Lecture 2: Evolution Of Plants

Question 1

Geological time scale

Answer 1

1. Present
2. Holocene: the current warm period. 11, 700 yr to present.
3. Quaternary: ice ages
4. Hominids
5. Extinction of the dinosaurs: 65 Ma
6. Flowering Plants: 145 Ma
7. Early Mammals: 208Ma
8. Gymnosperms (seed-producing plants) and amphibians: 362Ma
9. Land Plants: 420 Ma

Question 2

Origin of plants

Question 3

Precambrian (Earliest forms of plant life)

Answer 3

900 million years ago = ‘Supercontinent’
Algae

Question 4

Cambrian and Ordovician periods (540 - 440 Ma)

Question 5

Silurian period (440-410 Ma)

Answer 5

1st land plants
Soil begin develop
Plants move out of water onto land

Question 6

Cooksonia

Answer 6

Extinct group of primitive land plants

Question 7

Plant adaptations to survive on land

Answer 7

• surface to prevent drying out (cuticle)
• pores for gas exchange & regulate H2O loss (stomata)
• vascular system to distribute H2O, minerals & food (xylem & phloem)
• support to give structure to plant body (vascular tissue, lignin). Grow taller to reach light
• an anchoring system (roots)
  ……..

Question 8

The first forests

Answer 8

• 395-286 Ma. Devonian and Carboniferous
• terrestrial fauna evolved from one composed of small vascular & non-vascular plants to a vegetation that included trees towering…..

Question 9

Lepidodendron ‘scale tree’

Answer 9

• extinct genus of primitive tree related to the club mosses (not a moss)

Question 10

Lepidodendron ‘scale tree’

Question 11

Calamites: extinct genus of arborescent (trees) horsetails

Question 12

Coal formation

Answer 12

350-300 Ma - Carboniferous Swamp Forests

Question 13

% of CO2 & O2

Answer 13

CO2 removed by plant growth and limestone rock formation in Carboniferous

Question 14

Evolution of Gymnosperms (seed-producing plants)

Answer 14

• originated in early Carboniferous …

Question 15

Gymnosperms

Answer 15

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Question 16

Extant Gymnosperms

Answer 16

• Conifers
• Cycads
• Ginkgo biloba (maidenhair tree)
• Gnetales: Ephedra (arid areas), Gnetum (tropical evergreens), Welwitschia mirabilis

Question 17

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Question 18

Evolution of the Angiosperms
(Flowering Plants)

Answer 18

• 1st flowering plants appeared in the fossil record from ~140Ma (Cretaceous Peirod)

Question 19

Angiosperms

Question 20

Evolution of grasses: Eocene Epoch (Tertiary) (65 - 50 Ma)

Answer 20

• appearance of grasses mark one of most important evolutionary events for humankind.
• presently, there more than 10,000 species of grasses on the planet
• ## grass-dominated ecosystems (tropical & subtropical savannah, temperate grasslands, and steppes) cover more than 30% of earths land surface

Question 21

Changing earth

Question 22

Plate tectonics: why plant evolution related to periods of increased continental plate movement?

Answer 22

• amount of available land area (as compared to around of ocean)
  ….