Lecture 12

Question 1

phylum anthophyta

Answer 1

angiosperms all in one phylum, vast majority of seed plants

Question 2

flower

Answer 2

a specialized shoot with up to 4 whorls of modified leaves

Question 3

4 parts of flower

Answer 3

1. sepals (sterile)
2. petals (sterile)
3. stamens (anther + filament) - microsporophylls
4. carpels (stigma + stile + ovary) - megasporophylls

Question 4

ovary

Answer 4

base of carpel, contains 1 or more ovules

Question 5

perfect flower

Answer 5

contains both stamens and carpels

Question 6

imperfect flower

Answer 6

contains only stamens or carpels

Question 7

monoecious

Answer 7

imperfect male and female flowers on same plant

Question 8

dioecious

Answer 8

imperfect male and female flowers on different plants

Question 9

animal pollination

Answer 9

angiosperms are more reliant on animal pollinators, flowers modified to attract and dispense pollen, flowers provide food rewards (sugary fluids ie. nectar, or pollen itself)

Question 10

fruit

Answer 10

mature ovary containing seeds - the ‘container’ part of angiosperm, may be dry and thin or thick and fleshy, aid dispersal of seed

Question 11

cotyledons

Answer 11

embryonic seed leaves, present inside seed along with embryonic root (radicle), can have 1 or 2

Question 12

monocots and dicots

Answer 12

previous subdivision of Anthophyta based on 1 or 2 cotyledons

Question 13

angiosperm life cycle

Answer 13

1. anthers produce microspores that produce male gametophytes (pollen grains)
2. ovules produce megaspores that produce female megagametophytes (embryo sac)
3. pollen lands on stigma (pollination)
4. pollen germinates
5. double fertilization

Question 14

pollen grain 2 cells

Answer 14

1. generative cell –> sperm

2. tube cell –> pollen tube

Question 15

embryo sac

Answer 15

megagametophyte in angiosperms, contains only 7 cells (less than gymnosperms) and 8 nuclei

Question 16

polar nuclei

Answer 16

one cell in embryo sac contains 2 nuclei

Question 17

pollen germinates

Answer 17

generative cell divides to form 2 sperm cells, pollen tube grows down style to ovule in ovary, taking sperm with it

Question 18

double fertilization

Answer 18

1. one sperm nucleus fuses with egg nucleus –> 2n zygote

2. other fuses with the polar nuclei –> triploid endosperm

Question 19

endosperm

Answer 19

unique to angiosperms, takes nutrients from parent gametophyte, repeatedly undergoes mitosis to produce starchy food source for embryo which is maintained as starch or taken up by embryo and packed into cotyledons

Question 20

angiosperms appear

Answer 20

140 MYA, rapid diversification, viewed as “abominable mystery”, hypothesis: might have evolved from gymnosperm-like ancestors

Question 21

angiosperm-like pollination in gymnosperms

Answer 21

non-conifer gymnosperms pollinated by insects or insects and wind, weevils develop in male cones of some cycads dusted with pollen, and adult weevils are attracted to sugary fluid produced by female cones, but fertilized zygote nourished by preexisting gametophyte cells

Question 22

angiosperm-like fertilization in gymnosperms

Answer 22

several gnetophytes undergo something similar to double fertilization - one fertilized egg becomes zygote other aborts, still nourished by pre-existing tissues of gametophyte

Question 23

2 reasons angiosperm fertilization more efficient

Answer 23

1. food store (endosperm) develops only after fertilization

2. female gametophyte (embryo sac) reduced in size - inexpensive and quick to produce in only a few days

Question 24

amborella trichopoda

Answer 24

oldest extant angiosperm, small dioecious shrub whose
flowers parts are in whorls of 5-13, greeny-yellow with undifferentiated petals and sepals, grows only in New Caledonia, wind and insect-pollinated

Question 25

monocot classification

Answer 25

monophyletic 65 000 species

Question 26

dicot classification

Answer 26

paraphyletic, but eudicots (165 000) monophyletic

Question 27

monocot characteristics

Answer 27

1 cotyledon, parallel veins, scattered vascular tissue, fibrous roots, 1 opening in pollen, flower parts in 3s

Question 28

eudicot characteristics

Answer 28

2 cotyledons, netlike veins, ringlike vascular tissue, taproot, 3 openings in pollen, flower parts in 4s or 5s

Question 29

angiosperm importance to humans

Answer 29

80% of calories from 6 species, crops grown for oil, spices + flavour, sugar, drugs

Question 30

teosinte

Answer 30

cob with less kernels selectively bred to become domestic corn

Question 31

transgenic golden rice

Answer 31

contains genes from daffodils that make betacarotene (Vitamin A)