Using lac operon in E. coli and albumin gene in humans, compare and contrast the regulatory mechanisms of gene expression at the transcriptional level in prokaryotes and eukaryotes. In humans, somatic cells contain identical genes with the identical genome sequence (assuming no mutations or chromosome abnormalities are introduced). Yet, the cells in the brain are structurally and functionally quite different from the cells in the skeletal muscle. The major reason for this is that the cells in different organs express different sets of genes, which is called differential gene expression. Discuss how the differential gene expression is possible when all somatic cells carry identical genes and genome.

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.

Which of the following explains why a tree is often used as a model to represent the principle of common descent

Which of the following observation darwin shape his concept of descent with modification? a) species diversity declines farther from the equator. b) fewer species live on islands than on the nearest continents. c) birds live on islands located farther from the mainland than the bird's maximum nonstop flight distance. d) south american temperate plants are more similar to the tropical plants of south america than to the temperate plants of europe. e) earthquakes reshape life by causing mass extinctions.