Moving onto Land

Question 1

eras leading up to the emergence of life on land

Answer 1

• proterozoic

- cambrian

Question 2

proterozoic era

Answer 2

• eukaryotes evolved, acquired photosynthesis
• proliferation of bacterial mats
• animals: soft bodied, sessile or slow-moving
• at the end: multicellular photosynthesizers began to appear (algae)

Question 3

great oxygenation event

Answer 3

-cyanobacteria released oxygen as a waste product

• oxygen was initially fixed in dissolved iron or organic matter
• (aka oxygen sinks)

-after 200MY, sinks were saturated and O2 began building up in the atmosphere

• led to massive die-off of other bacterial species
• also formed Ozone Layer

Question 4

cambrian era

Answer 4

• shells and other “hard bodies” start to dominate
• animals become more motile
• explosion of evolution of new body types in animals

Question 5

early ordovician era

Answer 5

• bacterial mats seen in the Proterozoic were greatly reduced
• evolution of developed complex multicellular forms
• acquired the ability to respire with oxygen
• all life still in the ocean

Question 6

ordovician

Answer 6

early plants energy on lans

-first plants are very small, they do not produce flowers or seeds

Question 7

devonian

Answer 7

• the first animals leave the water (arthropods)
• vertebrates emerge shortly after
• animal life largely vulnerable to desiccation, still dependent on water for reproduction

Question 8

the carboniferous

Answer 8

• broke dependence on water for reproduction
• proliferation of forests
• carboniferous coal swamps

Question 9

barriers to adapting to land

Answer 9

1. desiccation
2. gas exchange
3. reproduction
4. buoyancy
5. temperature fluctuations
6. visual and hearing
7. mineral nutrition
8. harmful ultraviolet radiation

Question 10

desiccation

Answer 10

• drying out
• animals used to be surrounded by water, smaller you are the faster you dry out, no animals are water proof because they need gases and water to flow through body

Question 11

gas exchange

Answer 11

CO2 and O2 absorbed differently depending on if you are on land or water&raquo_space; gills vs lungs, plants and animals have different chambers that allow respiration to occur

Question 12

reproduction

Answer 12

most animals were releasing gametes into water, nothing on land could help move egg and sperm to meet

Question 13

buoyancy

Answer 13

water and water pressure would support body tissues, air would not, provided structural support for life

Question 14

temperature fluctuations

Answer 14

seawater = slow and little change , land = quick and large changes

Question 15

vision and hearing

Answer 15

light and sound waves move differently through water compared to air

needed to adjust vision and hearing

Question 16

mineral nutrition

Answer 16

-water contains dissolved minerals for added nutrition

need to find a way to supplement nutrition lost, many species were sessile in water (fixed), no terrestrial species&raquo_space; only plants who capture energy from sun could afford to be sessile

Question 17

harmful UV radiation

Answer 17

water = filter uv light, gases = poor filter, for most of eath’s history life could not withstand light on surface

Great oxygenation = created ozone shield

Question 18

First life on Land

Answer 18

-plants

Since autotrophs, all about getting most sun, which meant they would grow as near to surface as possible

First Photosynthesizers: appeared 3.4 billion years ago

Cyanobacteria = first to use chlorophyll , anything that uses photosynthesis evolved from this cell

Question 19

evolution of green algae

Answer 19

• concentrated in shallow water
• exposed to periods of drought
• evolved into forms that could survive on land: liverworts and mosses

Question 20

liverworts and mosses

Answer 20

• no roots
• no seeds
• no flowers
• very small
• no distinct leaves or stems
• no vascular system

Question 21

plants and animals in the late Devonian

Answer 21

• ferns, horsetails
• arthropods
• Vertebrates and Amphibians

Question 22

why could so many groups colonize land?

Answer 22

many animals preadapted to life on land

-structures that evolved for other uses are also effective for living on land

Question 23

what was the motivation to go to land?

Answer 23

predation, land as protection,

as plants made it to land&raquo_space; want to eat the plant have to go to land,