Plant Hormones Flashcards
What is a tropism?
A plants response to a stimulus by growing
What is a stimulus?
A change in the environment
What is a positive tropism?
When the plant grows towards the stimulus
What does it mean if a plants shoot shows positive phototropism?
The plant’s shoots grow towards light
What does it mean if a plants roots show positive gravitopism?
The roots grow down, towards the pull of gravitiy
Whats another word for gravitropism?
Geotropism
What are plant hormones?
Chemicals that cause changes in plants
What does the plant hormone auxins do to a plant?
Make cells grow longer
What does the plant growth substance gibberellins do to a plant?
Can make plant shoots grow longer and control when seeds germinate.
What are auxins the plant hormone affected by?
Light
Phototropism in shoots is caused by what plant hormone?
Auxins
The graph shows the results of an investigation on the effect of gibberllin on shoot growth. Describe the trends shown by the graph, and comment on how reliable these results are.
Growth increases with increasing gibberllin up to a maximum of about 1 microgram. Beyond this, adding more gibberllin has no effect. As each point is an average of 10 plants, this helps to average out random variation in the shoots and makes the results more reliable.
