If a lamb's chromosomes are XY, then it will be a male. True or False?

The statement is true because the XY sex-determination system is a common mechanism for determining male sex in mammals, including sheep. In this system, the presence of the Y chromosome typically indicates male characteristics, while two X chromosomes (XX) would indicate a female.

In the case of sheep and lambs, if the genetic makeup of a lamb is XY, it means that the lamb has inherited the Y chromosome from its sire (father) and an X chromosome from its dam (mother). This chromosomal arrangement generally leads to the development of male anatomical and physiological traits. Therefore, knowing that the lamb has XY chromosomes allows one to reliably conclude that it will be male, irrespective of breed or color variations.