Crossing over at chiasmata exchanges DNA between non-sister chromatids. Random orientation of bivalents and fertilization also create new allele combinations.
Genetic information controls the production of all proteins needed by the body to carry out its functions, including proteins acting as enzymes and hormones as well as proteins for structures and transport.
Explain the stages and processes of meiosis leading to genetic variation.
| a | meiosis divides a diploid nucleus to produce (4) haploid nuclei; |
| b | meiosis halves the chromosome number; |
| c | chromosomes consist of two sister chromatids at the start of meiosis; |
| d | homologous chromosomes are paired; |
| e | crossing over occurs between homologous chromosomes; |
| f | crossing over promotes genetic variation/new gene/allele combinations; |
| g | pairs of homologous chromosomes are randomly oriented/assorted in the first division of meiosis OR sister chromatids are randomly assorted during the second division of meiosis; |
| h | in the first division of meiosis pairs of homologous chromosomes are separated; |
| i | random orientation promotes genetic variation/new gene/allele/chromosome combinations; |
| j | meiosis produces haploid gametes (to ensure offspring have complete set of chromosomes); |
| k | fusion of gametes from different parents promotes (genetic) variation; |
Drawings which are annotated to explain are acceptable.