Sexual reproduction increase genetic variation in offspring. Which in turn increase the genetic variability in species. You can see the effects of this genetic variability if you look at the children in a large familyand note how each person in unique you know ( not to mention, all the families of all the sexually reproducing organisms on earth ). And you begin to get a feel for dramatic genetic impact of sexual reproduction.
MUTATION
DNA polymerase occasionally makes uncorrected mistakes when copying a cell's genetic information during DNA replication. These mistakes are called spontaneous mutations and they introduce changes into genetic code.
CROSSING - OVER
When homologous chromosomes come together prophase I of meiosis, they exchange bits of DNA with each other. This crossing over result in new gene combination and new changes for variety.
Independent assorment occurd when homologous chromosomes separate during anaphase I of meiosis.
FERTILIZATION
Fertilization presents yet another opportunity for genetic diversity. Imagine millions of genetically different sperm swimming toward an egg.
NONDISJUNCTION
Nothing's perfect, even in the cellular world, which is why sometimes meiosis doesn't separate the way they're supposed to, that's called nondisjunction.
Ever wish you could've been born the opposite sex so you wouldn't have to spend so much of your budget on make up or shave your face everyday every morning?
Sorry, but that was never really your decision to make, like all others genetic characters, gender is determined at chromosomal leverl
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