Life Moves onto Land!

Question 1

Marine Green Algae (eukaryotes) as Likely Ancestors of Earliest Land Plants

Answer 1

• first on land were mats of bacteria and algae
• land plants evolved from algae
• first spores form during ordovician period

Question 2

Ordovician Land Plants

Answer 2

• seedless, non-vascular mosses
• akin to modern mosses
• uses spores instead of seeds
• no multicellular roots
• no system for transporting nutrients and water
• no leaves

Question 3

Silurian Land Plants

Answer 3

• seedless plants with primitive vascular systems (cooksonia)
• rudimentary roots but no true leaves
• having conducting tissues of woody vessels to uptake and transfer water and nutrients which also serve as structured support

Question 4

Lycopod (Devonian Land Plants)

Answer 4

• seedless, vascular; plants, cool swamps
• dominant trees of the late Devonian and Carboniferous coal swamps
• led to major adaptive radiation that changed the planet

Question 5

First Gymnosperms (Devonian Land Plants)

Answer 5

• “naked seed plants” meaning the seed is not covered by the ovary
• seeds allow plants to withstand dire conditions; unbinding them from wet conditions

Question 6

How did the evolution of large plants with roots affect global carbon cycle and climate?

Answer 6

roots pump CO2 into soils and thereby enhance chemical breakdown of silicate minerals which pulls CO2 atmosphere levels DOWN

Question 7

Respiration Loop for Cycling Carbon

Answer 7

Trees give off Oxygen, animals take in and give off CO2 for the trees to take in and convert to oxygen

Question 8

Significance of Carbon BURIAL on Atmospheric Chemistry and Global Climate

Answer 8

• causes atmosphere to become more oxygen rich because trees take in CO2, output Oxygen and then don’t decompose (which would increase CO2)
• causes lower CO2 levels

Question 9

Carbon Cycle during the Carboniferous Period (Age of Coal)

Answer 9

trees intake CO2 and put out oxygen

• trees die, fall in to the swamp where they are preserved
• some die and decompose, releasing CO2

Question 10

Climate Change During Carboniferous

Answer 10

reduced rate of decomposition and high rate of burial of trees

• too many trees would normally give off CO2 were buried causing low levels of CO2

Question 11

First Land Animals (Ordovician/Silurian)

Answer 11

BUGS! (trigonotarbids and millipedes)

• trigonotarbids appear in the late silurian; approx. 420 Ma
• millipedes after but still in late silurian