Summary Matric IEB reproduction in flowering plants

REPRODUCTION
Theabilityoforganismstoproduceanewgenerationofthemselves
newindividualsareproducedfromanalreadyexistingindividual

Duringreproduction anorganism'sgenesare transferred tothe nextgeneration
EXTREMELYIMPORTANT Plantsdiefromold
agedisease beingeaten
newplants needtoreplacethosethatdie
Twotypes
ASEXUAL
productionof anewgenerationof thesamespecies
byoneparent
Theoffspringhavethesamegeneticcompositionastheparent eachother
nogametesinvolved newgenerationisproducedbymitosis
Advantages
1 allindividualscanproduceoffspring
2 noenergyexpenditureofenergydon'thavetoproducegametes findamate
3simple fastprocess onlyinvolvesmitosis
4usefulinstableconditions iftheparentiswelladaptedto aparticularenvironmentthegeneticallyidentical
offspringwillalsobeadapted
5 Favourablemutationscanspreadrapidly allowspopulation toadaptquicklyto newenvironmentalconditions
egresistancetoantibiotics
Disadvantages
1Novariation becausethereisnorecombinationofalleles unlessthereis amutation
alloffspringinheritthesame traits
unfavourable
population
may beunabletoadapttonewenvironmentalconditions
food
2 overcrowding shortsupplyofresourceseg


SEXUAL
Productionof anewgeneration of thesamespecies
bybringingtogetherthegeneticmaterial of
twoparents
offspringarenotidenticaltoeachother eitheroftheparents
gametesareformedbymeiosis
fertilisation fusionofthemale femalegametes producesazygote

, Advantages
basisofevolution
1 Resultsingeneticvariation
2 offspringmaybeabletoadaptinunstableenvironment betterchanceofsurvival
3Maypreventspreadofdisease offspringcanbegeneticallyresistant
4Mayreducechanceofinheritingadiseasefromaparent
Disadvantages
1 Highexpenditureofenergy
2 Feweroffspringproduced decreasechanceof populationsurviving
3 Reproductionprocessisslower timeneededforgameteproduction findingamateandfusionofgametes
4unfavourablemutationsmightbeexpressedinoffspring
5outsideagentsmaybeneededinplantstocarrypollen seeds




Thediploidparentsproducegametes sexcells bymeiosis
gametesarehaploid containhalf n thenumberof chromosomes

Themale femalegametes are broughttogether pollinationinplants matinginanimals
by
ptrocess
Thegametenucleifuse isknownas fertilisation
diploid
Thenewcelliscalled a zygote becauseit hastwosets 2n ofchromosomes

mitotic
Thezygotedividesby celldivisionintoanewindividual


Gametes

Plants Animals
Femalelargenotmotile ovuminanembryosac ovum
malesmallmotile Nucleusin apollen sperm
grain