Use meiosis, gamete fusion, ploidy and DNA-content evidence to explain how sexual life cycles maintain chromosome number and generate variation in IB Biology HL D3.1.2.
Members of a species typically all have the same number of chromosomes.
Explain the need for both fusion of gametes and meiosis in a sexual life cycle.
a. meiosis halves the chromosome number / allows production of haploid gametes/cells;
b. fusion of gametes/fertilization doubles (the chromosome number) / n+n=2;
c. meiosis prevents chromosome number doubling/conserves the chromosome number (between generations);
d. fusion of gametes brings together genes/alleles/chromosomes from two parents;
e. meiosis breaks up combinations of alleles/genes / segregation of alleles
OR
meiosis generates variation by independent assortment/crossing over;
f. fusion of gametes/fertilization/meiosis produces variation needed for natural selection/evolution/resilience/survivability/OWTTE;
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