On Becoming Multicellular

Question 1

what % of major groups of eukaryotes present within the supergroups contain only single-celled organisms?

Answer 1

70% (83/119)

Question 2

How is multicellularity exhibited in the remaining 36 lineages?

Answer 2

filaments, hollow balls, or sheets of little-differentiated cells

Question 3

What are the 3 properties of simple multicellular organisms

Answer 3

adhesion molecules - cause adjacent cells to stick together
cells retain full range of function (include reproduction)
every cell in contact with external environment

Question 4

What is included in complex multicellularity?

Answer 4

plants, animals, red and brown algae, and fungi

Question 5

how did complex mulitcellularity evolce?

Answer 5

at least 6 separate times in different eukaryotic lineages

Question 6

what are common features of complex mulitcellularity organisms?

Answer 6

highly developed mechanisms for adhesion between cells
specialised structures/mechanisms for cell communication
tissue and organ differentiation

Question 7

What is diffusion?

Answer 7

random motion of molecules; net movement from areas of higher to lower concentration; effective over short distances

Question 8

What is bulk transport?

Answer 8

molecules move through organisms at rates beyond those possible by diffusion across concentration gradients; movement can be due to pressure differences and/or requires energy

Question 9

What are some examples of bulk flow transport?

Answer 9

plant vascular system
mammalian circulatory system

Question 10

What allows for cell adhesion in animals?

Answer 10

cadherins and integrins, and additional transmembrane proteins.

Question 11

What genome has genes that code for cadherin and integrin proteins?

Answer 11

choanoflagellate genome

Question 12

what allows for cell adhesion in plants?

Answer 12

cell wall adhesion molecules are often pectins

Question 13

What are gap junctions? (communication in animals)

Answer 13

protein channels that allow ions and signaling molecules to move from one cell to another

Question 14

What are plasmodesmata (communication in plants)

Answer 14

intracellular strands of cytoplasm that extend to neighboring cells that perform similar functions

Question 15

What are molecular signals (communication)?

Answer 15

a signaling molecule synthesised by one cell binds with the receptor molecule on the surface of a seconf cell that activates or represses gene expression in the receptor cell’s nucleus

Question 16

What are transmembrane receptors (communication)?

Answer 16

respond to signals from the environment, as they are within the membrane of cells

Question 17

What are the meristems?

Answer 17

the actively growing primarily undifferentiated cells at the tips of stems and roots; grwoth and differentation is triggered by environmental signals

Question 18

Where is plant growth confined to?

Answer 18

meristems