What is a double cross in genetics?

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. in some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. if these resistant individuals continue to survive and prosper, new resistant populations might emerge. this would be an example of the founder effect artificial selection genetic drift natural selection sexual selection

Iguanas need to live in a habitat that is very warm, so the pet store warms their enclosures with "basking lights" which act as an artificial sun. describe how the three methods of thermal energy transfer may take place within the iguana's enclosure.

Read the article and use the information to answer the questions that follow discovering the structure of dna explain how the discoveries by rosalind franklin watson and crick build an accurate model of dna done