- Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16? a) Extra copies of the other somatic chromosomes are probably fatal. b) There are probably more genes on chromosome 21 than on either chromosomes 3 or 16. c) Nondisjunction of chromosomes 3 and 16 probably occurs more frequently. d) Down syndrome results in more serious symptoms than either trisomy 3 or trisomy 16.
- During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____. a) nondisjunction b) sticky chiasmata c) meiotic failure d) gametic infertility