3.6 Survival and response and receptors Flashcards
What is a stimulus ?
A detectable change in environment
What is tropism ?
When plants respond via growth to stimuli
What are the two stimuli plants respond to ?
- Light
- Gravity
What is IAA ?
It stands for indoleacectic acid and it is an important growth factor that can control tropisms. It is a type of auxin
What effect does IAA have on shoots ?
It is a type of auxin that can control cell elongation in shoots
What effect does IAA have on roots ?
It inhibits he growth of cells in roots
Where is IAA made ?
In the tips or the roots and shoots but can diffuse to other parts of the plant
What is a reflex ?
A rapid, automatic response to protect you from danger
Where are pacinian corpuscles located ?
Found deep in the skin and in fingers and feet
What do pacinian corpuscles detect changes in ?
Pressure
What happens when a pacinian corpuscle detects a stimuli ?
1- The layers are distorted causing the stretch mediated sodium channels to open, sodium ions enter the axon of the sensory neurone
2- Excess sodium ions cause depolarisation of the membrane
Do rod cells process images in black and white or colour ?
Black and white
What is an advantage of rod cells ?
They help us to see at night and in dim light. This is a survival mechanism
What optical pigment is found in rod cells ?
Rhodopsin
What is the job of rhodopsin in rod cells ?
It absorbs light energy. High energy breaks down rhodopsin. This meets threshold
