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Flashcards in Plants IV Deck (23)
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1
Q

Angiosperm defining features

A
  • flowers
  • double fertilization to make endosperm
  • seeds covered by mature flower tissue (ovary)
2
Q

When did they come about? and from where?

A
  • maybe seed ferns?

- oldest fossils from 125 mya

3
Q

Differences in Angiosperm when compared to gymnosperm

  • gametophytes
  • 2x fertilization
  • ovule
  • x/p
  • reproduction in general
A
  • reduced gametophytes (7 celled f) (2-3 celled m)
  • endosperm
  • 2 integument layers
  • vessel elements in primary x and companion cells in p
  • cheaper and faster reproduction
4
Q

Whorls

A

Sepals = outermost whorl– sometimes green – called a calyx when fused

Petals = 2nd whorl – colored if animal pollinator – called a corolla if fused

stamen = fused microsporangia (anthers) supported by stalk (filaments)— can be fused to each other or to petals

pistil = central structure made of one or more carpals (leaves with ovules) rolled into tubes – stigma, style, ovary

5
Q

Anfiosperm common ancester with gymnosperm

A
  • super ancient

- not an offshoot of any one particular group of gymnosperm

6
Q

Amborella trichopoda

A
  • most primitive angiosperm
  • dioecious, small, unisex flowers with spiraled parts
  • no vessels
7
Q

Regular vs Irregular
Complete vs Incomplete
Perfect vs Imperfect

A
  • regular = whorls are similar size/shape
  • complete = have all 4 whorls
  • perfect = has stamen and pistil
8
Q

Hermaphroditic angiosperm

A

-has perfect flowers

9
Q

monoecious angiosperm

A

imperfect flowers, but have staminate and pistilate flowers

-begonia, corn, pine

10
Q

dioecious angiosperm

A

plants have only staminate or pistilate flowers

-holly, wilow, ginkgo

11
Q

pollen development

A
  • happens inside anthers
  • tapetum cells nourish the spores and then degenerate
  • microspore mother cell makes 4 microspores
  • microspores divide 1x to make 2 celled gametophyte (1 tube cell and 1 generative cell)
  • mature pollen is brought to stigma by animal or wind
  • germinates and grows pollen tube to carry sperm to ovary
12
Q

Female gametophyte

A
  • develops inside ovule in ovary
  • comes from 1 megaspore
  • 3 mitotic divisions forms 7 celled female gametophyte (embryo sac)
  • 2 polar nuclei migrate from either end into the center
  • 3 antipodal cells go to end without micropyle
  • 2 synergid cells border egg cell
  • 1 egg cell
13
Q

pollination

A

generative cell divides to form 2 NON FLAGELLATED sperm cells

14
Q

double fertilization

A
  • 1 sperm fuses with egg to form zygote
  • 1 sperm fuses with polar nuclei to form endosperm nucleus
  • nucleus dvlps into endosperm
15
Q

angiosperm seed parts

A
  1. seed coat (2n) = remnants of integument and nucellus of parent sporophyte
  2. endosperm tissue (3n) = serves as food supply for embryo
  3. embryo (2n) = daughter plat of adult sporophytes
16
Q

How do angiosperms save energy during reproduction?

A
  • smaller gametophytes

- can abort seed/fruit if resources are limiting

17
Q

legume seeds

A

embryo food is stored in cotelydons

-usually no endosperm at maturity of embryo

18
Q

Grain and coconut seeds

A

abundant endosperm

19
Q

monocot seed

A
  • zea (corn)
  • outer wall (pericap) = fused seed coat and fruit wall
  • extensive endosperm
  • embryo with single cotyledon
20
Q

Evolution of endosperm

A
  1. double fertilization in gymnosperm makes 2 embryos which are fed by female gametophyte
  2. double fertilization in basal angiosperm makes a 2n embryo and a 2n endosperm
  3. double fertilization in derived angiosperm makes 2n embryo and 3n endosperm
21
Q

basal angiosperm vs derived angiosperm

A
  • basal have 4 celled female gametophytes and 2n endosperm

- Amborella has 7 celled female gametophyte and 3n endosperm even though its basal

22
Q

benefits of endosperms

A
  1. energy efficient: smaller/less costly than gymnosperm female gametophytes –> also made later
  2. flexibility : can abort ovules they can’t afford to mature, but gymnosperm have to commit to maturing their female gametophytes
23
Q

Trends over time in land plant evolution

A
  1. increase in size of vascular plants
  2. increase in protection of reproductive tissue
  3. Reduction of gametophyte size of vascular plants