Phototropism

The simplist way to clone a plant is to take a cutting of it. A cutting from an adult plant is taken at an angle and planted in damp compost. Plant hormones are often used to help the plant develop and grow roots quicker. The cutting is covered in a plastic bag and tied loosely with an elastic band to keep in the moisture. After a few weeks the cutting will have developed roots and formed a new plant. This plant will have the same genes as the parent plant so wil, be a clone of this plant.

Auxins

Auxins are hormones which are naturally found on plants. Auxins are mostly made in the tip of the roots and shoots but can diffuse to other parts of the roots or shoots. If a high concentration of auxins is produced or given to the plants then the cells in the shoots grow more but the cells in the roots grow less.

Phototrophism

In a shoot the shaded part contains more auxins than the part with light shining onto it because the light destroys the auxins. This causes the shaded part to grow longer which in turn causes the shoots to bend towards the light. In the roots the shaded part still has more auxins but instead the shaded part grows less than the lit part. This causes the plant to bend away from the light. If the plant has not shoots then no auxins can be made meaning they will not grow. Phototrophism increases survival rate for plants because the more auxins the shoots have then the more the plant will grow. The plant turn towards the light where it can photosynthesis more.

Experiment

If the tips are covered then this means the plants will grow straight because there is an equal concentration of auxins on both sides- the tip is will not be effected by the sunlight. If the shoots are left natural they will bend towards the light. An experiment to show this is to place 3 plants with shoots in a box with a source of a light only at one side and observing how different shoots grow. The 3 plants will have different shoots- one with no tips, one with covered tips and one with natural tips.

Credits:

Created with images by Amy Loves Yah - "Strawberries" • artursfoto - "rose pruning garden"

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