Chapter 39: Sexual Reproduction In Flowering Plants Flashcards
What is the difference between sexual and asexual reproduction?
Asexual - mitosis , one parent , identical offspring
Sexual - meiosis , two parents , variation
What is the male part of the flower?
Stamen
What are the parts of the stamen?
Anther
Filament
What is the function of the anther?
Produces pollen
What is the function of the filament?
Holds anther in place, has vascular bundles
What is the female part of the flower?
Carpel
What are the parts of carpel?
Stigma
Style
Ovary
What is the function of stigma?
Where the pollen lands
What is the function of the style?
Pollen travels down
What is the function of the ovary?
Contains ovules, formation of the female gamete
What is pollination?
The transfer of pollen from the anther to a stigma of a flower from the same species
What are the two types of pollination?
Self pollination
Cross pollination
What is self pollination?
Self fertilization
Seeds are less sturdy and vigorous
What is cross pollination?
Cross fertilisation - one plant fertilizes another
Seeds are more varied and vigorous
What are the two methods of pollination?
Animal
Wind
What are wind pollination adaptations?
Petals: small, not colored
Anthers: outside petal
Stigmas: large feathery and outside petals
Pollen: large numbers, light, dry and small
E.g. rye grass
What are the adaptations of animal pollination?
Petals: brightly coloured, scented with nectar Anthers: inside petals Stigmas: sticky, inside petals Pollen: small amounts, sticky E.g. daisy
What is fertilisation?
The union of the male and female gametes to form a diploid zygote
What is double fertilisation?
One sperm nucleus (n) fuses with an egg nucleus (n) to form a zygote (2n)
Then
The second sperm (n) fuses with the 2 polar nuclei (n) to form a endosperm (3n)
How is a seed formed?
The fertilised ovule becomes the seed
The zygote grows by mitosis - becomes embryo
Endosperm divides by mitosis - expands and absorbs nucellus - becomes food source
What is the function of the endosperm?
Food source
What are the parts of an embryo?
Radicle
Plumule
Cotyledon
What is the radicle?
Future roots
What is the plumule?
Future shoots
What is the cotyledon?
Stores food, used for germination
What are the two types of seeds?
Non endospermic
Endospermic
What is the difference between endospermic and non endospermic seeds?
Non endospermic - no endosperm because it is absorbed by cotyledon e.g. broad bean
Endospermic - endosperm present, it’s only partially absorbed by cotyledon e.g. maize
What is the difference between monocots and dicots?
Monocots - single cotyledon, long leaf, parallel veins, scattered vascular bundles, flowers in groups of 3, food stored in endosperm
Dicots - two cotyledons, broad lead, network of veins, ring of vascular bundles, flowers in multiples of 5, food stored in cotyledons
Describe the formation of fruit.
Ovary becomes fruit when seed develops
Wall of ovary become wall of fruit - pericarp
What is the pericarp?
Wall of fruit
What are fruits designed for?
Protection of seed
Help in seed dispersal
What is a false fruit?
A fruit that develop from other parts of the flower - not the ovary
How are seedless fruits made?
Parthenocarpy- fruit develops without egg being fertilised
How does fruit form?
Genetically - naturally or by special breeding e.g. bananas
Growth regulars - large concentration of auxins (ethene) e.g. grapes
What auxin ripens fruit?
Ethene
What is dispersal?
Transfer of a seed or fruit away from the parent plant
What are the advantages of dispersal?
Avoids competition
Increases chances of survival
Finds new areas for growth
Increase number of species
What are the four types of dispersal?
Wind,
Water,
Animal,
Self (explosive)
Describe wind dispersal.
Light seeds - little food supply
Uses wings or parachute devices e.g. dandelions, sycamore
Describe water dispersal.
Light, air filled fruits
Allows floatation e.g. coconuts
Describe animal dispersal.
Carried long distances
Two adaptations- sticky fruits, cling to fur e.g. goose grass -edible fruits, seeds pass through digestion system
Describe self dispersal.
Explosive mechanism, pods that dry out and split open e.g. peas
What is dormancy?
The resting period when seeds no longer undergo growth and have reduced all activity
What brings about dormancy?
Growth inhibitors
Testa impermeable by water
Testa too tough to allow embryo to emerge
Lack of growth regulator
What are the advantages of dormancy?
Plant avoids harsh conditions
Embryo gets time to develop
Allows time for seed to be dispersed
Maximizes growth season
What is germination?
The regrowth of an embryo after a period of dormancy
What are the conditions needed for germination?
Water
Oxygen
Temperature
Dormancy completed
What are the steps in germination?
- Water is absorbed
- Food reserves are digested
- Food is moved to the embryo
- Embryo starts to grow
- Glucose turned to ATP
- Radicle breaks through testa
- Plumule emerges above ground
How is the male gamete formed?
Microspore divides by meiosis
Produces 4 haploid cells - tetrad
Tetrad breaks into 4 pollen grains
What is a microspore?
Original parent cell in male part of flower
What is tapetum?
Food store for male part of flower
How many chambers are in the anther?
4
What are the parts of a pollen grain?
Exine
Intine
What is exine?
Thick outer wall of pollen grain, allows for survival, distinctive pattern
What is intine?
Thin inner coat of pollen grain
How does pollen mature?
Haploid nucleus divides by mitosis
Make generative nucleus
And tube nucleus
What are the parts of the ovary?
Ovary has one or more ovules Two walls (integuments) with opening (microphyle) Nucellus - food source for embryo sac
How does an embryo sac develop?
Megaspore divides by meiosis Produces 4 haploid cells 3 degenerate 1 embryo sac Embryo sac divides by mitosis to make 8 haploid nuclei 5 die 2 become polar nuclei 1 egg cell
How does fertilisation occur?
Pollen releases 2 sperm nuclei and degenerate tube nucleus into pollen tube, one sperm fuses with egg cell - zygote, other sperm fuses with two polar nuclei - endosperm
What are the materials needed for the experiment to show digestion?
Broad beans Starch agar dishes Disinfectant Forceps Sharp blade Incubator Iodine
What are the 7 steps in the digestion experiment?
- Soak broad beans
- Sterilize all equipment including seeds
- Boil half the seeds
- Split the seeds down the center using a knife
- Place the seeds face down into the agar. Boiled in one dish. Unboiled in the other.
- Store Petri dishes in incubator for 2 days at 20°
- Test both using iodine solution.
What are the results after an iodine test?
Starch turn blue black
Where there is no starch it is clear
What are the results of the digestion test?
Unboiled seed is negative for starch - it digested it
Boiled seed is positive for starch
What materials are needed for the experiment that investigates water, oxygen and temp effect on germination?
Broad beans Distilled water Anaerobic kit 4 Petri dishes Thermometers Fridge Cotton wool
In the oxygen, water, temperature test what should each Petri dish consist of?
- Cotton wool, water, seeds, incubate, anaerobic producing chemical in an anaerobic jar
- Cotton wool, water, seeds, fridge, has oxygen
- Cotton wool, water, seeds, incubator, oxygen
- Cotton wool, seeds, incubator, oxygen
What is the results of the water, oxygen temperature test?
The only seeds that germinated are the ones in the dish with cotton wool, water, oxygen, incubator
Appearance of plumule and radicle
