Week 13 L2: Plant Development General Principles

Question 1

What is the architecture of a plant?

Answer 1

How a plant is put together

form number and arrangement of plant body parts

Question 2

How does architecture vary?

Answer 2

within and between species

Question 3

How do cells achieve their specialised fates?

Answer 3

differential gene expression underlies development

genes are expressed differently; how where and when genes are expressed.

Question 4

What 2 factors can dictate gene expression?

Answer 4

genetics and environment

Question 5

How do animals grow and develop?

Answer 5

develop most of their bodies after embryogenesis
Plants all start off looking similar but eventually differentiate form one another

post-embryonically. growth and organogenesis.

Question 6

What gives rise to the complete adult organism?

Answer 6

pocket of stem cells in the shoot and root tips

Question 7

What do seedling emerge with?

Answer 7

embryonic stem (hypocotyl)
embryonic root
embryonic leaves (cotyledons)
Shoot and root tips

and a sense of polarity

Question 8

What gives plants the initial photosynthesis?

Answer 8

embryonic leaves on the apical axis

called cotyledons

Question 9

How many cells give rise to arial development?

Answer 9

35 stem cells in the shoot tip

Question 10

What are the cells called that can divide and differentiate in the shoot and root tip?

Answer 10

meristems

Question 11

What are meristems?

Answer 11

regions of unspecialised cells in plants that are capable of cell division

Packet of dividing stem cells which fuel the growing plant body

Question 12

Where are meristems found?

Answer 12

root and shoot tips and between xylem and phloem

Question 13

What do the meristems produce?

Answer 13

phytomers a module

Question 14

Do meristems continually and sequentially produce phytomers?

Answer 14

YES

Question 15

What is a phytomer?

Answer 15

one of the individual structural units that in serial arrangement make up the body of a plant a bud-bearing node is a typical phytomer.

Question 16

What are the components of a phytomer?

Answer 16

lateral organ
axillary bud
internode
node

Question 17

Can plants of the same species have different number of modules?

Answer 17

YES, plants which are genetically identical can have an intermediate amount of modules depending on their environmental control e.g. sunlight

Question 18

What are the traits that can develop according to enviroment?

Answer 18

Plasticity

Question 19

What is an example of plasticity/plastic response?

Answer 19

A plant maximising its leaf surface area in shade to maximise sun exposure and photosynthesis

Question 20

Why is plasticity important for plants?

Answer 20

they cant move, so need to be able to adapt to environment.

Plant’s offspring can be not near their mother so cannot determine its exact environment so need plasticity.

Question 21

Is plasticity genetically determined?

Answer 21

YES, the plant species has to have the ability to change its phenotype. e.g some plants cannot adapt to light conditions

Within a species there will be specific aspect of that development that is plastic

Question 22

What is it called when genes are unable to be plastic in a certain environment?

Answer 22

CANALISED

Question 23

What is an example of a canalised trait?

Answer 23

Arabadopsis always has 4 petals no matter the environment

very little plasticity in the floral programme

Question 24

Why is flowering usually canalised?

Answer 24

because the flowers architecture is really beneficial to the plant.

It is usually co-evolved with a certain pollinator and you don’t want to suddenly change the architecture and plant will not receive the correct pollinator.

Question 25

Do plants always canalise the same?

Answer 25

NO, it depends on the species

Question 26

What is the prymordia?

Answer 26

earliest stages of development
called primordial cells

e.g. buds on a stem blossom to flowers

Question 27

When are meristems formed?

Answer 27

during embryogenesis and then produce lateral structures

Question 28

What are lateral structures?

Answer 28

leaves and branches

Question 29

What is the purpose of meristem zones?

Answer 29

predict how cells within them are going to behave

Question 30

What are the 3 zones of the meristem at the shoot tip?

Answer 30

central zone
peripheral zone
rib meristem

Question 31

What are cells like in the central zone of the meristem?

Answer 31

pool of undifferentiated stem cells. cells divide slowly

Question 32

What are cells like in the peripheral zone?

Answer 32

proliferate faster and differentiate into lateral organs.

Question 33

What are cells in the rib meristem doing?

Answer 33

proliferate and differentiate into the stem in dicots. stem art of the phytomer

Question 34

How do cells enter the peripheral zone in the meristem?

Answer 34

As cells divide they push the outer cels out towards the peripheral zone.

They are pushed into position by division and cell growth.

Question 35

What determines the cells fate in plants?

Answer 35

their position