Plant responses

Tropic responses

Phototropism, geotropism, chemotropism, hydrotropism, thigmotropism

Phototropism

Change in plant growth in response to unidirectional light

Geotropism

Change in plant growth in response to gravity

Chemotropism

Change in plant growth in response to chemicals

Thigmotropism

Change in plant growth in response to touch

Advantages of tropisms

Allows plants to obtain more favourable growing conditions

How plants benefit from a phototropic response

As shoots are positively phototrophic it allows for increased photosynthesis

how do plants benefit from a geotropic response

Roots are positively geotropic so there is increased availability of soil water and better anchorage of roots

Meristem

Region of the plant where cells are actively dividing by mitosis to produce new cells for growth

Apical meristem

Located at root and shoot tips and in buds, responsible for growth in length, formation of leaves and auxiliary buds

Lateral meristems

Located around edge of plant stem and branches, responsible for growth in width or girth of stems and root, produces secondary xylem and phloem and bark

Positive growth

When growth response is towards the stimulus

Negative growth

When growth response is away from stimulus

Stimulus

Anything that causes a reaction in an organism or in any of its parts

Response

An activity of an organisms or cell due to a stimulus

Tropism

Plant growth responses to a stimulus which may be positive or negative