SOLVED

160. Blood type is a good example of a sex-linked trait, which means that certain blood types are more common in males than in females. 161. Sometimes in the process of meiosis genetic material crosses over from one allele in a chromosome to another. This process results in unique new recombinant alleles. 162 Because there are so many possibilities for how genes can combine in the process of human reproduction, two human parents theoretically could produce hundreds of trillions of genetically unique children. 163. Although it was earlier thought that cell mutations were quite rare, more recent research has found that they actually occur quite frequently. 164. It is true that genetic forces sometimes cause people to seek out certain types of environmental situations. 165. The idea that nongenetic factors can influence how genes behave is referred to as “polygenic” influences. 166. Each year in the United States congenital anomalies (or birth defects) affect between 10% and 15% of all births. 167. Sex-linked traits occur when the autosomes do not replicate correctly. 168.  Hemophilia and color blindness are examples of abnormalities associated with genes on the sex chromosomes. 169. Because the genes that code for Fragile X disorder are on the X chromosome, females are affected much more often and more seriously than males.