Reproduction and inheritance
Reproduction in plants
- Sexual vs asexualTwo parents or oneGametes fuse or notVariation or clones
- FertilisationGametes fuseZygoteEmbryo
- Flowers and pollinationInsect-pollinatedWind-pollinatedAnther to stigma
- Seed and fruit formationPollen tubeOvule to seedOvary to fruit
- GerminationWaterOxygenWarmthFood reserves
- Asexual reproductionRunnersCuttingsClones
Human reproduction
- Male systemTestesSperm ductProstate glandPenis
- Female systemOvaryOviductUterusCervix and vagina
- Menstrual cycleOestrogen repairs liningProgesterone maintains liningOvulation day 14
- FSH and LHBiology onlyFSH matures eggLH causes ovulation
- PlacentaDiffusion of nutrientsVilliUmbilical cord
- Amniotic fluidAbsorbs shocks
- PubertyOestrogenTestosteroneSecondary sexual characteristics
DNA and protein synthesis
- Genome: all the DNAentire DNA of organism
- Genesection of DNAcodes for a protein
- Chromosomes in nucleusgenes located on them
- DNA structureBiology onlydouble helixA–T and C–Gtwo strands
- RNABiology onlysingle strandeduracil replaces thymine
- TranscriptionBiology onlyin nucleusmakes mRNA
- TranslationBiology onlyat ribosometRNA anticodonsmRNA codonspolypeptide made
Inheritance
- Allelesalternative forms of gene
- Termsdominant, recessivehomozygous, heterozygousgenotype, phenotype
- CodominanceBiology onlyboth alleles expressedroan cattle
- Polygenic inheritancemany genese.g. height
- Monohybrid crossesPunnett square3 : 1 ratio
- Pedigrees and probabilitycarriers1 in 4 chance
- Sex determinationXX female, XY malesperm decides50% each
Cell division, variation and evolution
- Mitosistwo identical cellsdiploid, 46
- Uses of mitosisgrowthrepaircloningasexual reproduction
- Meiosisfour different cellshaploid, 23makes gametes
- Random fertilisationgenetic variation
- Variationgeneticenvironmentalor both
- Mutationrare, random changecan be inheritedsource of variation
- Mutation and phenotypeBiology onlychanges amino acid sequencemost: no effect
- MutagensBiology onlyionising radiationtobacco chemicals
- Natural selectionvariationsurvive and reproducealleles passed on
- Antibiotic resistancemutationselection pressurehard to control