Question

Which one of the following would represent allotetraploid?
A)AAABB
B)AAAA
C)AABB
D)BBBB

Answer 1

Hint: Allotetraploid is a hybrid. It occurs when a polyploid offspring is obtained from two distinct maternal and paternal species. It possesses four times of chromosomes that are present in haploid organisms.

Complete answer:
Ploidy is the number of complete sets of chromosomes in an individual. The diploid means the species having two sets of chromosomes that are inherited from each parent. Haploid means the number of chromosomes is halved. The gametes are haploid.
A condition in which the organism has more than two paired homologous chromosomes is called polyploidy. Polyploidy is of two types-
Autopolyploid – it occurs when the offspring is obtained from a single parental species. The chromosome set can be represented as AAAA, BBBB.
Polyploidy- When the offspring is obtained from two distinct parental species.

Allotetraploid is a hybrid in which 4 sets of chromosomes are present than that of haploid organisms. The representation of the genome is AABB. The Brassica species or mustard has allotetraploid set of chromosomes where 4X=38

AABB is called Allopolyploid as it has five sets of chromosomes obtained from two different parental species.

Hence, the correct answer is option (C)

Note: Abnormal cell division in mitosis or meiosis leads to polyploidy. It is more common in plants than in animals. Polyploidy can also be induced through the chemicals like colchicine, oryzalin. The polyploids with odd numbers of chromosomes like 3n, 5n are sterile. The polyploidy occurs in highly differentiated human tissues like heart, bone marrow, placenta.