Plant and Planetary Evolution

Question 1

Why are we studying evolution in forest plant biology?

Answer 1

Evolution is the key to plant biodiversity and it is the cornerstone of modern biology.
Helps us understand how organisms have changed over time

Question 2

How old is the Earth?

Answer 2

4.6 billion years (byr) old

Question 3

Where do we find fossil traces of bacteria?

Answer 3

Stromatolites found all over the world

Question 4

Why are bacterial cells simple?

Answer 4

They have no nucleus or other organelles.

Question 5

When were the origins of life?

Answer 5

4.1 billion years ago

Question 6

What is important within the evolution of species?

Answer 6

variation among organisms is what allows evolutionary selection to happen.

Question 7

How did life arise?

Answer 7

No one knows, but probably the ocean

Question 8

What was the Earth’s atmosphere like in early Earth?

Answer 8

Mostly nitrogen gas
CO2 concentrations were higher (10-30% of the atmosphere)
Large amounts of hydrogens, and hydrogen sulfide
No free oxygen

Question 9

What eventually came in short supply?

Answer 9

Chemical energy

Question 10

What gave organisms a significant advantage in survival?

Answer 10

Capturing light energy

Question 11

What were one of the most successful organisms and why?

Answer 11

Cyanobacteria

They developed photosynthesis using water as a source of electrons

Question 12

How long did cyanobacteria dominate the earth?

Answer 12

2 billion years

Question 13

What is the Snowball Earth hypothesis?

Answer 13

events were caused by a combination of low atmospheric CO2 concentrations and dimmer sunlight

Question 14

Why was the atmosphere able to accumulate oxygen at low levels 2.4 billion years ago?

Answer 14

The availability of oxygen permitted the evolution of aerobic respiration

Question 15

Why are eukaryotic organisms more complex?

Answer 15

They have cells with nuclei and other organelles like chloroplasts and mitochondria.

Question 16

What did the evolution of eukaryotes coincide with?

Answer 16

Sexual reproduction

Question 17

Why is sexual reproduction important for evolution?

Answer 17

Sexual reproduction promotes the production of variable progeny
This gives a greater pool for selection to choose from to speed evolutionary processes.

Question 18

What do all communities need?

Answer 18

Primary producers

Question 19

What was the order of the appearance of plants?

Answer 19

The colonization of land
Differences between sea and land environments “Adapting to the desiccating environment”
Early land plants

Question 20

Why did the move from an aquatic to terrestrial environment have a big impact on the planet?

Answer 20

Made conditions suitable for land animals and fungi

Had massive effects on Earth’s climate by creating a cooler atmosphere since it drew down lots of CO2.

Question 21

Why did it take so long for plants to evolve?

Answer 21

The development of the ozone layers made it possible by removing ultraviolet light from sun
O2 finally reached higher levels that allowed ozone to accumulate.

Question 22

How is weather different in the ocean than the land?

Answer 22

Ocean temperatures are moderate in comparison to daily/season terrestrial changes.

Question 23

How is water availability different?

Answer 23

Water is almost always available

Terrestrial environments need to obtain and conserve water

Question 24

How is reproduction different?

Answer 24

Water: reproductive cells can swim around to find each other
Terrestrial: tougher time for new mechanisms to exchange gametes.

Question 25

How are nutrients and light different?

Answer 25

Sea: light and nutrients are fairly evenly distributed.
Land: environment is partitioned between air and soil so plants need to develop one part of them in soil and one in air.

Question 26

How is Gravity different?

Answer 26

Sea: had structural support from water
Land: no support so have to develop structural support to keep the plant upright.

Question 27

What were early land plants like?

Answer 27

Flattened “thallus” type of body
Ex. liverworts
Developed epidermis and cuticle to help retain water