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Flashcards in APS122 - Biodiversity - Wellman Deck (112)
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1
Q

What is biodiversity?

A

The variety of life, in all its manifestations. It encompasses all forms, levels and combinations of natural variation

2
Q

What are the 3 elements of biodiversity?

A

Ecological, genetic and organismal

  • everyone thinks about populations
3
Q

What is species richness?

A

Number of different species

4
Q

What % of biomass (excluding microbes) is plant?

A

90%

5
Q

What are the major primary producers on the planet?

A

Plants (base of all terrestrial food chains)

6
Q

What do plants provide us with?

A

Food, drugs, materials to clothe and house us, fuel, jobs etc.

7
Q

What can we use to work out the origin of land plant life?

A
  • Evolutionary relationships of living plants
  • molecular clock evidence
  • Physiological/anatomical/genetic changes required to make transition from aqueous to subaerial existence
  • fossil evidence (plants + spores/pollen)
8
Q

Marine algae –> Pond/freshwater life –> ?

A

Land plants

9
Q

Land plants (embryophytes) are a … group

A

Monophyletic

- evolved only once from a freshwater multicellular green algae

10
Q

What are the problems associated with the transition to land?

A
  • Water balance (evolve roots/rhizoids, transport systems, cuticle etc)
  • availability of nutrients and gases (evolve stomata and roots)
  • Support (no longer supported by aquatic medium - evolve lignified conducting tissue)
  • UV protection (use cuticle)
  • Reproductive strategy (spore wall evolved + dispersal by new vectors)
11
Q

What is the most basal land plant group?

A

Liverworts

12
Q

Bryophytes are…

The dominant phase is…

A
  • non-vascular (do not have lignified) conducting tissues hydroids and leptoids
  • Homosporous
  • The gametophyte phase is dominant (sporophyte parasitic)
13
Q

In vascular plants (tracheophytes) the dominant phase is the….
The conducting tissues are…

A

Sporophyte phase

- lignified

14
Q

How many species of angiosperms are there?

A

250,000

15
Q

Lycopsid –> ? –> ferns

A

Sphenopsids

16
Q

What is the alteration of generations?

A

Gametophyte (haploid, n) phase and sporophyte (diploid, 2n) phase

17
Q

Bryophytes require a … … … to reproduce

A

film of water

  • sperm have 2 flagellae lol
18
Q

What are the three main bryophyte groups?

A

Liverworts, mosses, hornwarts

19
Q

What do epiphytes do?

A

Grow on other plants

20
Q

What is the male sex organ of algae, mosses, ferns, fungi, and other non-flowering plants?

A

Antheridium

21
Q

What is the female sex organ in mosses, liverworts, ferns, and most conifers?

A

Archegonium

22
Q

In the sporophyte what do cells undergo?

A

Meiosis

23
Q

What do elaters in sporophytes do?

A

Push out and release all of the spores

- spiral structures

24
Q

What do mosses have at their base?

A

Leafy gametophyte structure

25
Q

How do mosses disperse spores (considering they lack elaters)?

A

Use Peristome with teeth structures (which opens when it is dry) or other capsules (e.g. pepper-pot mechanism)

26
Q

What are moss stomata for?

- liverworts do not have stomata

A

Some think they are for moving water around the sporophyte or drying out the sporophyte, or releasing spores

27
Q

What sort of structure do bryophyte gametophytes often have?

A

Thalloid (particularly liverworts and hornworts)

28
Q

Hornworts have basal … cells

A

Meristem

- “conveyor belts of spores”

29
Q

When is it thought plants invaded the land?

A

475Ma

30
Q

What are the most primitive basal vascular plants?

A

Lycopsids

31
Q

In tracheophytes which stage is dominant?

A

Sporophyte phase

- sporophyte has lignified conducting tissues - can stand upright

32
Q

What reproductive strategy can lycopsids use?

A

Both homosporous and heterosporous strategies

- gametophyte very small and short-lived

33
Q

What are isospores?

A

All the same size

34
Q

What is the most famous genera of lycopsid?

A

Lycopodium (200sp.)

  • spine like leaves
  • roots
  • cones (with sporangia + produce isospores)
  • homosporous
35
Q

What is the most common genera of lycopsid?

A

Selaginella

  • upright or along ground
  • spiny leaves
  • rhizophores
  • heterosporous (sexual differentiation)
    • female megaspores + male microspores
    • still requires film of water
36
Q

What are the advantages of heterospory?

A
  • Encourages outbreeding (genetically healthier + more variation)
  • Megaspores have reserves and can survive for much longer (even a couple years) + can dry out
    • means can inhabit more seasonal and dry environments
37
Q

What gave rise to the zosterophylls (which then gave rise to the lycopsids?

A

Rhyniophytes - simplest vascular plants

- bifurcate determinately (whereas zosterophylls + lycopsids indeterminate)

38
Q

Why did lycopsid trees go extinct?

A

Environment dried out (require film of water for reproduction)

39
Q

Sphenopsids are actually a highly derived group of…

A

ferns

40
Q

Equisetum (a sphenopsid) has

A

nodes and whirls of leaves

  • Rhizoids - nightmare for gardeners
  • homosporous (produces isospores)
  • sunken stomata
  • “elaters” on outer layer of spores help to disperse them (4 per spore)
41
Q

What are reasons why plants grow tall?

A
  • intercept more sunlight
  • shade out competitors
  • better spore and seed dispersal
42
Q

What are the marattiales?

A

Tree ferns

- trunk made of dead leaf bases with adventitious roots wrapped around

43
Q

On ferns where are sporangia?

A

On the underside of leaves

44
Q

What are hydropteridales?

A

Water ferns

  • hairs repel water
  • roots hang down
  • the only heterosporous fern
    • “velcro-like” system of megaspores and microspores
45
Q

Are leaves homologous?

A

No - evolved several times independently - so did heterospory

46
Q

How is it suggested megaphyll leaves evolved?

A

Webbing between branches

47
Q

How is it suggested microphyll leaves evolved?

A

Either:

  • Reduction
  • Enation
  • Sterilisation
48
Q

What are the gymnosperms?

A

Seed plants

  • gingkos
  • cycads
  • conifers
  • gnetales
49
Q

In gymnosperms the gametophyte grows inside…

A

the spore (called a pollen grain)

50
Q

The pollen grain is … whereas the megaspore is …

A

male (microspores), female (ovule)
- when fertilised becomes seed

  • dependence on water for reproduction removed
51
Q

When was the plant equivalent of the cambrian explosion?

A

Devonian

52
Q

What are cycads characterised by?

A

Big phat cones

53
Q

What do gingkos and cycads have?

A

Both male and female plants

- can switch if not pollinated for a long period

54
Q

What do conifers have on their pollen to help it fly and distribute?

A

Air sacs (2 of them would you beleive?!!) WOWWWW

55
Q

What do gnetales have?

A

Flower-like structures

56
Q

How many cell types occur throughout the plant kingdom?

A

Around 40 only

- plants have very basic needs

57
Q

Since plants are sedentary reproductive propagules are dispersed…

A

vast distances

58
Q

Plants can often … in times of stress

A

regenerate

e.g. from underground stems and rhizomes

59
Q

What are the two types of polyploidy?

A

Autopolyploidy

Allopolyploidy (hybrid) - responsible for a lot of plant speciation

60
Q

What is mosaic evolution?

A

Only evolving certain parts of plants at once - rest remains the same

61
Q

What is the key driver of plant evolution?

A

Evolution of new more effective and efficient reproduction strategies

62
Q

What are angiosperm seeds used for?

A

Food, vitamins, oils, spices, stimulants, drugs, waxes, vegetable ivory, dyes, ornaments

63
Q

What are seeds?

A

Reproductive bodies formed from fertilised ovules

64
Q

What is the endosperm?

A

Nutrient store

65
Q

What are the functions of seeds?

A

Multiplication, perennation (survival), dormancy and dispersal

66
Q

Why are seeds superior to spores?

A

Nutrient store, multicellular - headstart - better transfer of genetic material to the next generation

67
Q

What is the biggest seed?

Smallest?

A

Coco de mer (Buoyant)

Slipper orchid

68
Q

What makes a successful seed?

A

Seed number - some species can have a potential of 1 billion offspring

69
Q

As seed mass increases, offspring survival…

A

increases

70
Q

What is the tradeoff in angiosperm seeds between

A

seed mass and seed number

71
Q

What are the advantages to bigger seeds?

A

More resources
Emergence from a greater depth
Aggressive early growth
Greater stress tolerance

BUT fewer seeds

72
Q

In favourable environments … seeds are better

A

Small

73
Q

In stressful environments … seeds are better

A

Large

74
Q

Competition leads to … seed mass

A

Lower - due to more root mass investment

75
Q

What determines seed size?

A
Size of parent + form of parent
Dispersal mode
Environment
Predation risk
Lifestyle
76
Q

Why do seeds need to be dispersed?

A

Avoid competition with kin
Avoid inbreeding
Exploit new habitats

77
Q

What is anemochory?

A

Seed dispersal by wind
- often pioneer vegetations

  • flyers - balloons - plumes - wings - tumbleweed
78
Q

What is hyrdochory?

A

Seed dispersal by water

  • buoyant seeds (corky fruits or air-containing fruits)
79
Q

What is zoochory?

A

Seed dispersal by animals

  • endozoochory (in)
  • Epizoochory (on)
  • synzoochory (deliberately)
  • sticky, useful or tasty
80
Q

What is myrmecochory?

Chiropterochory?

A

Seed dispersal by ants

- By bats

81
Q

Why do island seeds tend to have decreased dispersal?

A

So seeds don’t end up in the sea

82
Q

Angiosperms bear seeds…

A

enclosed within an ovary (fruit)

83
Q

What are internodes?

A

Gaps between leaves on stem

84
Q

What are the two main plant systems?

A

Shoot system and root system

85
Q

What is the end of the female part (pistil/carpel) of the flower called?

A

Stigma (on the end of the style)

86
Q

What is the male part of angiosperms called?

A

Stamen (+anthers)

87
Q

When did the angiosperms emerge?

A

Mesozoic era

88
Q

Evidence suggests the angiosperms and gymnosperms are … …

A

Sister clades

89
Q

What are the main groups of angiosperms?

A

Eudicots, monocots (grasses), magnolids

90
Q

What are cotyledons?

A

Seed leaves

  • formed in the seed
  • Carry a food source for growing leaves
  • very different to ‘true’ leaves
91
Q

Monocots have … vascular tissue

A

Parallel

92
Q

In monocots stomata are..

A

Present in lines and present on both surfaces of the leaf

more scattered in dicots and more on underside of leaf

93
Q

Eudicots can make … as they have cambium

A

wood

94
Q

Monocots have … roots

A

adventitious
+ fibrous

(eudicots have taproots)

95
Q

Monocot flowers have multiples of … parts

A

3

4 or 5 in eudicots

96
Q

Monocots have … pollen grains, whereas eudicots have … pollen grains

A

Monosulcate, tricolpate

97
Q

What is the major factor determining seed size?

A

Size of the parent

98
Q

Shrub has wood in it. What doesn’t?

A

Forb

99
Q

If you can produce toxic seeds you can…

A

invest in larger seeds

100
Q

What is iteroparity?

Semelparity?

A

Reproduces many times during life cycle (most perennial plants

  • Reproduces once during lifestyle (large and fatal - most annual plants) - actually quite rare
    • Synchronised flowering over vast areas known as masting
101
Q

What is a perennial?

A

A plant that lives for over 2 years

102
Q

Why does semelparity exist?

A
  • Predator satiation (too many for predators to eat)

- Increase recruitment after fire (competitors will have been removed)

103
Q

What is seed dormancy?

A

When a seed doesn’t germinate until environmental conditions are favourable (avoids unfavourable conditions)

104
Q

What is the purpose of seed dormancy?

A
  • avoid unfavourable periods (e.g. cold winter)
  • Wait for favourable environment (cueing)
  • Give dispersing agents time to act
  • Reduce kin competition
105
Q

What control seed dormancy?

A
  • Hormones (auxin promotes dormancy, giberellins break dormancy)
  • After-ripening (after set time)
  • Abiotic factors such as light and temperature
  • Physical dormancy (seed coat)
106
Q

What is pollination?

A

The process of getting pollen (male gametes) onto stigma to facilitate fertilisation and reproduction

107
Q

Where does female gametophyte production occur?

What happens?

A

In the ovary (produces ovules)

  • single diploid nucleus –> four haploid nuclei
  • only one of the nuclei survive
  • splits by mitosis to form 8 haploid nuclei, in 7 cells, within a single embryo sac
108
Q

Where does male gametophyte production occur?

What happens?

A

Microsporangium (anther) to produce pollen

  • single diploid nucleus –> 4 haploid nuclei
  • none wasted
  • each haploid nuclei undergoes mitosis to produce pollen with one generative cell and one tube cell
109
Q

Tube nucleus is responsible for…

A

burrowing into the style

- two generative cells follow to fertilise eggs

110
Q

What does the second generative pollen nucleus do?

A

Fuses with two polar nuclei inside the ovule to form the TRIPLOID endosperm (2/3 maternal, 1/3 paternal DNA)
- endosperm feeds plant

111
Q

Perfect plants have…

A

Both male and female parts

112
Q

Most plants are self-

A

Incompatible

- if same copy of S gene, pollen tube is aborted