Explain how meiosis maintains chromosome number and how gamete fusion combines parental genes in sexual life cycles for 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=2n;
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;