Phototaxisthe Phenomenon of movement of motile unicellular organis.pdf

Phototaxis
the Phenomenon of movement of motile unicellular organisms such as algae and bacteria toward
or away from light is termed as phototaxis movement.
This is advantageous for phototrophic organisms as they can orient themselves most efficiently
to receive light for photosynthesis.
Phototaxis is called positive if the movement is in the direction of light and negative if the
direction is opposite.
Phototropism,
Growth with respect to light, expressed in all shoots and some roots.
Phototropism is one of the many plant tropisms or movements which respond to external stimuli
Charles Darwin studied plant growth phenomena involving tropisms.
He found the bending of plants toward light. This phenomenon, which is caused by differential
growth, is called phototropism.
In experiments he used seedlings of canary grass (Phalaris canariensis), the youngest leaves are
sheathed in a protective organ called the coleoptile.
Coleoptiles are very sensitive to light, especially to blue light . If illuminated on one side with a
short pulse of dim blue light, they will bend (grow) toward the source of the light pulse within an
hour.
Simillarity between Phototaxis and phototropism
Both are related with abiotic factor i.e light.
___________________. .
Solution
Phototaxis
the Phenomenon of movement of motile unicellular organisms such as algae and bacteria toward
or away from light is termed as phototaxis movement.
This is advantageous for phototrophic organisms as they can orient themselves most efficiently
to receive light for photosynthesis.
Phototaxis is called positive if the movement is in the direction of light and negative if the
direction is opposite.
Phototropism,
Growth with respect to light, expressed in all shoots and some roots.
Phototropism is one of the many plant tropisms or movements which respond to external stimuli
Charles Darwin studied plant growth phenomena involving tropisms.
He found the bending of plants toward light. This phenomenon, which is caused by differential
growth, is called phototropism.
In experiments he used seedlings of canary grass (Phalaris canariensis), the youngest leaves are
sheathed in a protective organ called the coleoptile.
Coleoptiles are very sensitive to light, especially to blue light . If illuminated on one side with a
short pulse of dim blue light, they will bend (grow) toward the source of the light pulse within an
hour.
Simillarity between Phototaxis and phototropism
Both are related with abiotic factor i.e light.
___________________. ..

1. Phototaxis
the Phenomenon of movement of motile unicellular organisms such as algae and bacteria toward
or away from light is termed as phototaxis movement.
This is advantageous for phototrophic organisms as they can orient themselves most efficiently
to receive light for photosynthesis.
Phototaxis is called positive if the movement is in the direction of light and negative if the
direction is opposite.
Phototropism,
Growth with respect to light, expressed in all shoots and some roots.
Phototropism is one of the many plant tropisms or movements which respond to external stimuli
Charles Darwin studied plant growth phenomena involving tropisms.
He found the bending of plants toward light. This phenomenon, which is caused by differential
growth, is called phototropism.
In experiments he used seedlings of canary grass (Phalaris canariensis), the youngest leaves are
sheathed in a protective organ called the coleoptile.
Coleoptiles are very sensitive to light, especially to blue light . If illuminated on one side with a
short pulse of dim blue light, they will bend (grow) toward the source of the light pulse within an
hour.
Simillarity between Phototaxis and phototropism
Both are related with abiotic factor i.e light.
___________________. .

Solution

Phototaxis
the Phenomenon of movement of motile unicellular organisms such as algae and bacteria toward
or away from light is termed as phototaxis movement.
This is advantageous for phototrophic organisms as they can orient themselves most efficiently
to receive light for photosynthesis.
Phototaxis is called positive if the movement is in the direction of light and negative if the
direction is opposite.
Phototropism,
Growth with respect to light, expressed in all shoots and some roots.
Phototropism is one of the many plant tropisms or movements which respond to external stimuli
Charles Darwin studied plant growth phenomena involving tropisms.

2. He found the bending of plants toward light. This phenomenon, which is caused by differential
growth, is called phototropism.
In experiments he used seedlings of canary grass (Phalaris canariensis), the youngest leaves are
sheathed in a protective organ called the coleoptile.
Coleoptiles are very sensitive to light, especially to blue light . If illuminated on one side with a
short pulse of dim blue light, they will bend (grow) toward the source of the light pulse within an
hour.
Simillarity between Phototaxis and phototropism
Both are related with abiotic factor i.e light.
___________________. .