Lecture 6- Determinate and indeterminate development

Question 1

early plant development steps

Answer 1

division of the fertilised egg to produce an apical and a basal cell
auxin burst b>a, then auxin switches directions
auxin helps set up general directional development, and the location of the 2 meristems

Question 2

what maintains the state of stem cells

Answer 2

‘organising centres’, which are repressed by stem cells to keep them an appropriate size
cells far away don’t get the signals to remain stem cells, so can differentiate

Question 3

lateral inhibition

Answer 3

allows a ‘spiral-like’ formation, by inhibiting expansion at middle-ish sections of the plant to produce primordia at appropriate points

Question 4

what is indeterminate development

Answer 4

system of development where the structure of the organism as an embryo is not the same as an adult

Question 5

example of a determinate organ in plants

Answer 5

flowers- have quite symmetrical and structured sepals/petals/carpals etc

Question 6

why animals vs plants benefit from different types of development

Answer 6

-animal cells more adaptable (can change shape), so can fold in on themselves etc, removing the need for division and expansion to change overall shape
-animals can move, plants can’t- means being able to adapt through development is more important

Question 7

examples of ‘plant-like’ animals

Answer 7

sponges- can adapt to changes in things like water currents through changes in body shape, possible branching before determinate dev became the standard?
sessile invertebrates with plant-like developmental styles