Sexual Reproduction In The Flowering Plant Flashcards
Sexual reproduction
Two parents involved…fusion of two sex cells
Gamete
Haploid cell capable of fusion
Advantages of sexual reproduction
Introduces variation in the in the offspring
What is variation
Differences in members of the same species
Name the features of the flowering plant and their purpose
Petal- brightly coloured to attract insects
Sepal- protects flower as a bud
Stalk
Receptacle
Carpel- female reproductive part
- stigma- entry point of pollen into carpel
-style- pollen grain enter to ovule through here
-ovary
stamen- male reproductive part
-Anter- pollen production
-filament-
Pollination
The transfer of pollen from the anter to the stigma of a flower from the same species.
Self pollination
Transfer of pollen from the anter to the stigma of the same plant
Cross pollination
Transfer of pollen from anter to stigma of a different plant from the same species
Give the features of a wind pollinated plant and give examples
Eg grasses
Small/absent petals
Pollen is small, light, dry and produced in large amounts
Angers are large and outside petals, long filaments
Stigmas are large and feathery increase surface area , outside petals
Give the features of a insect pollinated plant and give examples
Eg buttercups
Petals are large and brightly coloured, nectary present
Pollen is large, sticky, heavy and produced in small amounts
Antlers are small, inside petals
Stigmas are small, sticky and inside petals
2 ways a plant can be pollinated
Wind and insects
Describe the formation of the male gametes/ mature pollen grain
The microspore mother cell ( diploid) divides my meiosis to create 4 haploid cells clumped together ( tetrad).
Cells separate, they divide by mitosis to form 2 haploid nuclei ( generative nuclei and the tube nuclei) the generative nucleus divides by mitosis to form 2 male gametes, the tribe nucleus will go on to form the pollen tube
Describe the development of the embryo sec
Megastore mother cell ( diploid) divides by meiosis to form 4 haploid cells, 3 die /degenerate, the surviving cell divides by mitosis 3 times to form 8 haploid nuclei. 5 die and 3 haploid nuclei remain. 2 of these cells form 2 polar nuclei (n), the remaining cell forms the egg cell (2n)
Describe the process before fertilisation
The pollen grain lands on the sigma, the generative nucleus divides by mitosis to form 2 male gametes by hormones and enzymes ,the tube nucleus forms the pollen tube. The male gametes travel towards the pollen tube through the micropile ( opening) to enter the embryo sac.
What is double fertilisation and where does it occur
Occurs in the ovule - becoming enters sac
It is when one male gamete fuses (n)with the egg cell(n) to form the zygote(2n)
The other male gamete fuses with the 2 polar nuclei (n+n) to form the endosperm nucleus (3n)
What does the zygote go on to form
Zygote divides my mitosis to form the embryo which will develop the radical and the plumule
What is the purpose of the endosperm
Divides by mitosis to become a source of food for the developing embryo
Name the sources of food storage in a seed
Cotyledon, endosperm
What is the seed formed from?
Ovule
What is the testa formed from
Ovule wall/ integument
What is the fruit formed from
The ovary
What does the ovary wall form
Pericup
Name the two types of seed and give an example
Endospermic seed eg corn
Non endospermis seed eg broad bean
What is an endospermic seed
The endosperm remains as a food store
Usually monocot
What is a non endospermic sead
The endosperm is absorbed by the cotyledon
Usually dicot
What is a monocot seed
1 seed leaf
What is a dicot seed
Contains two seed leafs
List the features of a endospermic seed
Tests- seed coat
Endosperm,
Plumel , radical
Cotelydon
What will the radical go on to form
The future root
What will the plumel go to form
Future shoot
Name the types of fruit
Fleshy fruits
Dry fruit
false fruits- don’t develop form ovary
Seedless fruits
How are seedless fruits formed
Spray plants with growth regulators
Selective breeding
What is seed dispersal
Dispersal is when seeds are scattered away from the parent plant
Advantages of seed dispersal
Reduce competition , less overcrowding
Colonise new habitats
Methods of seed dispersal
Water eg coconut
Wind - dandelion ( wings, hairs)
Animal- tomato ( edible fruits w/seeds)
Self- eg poopy
What is Dormancy
A period of low metabolic activity when seeds do not germinate
Advantages or dormancy for the seed
Allows seeds to survive unfavourable conditions
Give time for embryo to develop
Allows time for seed dispersal
Reasons of dormancy
Testa is too tough for emerging embryo
Tests importable to water oxygen
Presence of growth inhibitors
Advantages for farmers of dormancy
Provides knowledge on how to store seed without germination occurring
Provides knowledge on to treat seeds before
Why does the embryo mass increase
The use of dissolved foods, the food reserves are digested and dissolved and transported to the embryo
Why does the endosperm mass fall
It’s being used up for food ( using up food store)
What is germination
The re growth of the embryo after a period of dormancy if conditions are suitable
What are the factors required for germination
Water- medium necessary for chemical reactions to occur/enzymes dissolve and transport digested biomolecules
Suitable temperature-optimum enzyme activity @ 27C
Oxygen -aerobic respiration
What occurrs during germination?
The water is absorbed and enzymes activated
Enzymes digests fats and starch and transported to the growing embryo
This provides energy and other resources used in respiration
The dry weight of the seed falls due to food being used in respiration, weight of embryo increases
Why is dry weight used
Water content varied between seeds so dry weight is more reliable ( bake in over)
Explain the process for the experiment of factors necessary for germination
Radish seeds in test tubes
Keep one dry
Keep one anaerobic( boiled water with a layer of oil on top
Keep one refrigerated
Keep one perfect( this one germinates as it has all the conditions for germination)
What is nutrient agar
A medium that contains all the food in a microorganism needs to grow
Describe method of showing starch is digested during germination
Soak broad beans overnight- softens tests and commences the germination process
Boil half of the seeds as control- denatures
Soak seeds and wash disinfectant to kill mo
Sterilise forceps under flame
Split each bean in half to separate cotyledons( ls) with a backed blade, place face down
Minimal opening( minimise contamination)
Incubate plated @ 27Cc for 72 hrs allow germination
Flood plated with iodine
Describe the results for showing starch is digested during germination.
Unboiled
Iodine remains brown under areas of bean( starch has been digested during germination)
Boiled( entire plate is blue black starch has not been digested by living seed during germination )
