Origin & Importance of Plants

Question 1

Define ‘producers’

Answer 1

organisms that can use light energy from the sun to produce food

Question 2

List some producer taxa

Answer 2

plants, algae and certain bacteria

Question 3

How long ago was photosynthesis innovated?

Answer 3

3.5Bya

Question 4

How many plant species are used by humans?

Answer 4

17,000 to 40,000

Question 5

How many plant species have humans domesticated?

Answer 5

A couple of hundred

Question 6

Describe some roles of producers

Answer 6

• provision of food to consumers
• regulation of atmospheric gases and temperatures

Question 7

Define ‘consumers’

Answer 7

organisms that obtain energy from the food they consume

Question 8

List some consumers

Answer 8

animals, fungi and other bacteria

Question 9

Greater than … of earth’s land has been cleared for the approximate … plant species in the human food chain (…).

Answer 9

• 40%
• 150
• the equivalent of the area of South America and Africa combined

Question 10

… species provide ¾ of the world’s food

Answer 10

12

Question 11

List some megacrops

Answer 11

• maize
• rice
• wheat

Question 12

Plants are also used in … of prescription medicines, and approximately … people are reliant upon basic plants for medicinal needs

Answer 12

• 25%
• 2Bn

Question 13

Only … of plants ever in existence are extant, with … having gone extinct

Answer 13

• 1%
• 99%

Question 14

Only … of plants have been described

Answer 14

10-20%

Question 15

Only a … of plants have had their genomes sequenced.

Answer 15

small fraction

Question 16

Define photosynthesis

Answer 16

production of food using radiant light energy from the sun, via carbon dioxide

Question 17

Photosynthesis can be found across … bacterial phyla

Answer 17

6

Question 18

Describe the basics of anoxygenic phototrophism

Answer 18

• exhibited by 5 of the 6 photosynthesising bacterial taxa
• anaerobic conditions

Question 19

Describe the specifics of anoxygenic phototrophism

Answer 19

• uses a variety of reduced inorganic sources (sulphide, ferrous iron and hydrogen) as electron donors
• has a non-cyclic electron transport chain

Question 20

Describe oxygenic photosynthesis

Answer 20

• polyphyletic phenomenon
• facilitated by the Great Oxidation Event
• exhibited by cyanobacteria and plants
• uses water as its electron donor
• electron transport chain is cyclic

Question 21

How long ago was the Great Oxidation Event

Answer 21

2.5Bya

Question 22

Describe Bangia atropurpurea

Answer 22

• extant photosynthetic multicellular eukaryotic red alga with differentiated cells and reproductive structure
• approximately 1.2Bya

Question 23

When was the origin of oxygenic photosynthesis?

Answer 23

2.5Bya

Question 24

Describe the origin of oxygenic photosynthesis

Answer 24

facilitated by primary photosynthetic endosymbiosis

Question 25

Describe primary photosynthetic endosymbiosis

Answer 25

the grazing of a mitochondria-containing heterotrophic eukaryotic cell on cyanobacterium, resulting in engulfment.

Question 26

Describe the evidence for primary photosynthetic endosymbiosis

Answer 26

- chloroplast DNA shape (circular) and sequence - 70s ribosomes - binary fission division

Question 27

Describe secondary endosymbiosis

Answer 27

- facilitates photosynthesis - the grazing and consequent engulfment of a unicellular primary plastid-containing, oxygenic photosynthesising eukaryotic alga by another eukaryote

Question 28

Evolution of the Embryophytes is suggested to be

Answer 28

- around 460-470Mya - microfossil sporopollenin spores

Question 29

Describe producer life cycles

Answer 29

designed to regulate ploidy levels.

Question 30

Describe the life cycle of a Streptophyte algae

Answer 30

- haplontic - only diploid cell is the zygote

Question 31

Describe alternation of the generations - the basics

Answer 31

- occurs at the Embryophyte node in the phylogenetic tree - haplodiplontic life cycle

Question 32

Describe alternation of the generations - the specifics

Answer 32

- in the haplontic generation, the plant is in its multicellular gametophytic phase, where it produces its gamete - plant exists, also multicellular, in its diplontic generation: sporophytic phase

Question 33

Describe the sporophytic phase

Answer 33

produces a spore via meiosis (reduction division)

Question 34

Meiosis is ...

Answer 34

the process which an organism reduces ploidy.

Question 35

At the Embryophyte node...

Answer 35

– delay interpolates mitosis, which creates a multicellular zygote, the embryo - causes the rise of the sporophyte and the demise of the gametophyte

Question 36

Describe the gametophytic generation in angiosperms

Answer 36

- haploid - occurs in an embryo sac - extraordinary reduction of the haploid stage as the diploid stage took over

Question 37

Describe embryophytic innovation

Answer 37

- allows for terrestrialisation (into an dessicating environment) - evidenced by green algae in desert

Question 38

Describe crypto spores

Answer 38

- tetrahedral tetrads - products of meiosis - produced in 4s - trilete mark is a physical scar

Question 39

Describe terrestrial plants

Answer 39

capable of forming complex ecosystems (evidenced by the Rhynie Chert)

Question 40

Gross primary production (GPP) =

Answer 40

photosynthetic CO2 fixation

Question 41

Net primary production (NPP) =

Answer 41

GPP – autotrophic respiration

Question 42

Describe the Rhynie Chert

Answer 42

- oldest ecosystem preserved in situ - displays the oldest terrestrial arthropods, decomposing fungi and mycorrhizae - evolved 407 Mya