Chapter 26: Multicellularity

Question 1

Of the 119 major groups of eukaryotes present within the 7 superkingdoms ______ contain only single-celled organisms

Answer 1

83

Question 2

Simple Multicellularity

Answer 2

mostly in the form of filaments, hollow balls, or sheets of little-differentiated cells (36 branches) ( most common in algae)

Question 3

Four key points of complex multicellularity

Answer 3

complex multicellular organisms can be a little or a lot of cells in close coordination; they have evolved half a dozen times; colonies of prokaryotes is not multicellularity; no bacteria can develop bodies with functionally differentiated tissues

Question 4

Who are the simple multicellulars?

Answer 4

fungi, algae, slime molds, sporozoans and Cnidosporas, dinoflagellates

Question 5

Coenocytic organization

Answer 5

the nucleus divides multiple times, but the cell does not (so the nuclei are not partitioned into individual cells)

Question 6

Advantages to being multicellular

Answer 6

avoid predators, float better, hold together better, withstand disturbance and desiccation better

Question 7

fundamental features of complex multicellulars

Answer 7

highly developed mechanisms for adhesion between cells; specialized structures for cell communication; tissue and organ differentiation; small subset of cells contribute to reproduction; cell or tissue loss can be lethal for the organism; presence of both interior + exterior cells; genome reorganization

Question 8

Multicellularity has evolved at least ____ separate times across some major eukaryotic groups

Answer 8

six

Question 9

In complex multicellular organisms, ________ circumvents the limitations of diffusion

Answer 9

bulk flow

Question 10

Bulk transport

Answer 10

the means by which molecules move through organisms at rates beyond those possible by diffusion (due to pressure gradient)

Question 11

Circumventing limits from diffusion

Answer 11

short distance transport limits size and shape

Question 12

Transport of water and solutes is done by…

Answer 12

individual cells

Question 13

short-distance transport of substances from cell to cell is done…

Answer 13

at the levels of tissues and organs

Question 14

long distance transport within xylem and phloem are…

Answer 14

at the level of the whole plant

Question 15

complex multicellularity depends on…

Answer 15

cell adhesion, communication, and a genetic program for development

Question 16

What are the mechanisms for cell adhesion for animals?

Answer 16

cadherins, integrins, and transmembrane proteins

Question 17

What are the mechanisms for cell adhesion for plants?

Answer 17

pectins

Question 18

What are the mechanisms for cell communication in plants?

Answer 18

plasmodesmata

Question 19

What are the mechanisms for cell communication in animals?

Answer 19

gap junctions

Question 20

gap junctions

Answer 20

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

Question 21

plasmodesmata

Answer 21

intracellular strands of cytoplasm that extend to neighboring cells allowing the same type of communication

Question 22

What are the drawbacks to being large and anchored into the ground?

Answer 22

have had to evolve mechanisms of transport (for water and nutrients), have to adjust to environmental signals (adjust their meristem), and they have evolved mechanical structures and poisons to keep from being eaten

Question 23

How do animals respond to a challenge in their environment?

Answer 23

by changing their behavior

Question 24

How do plants develop?

Answer 24

meristems

Question 25

How do animals develop?

Answer 25

gastrulation