Coordination and Response Flashcards
What is sensitivity?
This is the ability that organisms have to respond to the changes in their environment.
What is homeostasis?
The maintenance of a constant internal environment. E.g thermoregulation and osmoregulation.
What does a coordinated response require?
A stimulus, a receptor and an effector.
What is geotropism?
Plants respond to stimuli as they are living organisms. Geotropism is growth in response to gravity.
- roots carry out positive geotropism as they grow towards gravity to find moisture, minerals and anchorage.
- stems carry out negative geotropism as they grow upwards to find light.
What is phototropism?
Phototropism is the growth of a plant in response to the direction of light.
*stems carry out positive phototropism to gain maximum light for photosynthesis.
How do plants carry out phototropism?
With the help of the plenty hormone ‘Auxin’, which is responsible for controlling the direction of growth. It is made at the tips of stems and roots and is moved in solution to older parts of the stem and root. This changes the elasticity of the cells= increases absorption of water + longer growth
What is the difference between a hormonal and nervous response?
Nervous= electrical, hormonal= chemical Nervous= effectors are muscles/glands, hormonal= targets specific organs Nervous= very rapid and short, hormonal= slow and long
What does the CNS consist of?
The brain and spinal chord. It is linked to sense organs (e.g. Eyes/skin) by nerves.
What happens when receptors detect a stimulus?
They send an electrical impulse along many nerves into and out of the CNS, resulting in rapid responses.
Describe a reflex arc.
1) Pain receptors detect a stimuli (e.g. Hot object) and transduce this energy from the stimulus into an electrical message.
2) Sensory neurones send this message to a relay neurone which relays this message along a synapse to a motor neurone.
3) The motor neurone passes this message on to an effector which produces a response (e.g contraction of a muscle)
What is an eye?
A receptor of light that has receptor cells in its retina to turn a stimuli into an electrical impulse.
What is the cornea
A convex and transparent coat around the Scerla. It retracts light as it enters the eye and also protects they eye.
What is the iris
It is pigmented (light cannot pass through) which decides the colour of your eyes. It’s muscles contract and relax to alter the size of the pupil to control how much light is let in.
What is the lens
A transparent, biconvex and flexible disc behind the iris that is attached by suspenseful ligaments to the ciliary muscles. It focuses light onto the retina.
What is the retina?
Contains rods (sensitive to dim light and black and white colours) and cones (sensitive to colour). It is the screen that images are formed on. ( has a point called the fovea where there are more comes that rods)
