ORIENTATION RESPONSES IN PLANTS

 Plants are autotrophs – making food from photosynthesis.  Apart from reproductive organs (flowers) plant structure and functions are adapted for photosynthesis directly or indirectly.

ORIENTATION RESPONSES IN PLANTS  Plants are autotrophs – making food from photosynthesis.  Apart from reproductive organs (flowers) plant structure and functions are adapted for photosynthesis directly or indirectly.  Unable to move from where they germinate, but can move leaves and stems.

ORIENTATION RESPONSES IN PLANTS  Plants are autotrophs – making food from photosynthesis.  Apart from reproductive organs (flowers) plant structure and functions are adapted for photosynthesis directly or indirectly.  Unable to move from where they germinate, but can move leaves and stems.  Movements are much slower than animals because the cellulose cell wall of plant cells prevents repid change in cell shape.

ORIENTATION RESPONSES IN PLANTS  Plants are autotrophs – making food from photosynthesis.  Apart from reproductive organs (flowers) plant structure and functions are adapted for photosynthesis directly or indirectly.  Unable to move from where they germinate, but can move leaves and stems.  Movements are much slower than animals because the cellulose cell wall of plant cells prevents repid change in cell shape.  Plant movements are limited to changes in cell turgor (nastic responses) or growth (tropisms).

TROPISMS  Growth responses – due to abiotic factors (light intensity, chemicals, gravity, water and touch).

TROPISMS  Growth responses – due to abiotic factors (light intensity, chemicals, gravity, water and touch).  Response to put the plant into favourable conditions and away from unfavourable.

TROPISMS  Growth responses – due to abiotic factors (light intensity, chemicals, gravity, water and touch).  Response to put the plant into favourable conditions and away from unfavourable.  Eg – growth towards maximum light intensity for photosynthesis in a forest. 

TROPISMS  Positive phototropism – growth of a stem towards light.  Positive gravitropism (aka geotropism) – growth of young root from the seed downwards. Anchoring the plants and enabling uptake of water and nutrients.

TROPISMS  Positive phototropism – growth of a stem towards light.  Positive gravitropism (aka geotropism) – growth of young root from the seed downwards. Anchoring the plants and enabling uptake of water and nutrients.  Negative gravitropism – growth of the young shoot upwards towards the surface.

TROPISMS  Positive phototropism – growth of a stem towards light.  Positive gravitropism (aka geotropism) – growth of young root from the seed downwards. Anchoring the plants and enabling uptake of water and nutrients.  Negative gravitropism – growth of the young shoot upwards towards the surface.  Positive hydrotropism – growth of roots towards a water source.

TROPISMS  Positive phototropism – growth of a stem towards light.  Positive gravitropism (aka geotropism) – growth of young root from the seed downwards. Anchoring the plants and enabling uptake of water and nutrients.  Negative gravitropism – growth of the young shoot upwards towards the surface.  Positive hydrotropism – growth of roots towards a water source.  Positive chemotropism – pollen tubes growing down a stigma towards the ovary is guided by chemicals. This response ensures male gametes reach female gametes so fertilisation can occur.

TROPISMS  Positive phototropism – growth of a stem towards light.  Positive gravitropism (aka geotropism) – growth of young root from the seed downwards. Anchoring the plants and enabling uptake of water and nutrients.  Negative gravitropism – growth of the young shoot upwards towards the surface.  Positive hydrotropism – growth of roots towards a water source.  Positive chemotropism – pollen tubes growing down a stigma towards the ovary is guided by chemicals. This response ensures male gametes reach female gametes so fertilisation can occur.  Positive thigmotropism – growth of stem of climbing plants around a host plant. 