angiosperms Flashcards
what are angiosperms
flowering plants
what do angiosperms contribute to humans
- provide us and our livestock for food
- provide us with raw materials
- used for medicines and other biotech products
- important part of ecology and biodiversity on earth
what are some special features of angiosperms
- flowers
- ovules enclosed in carpels
- carpels develop into fruit
- xylem with vessels
- phloem with sieve tube elements
- no antheridia or archegonia
what are the different families of angiosperms
1) dicots
2) monocots
what are the differences between monocotyledons and dicotyledons
mono
- once cotyledon in seed
- root xyelm and phloem in a ring
- vascular bundles scattered in a stem
- flower parts in threes or fives
dicots
- two cotyledons
root phloem between arms of xyle
vascular bundles in a distinct ring
flowrs in fours or fives
give and example of a monocot and a dicot
1) palm trees = monocot
2) oak trees = dicot
outline the generalised life cycle of an angiosperm
1) flowers produce stamens (male) and or carpels (females)
2) stamens produce pollen, carpels produce ovules
3) after pollination and fertilisation, seeds are produced in a fruit
4) seeds are dispersed but remain dormant
what is the name for grouped flowers
an inflorescence
where is each flower formed
a receptacle
what do stamens and carpels form
stamens = the androecium
carpels = gynoecium
outline the structure of a stamen
the stamen represents the micro sporophylls of the flower
- stamens are made up of a filament and two lobed anther
- each lobe has a pair of microsporangia (pollen sacs)
what does each pollen grain consist of
3 cells
- a tube cell
- 2 sperm cells from the generative nucleus
outline the structure of a pollen grain
an inner wall called the intine and an outer wall called the exine which is resistant
often packed with startch and oil
what is the exine wall made up of
sporopollenin
outline the structure of the carpel
represent the megasporophylls
made up of the over, style and stigma and is often compound of up to two + fused carpels
what processes occur in the embryo sac of the megagametophyte
a single 2n megaspore mother cell in the nucellus undergoes meiosis producing 4 haploid megaspore cells (of which only one survives)
the surviving megaspore enlarges and the nucleus divides to produce 8 haploid nuclei
- 3 antipodals
- oosphere
- 2 syngergids
- 2 polar bodies which fuse to form a polar nuclei
outline pollination in angiosperms
1) pollen reaches the stigma surface where it takes up water and germinates forming a pollen tube
2) the pollen tube grows through the stigma and style to the ovule entering via the micropyle
outline fertilisation in angiosperms
1) the generative nucelus divides producing two sperm cells
2) one fuses with the egg cell forming a 2n zygote
3) one fuses with the 2 polar nuclei to form a 3n endosperm
what happens to the ovule, ovary, zygote and integument
1) ovule becomes the seed
2) ovary develops into the fruit
3) zygote develops into an embryo which is nourished by the endosperm
4) integument becomes the seed coat
outline what is needed for self pollination to occur
- stamens and styles should be near each other in the flower
- flowers must be self compatible
- stamens and styles should develop together or mature together
what are the advantages and disadvantages of self pollination
+= pollination is assured
- = inbreeding leading to lower heterozygosity and inbreeding depression
outline what is needed for cross pollination
- essential if ourbreeding is to occur
- flower must be self-incompatible
- design must prevent self pollination
- may show specific adaptations to promote transfer of pollen from one flower to another
what is protandry
when stamens develop and mature before carpels have a receptive style or stigma
what is protogyny
when carpels develop and mature before stamens
what is heterostyly
when stamens and styles are at different positions in the flower
what is dioecy
the plant is either male or female so doesnt contain both structures
what are some pollen transfer methods
1) wind
2) water
3) insects
4) birds
5) bats
6) other animals
what traits do insect pollinated flowers have
1) bright colours which can act as guides
2) scents which can be associated with certain flowers
3) rewards for pollinators such as pollen which is high in protein and starch or nectar which is high in sugars
4) mimicry - some plants produce pheramones which mimic the female of a species
5) morphology
how are flowers evolved for pollination by birds
- production of large amounts of nectar and floral parts
- have no scent as bird smell is poor
- brightly coloured to attract
- often large and hangining
outline how flowers are adapted for wind pollination
- smooth boyant pollen
- dense inflorescences
- stamens exposed
- stigmas exposed with a feathery appearence increasing SA
- lack colour
- no scent
what are the two types of fruit
1) dry
2) fleshy
what are some ways of fruit and seed dispersal
1) wind
2) water
3) mechanical
4) animals
define endozoochory
when animals ingest fruit and seeds which are then excreted, regurgitated or discarded
outline coevolution between fruits and animals which are specialised to eat fruit
- large seed
- nutritious
- high qualitiy food
- not available in abundance
outline how coevolution between fruits and animals which are not specialsied to eat
- smaller seeds
- carbohydrate rich
- eaten by wide variety of species
- easily found
