IGCSE›Cambridge IGCSE Biology›Mind mapsSexual ReproductionCambridge IGCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhat is it?Fusion of the nuclei of two gametesForms a zygoteOffspring are genetically differentGametes are haploid, zygote is diploidAdvantagesProduces genetic variationHelps survival if environment or disease changesNew trait combinations can be bred into cropsDisadvantagesSlower than asexual reproductionNeeds two parentsCan break up gene combinations that worked wellSexualreproductionIn plantsPollination: anther to stigmaCross-pollination: a different plant, same speciesPollen tube carries male nucleus to ovuleSeeds need water, oxygen, suitable temperatureIn humansSperm: flagellum, mitochondria, acrosome enzymesEgg: energy stores and jelly coatEgg is larger, non-motile, made in small numbersPlacenta exchanges nutrients and gases with fetusFSH, LH, oestrogen, progesterone control menstrual cycleExam tipsFertilisation is fusion of nucleiWind-pollinated flowers: feathery stigmas, light pollenInsect-pollinated: bright petals, sticky pollen