week 26 Flashcards
what is morphogenesis in plants
the process of plants developing their shape, size and arrangment
what is plant embryogenesis
process by which a plant embryo develops from a fertilised ovule into a mature plant
how do somatic and zygotic embryogenesis differ in plants
zygotic- embryo from a fertilised egg (zygote) after fusion of male and female gametes. sexual reproduction.
somatic- formation of embryo from somatic (non-reproductive) cells. asexual reproduction.
how does plant morphogenesis arise
cell division and cell lineage
what does polarity in anatomy refer to
having direction or different properties at different ends. Germination leads to polarisation of organisms.
give some examples of factors which induce germination
light, heat, osmotic gradient, ph and salt, fertilisation
what drives cellular motility
actin and myosin. Actin interacts with myosin to generate directional force. Ca2+ is a key regulatory factor.
how can actin generate force without myosin in plants
dynamic equilibrium between globular and filamentous actin (actin treadmills), which generates force without myosin.
what are plant stem cells
meristem
what is the role of auxin in plant polarity
Auxin triggers cellular changes, including Ca2+ concentrations, which is a key factor in polymerisation and movement.
how does polarity of an organism arise
Germination leads to polarization
what are PIN proteins important for in plants
the directional (polar) transport of auxin, helping create auxin gradients
what is signal transduction
processes that operate to couple a stimulus to a response. involves a receptor for stimulus, a transduction process and response to act on signal
what is a second messenger of signal transduction in cells
external stimulus receptors require a second messenger to amplify/ relay the internal signal to the response mechanism.
how is stomata movement tightly controlled
guard cells surround stomata, regulating size to control CO2 entry and O2 and water exit.
what controls stomatal closure
abscisic acid (ABA). drought stimulated roots to synthesise ABA, which travels to leaves. ABA stimulus overrides light, CO2 and photosynthetic demand.
how can ion channels be measured
voltage clamping
what are jaffes laws for biological responses
- stimulus, second messenger and response must be related in time and space.
- blocking a signal/ messenger must block signal and repsonse downstream
- introducing a second messenger without the primary stimulus must give the response downstream.
Ca2+ (calcuim ion) is needed to regulate ion channels. true or false
true
what are the three plant pathogens
bacteria, viruses and fungi
what is the most widespread and damaging bacterial pathogen
pseudomonas syringae
how do necrotroph pathogens kill plant host cells
grow in dead tissue- invasion, secrete cell-degrading enzymes to kill host cells, utilise nutrients released for growth.
how do biotroph pathogens invade plant host cells
grow in living tissue. utilise nutrients released for growth or develop feeding structures to extract nutrients.
what does plants innate immunity mean
unlike mammals (with adaptive immune systems) plants ability to recognise and defend against parasites is inherited- innate immunity.
