Answer:
All of the above answer choices are correct.
Explanation:
Test cross is done to find out the genotype of an individual displaying dominant phenotype as it can be homozygous or heterozygous. To find this the individual is crossed with a recessive phenotype individual. For example: a dominant trait tall height can be homozygous TT or heterozygous Tt. If it is TT all the offspring of test cross with tt will be tall. If it is Tt half of the offspring will be tall and half of the offspring will be short.
Multiple offspring are required to come to the final result because offspring production happens in random order and it might take a few tries before another type of phenotype is produced. For example: If a test cross produces an individual with dominant phenotype we can still not surely say if the test individual is homozygous or heterozygous because both can produce dominant phenotype in test cross. We need more offspring to check if the recessive phenotype is produced or not and accordingly decide the genotype of test individual.
Hence all of the above answer choices are correct.
Hmm this is a rough explanations but because to be sure cells are made properly and not misfunctioning or going Rouge.
Cancer cells is an example of this, a cell goes rouge and starts doing it's function on it's own but outside of it's brother cells function slightly different turning into a growth or etc. The body thinks it is normal during the check body it's composed of the dna that passes this check.
viruses and other things don't pass this check and things like white blood cella come shut it down.
that's why doctors poison the area they find the cancer. to send white blood cells there to shut the area down not passing the check.
