Why are plasmids so widely used in recombinant dna studies?

a. because they naturally contain much foreign dna
b. because they can be used to transform bacteria
c. because it is difficult to insert new genes into them
d. because they cannot be cut with restriction enzymes

sand 60

clay 10

silt 30

sandy loam should be dominated by the sand. as the amount of sand increased, the amount of slit needed to anchor the plants' roots to the sand will also be increased. even though the amount is very little, 10% part of clay is still necessary for proper oxidation.