Question 14 - Case Based - CBSE Class 10 Sample Paper for 2022 Boards [Term 2] - Science Solution - Solutions to CBSE Sample Paper - Science Class 10

Sahil performed an experiment to study the inheritance pattern of genes. He crossed tall pea plants (TT) with short pea plants (tt) and obtained all tall plants in F1 generation.

a. What will be set of genes present in the F1 generation? 

Ans

In our case

Dominant trait is tallness which is represented by TT

Recessive trait is dwarfness wbich is represented by tt

On crossing of dominant trait with dwarf trait, following happens

TT* tt =Tt

hence, Genes present in F1 Generation is Tt

b. Give reason why only tall plants are observed in F1 progeny. 

According to Mendels Law of Monohybrid Inheritance and Law of Segregation

If single pair of contrasting characterstics were cross bred by self pollination

In F1 Generation, plants with dominant traits are produced

Dominant traits is tallness which are produced in our case in F1 Generation

c. When F1 plants were self - pollinated, a total of 800 plants were produced.

How many of these would be tall, medium height or short plants? Give the genotype of F 2 generation.

In F2 Genration, different traits are obtained in the ratio of 3:1

Hence out of 800 plants produced,600 will be tall plants and 200 will be dwarf plants

OR

When F1 plants were cross - pollinated with plants having tt genes, a total of 800 plants were produced. How many of these would be tall, medium height or short plants? Give the genotype of F2 generation.

Answer

We have learnt in Part A that

F1 Plants are represented by Tt

They are cross pollinated with plants having tt genes

Following happens

Hence, in this case , 2 Tt and 2 tt are produced

Ratio is 2"2=1"1

Hence out of 800 plants produced,

400 will be TT

400 wlll be Tt