what are the external stimuli in the following cases? a. the leaves of many flower's like camel's foot or Gul mojar close. b. earthworms are moving away. c. the leaves of touch-me-not plant gets closed. d. we cover our nose. e. the plant kept in a dark room bends towards the window. f. we blink our eyes.
Answers
External Stimuli
Explanation:
a. The leaves of many flower's like camel's foot or Gul mohar close- The external stimuli is light and plant responds to light; the closing of flowers/leaves at night. The movement is also referred to as Nyctinasty.
b. Earthworms move away to protect themselves from the heat and light of the sun which might dry their skin and also kill them. Therefore external stimuli may be heat or light.
c. The leaves of touch-me-not plant close as they are sensitive to the external stimuli of physical touch. It happens due to the chemicals released from the stem upon touching the plant. It results in loss of turgor pressure as the water moves out of the cell which then results in drooping down of leaves.
d. We cover our nose when the external stimuli is a bad odour or smell.
e. The plant kept in a dark room bends towards the window - This happens in response to external stimuli of light which it seeks from the window. This movement of plant towards light is also called phototropism.
f. We blink our eyes - Sometimes we tend to blink our eyes in response to bright light. Also blinking on a regular basis is important to keep the eyes moist.