The ability to replace the wildtype alleles with a knockout allele in mice has enabled researchers to carry out important reverse genetics studies on gene function. Please select all of the statements below which correctly describe the creation of gene knockout mice. Multiple answers are possible, and partial credit will be given.

A. Homologous recombinants of the knockout alleles are desired since they will replace the wildtype allele.

B. Resistance to the anti-viral drug ganciclovir indicates that homologous recombination has occured.

C. The embryonic stem cells carrying homologous recombinants of the knockout allele are placed back into a blastocyst and injected into a surrogate mother to produce mice carrying the knockout allele.

D. Illegitimate recombinants have the knockout allele randomly inserted and do not replace the wildtype alleles and may potentially insert into other genes and confound the analysis.

E. Resistance to neomycin indicates insertion of the knockout allele but does not distinguish between homologous and non-homologous recombinants.

a.) a destruction fo cells by viral reproduction

the element that provides strength to the exoskeletons of clams and oysters is phosphorus.

this is so because calcium carbonate is the main component in the shells. calcium carbonate is strengthened by phosphorus.

explanation:

answer and explanation;

volcanic rocks are igneous rocks which form from lava, molten rock which has been thrust out of a volcano onto the surface of a rocky body such as an asteroid, planet, or dwarf planet.  

plutonic rocks are igneous rocks which form from subterranean chambers of molten rock or magma. plutonic rocks make up the base of continental crust as well as oceanic crust. their slow rate of formation causes them to be coarse grained since there is plenty of time for large crystals to form before the magma solidifies into rock.

the textural difference is that plutonic rocks are more coarse grained than volcanic rocks. plutonic rocks are coarse grained while volcanic are fine grained ; glassey or fragmental. since fine and coarse are adjectives the decision as to whether a rock is fine or coarse grained is generally made on the bases of whether or not the individual crystals can be seen in most if the rock.