Plant responses & Hormones Flashcards
What responses are seen in trees in temperate regions to avoid water stress in winter when soil may be frozen?
- leaf abscission (fall)
- leaf dormancy
What is photoperiodism?
the term used to describe the sensitivity of plants to the balance of hours of daylight and dark over the course of a day.
What is abscission?
the separation of part of a plant such as a leaf, fruit or flower causing it to fall.
How do plants prevent themselves from freezing in winter?
they produce solutes in winter to lower the melting point of plant cell cytoplasm.
How do stomata help prevent overheating in plants?
They open to increase transpiration which cools the plant by evaporation.
What are physical defences in plants?
- spikes
- thorns
- hairs
- tough tissues
Which type of plant defence chemicals have a bitter taste, are toxic to insects and are present in tea and red wine?
tannins.
What are alkaloids?
a group of plant chemical defences (including caffeine, nicotine, cocaine).
How do plant pheromones protect a plant?
this group of plant defence chemicals can affect the behaviour of social insects.
Which two environmental stimuli typically bring about tropic responses in plants?
- gravity
- light
What is apical dominance?
the promotion of main shoot growth in plants, caused by suppression of lateral shoot growth.
What do auxins do/cause in a plant?
They have a role in:
- cell elongation
- apical dominance
- tropisms
What does gibberellin do/cause in plants?
It has a role in:
- stem elongation
- mobilising food reserves in seedlings
Which plant hormone causes fruit ripening?
ethene.
What does ABA (abscisic acid) do?
keeping seeds and buds dormant.
