One of the characteristics of life on earth is sensitivity to the surroundings. In the case of animals how they react to external stimuli is easy to see, however, it is not always so obvious for plants. Plants don't have a nervous system or muscles but they do have hormones which they use to give them sensitivity to their surroundings. The sensitivity granted by the hormones enables plants to grow towards light and makes their roots push down into the soil. Certain plants living in areas where conditions mean that there are few nutrients have developed carnivorous habits. For example: the... Show more

One of the characteristics of life on earth is sensitivity to the surroundings. In the case of animals how they react to external stimuli is easy to see, however, it is not always so obvious for plants. Plants don't have a nervous system or muscles but they do have hormones which they use to give them sensitivity to their surroundings. The sensitivity granted by the hormones enables plants to grow towards light and makes their roots push down into the soil.

Certain plants living in areas where conditions mean that there are few nutrients have developed carnivorous habits. For example: the venus fly trap which has small hairs on its 'traps' that detect insects and close the trap, but there are others such as the sundew and pitcher plants. These plants have evolved to trap flies and other insects. They secrete digestive juices that slowly break down the insects into the nutrients that the plant needs. These are then absorbed by the plant cells and transported in the sap to where they are needed.

As well as for sensitivity, plants also use hormones to control their biological processes. Growth of plants is controlled by hormones but plants also use them to control their formation of flowers, stems and leaves, and for their shedding of leaves.

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