Tropisms in plants

Question 1

What is a tropism?

Answer 1

• plant growth response to stimuli from one direction
• differential growth of plant cells triggered by chemical message produced in response to a particular stimulis

Question 2

What are the types of tropisms?

Answer 2

• phototropism
• geotropism
• chemotropism
• thigmotropism
  
  • touch

Question 3

Why are tropisms important?

Answer 3

• plants grow and respond to variation in the environment
• makes maximum use of the external conditions
• e.g. in once a seed begins to germinate
  
  • roots must grow downward for support, minerals and water
  • shoot must grow towards light
  • in order to survive

Question 4

Why is research on tropisms mainly use germinating seed and very young seedlings?

Answer 4

• easy to work with and minipulate
• grow and respond very rapidly
  
  • any changes show up quickly
• changes tend to affect the whole organism rather than a small part (as with a mature plant)
  
  • this makes any tropisms easily to observe and measure

Question 5

Why are seedling of monocotyledonus plant (e.g. cereals such as wheat and oats)?

Answer 5

• shoot emerges in a single spike
• with no apparent leaves as a coleoptile
• easier to manipulate than a dicotyledonus shoot
• although they are more simple