lecture 7: angiosperms - pollination to dispersal

Question 1

angiosperm

Answer 1

◆ 2nd type of vascular, seed plant
◆ aka flowering plants
◆ angios = “container”, sperma = “seed”
◆ the most dominant plant group today
◆ 3 major innovations:
- flowers (pollination/protection)
- endosperm (seedling establishment)
- fruits (protection/dispersal)
◆ 3 components of the seed:
1) embryo = zygote + mitosis
2) food supply = endosper
3) seed coat = hardened integument

Question 2

determinate growth

Answer 2

growth of a plant stem that is terminated early by the formation of a bud
- naturally self-limited growth, resulting in a plant of a definite maximum size

◆ a flower is a determinate structure – a defined end

Question 3

whorls

Answer 3

◆ part of a flower
◆ a flower’s parts are arranged on that axis in a sequential order in whorls of one or more organs of the same type

Question 4

sepal, petal

Answer 4

◆ sepal: offer protection to the bud
◆ petal: often bright, large and attractive to pollinators
◆ stamen: fertile organs that produce and bear pollen
- filament = stalk that bears the anthers
- anther = sac that contains the microsporangia where microspores form and germinate to become pollen (gametophyte)
◆ sepal –> petal –> stamen

Question 5

carpel (pistil, stigma, style, ovary)

Answer 5

sporophyll fused into a container within which the ovules are found

◆ pistil = single carpel or collection of fused carpels
- receive the pollen and encases the ovary/seed
◆ stigma = sticky surface where pollen lands and pollen tube germinates
◆ style = tract down which the pollen tube migrates to reach ovules
◆ ovary = protective container around the ovules

Question 6

inflorescence

Answer 6

the flowering stalk
- flowers are often found together

Question 7

self pollination

Answer 7

helpful when…
- lower pollinator availability
- high competition for pollinators
- dispersal to new habitats
- in-crop breeding

Question 8

inbreeding depression

Answer 8

deleterious recessive mutations are exposed in offspring, lowering fitness
- happens with self-pollination
- this is why there is an evolutionary benefit to sex

Question 9

nectar guide

Answer 9

markings that attract and orient pollinators

Question 10

coevolution

Answer 10

the joint evolution of two interacting species in response to selection imposed by the other

Question 11

pollination syndromes

Answer 11

suites of plant traits that suggests co-evolution with a particular group

Question 12

buzz pollination

Answer 12

a type of pollination in which bees use vibrations to remove and collect pollen from flowers incidentally fertilizing them

Question 13

double fertilization / central cell

Answer 13

1st central cell nucleus (n) + 2nd central cell nucleus (n) + 1 sperm nucleus (n) = 1 endosperm cell (3n) –> new!

Question 14

endosperm

Answer 14

associated with seedling establishment

◆ the ovary becomes a fruit containing the seeds
◆ fruits and seeds are dispersed by an animal, wind, or water
◆ when a seed germinates, the embryo develops into a plant
- the ovule becomes a seed containing an embryo and food supply

Question 15

monocot

Answer 15

◆ one cotyledon (embryonic leaves)
◆ ex: corn
◆ characteristics
- the endosperm starts as a liquid with loose nuclei floating around
- then, cellularizes into a starchy solid that is rich in fats and proteins that provides nutrition to the embryo post-germination

Question 16

eudicot

Answer 16

◆ two cotyledons (embryonic leaves)
◆ ex: beans, tomatoes, peppers, peanuts
◆ characteristics
- the endosperm starches are taken up by the growing embryo as the seed develops, and stored in the cotyledons
- aka endosperm is just inside the paper-like outer layer