Crosses between two tailless mice produces tailless and wild-type offspring in a 2: 1 ratio. tailless mice crossed with wild-type mice produce a 1: 1 ratio of tailless to wild-type progeny. what is the best explanation?

In first generation one allele pair with an offspring  is lethal, hence the phenotypic ration is 2:1

Explanation:

Let the allele representing the  tailless trait with in mice be "t"

the allele representing the wild-type offspring  trait with in mice be "t+"

Generation I

Genotype of tailless mice is "tt+"

Cross between two tailless mice will produce following offspring

tt+ * tt+

tt, tt+, tt+, t+t+

Out of four offspring, the one with genotype "tt" is lethal, thus ration of tailless and wild-type offspring is

2:1

Generation I

Genotype of tailless mice is "tt+"

Genotype of wild-type offspring  is "t+t+"

Tailless mice crossed with wild-type mice produce-

tt+ * t+t+

tt+, tt+, t+t+,  t+t+

Ratio of tailless to wild-type progeny is

2:2

1:1

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

if you add everything up correctly you should get 69 i got this because 50 plus 19 is it