Coordination And Control Flashcards
What occurs in a long day short night in plants
P730 accumulates during the long day, and is not sufficiently removed during the short night so is mostly P730, so long day plants flower
What occurs in a short day long night in plants
P730 is removed during the long night and is not produced sufficiently during the short day, little P730, short day plants flower
What occurs in a short day long night, interrupted by a short light in plants
During the night, the short light period converts P660 to P730, enabling sufficient P730 to accumulate so Long day plants flower
What’s the difference between red light and far red light
Red light is rapid conversion of P730
Far red light is rapid conversion of P660
What are the 3 growth hormones in plants
Auxins
Cytokinins
Gibberellins
Where are Auxins produced and what is their effect
Produced in the growing tip of the stem, and stimulate elongation of cells
Where are Cytokinins produced and what is their effect
Produced in actively dividing tissues and promote cell division
Where are Gibberellins produced and what is their effect
Produced in the apical buds and leaves, and stimulate elongation of intermodal regions
What is the process of auxin action
Produced in the apical meristem
They diffuse down the shoot
They then bind to specific receptors sites, which causes the membrane pumps to move H ions out
What is the structure of a neuron
A centron which contains the nucleus and other organelles
Dendrons which transmit impulses to the cell body
Axons which transmits impulses away from the cell body
What are the axons and dendrons myelinated in, and what is there function
A myelin sheath of Schwann cells, which insulated the axon, preventing ion movement
What are the gaps in the myelin sheath called
Nodes of Ranvier
What is the resting potential
When the large potential difference in the neurone occurs at rest
What is the action potential of a neurone
The reserve of the potential difference
Why does an action potential occur
When a neurone is stimulated, the cell-surface membrane allows sodium ions to diffuse in, changing the potential difference
What is the threshold value
When a critical potential difference is reached, then ions surge in and the neurone becomes depolarised
What is the refractory period
The recovery period after an action potential occurs
What occurs on both sides of axons or dendrons during local circuits
On one side, the membrane is still recovering its resting potential, and on the other excitable side, the local circuits triggers depolarisation and the formation of an action potential. This process is repeated at each section of the membrane along the neurone
Why can local circuits not occur in a myelinated neurone
It cannot be set up in the parts of the myelin sheath
How does a myelinated neurone have local circuits
The action potential ‘jumps’ from one Node of Ranvier to the next, called Saltatory Conduction
What is the first step of Synaptic transmission
The impulse arrives at the synaptic bulb, and the membrane becomes permeable to calcium ions which diffuse into the bulb
What is the last step of synaptic transmission
The breakdown products diffuse across the cleft and are reabsorbed into the synaptic bulb where they are resynthesised into the neurotransmitter using energy in the form of ATP
What is the role of calcium ions in synaptic transmission
They stimulate movement of synaptic vesicles towards the pre-synaptic neurone
What is the function of synaptic vesicles in synaptic transmission
They fuse with the pre-synaptic membrane and release the neurotransmitter molecules by Exocytosis into the synaptic cleft
What is the function of neurotransmitter molecules in synaptic transmission
They diffuse to the post-synaptic membrane, where they attach to specific receptors causing ion channels to open so that the potential difference in the post-synaptic membrane is altered
What occurs when a neurotransmitter molecule attaches to a receptor site
A sodium ion channel opens and the post-synaptic membrane becomes depolarised
Why is the breakdown of the neurotransmitter important in synaptic transmission
It allows the resting potential to be established, where they diffuse across the synaptic cleft and are reabsorbed into the synaptic bulb
