or solid structures to gain support.
what is it called when a plant responds towards a stimulus?
positive tropic response
what is a negative tropic response?
when a plant responds away from a stimulus.
what is a nastic response?
a non-directional response to external stimuli.
name 5 plant hormones.
cytokinins abscisic acid auxins gibberellins ethene
what do cytokinins do?
- promote cell division
- delay leaf senescence
- promote cell expansion
what does abscisic acid do?
- inhibits seed germination and growth
- causes stomatal closure when plant is stressed by low water availability
what do auxins do?
- inhibits leaf fall
- promote cell elongation
what does ethene do?
promotes fruit ripening
what hormone is responsible for leaf loss in
deciduous plants?
abscisic acid generally initiates stress responses in plants, like winter dormancy in deciduous plants.
what hormone is responsible for seed germination?
gibberellins
what hormone is responsible for stomatal closure?
abscisic acid
what are the differences between nastic and trophic responses?
nastic: non directional, fast, specific place in plant, action potentials cause a change in cell turgidity, can be temporary.
trophic: directional, slow, can be throughout whole plant, action of gene causes change in plant growth, permanent.
what are the differences between animal and plant hormones?
plant: produced by variety of specialised cells, transported in vascular system, operate close to where they’re produced.
animal: produced by glands, transported in blood, may travel long distances before they have an affect.
what is apical dominance?
inhibition of lateral buds further down the shoot by chemicals produced by the apical bud at the tip of a plant shoot.
how do gibberellins promote seed germination?
when the seed absorbs water, the embryo releases giberellin, which travels to the aleurone layer of the endosperm region of the seed. this enables the production of amylase which breaks down starch into glucose, so the embryo can respire and grows.
what did darwin’s experiments show to do with phototropisms?
confirmed the shoot tip was responsible for phototropic responses.
what did boysen-jensen’s experiments show to do with phototropism?
water and/or solutes need to be able to move from the shoot tip for phototropic responses to happen.
how does auxin work?
increases the stretchiness of the cell wall by promoting active transport of H+ by an ATPase enzyme on the plasma membrane, into the cell wall. the resulting low pH provides optimum conditions for expansins (wall loosening enzymes) to work. these enzymes break bonds within the cellulose so the walls become less rigid.
how does light cause the redistribution of auxins?
phototropins’ activity is promoted by blue light-more phototropins on the light side- thought to influence PIN proteins, which control how much auxin goes though cell membranes. activity of PIN proteins is controlled by a molecule called PINOID.
how does auxin cause geotropic responses of roots?
auxin accumulates on the lower side, where it INHIBITS cell elongation.
what are the commercial uses of auxins?
- prevent leaf and fruit drop
- taking cuttings
- seedless fruit
- herbicides
what are the commercial uses of cytokinins?
- prevent yellowing of lettuce leaves after they’ve been picked.
- tissue culture
what are the commercial uses of gibberellins?
- fruit production: delay citrus senescence, elongate apples and grapes
- brewing
- sugar production
- plant breeding
what are the commercial uses of ethene?
- speed up apple, tomato, citrus ripening
- promoting cherry, walnut, cotton fruit drop
- promoting female sex expression in cucumbers, reducing self pollination
because ethene is a gas how is it used?
scientists developed 2-chloroethylphosphoric acid-solution, easily absorbed, slowly releases ethene inside the plant.
what is the autonomic nervous system?
part of the nervous system responsible for controlling the involuntary motor activities of the body.
what is the peripheral nervous system?
the sensory and motor nerves connecting the sensory receptors and effectors to the CNS.
what is the somatic nervous system?
the motor neurones under conscious control.
what is the PNS divided into?
the sensory system and motor system
what is the motor system divided into?
the somatic nervous system and autonomic nervous system.
what is the spinal cord protected by?
the vertebral column
what is the role of the PNS?
to ensure rapid communication between the sensory receptors, CNS, and effectors.
what does the somatic nervous system consist of?
motor neurons that conduct action potentials from the CNS to the effectors that are under conscious control.
what are the neurons like in the somatic nervous system and why?
myelinated to allow rapid response
how many motor neurons are involved between the CNS and effector in the somatic system?
1
what does the autonomic nervous system consist of ?
motor neurons that conduct action potentials from the CNS to effectors that are not under voluntary control.
what are examples of effectors not under voluntary control?
glands, cardiac muscle, smppth muscle in blood vessel walls, airways, wall of digestive system
what are the neurons like in the autonomic nervous system and why?
mostly non-myelinated-doesn’t require rapid response.
how many neurons between the CNS and effector in the autonomic system?
at least 2
how are neurons between the CNS and effector connected?
small swellings called ganglia.
how can the autonomic system be divided?
sympathetic and parasympathetic
what is the role of the sympathetic system>?
prepares body for activity
what is the role of the parasympathetic system?
conserving energy
what neurotransmitter does the sympathetic system use?
noradrenaline
what neurotransmitter does the parasympathetic system use?
acetylcholine
when Is the sympathetic system most active?
times of stress
when is the parasympathetic system most active?
sleep or relaxation
what are some effects of the sympathetic system?
increases heart rate dilates pupils increases ventilation rate reduces digestive activity orgasm
what are some effects of the parasympathetic system?
decreasing heart rate constricting pupils reducing ventilation rate increasing digestive activity sexual arousal
what are the 2 cerebral hemispheres connected by?
the corpus callosum
what are the functions of the cerebrum?
conscious thought
conscious action, including the ability to override some reflexes
emotional responses
intelligence, reasoning, judgement, decision making
factual memory
what is the role of the cerebellum?
to coordinate fine control of muscular movements
what are the cerebellum and cerebrum joined by?
the pons.
what is the role of the hypothalamus?
to control homeostatic mechanisms in the body,
what are the 2 lobes of the pituitary gland?
posterior lobe
anterior lobe
what does the medulla oblongata do?
controls the non-skeletal muscles-cardiac and smooth muscles-by sending action potentials out through the autonomic nervous system.
what is a reflex action?
response to a change in the environment that does not involve any processing in the brain to coordinate movement.
what kind of reflex is the blinking reflex?
cranial reflex-nervous pathway passes through the brain.
what’s faster the corneal reflex or the optical reflex?
corneal
what kind of reflex is the knee jerk reflex?
spinal reflex
how is the knee jerk reflex unusual?
it only uses 2 not 3 neurons (skips relay)
what is adenyl cyclase?
an intracellular enzyme activated by certain hormones.
what is cyclic AMP (cAMP) ?
a secondary messenger released inside cells to activate a response.
which nerves from the cardiovascular centre in the medulla oblongata supply the SAN?
accelerans nerve
vagus nerve
what kind of nerve is the accelerans nerve?
sympathetic
what kind of nerve is the vagus nerve?
parasympathetic
what do action potentials sent down the accelerans nerve do?
cause the release of noradrenalin, increasing heart rate.
what do action potentials sent down the vagus nerve do?
cause the release of acetylcholine, reducing heart rate.
what are the 3 types of muscle?
smooth (involuntary)
cardiac
skeletal (voluntary, striated)
where is involuntary muscle found?
walls of tubular structures such as digestive system and blood vessels.
what are the cells in cardiac muscle joined by?
intercolated discs
how is contraction of skeletal muscle stimulated?
1) action potentials arrive at end of axons+ cause calcium ions to flood into end of axon
2) vesicles of acetylcholine fuse w end membrane
3) acetylcholine molecules diffuse across gap and fuse w receptors on sarcolemma
5) wave of depolarisation spreads along sarcolemma.
what is a sarcomere?
the distance between 2 Z lines (at rest, about 2.5 um)
what are myofibrils?
the contractile units of skeletal muscle
what is creatine phosphate?
a compound in muscle that acts as a store of phosphates and can supply phosphates to make ATP rapidly.
which 3 mechanisms are involved in maintaining the supply of ATP?
aerobic respiration in mitochondria
anaerobic respiration in the sarcoplasm of muscle tissue
creatine phosphate
WHat is the structure of cardiac muscle?
- long fibres with branching cross bridges between them
- intercolated discs
what is the purpose of the cross bridges in cardiac muscle?
allow electrical stimulation to spread evenly
allow contraction of the muscle to be squeezing rather than linear.
what is the structure of skeletal muscle?
- muscle cells forms fibres, each fibre is multinucleate.
- surrounded by a membrane called the sarcolemma.
- cytoplasm is called sarcoplasm
- fibres arranged into myofibrils which are divided into units called sarcomeres
dark bands=?
A bands
light bands=?
I bands
what is myosin?
fibrous protein
what is the structure of myosin?
each myosin molecule has a head and a tail
several myosin molecules lie in a bundle together, with their heads pointing in the same direction.
what type of filaments does myosin make?
thick filaments
what bands does myosin make?
dark bands
what is actin?
globular protein
how does actin join together?
long chain, 2 these chains twisted together form an actin filament
what is also twisted around the actin chain?
tropomyosin
what is tropomyosin?
fibrous protein
what is attached to the actin chain at regular intervals?
troponin
what, together, forms a Z line?
troponin, tropomyosin, actin
what is the folding of a sarcolemma called?
t-tubule
why is glucose required for the contraction of skeletal muscle?
to make atp
for respiration/to release energy
atp needed in muscle contraction for breaking down cross bridges between actin and myosin
atp hydrolysed to reset myosin heads
atp needed for active transport of Ca2+ out the sarcoplasmic reticulum.
what is thigmonasty?
non directional response in plants to the stimulation of contact (touch)
what do gibberellins do?
promote seed germination and growth of stems
where are apical meristems found and what do they do?
at tips of roots and shoots-make them longer
what can lateral bud meristems cause?
side shoots
where are lateral meristems found?
near outside of roots and shoots
where are auxins produced?
apex of shoot
what happens when barley seeds germinate?
aleurone layer of seed produces amylase enzymes that break down stored starch into maltose
adding gibberellins to barley seeds can speed up what process?
germination
what happens when you spray sugar cane with gibberellins?
stems elongate-more sugar available from each plant
what happens when you spray plants w gibberellin synthesis inhibitors?
keep flowers short and stocky
what are biennial plants?
plants which flower only in the 2nd year of their lives
what does pollination do to cucumbers?
makes them taste bitter
what conditions prevent ethane synthesis and fruit ripening?
low temp, low o2, high co2
what connects the 2 cerebral hemispheres?
corpus callosum
what does the outermost layer of the cerebrum consist of?
cerebral cortex
what is the cerebral cortex subdivided into?
sensory, association, motor areas
what do association areas do?
compare sensory inputs w previous experience, interpret what they mean, judge appropriate response
the conscious decision to contract voluntary muscles is initiated in…
the cerebral cortex
what are some actions that would be coordinated by the cerebellum?
riding a bike
playing sport
playing musical instruments
walking + running
what are examples of centres in the medulla oblongata?
cardiac
vasomotor
respiratory
in the sympathetic system are there many or a few nerves leading out of the CNS?
many, each leading to a separate effector
in the parasympathetic system are there many or a few nerves leading out of the CNS?
a few, which divide up and lead to many effectors
where are the ganglia of the sympathetic nervous system?
just outside CNS
where are the ganglia of the parasympathetic nervous system?
in effector tissue
how long are the pre-ganglionic neurones of the sympathetic nervous system?
short
how long are the pre-ganglionic neurones of the parasympathetic nervous system?
long
how long are the post-ganglionic neurones of the parasympathetic nervous system?
short
how long are the post-ganglionic neurones of the sympathetic nervous system?
variable in length but long
what does CRH cause the release of?
ACTH (adrenocorticotropic hormone)
what does ACTH do?
stimulates adrenal cortex to secrete corticosteroid hormones
what does TRH cause the release of?
TSH (thyroid stimulating hormone)
what does TSH do?
causes the thyroid gland to release more thyroxine
what does thyroxine do?
increases metabolic rate and makes cells more sensitive to adrenaline
where do tropic hormones get released from?
anterior pituitary
what do releasing hormones/releasing factors do?
stimulate release of tropic hromones from anterior pituitary
what does sensory input to the CVC include?
stretch receptors in muscles
chemoreceptors
co2 conc in blood
stretch receptors in carotid sinus
what do stretch receptors in muscle do?
detect limb movement
where are chemoreceptors found?
aorta, brain, carotid arteries (in neck)
what do chemoreceptors do?
monitor blood pH
what do stretch receptors in the walls of the carotid sinus do?
monitor blood pressure
what is the carotid sinus?
small swelling in carotid artery
what are the shapes of involuntary (smooth) muscle cells?
spindle shaped
how fast does involuntary (smooth) muscle contract?
slooow
what system is involuntary (smooth) muscle controlled by?
autonomic
where is involuntary (smooth) muscle found?
walls of tubular structures like digestive system and blood vessels
how is involuntary (smooth) muscle arranged?
longitudinal and circular layers that oppose eachother
what do the cross bridges of cardiac muscle do?
help ensure electrical stimulation is spread evenly across walls of the chambers+that action is squeezing
what are intercolated discs?
specialised cell surface membranes fused to produce gap junctions that allow free movement of ions between cells
what’s the point of intercolated discs?
action potentials pass easily +quickly throughmuscle fibres
what is muscle cell cytoplasm called?
sarcoplasm
what is a motor unit?
when many motor neurones divide +connect to several muscle fibres which all contract together so the contraction is stronger.
thin filaments make up the…
light band
thick filaments make up the…
dark band
what is the H zone?
In the middle of the dark band where there’s no overlap w the light band.
what does each troponin molecule consist of?
3 polypeptides:
1 binds to actin, 1 to tropomyosin, 1 to Ca2+ when there
DURING MUSCULAR CONTRACTION ATP IS USED TO BREAK WHAT
CROSS BRIDGES that hold the actin and myosin together.
