Explanation:
<h2>Chemicals can be toxic because they can harm us when they enter or contact the body. Exposure to a toxic substance such as gasoline can affect your health. Since drinking gasoline can cause burns, vomiting, diarrhea and, in very large amounts, drowsiness or death, it is toxic.</h2>
1) As blood groups A and B are equally dominant so the individual will express both characteristics in the phenotype.
Notice how in all the 3 other examples the organism is only expensive 1 version (allele) of each gene. For example the mouse with brown fur may have 2 brown fur alleles (and so would have to express this characteristic even if it was recessive) but it could have 1 allele which is less dominant than the brown, in which case brown would be expressed. In this case the alleles were not co-dominant.
Each person carries 23 pairs of chromosomes in every cell that makes up their body, with the exception of gametes, which contain 23 SINGLE chromosomes. So when a sperm and egg meet, they then have 23 pairs. In the process of meiosis 'crossing-over' occurs, which means that the chromosomes get "shuffled". This means that the child can receive random traits not only from the parents, but also the grandparents. so there is about 2⁴⁶ possible pairings, excluding the risk for things such as Down-Syndrome
By studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth. There are gaps in the fossil record because many early forms of life were soft-bodied, which means that they have left few traces behind. This is why scientists cannot be certain about how life began.
