Orientation in Space Flashcards
what are tropisms
tropisms are directional responses to directional external stimulus
what is a positive tropism
when the plant grows towards a stimulus
what is a negative tropism
when the plant grows away from the stimulus
what are some examples of stimuli
light chemicals gravity water physical contact or touch
what are the types of tropisms based on stimuli
light = phototropism chemical = chemotropism gravity = gravitropism and geotropism water = hydrotropism temperature = thermotropism physical contact or touch = thigmotropism
why are tropisms important
tropisms are important as the plants can grow towards good things and away from harmful things that could kill them
what are some general examples of positive and negative tropisms
plants will generally have a positive hydrotropism and positive phototropism as plants need water and sunlight to carry out photosynthesis
they will have a negative chemotropism as they will want to grow away from any harmful chemicals
what tropism is known for being either positive or negative depending on the plant
thigmotropism
what are nastic responses
nastic responses are non-directional responses to the intensity of the stimulus
how are nastic responses different to tropisms
they aren’t always growth movements, a photonasty could be a flower opening up during the day and closing at night
what is a hormone
a hormone is a molecule that is often produced in one location that will do stuff in another location
what is auxin
auxin is a type of hormone
where is auxin produced and what is the effect
auxin is produced in the plant shoots of plants and they cause cells to grow longer than normal
what is the role of auxin in phototropism (draw diagram)
the plant shoot is exposed to light and auxin diffuses down the dark side of the plant, therefore the cell on the dark side grows longer- they elongate, and the part exposed to light does not grow and so the plant shoot grows towards the light
what is the role of auxin in roots
auxin has the opposite effect in roots, it prevents the roots from elongating, with gravitropism the plant roots grow downwards, due to gravity auxin moves to the lowest side of the roots. The loss of auxin on the high side causes the cells to elongate while the cells on the lower side stay the same and the result is the roots start to bend and grow downwards
what is a taxis response
a taxis response is a directional response involving the movement of the animal either towards or away from te directional external stimulus
what is the difference between taxis response and tropisms
tropism are growth response in plants whereas taxis response is movement response in animals
what is the difference between a positive and negative tais
moving towards the stimulus is a positive taxes and moving away from the stimulus is a negative taxes
what are the types of taxes based on stimuli
light = phototaxis chemical = chemotaxis gravity = gravitaxis and geotaxis water = hydrotaxis temperature = thermotaxis physical contact or touch = thigmotaxis
what is the definition of kinesis
kinesis is a non directional response where the rate of movement or activity is influenced by the external stimulus
what are the two types of kinesis
orthokinesis and klinokinesis
what is orthokinesis and what is an example of orthokinesis
orthokinesis involves a change in the speed of an animals movement, where the movement is faster in un-favourable condition but slower in favourable condition, eg woodlice move slower when its really really humid
what is klinokinesis and what is an example of klinokinesis
klinokinesis involves in the rate of the turning of organisms, the rate of turning is faster in unfavourable conditions nad slower in favourable conditions
eg flatworms turn more often where there is more light so that it ends up spending more time in the dark
what is homing
homing involves an animal finding its way ‘home’ over unfamiliar areas often after migrating to new locations
how can animals navigate
they can use landmarks such as rivers and mountains, even roads to navigate. some animals can use solar or magnetic compasses but following the direction of the sun of the direction of the earths magnetic field lines
what is migration
migration is the regular movement of whole populations to a specified location
what is important thing to know about migration
IT IS NOT RANDOM
why do animals migrate
to move to a more favourable location for teh populations survival
what are reasons for migration
food and breeding
they can move to a place with more food because their current location is going through a food shortage during a certain time of year
they can move to a place more appropriate for giving birth if their current location has predators or harmful weather etc
what are some triggers and factors that play into migration
migration relies on internal and external factors
triggered by changing day length, changes in climate
how is the animal prepared for migration
the internal clock can prepare the animal for migration and so the animal will know to increase their energy supplies for a long journey or increase fat layers for a cold journey, or some animals like birds can shed their feathers and replaces them with lighter ones to help
