Question

When a plant with \[6\] feet height was crossed with a plant with \[4\] feet height, then plants \[5\] feet height was obtained. When it is selfing \[1/256\] plants having \[4\] feet height and \[1/256\] plants having, \[6\] feet height was obtained. Find out how many polygenes are controlling inheritance?
(1) \[4\]
(2) \[3\]
(3) \[2\]
(4) \[6\]

Answer 1

Hint: Polygenic inheritance occurs once, where one characteristic is controlled by \[2\] or additional genes. Usually, the genes are large in amount. Examples of human heritable inheritance are height, skin colour, eye colour and weight. Polygenes exist in alternative organisms as well.

Complete answer: A monohybrid cross is a cross between \[2\] organisms with completely different variations at one genetic body of interest. The character (s) being studied during the cross are ruled by \[2\] or multiple variations for one locus. To hold out such a cross, every parent is chosen to be homozygous or true breeding for a given attribute (locus). Once the cross satisfies conditions, it is sometimes detected by a characteristic distribution of second-generation (F2) offspring that are typically known as the crossbreed ratio. For a monohybrid cross;
We know that, if we take \[2\] parents and perform selfing between them, we get \[4\] gametes
Similarly, if we perform selfing between \[4\] gametes, then we get 16 gametes and so on.
It follows the rules of \[{2^n}\] to get the total number of gametes, where ‘n’ is the parent which takes into consideration.
So, for \[256\]gametes, we have to take 16 parents first then undergo selfing;
So, for \[16\] parents \[{2^n}\]= \[16\]
So n=\[4\]
Hence, the correct answer is option A.

Note: Usually, traits are inheritable once there is a wide variation within the trait. For example, humans are of many alternative sizes. Height could be an inheritable trait, controlled by a minimum of 3 genes with six alleles. If you're dominant for all of the alleles for height, then you'll be tall.