Plant orientation responses Flashcards
Abiotic factors
non-living physical and chemical components of the ecosystem
Biotic factors
Living aspects of the environment that affect an organism
Habitat
where it lives/eats
Ecological niche
An organism is the perfect match of adaptations to its habitat
Adaptative advantage
A reproductive benefit an organism derives from being well-suited to the environment in which it lives
Adaptations
- Any traits that enable it to survive in its habitat
- Controlled by genes giving the organism a reproductive advantage
Structural adaptation example
Long beak on kiwi
Physiological adaptation example
Large eggs twice the size of the body of a kiwi
Behavioural adaptation
Nocturnal for kiwis
Orientation
Way in which the organism positions itself in response to stimulus from the environment
Stimulus
Change in internal or external environment that evokes a response
Light prefix
Photo
Gravity prefix
Geo
Temperature prefix
Thermo
Water prefix
Hydro
Chemicals prefix
Chemo
Touch prefix
Thigmo
Tropism
The growth response towards or away from an environmental stimulus in plants
Direction of positive
Towards the environmental stimulus
Direction of negative
Away from the environmental stimulus
Auxin full name
Indoleacetic acid (IAA)
Auxin
The plant growth hormone that controls the tropic response
Where is auxin produced
- Growing tip of the shoot - meristematic tissue
- produced in high concs in apical meristem
Auxin causes
elongation of the cells promoting upwards growth
What happens when light is shone on auxin
Migrates to the dark side causing uneven plant tissue growth/elongation on one side
Ethylene
Phytohormone that controls ripening of fruit
Gibberellins
Phytohormone that controls the germination of seeds
Cytokinins
Promotes cell division
Abscisic acid
Phytohormone that controls the closing of stomata
Adaptive advantages always relate back to
food, shelter, mates
High concentration of auxin
Inhibits buds and roots but stimulates stems
Nastic responses
Non-directional responses of the plants to stimulus
Explain thigmonasty in terms of turgor pressure
- The hinge of the leaf called the pulvinus is filled with water
- when touched, rapid loss of water occurs
- loss of turgor pressure
- hinge collapses
key adaptive advantages of nastic responses
- faster movements that avoids unfavourable conditions
- accesses resources
Rate of frequency of responses increases as…
Intensity of stimulus increases
Adaptive advantages of tropisms
- Growth towards favourable conditions eg. light, increased photosynthesis, growth, flowers, seeds
- Growth away from unfavourable conditions eg. chemicals
