💚plant responses💚

what do plants need to respond to?

abiotic stress and attention of herbivores

do auxins make fruits ripen?

yes

what are tropisms?

directional growth in response to environmental stimulus

what is phototropism?

growth of plant in response to light

what is geotropism?

growth of plant in response to gravity

what is hydrotropism?

plant growth in response to water

what is thigmotropism?

plant growth in response to contact with an object

what is thermotropism?

plant growth in response to temperature

what is chemotropism?

growth of plant in response to chemicals

shoots have what phototropism?

positive

roots have what phototropism?

negative

shoots have what geotropism?

negative

roots have what geotropism?

positive

define antagonistic?

hormones working against eachother

define synergistic

hormones working together to promote the same response

where are plant growth hormones produced?

roots and shoots tips

what is gibberellin?

growth hormone

what are auxins?

growth hormones

what happens if a seed does not have gibberellin?

it will not germinate

what 2 hormones aid leaf drop?

auxin and ethene

when a seed absorbs water what is activated and what is produced?

embryo is activated and begins to produce gibberellin

what is the shoot tip at the top of a flowering plant called?

apical bud

what are examples of abiotic stress?

lack of water

excess water

wind

cold/heat

salinity

why is leaf loss good in winter?

go into dormancy to conserve energy and water

healthy plants produce what?

auxin

in healthy plants explain the abscission zone.

lots of auxin so insensitive to ethylene

what does auxin inhibit?

ethene

when auxin level decreases explain abscission zone.

increase in ethene to activate enzymes to digest zone

after germination how is growth controlled?

auxins (IAA and more)

high concentration of auxins suppresses what growth?

lateral shoots (apical dominance)

apical dominance is what?

growth of apical bud and inhibition of side shoots

where are auxins found?

meristem cells

what increases plasticity of cell wall?

auxins

after being made what do auxins do?

diffuse away from tip, bind to receptor sites

what do auxins activate?

hydrogen ion pumps

what does ethene do?

accelerates the ripening of climatic fruits

how does ethene effect fruits?

makes it softer, sweeter and change appearance

what does ethane do on a molecular level?

breaks down cell wall and chlorophyll and converts starch to sugar

what does a peak of ethene level trigger?

series of chemical reactions and increase respiration rate

when is ethene used practically?

in supermarkets to evenly ripen fruits

when are auxins used?

cuttings and micropropogation

what happens when balance of plant hormones is lost?

metabolism and growth affected leading to plant death

what can be used as weed killers?

synthetic auxins

what do synthetic weed killers target?

dicotyledons

how do synthetic auxins work as a weed killer?

increase growth rate to such a high extent that it is no longer sustainable causing death of the weed

what is used to make seedless fruit?

auxins

what can be used to promote fruit dropping?

ethene

what is used to prevent aging of fruit and lettuce?

cytokinins

what are gibberellins used for?

encourage flowering

delay ripening

improve size and shape of fruit

speed up germination

what does abscisic acid do?

inhibit other hormones

what are weeds called?

dicotyledons

what are most plants called?

monocotyledons

define herbivory

the act of a plant being eaten by a herbivore

why do plants have defences?

since they can’t move away from danger and attacks by herbivores

what is a chemical that has a very bitter taste and are toxic to insects?

tannins

what is the chemical that tastes bitter which is toxic to insects and fungi and inhibits seed germination?

alkaloids

what is a chemical like citronella which acts as insect repellent?

terpenoids

why are alkaloids goof chemical defence?

poisonous for most insects

what does giberellins trigger?

breakdown of starch into glucose to allow the embryo to respire and germinate