Plant Responses Flashcards
Ch 32
Which is singular/plural between stimuli and stimulus?
sing = stimulus
pl = stimuli
What is a stimulus?
anything that causes a reaction in an organism or in any of it’s parts
What is a response?
the activity of a cell or organism as a result of a stimulus
Name some animal stimuli.
feeling pain/hunger, hearing a noise
Name some plant stimuli.
light, temperature, gravity
Name some animal responses.
movement, feeding, production of enzymes
Name some plant responses.
growth, flowering
What 4 structures are needed for response?
(2 of them are only animals)
- chemical/hormonal system (plants and animals)
- nerve and sense organ system (animals)
- method of movement so growth, muscular and skeletal system (animals)
- defence/immune system
Growth of flowering plants can be controlled by what two types of factors?
external and internal factors
Name 4 external factors for responses in flowering plants.
light
day length
gravity
temperature
Give 5 points on light as an external factor for responses in flowering plants.
1) provides energy
2) produce chlorophyll
3) fully formed chloroplasts
4) normal-sized leaves
5) strong stems
Describe day length as an external factor for responses in flowering plants.
plays a role in causing plants to flower,
also for fruit and seednformation, dormancy and germination
Describe gravity as an external factor for responses in flowering plants.
can cause roots to grown down into soil
and shoots grow upwards away from gravity
Describe temperature as an external factor for responses in flowering plants.
affects rate of enzyme reactions/activity, plants also grow faster at higher temperatures
Describe internal factors for responses in flowering plants.
produce chemicals called growth regulators, which are produced in the meristematic regions
Growth regulators are produced where?
in the meristematic regions
Root tip, shoot tip = ?
region
Region = ?
root tip, shoot tip
Definition of a tropism?
is the growth of a plant in response to a stimulus
Definitions of a positive tropism and a negative tropism?
positive = occurs when the growth is TOWARDS the stimulus
negative = occurs when the growth is AWAY from the stimulus
Main advantage of tropism is?
they allow plants to obtain more favourable growing conditions
Definition of phototropism?
is the growth of a plant in response to LIGHT
The growth of a plant in response to LIGHT is called?
phototropism
Definition of geotropism?
is the growth of a plant in response to GRAVITY
The growth of a plant in response to GRAVITY is called?
geotropism
3 benefits of geotropism?
- can anchor plants
- absorb more water
- absorb minerals
2 points on geotropism in relation to how parts of the plant grow?
stems grow away from gravity,
roots grow towards gravity
Definition of thigmotropism?
is the growth of a plant in response to TOUCH
The growth of a plant in response to TOUCH is called?
thigmotropism
An example of a climbing plant?
ivy
Definition of hydrotropism?
is the growth of a plant in response to WATER
The growth of a plant in response to WATER is called?
hydrotropism
What type of tropism are climbing plants?
thigmotropism
Climbing plants have what special parts? What do they do?
tendrils: wrap around supporting structures
Definition of chemotropism?
is the growth of a plant in response to CHEMICALS
The growth of a plant in response to CHEMICALS is called?
chemotropism
What would positive hydroptropism look like?
roots and pollen tubes grow towards water
Definition of a growth regulator?
a chemical that controls the growth of a plant
Most growth regulators are produced in ___ amounts where? And….
small amounts in one part of a plant and transported to another part where they cause an effect
Most growth regulators are transported how?
by diffusion in vascular tissue (xylem and phloem)
Growth regulators can act as what 2 things?
growth promoters,
growth inhibitors
Definition of a growth promoter?
a chemical that causes increased growth in plants
Auxin is a?
plant growth regulator
An example of a growth regulator is?
auxin
Name an auxin.
IAA
Auxin is produced in what 6 places?
meristematic tissue
tips of shoots
young leaves
seeds
root tips
buds
6 functions of auxin?
- inhibit side branches in stems
- stimulate stem elongation
- stimulate root growth
- develop fruit
- cause phototropism
- cause geotropism
Name 4 effects of auxins.
tropisms
apical dominance
fruit formaiton
Root growth
Describe tropisms as an effect of auxin.
auxins cause cell elongation and growth/bending
Describe apical dominance as an effect of auxin.
slows down the growth of side branches,
(if apical bud is removed side branches develop)
Describe fruit formation as an effect of auxin.
IAA made in developing seeds, stimulating food to form in the fruit that surrounds the seed
Describe root growth as an effect of auxin.
low concentration, IAA causes roots to grow
Give 4 points on the role of auxin/IAA in phototropism.
1) IAA produced in growth tips/meritstems of the stem
2) if stem is exposed to light from one side, more IAA will diffuse down the shaded side
3) higher auxin concentration results in more growth
4) as a result of uneven growth, the stem bends towards the light (phototropism will result)
What are growth inhibitors?
a chemical that causes a reduction in growth of plants
2 examples of growth inhibitors in plants?
ethene
abscisic acid
Ethene is the only regulator that is?
a gas
Ethene is made by plants in what 3 places?
stem nodes, ripe fruits, decaying leaves
Give 3 functions of ethene.
- ripening fruits
- causing fruit colour to form, fruit flavour to develop and fruit tissues to soften
- ageing of plants
- stimulating leaves to fall in autumn
Ethene is used commercially for?
ripening bananas
Abscisic acid is produced in what 3 places?
leaves, stems, root caps
2 functions of abscisic acid?
- causing plants to respond to harmful conditions
- inhibiting seed germination, allowing seeds to remain dormant in the soil during winter
Commercially prepared growth regulators, give 3.
- rooting powders (contain NAA)
- seedless fruits
- fruit ripening (ethene)
Surroundings that are harmful to organism(s) = ?
adverse external environment
Plant adaptations for protection consist of what 2 types?
chemical and anatomical/structural
Give 2 anatomical/structural protective features.
thorns - blackberry bushes
bark - prevent pathogen entry
guard cells - shortage of water causes them to shrivel, closing the stomata and reduce further water loss
stinging hairs - nettle leaves
Give 2 chemical protective features.
chemicals
heat shock proteins - surround other proteins and help maintain their shape
stress proteins
