L8 and 9 Karin Kjernsmo - Pollination, fruits and seeds

Question 1

Allogamy

Answer 1

Cross pollination, from flowers with different genetic constitutions

Question 2

Autogamy

Answer 2

Self pollination, same genetic constitution.

Question 3

Anemophily

Answer 3

Wind pollination

Question 4

What characteristics do wind pollinated plants have?

Answer 4

small flowers grouped together

produce a lot of pollen, as not always very efficient.

Question 5

what type of pollination do 87% of plants undergo?

Answer 5

Animal pollination
Mutualism, so costs are involved too
Co evolution of flowers and pollinators

Question 6

How do plants compete with each other for pollinators?

Answer 6

much competition for cross pollination, need to attract polltinators and ensure they remember the specific plant in order to return. 
use colour and UV guides to attract.
Nectar guides
Conical cells
Irridescence

Question 7

What pigments make colour in flowers?

Answer 7

Carotenoids - absorb blue, reflect yellow - red, rich orange colour
Bilirubin - deep purple/blue colours, when chlorophyll is broken down
Flavenoids - flavenols and anthrocyanin, magenta violet colours
Betalins - red - violet colours

Question 8

How do nectar guides work?

Answer 8

guide pollinator towards reproductive organs and reward. Colour in centre is much more distinctive.

Question 9

What do conical cells do?

Answer 9

tactile and colour cues which bumble bees detect. Allow bees to grip onto tissue. Bees can discriminate against snapdragons without conical cells.

Question 10

How is irridescence used?

Answer 10

structural colour formed by microstructures on petal surface. Visual cue for pollinators, can discriminate btw rewarded and unrewarded flowers.

Question 11

How can bees remember the location of a flower?

Answer 11

Using floral electric fields

Question 12

How have flowers adapted to pollinators using echolocation?

Answer 12

Developed acoustic mirrors, eg Marcgarvia evenia

Question 13

What is flower constancy?

Answer 13

How honey bees are seen to travel back to the same flower even though they pass other, equally good/better flowers. Darwin suggested because earning to extract nectar from a new species is risky.

Question 14

2 examples of coevolution of pollinators and flowers

Answer 14

1. Diascia flowers evolved oil in 2 spurs. Rediviva bees have developed unusually hairy forelegs to collect oil.
2. Darwin’s orchid - extremely long corolla, most likely to be pollinated by moth w v long tounge. 40 years later discovered Hawk moth.

Question 15

example of deception

Answer 15

Chiloglottis orchid secretes chlioglottone which mimics pheromone produced by female wasps to sexually attract males

Question 16

What s a pollination syndrome?

Answer 16

Suites of flower traits, eg flower shape,size, colour, odour etc which have evolved in response to NS due to pollinators.

Question 17

Pollination by:
wind
beetles
bats
insects
water
slugs
bees
flies
ants
birds
butterflies

Answer 17

Anemophily
Cantharophily
Chiropterogamy
Entomophily
Hydrophily
Malacophily
Melittophily
Myophily
Mymecophily
Orthinogamy
Psychophily

Question 18

What colour flowers do bees usually pollinate?

Answer 18

not red, see blue, green and UV light do often go for yellow, blue or white flowers.

Question 19

why would flowers change colour

Answer 19

Dynamic signals allow flowers to change colour if not enough pollen is received, so can attract different pollinators

Question 20

What other rewards do pollinators seek?

Answer 20

Nursery eg figs for wasps

heat eg skunk cabbage

Question 21

example of plant mimicry

Answer 21

1. Disa nervosa (orchid) doesnt actually contain reward but mimics Watsonia densiflora (rewarded iris)
2. S Africn Daisy mimics insect shape and colouring, spots reveal UV colouring similar to female beesbody
3. Mirror Orchid - sexual deception. attracts male scoliid wasps.

Question 22

Why is outbreeding less easy in plants than animals?

Answer 22

animals have separate male and female individuals

flowers often have both make and female parts, so increased inbreeding. can cause inbreeding depression.

Question 23

what is the result of an inbreeding depression?

Answer 23

reduced biological fitness
Less seeds in self pollinated fruits
eg Banksia spinulosa - 63% decrease in seed set, smaller seed size and fruit set and quality.

Question 24

How can plants ensure outcrossing?

Answer 24

• timing eg Erythronium grandiflorum staggers pollen release by opening flowers in an order to increase pollinator variation.
• Morphology - stigma can be higher than anthers so unlikely for pollen to fall onto stigma
• Develomental - temporal separation of male and female organs
• Biochemical - SI self incompatability systems

Question 25

What are 7 prezygotic events in pollination?

Answer 25

1. Pollen capture on stigma
2. Pollen adhesion
3. Pollen hydration
4. Pollen germination
5. pollen tube penetration of stigma
6. Growth of pollen tube towards ovule
7. Entry of pollen tube onto ovule leading to fertilisation

Question 26

what does the S locus do?

Answer 26

Controls the SI system
If plants share the same incompatibility allele, unable to mate.
Highly polymorphic locus - populations maintain 40 different S alleles by negative frequency dependent selection.

Question 27

Describe the ovule

Answer 27

micropyle is where pollen tube enters ovule.
egg is next to micropyle and 2 synergid cells
2 central cell nuclei
3 antipodal cells at top of ovule.

Question 28

What is inside the pollen grain?

Answer 28

Gametophyte - develops into a sperm cell and a vegetative cell (controls continuous growth of pollen tube).

Question 29

After fertilization what happens?

Answer 29

Diploid zygote forms and develops into an embryo.

Question 30

how does the endosperm form?

Answer 30

single sperm cell fertilises 2 central cells in the ovum. endosperm is 3n.
Endosperm nucleus divides to form mass of nutritive protoplasm and nuclei for embryo.
As seed matures, endosperm undergoes cellularisation.
Good feature as food sources are only laid down after fertilisation.

Question 31

What are the antipodal cells for?

Answer 31

give nourishment to the embryo sac.

Question 32

What are the synergid cells for?

Answer 32

Guide the pollen tube which enters through them and releases sperm nuclei to the egg.

Question 33

what is a caryopsis?

Answer 33

grain - eg of cereal
Dry, one seeded fruit.
Composed of endosperm, germ and bran

Question 34

What are pulses?

Answer 34

Fabaceae

legumes, peas, bean family

Question 35

What are 4 pre dispersal hazards?

Answer 35

1. Incomplete pollination
2. Self pollination, geitonogamy. Causes ovule abortion
3. Resource limitation/stress. Late in season so often have reduced size. Can cause ovule abortion, incomplete fruit set.
4. pre dispersal seed predation - florivory

Question 36

4 methods of seeddispersal

Answer 36

Wind
water
Animals
Exposion

Question 37

example of wind dispersal

Answer 37

orchid ‘dust seeds’ - v small, lightweight.
Propagules are structures attached to seeds to aid dispersal eg bud, sucker, spore, on dandelions, sycamore, tumble weeds

Question 38

How have plants adapted to water dispersal?

Answer 38

traits enabling flotation - air pockets, spongy mesophyll, oils and lipids
40% of uK seeds float for a week, 25% for a monthand 15% for 6 months.

Question 39

example of explosive dispersal

Answer 39

Himalayan balsam

pods shoot out seeds, v successful. seeds then travel downstream.

Question 40

4 types of dispersal by animals

Answer 40

1. endozoochory - mutualistic, transport in gut
2. Myrmecochory - dispersal by ants, elaiosomes- structure rich in AA, lipids and nutrients to attract ants.
3. Human mediated dispersal - technical transport = high mobility and large geographic scales.
4. Movement on outside of animal body - velcro structures of propagules.

Question 41

why do some plants have poisonous fruit?

Answer 41

perhaps regulate timing of germination, increase spread as dispersers won’t stay there, alter speed of passage through gut, maybe toxic to predators but not dispersers, defend against microbial pathogens.