Coordination and control in plants Flashcards
During growing season where does cell division take place?
Apex (tip) of the plant called the apical meristem. These cells then enlarge in the zone of elongation. And at certain times of the year the inter nodal region also enlarges.
Where are auxins produced? and what is their main function?
Produced in the tip (Apical meristem)
Stimulates the elongation of cells in the zone of elongation
Where are cytokines produced? and what is their main function?
Produced actively dividing (meristematic) tissues
Promotes cell division in the apical meristems (zone of division)
Where are gibberellins produced? and what is their main function?
Produced in leaves
Stimulates elongation of inter nodal regions
Give a brief outline of auxin (7)
Produced in the cells of the apical meristems
Diffuse down shoot to zone of elongation
Bind to specific receptors on cell surface membranes
Causes hydrogen ions to be pumped into cellulose cell wall
Acidification activates elastins in cell wall
Cell absorbs water by osmosis
The more auxin the more elongation.
What is the pigment and where is it found in flowering plants?
Phytochrome found in the leaves of flowering plants
What are the two categories of plants and give an example of each.
Long Day Plants - Poppy - flowers only if daylight exceeds a critical value
Short Day Plants - Strawberry - flowers only if daylight is shorted than a critical value.
What are the two photoreceptor pigments and what type of light do they absorb?
P660 - absorbs RED light
P730 - absorbs FAR RED light
What is the conversion of P660 to P730 happen in and at what speed?
Rapid in daylight (RED light)
What is the conversion of P730 to P660 happen in and at what speed/
Slowly in darkness (FAR RED light)
Which out of the two pigments is active?
P730 is the physiologically active form and either operates to stimulate or inhibit flowering. During the day P660 to P730 and P730 accumulates.
What do Long Day Plants and Short Day Plants need?
Long Day Plants need sufficient amounts of P730 in order to flower while in Short Day Plants the inhibitory effect of P730 must be removed in order to stimulate flowering.
When answering questions on SDPs and LDPs what must you say
You must state whether the level of P730 is either above or below the critical level and the effect that this bring about.
What happens to both a SDP and LDP if there is a short day long night but the night is interrupted by a short light period?
During the short light period P660 is converted to P730 and the conversion is rapid, which means the level of P730 is above a critical level. This causes for flowering in LDPs and flowering is inhibited in SDPs.
