The websites below allow students to explore the evidence for evolution:

Evidence for Evolution Web Quest

Evidence for Evolution Teacher Notes Page

California State Science Standards

A multi cellular organism develops from a single zygote, and its phenotype depends on its genotype, which is established at fertilization. As a basis for understanding this concept:

• 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).


• Students know the genetic basis for Mendel's laws of segregation and independent assortment.


• Students know how to predict the probable mode of inheritance from a pedigree diagram showing phenotypes.


• Students know how to use data on frequency of recombination at meiosis to estimate genetic distances between loci and to interpret genetic maps of chromosomes.

Genes are a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism. As a basis for understanding this concept:

• Students know how mutations in the DNA sequence of a gene may or may not affect the expression of the gene or the sequence of amino acids in an encoded protein.


• Students know specialization of cells in multi cellular organisms is usually due to different patterns of gene expression rather than to differences of the genes themselves.


• Students know proteins can differ from one another in the number and sequence of amino acids.

Evolution is the result of genetic changes that occur in constantly changing environments. As a basis for understanding this concept:

• Students know how natural selection determines the differential survival of groups of organisms.


• Students know a great diversity of species increases the chance that at least some organisms survive major changes in the environment.


• Students know how to use comparative embryology, DNA or protein sequence comparisons, and other independent sources of data to create a branching diagram (cladogram) that shows probable evolutionary relationships.

California State Science Standards

The Molecular Basis of Heredity

• In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular ''letters") and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.


• Most of the cells in a human contain two copies of each of 22 different chromosomes. In addition, there is a pair of chromosomes that determines sex: a female contains two X chromosomes and a male contains one X and one Y chromosome. Transmission of genetic information to offspring occurs through egg and sperm cells that contain only one representative from each chromosome pair. An egg and a sperm unite to form a new individual. The fact that the human body is formed from cells that contain two copies of each chromosome – and therefore two copies of each gene – explains many features of human heredity, such as how variations that are hidden in one generation can be expressed in the next.


• Changes in DNA (mutations) occur spontaneously at low rates. Some of these changes make no difference to the organism, whereas others can change cells and organisms. Only mutations in germ cells can create the variation that changes an organism's offspring.

Biological Evolution

• Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.


• The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.


• Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms.


• The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors.


• Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification.