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Theory Questions - Cellular Respiration

Theory Questions - Irritability:

1a. Define the term irritability.
b. list the different types of responses in plants.
c. Explain any th...

 

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Evaluation Questions

1a. Define the term irritability.

Answer:

Irritability is the ability of an organism to respond to stimuli or changes in its environment.

 

b. List the different types of responses in plants.

Answer:

Responses in plants are:

  • Nastism
  • Tropism
  • Taxism

 

c. Explain any three of the responses listed above.

Answer:

i. Nastism: This is the non-directional response of part of an organism to a non-directional stimulus.

ii. Tropism: is a growth movement of a plant in response to a directional stimulus. The direction of response is related to that of the stimulus.

iii. Taxism: is the movement of a whole organism towards or away from a directional stimulus.

 

2a. State three differences between tropism and Nastism

Answer:

Three Differences between Tropism and Nastism:

  Tropism Nastism
i. Stimulus and response are directional Stimulus and response are non-directional
ii. It is a growth movement May or May not be a growth movement
iii. Response depends on the direction of the stimulus. Response does not depend on the direction of the stimulus.
 

b. Describe an experiment to show that shoots of plants are positively phototrophic

Answer:

Experiment to show that plant shoot is positively phototropic

Apparatus: Two cardboard boxes, Ruler, two small lamps, Knife, Masking tape, Black cellophane Potted Plants.

Method: Make a hole of about 5cm in diameter at about 8cm from the bottom of the box.

  • Cover the hole in one box with clear cellophane and the other with black cellophane
  • Place the potted plants in each box, about 5cm away from the cellophane window
  • Take a photograph of the plants in the pot in each box.
  • Keep the boxes apart
  • Place the lamp on the side of the cellophane windows to give light to the boxes
  • Turn off the light every night and turn it on in the mornings.
  • Leave plants to grow for a week
  • After a week remove the lids of the boxes and take photos from the top and from the front.

Results: In the box with the dark cellophane covering the hole the shoots grew upwards while in the box with the transparent cellophane covering the window the shoots bents towards the light source.

Conclusion: Since the shoots of the plant bent towards the light, it shows that it is positively phototropic.

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