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