In corn, the allele A allows the deposition of anthocyanin (blue) pigment in the kernels (seeds), while aa plants have yellow kernels. At a second gene, W– produces smooth kernels, while ww kernels are wrinkled. A plant with blue smooth kernels was crossed to a plant with yellow wrinkled kernels. The progeny consisted of 1447 blue smooth, 169 blue wrinkled, 186 yellow smooth, and 1510 yellow wrinkled.

a. Are the a and w loci linked? If so, how far apart are they?
b. What was the genotype of the blue smooth parent? Include the chromosome arrangement of alleles
c. If a plant grown from a blue wrinkled progeny seed is crossed to a plant grown from a yellow smooth F, seed, what kinds of kernels would be expected, and in what proportions?

Explanation:

As given,

Allele A for  blue anthocynin.

aa for yellow kernel;

at  second locus;

W produce smooth kernel,

ww for wrinkled kernel;

Parents as given are:  AaWw and aaww

Progeny are:

blue smooth ( AaWw)= 1447;

blue wrinkle (Aaww)= 169;

yellow smooth (aaWw)= 186;

yellow wirnked (aaww)= 1510

a)

Recombinant progeny are  169+ 186= 355

non- recombinant progeny are = 1447+ 1510= 2957

so recombination frequency (RF)= 346/2957×100= 12.0054%

So a and w are linked genes.

They are 12 mu far away from each other.

b) Blue smooth parent= AaWw.

c) Aaww crossed with  aaWw

progeny are= AaWw, Aaww, aaWw, aaww,

They all are produced in same proportion =0.25% or 1/4.

the answer is b.) hydrogen bonds between bases.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.