Wheat varieties are usually purelines because Group of answer choices there is little available genetic variation in wheat germplasm breeders do not want farmers to save their own seed the potential for exploiting hybrid vigor in wheat is limited wheat is predominantly outcrossing

little available genetic variation

Potential for exploiting hybrid vigor in wheat is limited wheat is predominantly outcrossing

Explanation:

Pure lines are varieties with little genetic variation. Pure lines are generated from crops that have undergone selection to the point of uniformity this is done to reduce variation that may occur genetically and to get varieties that are the same genetically.

Pure lines are they are the same genetically with no segregating genes. variation or changes in pure lines is mostly associated with the environment. wheat is an outcrossing crop generating a pure line will help have good vigour as selection would have been done to generate varieties that are strong and high yielding.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.