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Biological Systems > Chapter 27 Reproduction of flowering plants > Flashcards

Chapter 27 Reproduction of flowering plants Flashcards

1
Q

How do most angiosperms reproduce?

A

Sexually - leads to genetic diversity

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2
Q

How does sexual reproduction in angiosperms differ to vertebrate animals?

A

Meiosis - spores then Mitosis - gametes
Plants = alternation of generations
In plants, cells that will form gametes develop in adult organism

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3
Q

What are the 4 concentric groups of organs in a flower

A

Sepals
Petals
Carpels
Stamens

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4
Q

What are carpels?

A

Female sex organs

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5
Q

What are stamens?

A

Male sex organs

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6
Q

What are the 7 cells most female gametophytes consist of?

A

1 egg cell
2 synergids (attract pollen tube and remove sperm)
3 antipodal cells (degenerate)
1 central cell with 2 polar nuclei

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7
Q

What is the role of the 2 cells in a male gametophyte/

A

Double fertilization

1 fertilizes egg
Other haploid nuclei of female gametophyte to form triploid cell (gives rise to endosperm that nourishes embryo during early development)

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8
Q

How are wind pollinated plants adapted?

A

they have sticky, featherlke stigmas and produce a large number of pollen grains

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9
Q

How is selfing prevented by monoecious species?

A

physical separation of male and female flower or maturaton at different times

Some are genetically self-incompatable

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10
Q

What controls self incompatability?

A

cluster of linked genes in the S locus

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11
Q

What are integuments

A

tissue layers that surround megasporangium and develop into seed coat

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12
Q

What part of the flower becomes the fruit?

A

ovary

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13
Q

How do seeds prepare for dormancy?

A

Lose 95% of water

- protective proteins keep seed in viscous state

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14
Q

What are the functions of fruit?

A
  • protect seed from damage by animals and infection by microbial pathogens
  • Aid in seed dispersal
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15
Q

What are the different methods of fruit dispersal?

A

Wind
Attached to animals
Disperesed by water
Swallowed by animals then deposited far away

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16
Q

What does flowering represent?

A

reallocation of energy from vegetative growth to reproductive growth

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17
Q

What are the 3 types of plants according to their lifespan?

A

Annual - complete life in a year
Biennial - take 2 years, vegetative growth in first year then reproductive growth in the second
Perennials - live 3 or more years, and typically flower every year

18
Q

What happens to the shoot apical meristem during reproductive growth?

A

Becomes an inflorescence meristem when it produces floral parts

Floral meristem - only produces a single flower

19
Q

What have scientists been studying in arabidopsis?

A

Genes that determine transition to flowering

  • Meristem identity genes
  • Gloral organ identity genes
20
Q

What do Meirstem identity genes do?

A

LEAFY and APETALAI initiate cascade of gene expression

21
Q

What do floral identity genes do?

A

produce transcription fctors that determine whether cells in the floral meristem will be sepals, petals, stamen or carpels

22
Q

What external cues initiate genes for floewring?

A
  • Photoperiod

- Temperature

23
Q

What is the difference between short day plants and long day plants?

A

SDPs - flower when day is shorter than critical maximum

LDPs - flower when longer than critical minimum

24
Q

WHat is the significance of photoperiodic control of flowering?

A

Local population flowers at the same time which promotes coss-pollination

25
Q

What has experiments shown regarding the length of night and plant flowering?

A

It is the length of darkness, not light that triggers flowering
Pft converted to Pr at night, SDP flower when ratio of Pft to Pr is low, LDPs when ratio i shigh

26
Q

Where are phytochrome located? What does this mean for flowering signal?

A

In leaf

Signal must travel. Is diffusable protein florigen

27
Q

What are the features of florigen

A

Protein that triggers flowering

  • Small and can pass though plasmodesmata
  • Diffuses to shoot apical meristem and combines with another protein to stimulate transcription of genes that initiate flowering
28
Q

What genes are involved in flowering?

A

FT (Flowering locus T) codes for florigen
CO (Constans) codes for transcription factor that activates synthesis of FT
FD (Flowering locus D) codes for transcription factor that binds to FT in shoot apical meristem

29
Q

How does temperature affect flowering?

A

Some plants require period of cool temperature (Vernalization)
- Inhibit synthesis of FLC protein which inhibits expression of FD and FT

30
Q

How are gibberellins involved in flowering?

A

activate meristem identity gene LEAFY which promotes transition to flowering

31
Q

What is another mechnism that triggeres flowering (not environmental)?

A

Position of bud

  • determined by concentration gradient of substance along apical-basal axis
  • Inhibitor of FT-FD pathway from root has lower concentration in stem
32
Q

What are the disadvantages of asexual reproduction?

A

no genetic diversity except from mutations

33
Q

What are the advantages of asexual reproduction?

A
  • parent always pass on advantageous allele combinations
  • avoid cost of producing flowers
  • avoid potential risky process of cross-pollination and seed germination
34
Q

How does vegetative reproduction occur

A

Modification of vegetative organs

  • bamboo have underground rhizomes that produce new plants
  • Garlic bulbs are modified stems that can produce new plants
35
Q

What sort of environment to plants that reproduce vegetatively usually live in

A

Unstable (e.g.e eroding hillsides) where germination is unreliable
- Common in desserts

36
Q

What is Apomixis?

A

asexual reproduction of seeds - results in clones

37
Q

What are the mechanisms of apomixis?

A

Megasporocyte does not undergo meiosis - results in diploid cell that becomes embryo and seed
- Diploid cells from integument form a diploid embryo sac which becomes an embryo and seed

38
Q

What is grafting?

A

attaching a bud or piece of stem from one plant to a root bearing stem of another plant

39
Q

What is the stock and scion of grafted plants?

A

Stock - root bearing part

Scion - grafted part

40
Q

What is meristem culture

A

piece of shoot apical meristem cultured on growth media

- then planted in a field

41
Q

What is meristem culture used for?

A

strawberries and potatoes and forestry

Biological Systems (20 decks)

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