Unit 2: Sensory Reception Flashcards
What is a stimulus and what effect does it have?
A detectable change in the environment that produces a response.
What are receptors?
a cell adapted to detect stimuli
What are effectors?
an organ that responds to stimulation by a nerve impulse.
What are tww forms of communication in the human body?
The Endocrine system and the nervous system
What is a taxis?
A directional response to a directional stimulus. Either positive or negative.
What is a positive taxis?
When the movement is towards the stimulus
What is a negative taxis?
When the movement is away from the stimulus.
Explain why algae has a positive phototaxis response
To increase their chance of survival as they need light for food so they move towards the light to be more photosynthetic.
Explain why earthworms have a negative phototaxis response
to increase their chance of survival as they prefer dark, moist conditions. They move away from light into the soil so that they can converse water, find food and avoid predators.
Explain why some bacteria have a positive chemotaxis to glucose
to increase their chance of survival as glucose is their food source.
What is kinesis?
a non-directional response to a stimulus
Give some examples of stimulus
light, chemicals, humidity, temperature
How does an organism stay in a favourable environment?
Moves slowly and turns more to stay in the favourable environment
What does an organism do to move away from an unfavourable environment?
Moves quickly and turns less to get away from the unfavourable environment
Explain why woodlice have a kinetic response to humidity
Woodlice, who breathe using gill, prefer damp, dark conditions. In dry environments, the move quickly and turn less to move out of that condition into a more humid one so that they do dry out. Increases their chance of survival as it reduces water loss and keeps them concealed.
What is tropism?
A plants directional growth response to a directional stimulus
Why do plants response to a stimuli using tropism?
because they don’t have a nervous system or endocrine system.
Describe the type of phototropism a plant has
the shoots has a positive phototropism and the roots have a negative phototropism
Describe the type of gravitropism a plant has
the roots have a positive gravitropism and the shoots have a negative gravitropism
Why do roots have a positive gravitropism?
because its better for absorbing water and minerals
What type of hydrotropism does roots have?
positive
