2. Mutation and sexual reproduction lead to genetic variation in a population. As a
basis for understanding this concept:
a. Students know meiosis is an early step in sexual reproduction in which the pairs
of chromosomes separate and segregate randomly during cell division to pro
duce gametes containing one chromosome of each type.
b. Students know only certain cells in a multicellular organism undergo meiosis.
c. Students know how random chromosome segregation explains the probability
that a particular allele will be in a gamete.
d. Students know new combinations of alleles may be generated in a zygote through
the fusion of male and female gametes (fertilization).
e. Students know why approximately half of an individual’s DNA sequence comes
from each parent.
f. Students know the role of chromosomes in determining an individual’s sex.
g. Students know how to predict possible combinations of alleles in a zygote from
the genetic makeup of the parents.
3. A multicellular organism develops from a single zygote, and its phenotype depends
on its genotype, which is established at fertilization. As a basis for understanding
a. Students know how to predict the probable outcome of phenotypes in a genetic
cross from the genotypes of the parents and mode of inheritance (autosomal or
X-linked, dominant or recessive).
b. Students know the genetic basis for Mendel’s laws of segregation and indepen
c.* Students know how to predict the probable mode of inheritance from a pedigree
diagram showing phenotypes.