Why are some of the geological time periods not represented in the strata forming the grand canyon? a. the age of some of the grand canyon's layers is unknown. b. unconformities resulted in the erosion of some representative layers. c. during certain times of earth's past, sedimentary layers were not forming. d. most of the grand canyon's layers are made of igneous and metamorphic rocks.  is the answer b?

Use the above pedigree for questions 1,2, and 3 1. what kind of genetic disorder is represented in the pedigree? a. recessive b. dominate refer to the pedigree in question 1. 2. is the mutated gene in this disorder located on a sex chromosome (x or y) or an autosome? a. sex chromosome b. autosome refer to the pedigree in question 1. 3. which generation has individuals that you are certain are heterozygous for the mutated gene? a. generation 1 b. generation 2 c. generation 3