Question

In the XX/XO form of sex determination, sex is determined by the presence or absence of a chromosome, whereas in the XX/XY scheme, the Y chromosome may be sex determining. In some cases, however, the autosomes play a role in sex determination. The Protenor form of sex determination involves the XX/XO condition, whereas the Lygaeus mode involves the XX/XY condition.

Answer 1

Sex determination in dioecious organisms is often achieved through various sex chromosome systems such as XX/XO and XX/XY, with examples including the Protenor and Lygaeus modes, respectively.

Step-by-step explanation:

In dioecious organisms, sex determination can vary, and it's often regulated by sex chromosomes. The XX/XO system, such as in the Protenor mode, determines sex by the presence or absence of the Y chromosome, which is sex-determining in the XX/XY system, seen in the Lygaeus mode. In the latter, females are homozygous XX and males heterozygous XY.

Birds, however, follow a different scheme, where females are heterozygous ZW and males homozygous ZZ. This chromosomal basis for sex determination is crucial for understanding patterns of inheritance, including sex-linked traits, which are associated with genes found on sex chromosomes. For instance, color blindness is often cited as an example of an X-linked trait in humans.