Combustion engines became common in the mid-1800s when people began to use them to power ships, trains, and machinery in factories. Combustion engines add carbon dioxide to the air, and as a result, carbon dioxide in the atmosphere increased quickly. How did this change the total amount of energy in the Earth system, and how did this change happen? How did this affect global average temperature?

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?

What is used to keep track of the gamates and possible offsprings combination

Why has two different alleles for the same trait?