the sarcomere shortens when the myosin heads of the thick filaments, in a cocked position, form cross bridges with the actin molecules in thin filaments. this activity will test your understanding of the steps that occur in one complete cross bridge cycle.

Which worm has eyespots that are used to detect light? a fluke b marine worm c planarian d tapeworm

The frequency of alleles in a population that is in hardy weinberg equilibrium? a . changes in each successive generation b. is less important than the frequency genotypes c. shows evidence of the process of natural selection d. remains the same over several generations

Which label correctly identifies what x represents in the concept map?