Plant revolutions

Question 1

What are the aquatic ancestors of the Land Plants?

Answer 1

Green algae. Present in Cambrian and Pre-Cambrian sediments.

Question 2

When did plants invade land?

Answer 2

Plants were growing on land sometime before 470mya. Spores were found in 470 ma old sediments. Free sporangia containing spores found in slightly younger rocks.

Question 3

Earliest diverging group of land plants?

Answer 3

Liverworts

Question 4

What was the first discovered plant with vascular properties?

Answer 4

Cooksonia pertoni from 425mya.
Had differentiated water transporting cells (xylem).
Allowed for vertical growth due to the water conducting cells and therefore the ability to transport water.

Question 5

Changes to atmosphere as a result of land plants?

Answer 5

Delivered large amounts of carbon to the terrestrial environment via photosynthesis.

Question 6

When did trees evolve?

Answer 6

Around 460 mya, with extensive forests developing by 350 mya.

Led to competition for light and nutrients.

Question 7

What effects did big plants have on the environment?

Answer 7

Bigger roots, which produced the first complex soils and carbon burial in soils (removing carbon dioxide from the atmosphere).
Silicate weathering removed carbon dioxide from the environment.
Enhanced weathering would have caused cooling. The Late Ordovician ice age and a marine mass extinction followed, all due to decreasing carbon dioxide levels.

Question 8

Founder crops of the fertile crescent?

Answer 8

Emmer wheat 
Einkorn wheat 
Barley 
Lentils
Chickpeas 
Bitter vetch 
Flax

Question 9

Where did domestication begin?

Answer 9

Independently in different locations around the world
SE Asia (fertile crescent)
China
Eastern North America

Question 10

Describe the first green revolution?

Answer 10

1960-2010.

Provided high yielding crops.
Availability of cheap fertilisers.

Cereal yields increased by nearly 150% but the fertiliser had to increase by 600%.

Food production needs to increase by 75% in the next 38 years.

Question 11

Plants as sources of commodities for humans?

Answer 11

Food (rice, maize, wheat)
Fibre (cotton linen)
Fuel (wood)
Shelter (wood)

Question 12

Plants as sources of ecosystem services for humans?

Answer 12

Clean water
Clean air
Carbon sequestration
Shelter

Question 13

Describe the second green revolution?

Answer 13

Challenge: use plant breeding to increase yields and decrease inputs.

Desire cereal crops which can fix their own nitrogen as the average nitrogen content of an english wheat field is 20% of that needed to produce an economically viable crop.

Question 14

How will climate change affect crops?

Answer 14

Climate change will increase the frequency of extreme climate events.

Rice is susceptible to flooding, as the rice grows out of the water, and exhausts its carbohydrate stores.

Mutations in SUB1 gene make rice insensitive to flooding.

Marker assisted breeding and complete genome sequences accelerated the introduction of sub1 allele into locally adapted high yielding rice varieties.