When the atlantic ocean opened during the middle mesozoic era around 144 million years ago, the differences between the species living on opposite shores gradually the greater the distance, the the number of characteristics in common. plate activity resulting in continental drift forced diversification of life.

In which situations is the principle of cross-cutting relationship useful in determining relative age?

Coat color in cats is determined by genes at several different loci. at one locus on the x chromosome, one allele (x ) encodes black fur and another allele (xo) encodes orange fur. females can be black (x x ), orange (xoxo), or a mixture of orange and black called tortoiseshell (x xo). males are either black (x y) or orange (xoy). bill has a female tortoiseshell cat named patches. one night, patches escapes from bill\'s house, spends the night out, and mates with a stray male. patches later gives birth to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. what are the genotypes of patches, the stray male, and the kittens?

If an organ has six haploid chromosomes, how many chromosomes are present. 6 12