Lecture 24 Flashcards

1
Q

What are angiosperms? and when did they first evolve?

A

• c. 250,000 species (note, only 600 species of conifers) Why? • Dominate most terrestrial ecosystems • Basis of world agriculture • Origin in Early Cretaceous (130 million years ago); dominant by 65 million years ago) reproduce by flowers -much more diverse than conifers -dominate almost everywhere but not in arborial trees -enormous diversity of sizes and morphology… –there are more types of eucalypt flowers than conifers

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2
Q

What are the flowers for?

A

-to attract pollinators

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3
Q

Why are angiosperms so incredibly successful?

A

1) Vegetative or morphological features 2) Reproductive features

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4
Q

What are the vegetative or morphological features of angiosperms that make them so successful?

A

-• Vessels in xylem: large, thin-walled, with open ends - continuous piping system. Fiber cells for strength. • Sieve cells (no nuclei) controlled by companion cells (with nuclei) in phloem -tracheids found in some primitive flowering plants (provide structure and support as well) -but still the piping system doesn’t explain why are they so much more succesful than conifers

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5
Q

How many species of flowering plants are there?

A

250 000 species of flowering plants

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6
Q

Do angiosperms have sporophyte or gametophyte dominance?

A

-complete sporophyte dominance

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7
Q

How is reproduction achieved in angiosperms?

A

• Double fertilization: 1) one gives rise to the embryo, 2) other gives rise to the endosperm (food reserves, but only if fertilized!) • Pollination diverse mechanisms (e.g., wind, insects); many are specific.

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8
Q

Describe the reproductive system of angiosperms.

A

• Stamens (male) • Carpels (female)
consists of ovary, ovules, style and stigma
• Pollen lands on stigma surface; pollen tube grows to the ovule
• Angiosperms - seed in a vessel (refers to the carpel).

angiosperm= means seed in a vessel
self incompatibility= can’t have sex withe themselves= leads to greater variability, females develop at different types, stigma recognises cell from non cells so as to not self fertilise

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9
Q

Describe the ovule in gymnosperms and angiosperms:

A
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10
Q

Describe the process by which the sperm gets to the egg:

A
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11
Q

Describe the first and second fertilization:

A
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12
Q

Why is the reproduction of angiosperms advantageous?

A

advantages of angiosperm= double fertilisation, quicker seed set, self incompatibility
-fruit=

seed is set in months not years= as in conifers where it take 2 years for seed to emerge

fruit like a fertliser for the seed= when shit of birds
=good for dispersal
three layers in grapes and peach, seed, flesh and skin
-in apples=layers derived from flower and supporting leaves

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13
Q

Describe the life cycle of an angiosperm:

A
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14
Q

What do ovules and carpels develop into?

A

Ovules develop into seeds Carpel wall develops into fruit

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15
Q

What are fruits for?

A
  • dispersals of seeds
  • grizzly bears= eat berries= dispersal

=co evolutionary thing bears and berries

  • in Australia= ants are important dispersers, the seeds have sticky bit they eat but take them to their nest so= dispersal
  • the sticky seeds= get on your clothes and fur
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16
Q

Why is wind pollination more limited?

A

wind pollination= need large population to fertilise

-conifers do it

17
Q

What mechanisms do angiosperms use to pollinate?

A

• Diverse mechanisms (e.g., wind, water, insects, birds, mammals); many are specific, such as the orchids.

coconuts= water dispersal, last for months in water

wind pollination causes athma and alergies!

18
Q

What are the pollination strategies of orchids?

A

-this one, flower looks like a female insect so the males try to have sex= get pollen all over and disperse it

  • orchids are rare, almost all have specific pollinators= co evolution, can’t take them away!
  • then the orchid which smells like meat= so bugs come

also an orchid=moves when the insect lands= moves it to the pollen (Stylidium)

  • whack!
  • takes 20 min to load
19
Q

List 4 adaptive features that my have lead to the dominance of angiosperms over other land plants and state their advantages?

A

endosperm, pollination, self incompatibility…fruit

20
Q

What is Flowering Plant Diversity?

A
  • Taxonomy(e.g.,eudicotsv. monocots)
  • Ecologically (aquatic, terrestrial, xerophytic)
  • Morphologically (carnivory, parasitic)
  • Biogeography (Australian flora, Gondwana)
21
Q

What are the two basic flower types?

A

-count flower parts

if the same width on the bottom and top= monocots

22
Q

What are the differences betweed monocots and dicots?

A

seeds are different when germinate
-dicots= cotyledons
-venation in leaves, dicots= network of veins
dicots= secondary growth in circles, monocotes= not as much, as vascular bundle is dispersed in the plant

23
Q

List some examples of monocots and dicots:

A

monocots: orchids, palms, grasses
dicots: eucalyptus,acacia, peas, buttercups, daisies, banksia

24
Q

What are some parasitic angiosperms?

A
  • mistletoe (on eucalypts and conifers eg)
  • rafflesia
25
Q

Why are some angiosperms carnivorous?

A

-when not enough nutrition, supplement it by ingesting organisms

26
Q

What are the characteristics of the modern Australian flora?

A

23-till present million yrs ago

angiosperms dominant

-most conifers decline except cypress family

  • Northerly drift of Aust but climatic cooling.
  • Aridification & decline of rainforests.
  • Fire-adapted floras; low-nutrient adaptations

(The winners during drying of the continent: Family: Proteaceae (Banksias, grevilleas, hakeas etc) - adapted to low-nutrient soils)