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Being Multicellular

•  Being Multicellular –  Division of labor –  Self- vs non-self –  Communication & Coordination –  Bulk transport

•  Plant structure –  Meristems and primary growth –  Tissue systems –  Stem structure –  Roots

November 1, 2021

Brief history of life

Cells of this colonial alga are connected, but it is not truly multicellular

Volvox

What is needed for true multicellularity?

Specialization of different cell types

Recognize Self vs Other

http://www.scielo.br/scielo.php?pid=S1982-56762008000500007&script=sci_arttext

Communication between cells

Animals cells can have gap junctions

Plant cells have plasmodesmata

10/30/21

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Bulk Transport Animals and Plants develop differently

Plant cells can’t move, so all growth is from meristems

Animal cells can migrate

Plant shoots are made from repeating modules: Stem, Leaf, Bud

http://www.uwgb.edu/biodiversity/herbarium/trees/node_internode01web_gf.jpg

Plants have Indeterminate Growth

Shoot apical meristem

Young leaf

Developing vascular strand

Axillary bud meristems

0.25 mm

Primary Shoot Growth

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Epidermis Ground Vascular

Stem structure

Monocot

Eudicot

Vessel element

Pits

Vessel Tracheids 100 µm

Vascular Tissue

Roots Ground

Dermal

Key to labels

Vascular

Root hair

Epidermis

Cortex Vascular cylinder

Zone of differentiation

Zone of elongation

Zone of cell division

Apical meristem

Root cap

100 µm

Roots

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Root structure

Monocot Dicot

Roots