Multicellularity

Question 1

Unicellular

Answer 1

Single cell, simple body composition, exposed cell body, short lifespan, damage can cause serious injury or death

Question 2

Multicellular

Answer 2

More than one cell, complex organisation, division of labour, only outer cells are exposed, longer lifespan, potential for more complex behaviour, damaged cells may be replaced

Question 3

Simple

Answer 3

Limited co-ordination and differentiation, may be unicellular or multicellular

Question 4

Complex

Answer 4

Multicellularity required for survival, several distinct and differentiated cell types, generated by cen type specific genes and intricate coordination of development processes

Question 5

Simple multicellularity

Answer 5

May enhance or protect from predation

Question 6

Complex multicellularity

Answer 6

Only found in animals, land plants, brown algae, fungi, and red algae

Question 7

Aggregative pathway

Answer 7

Separate cells converge and adhere to each other, occurs in response to adverse conditions, only associated with simple multicelularity, gives rise to spherical masses of spores/cysts, aggregate is formed of quiescent cells that don’t feed/divide

Question 8

Motility

Answer 8

Transient step towards formation of the aggregate

Question 9

Clonal pathway

Answer 9

Serial cell division without dispersion of sister cells resulting from changes in the cell cycle and ECM genes, more widespread and diverse, occurs in complex multicellularity and some simple multicollularity

Question 10

Origin of multicellular life

Answer 10

Proliferating cells develop ability to switch between unicellularity and multicellularity, division of labour occurs, cells are locked in multicellular condition, development of organs, cells become dependent on other cell types

Question 11

Requirements for embryonic development

Answer 11

Regulated cell cycle, regulated programmes of gene activity, cell differentiation, signal transduction, cell mobility and cohesion

Question 12

Single cel organisms ancestral to animals possessed.

Answer 12

Eukaryotic cell cycle, ability to undergo cellular differentiation, cell signalling molecules, cadherin-mediated cell adhesion

Question 13

Clonal multicellularity in animas is marked by…

Answer 13

Explosive diversification of transcription factor families and signalling molecules

Question 14

Choanoflagellates

Answer 14

Closest living unicellular relative to animals, each cell consists of a cell body, flagellum, and a collar of actin-filled tentacles

Question 15

Sponges

Answer 15

Multicellular animals composed of spicules and choanocytes

Question 16

Chlamydomonas phases

Answer 16

Swimming phase (cells have flagella), non-swimming phase (flagella resorbed, cell divides)

Question 17

Graded complexity within the volvocine algae enables…

Answer 17

Exploration of the mechanisms underlying the evolution of multicellularity

Question 18

Cancer and multicellularity

Answer 18

Cancer causes loss of cooperation and altruism between cells, causing them to resemble and behave like unicellular organisms