Angiosperm Apathy Flashcards
(39 cards)
when did angiosperms first evolve?
- the cretaceous period (~140 million years ago)
but most species arose in the last 50 million years
how much of our food supply comes from angiosperms?
~99% of our food supply comes from angiosperms
What are angiosperms?
- trees, shrubs, aquatic and marine, herbs, (highly diverse)
What does the age of mammals mean?
most animals have developed within the last 60 million years = ‘the age of mammals’
what is the smallest plant?
- duckweed
What are parasitic, saprophytic, and carnivorous plants?
- parasitic: absorbs everything from host plant, no leaves but has flowers and produces seeds
- saprophytic plants: underground photosynthetic plants
- carnivorous (still photosynthetic!!) :digests insects
what is the world’s largest flower?
- the corpse flower (smells awful because it has 4 million seeds but it has short period of flowering so must attract pollinators)
- AKA monster flower
What percentage of plants are flowering?
- over 90% of plant species are flowering = astounding variation
why are there many different types of flowering plants?
- plants are highly adaptive
- random mutations and natural selection
- artificial selection
why are angiosperms the most successful plant group?
- highly adaptive and superior reproductive system
- also special mechanisms for pollination/seed dispersal
what are two examples of aquatic angiosperms?
water Lilly and sea grass: compete with algae
Describe the parts of the flower
4 whorls: whorl of carpel, stamen, calyx, corolla
what is the corolla and the calyx called together?
the perianth
describe the ovule
unfertilized megaspore surrounded by megasporangium and th integuments
- the megasporangium provides nutrients to the megaspore
Describe the fertilised ovule
- mature megagametophyte (embryo sac) and the eggs inside
- two integuments outside
- the megaspore undergoes 3 rounds of mitosis to form 7 celled, 8 nucleated megagametophyte
What is the mature megagspore consist of?
- 3 antipodal cells, 2 synergies, 1 egg cell and one polar nuclei
describe the structure of the ovule after fertilisation
- megagametophyte with 7 cells, 8 nuclei
- surrounded by nucellus (megasporangium derived) and 2 integuments
What are the differences in the ovules in angiosperms from gymnosperms?
- double fertilisation
- 7 cells, 8 nuclei
- no archegonia (primitive), instead just the megagametphyte surrounded by the megasporoangium (nucellus)
- 2 integuments
- polar nuclei to form endosperm
describe the development of anther
microsporpcytes undergo meiosis to produce 4 haploid microspores
- the tapetum layer of the microsporangia provides nutrients to the microspores and then undergoes programmed cell death
- the anther is modified microspoprhyll: has microsporangia (pollen sacs) which eventually yield pollen (immature microgametophyte)
how do pollen recognize the correct plants to pollinate?
- pollen have specific wall growths
- when the recognition factor of a compatible pollen identifies a receptive stigma it encourages the pollen tube tp grow down the style
- the style transmitting tissue encourages the pollen tube to grow down to the ovary
What is the style transmitting tissue?
- differentiated tract between the stigma and the ovary
what is the fastest growing cell? Does pollination guarantee fertilization?
the pollen tube is the fastest growing cell
- pollination does not guarantee fertilisation
describe double fertilization, what does the endosperm do?
- two sperm cells produces: one fertilizes the polar nuclei to produce triploid endosperm - initially it is one nucleus but undergoes mitosis to produce multinucleate cell that provides nutrients to the embryo
- the other sperm fertilizes the egg to produce the zygote
describe the development of the endosperm in angiosperms
- starts out as a triploid nuecli in a large open sac
- divides many times forming a multi-nucleated endosperm to provide nutrients for the embryo
