Why do plants produce plant hormones?
Enjoying Flashcards?
Tell us what you think
Why do plants produce plant hormones?
Plants produce hormones in order to coordinate and control growth and development.
Why do plants need to respond to stimuli such as light and gravity?
Plants need to respond to stimuli to ensure that they can maximise their growth, e.g.
responding to light ensures their leaves can absorb maximum light energy for photosynthesis
responding to gravity ensures that shoots grow upwards towards light and roots grow downwards towards water and mineral ions
Define the term phototropism.
Phototropism is the directional growth of plants in response to light, allowing shoots to grow towards light to optimise photosynthesis.
Define the term gravitropism (or geotropism).
Gravitropism, also known as geotropism, is the directional growth response of plants in relation to gravity; roots grow downwards and shoots grow upwards.
True or False?
Unequal distribution of auxin results in uneven growth in plant shoots and roots.
True.
Auxin distributes itself unevenly in shoots and roots due to the direction of light and gravity. This uneven auxin distribution results in uneven growth.
What effect does auxin have on cells in the shoots of plants?
Auxin stimulates cell elongation in plant shoots.
How does auxin distribution in response to light lead to phototropism?
Auxin accumulation on the shaded side of a shoot causes cells on the shady side to elongate at a faster rate than cells on the light side; this leads to bending of the shoot towards the light.
True or False?
Auxin inhibits the growth of cells in plant roots.
True.
Auxin accumulates on the lower side of plant roots, inhibiting cell growth and causing roots to bend downwards towards gravity.
True or False?
Auxins can be used in agriculture as a weedkiller. (Higher Tier Only)
True.
Auxins can be used as weedkillers in agriculture; this is because they cause broad-leaved weed species to die while allowing narrow-leaved crop species to grow normally.
How can auxins aid the production of new plants? (Higher Tier Only)
Auxins can aid the production of new plants when it is added to:
rooting powder that encourages plant cuttings to grow new roots
cells in a tissue culture to promote growth
How are gibberellins used in the plant growing industry? (Higher Tier Only)
Gibberellins can be used to:
initiate seed germination by ending seed dormancy
promote flowering
increase fruit size
promote formation of seedless fruits
True or False?
Ethene prevents fruit ripening. (Higher Tier Only)
False.
Ethene causes fruit ripening. In the food industry the ripening of fruits can therefore be slowed by inhibiting ethene production.