Question

1. If the chromosome constitution of a diploid individual with four pairs of chromosomes is specified as AA BB CC DD, what names are used to describe individuals with the following chromosome constitutions:
   

1. A B C D
2. AA BB CC D
3. AA BB CC DDD
4. AAA BBB CCC DDD
5. AAAA BBBB CCCC DDDD
6. AAaa BBbb CCcc DDdd (where lower case letters indicate origin from another species)

Answer 1

In diploid, there are two copies of each chromosome.

a) A B C D- there are only one copy of each chromosome, so it is haploid.

b) AA BB CC D- there is only one copy of chromosome D- Monosomy of chromosome D

AA BB CC DDD- there are three copies of chromosome D- trisomy of chromosome D

( changes in the chromosome number is called aneuploidy, monosomy-there is only one copy of the chromosome, trisomy-there are three copies of a chromosome, nullisomy-there are no copies of the chromosome)

AAA BBB CCC DDD- there are three copies of each chromosome- Triploid.

AAAA BBBB CCCC DDDD- there are four copies of each chromosome- tetraploid.

AAaa BBbb CCcc DDdd (where lower case letters indicate origin from another species)- there are 2 sets of chromosomes from two different species, so this an allopolyploid,( alloploid has chromosomes from different species) and there atr total of four sets of chromosomes, so this is allotetraploid.