Answer
363k+ views
Hint: As we can see in the question, it is a monohybrid cross (when inheritance of only one character is observed). To find the ratio of \[{F_2}\] generation, first we need to cross TT $ \times $ tt and then self-cross of the hybrid of \[{F_1}\] generation to get the progenies of \[{F_2}\] generation. A pure tall plant means its allele should be genotypically homozygous, i.e., TT.
Complete answer:
Mendel has chosen as pairs \[14\] true pea varieties. One of them is the height of the plant recognized with the allele ‘T’ that represents the dominant condition ‘tall’ and the allele ‘t’ which is ‘dwarf’ and recessive.
Monohybrid phenotypic ratio- \[Tall:{\text{ }}Dwarf\]= \[\;3:{\text{ }}1\]
Monohybrid genotypic ratio –\[\;TT:{\text{ }}Tt:{\text{ }}tt\]= \[1:{\text{ }}2:{\text{ }}1\]
Hence, A pure large plant with a pure, short plant is crossed (tt). In generation \[F2\]the ratio of pure large plants to pure short plants is \[TT:{\text{ }}tt{\text{ }} = {\text{ }}1:1\].
Note:
The ratio of tall: dwarf plants would be\[3:{\text{ }}1\]. But here, in the question it has been asked to find the ratio of pure tall and pure dwarf plants. Out of these \[3\]tall plants, only one is pure homozygous (TT) tall and the other two are heterozygous (Tt) tall. So, the actual genotypic ratio is\[TT:{\text{ }}Tt:{\text{ }}tt{\text{ }}-{\text{ }}1:2:1\].
Additional Information:
Mendel laws:
Law of Dominance: It says that a dominant allele shows its effect in \[{F_1}\]generation in heterozygous condition and recessive allele fails to express itself in presence of dominant allele. It has exceptions of non-mendelian inheritances like codominance, incomplete dominance, etc.
Law of Segregation/ Law of Purity of gametes: According to this law, the alleles present in \[{F_1}\]generation segregate at the time of gamete formation, therefore gametes are pure for a particular trait. This law has no exception.
Law of Independent Assortment: This law cannot be seen in a monohybrid cross. The law states that when two pairs of hybrid features are combined, one pair is separated from another. Exception, connection.
DIHYBRID CROSS
Phenotypic ratio: Round Yellow: Round green: wrinkled Yellow: wrinkled green
(R Y) : (R_yy) : (rrY) : (rryy)-
Nine : Three : Three : One
Genotypic ratio: RRYY: RRYy: RrYY: RrYy: RRyy: Rryy: rrYY: rrYy: rryy-
One : Two : Two : Four : One : Two : One : Two : One
Complete answer:
Mendel has chosen as pairs \[14\] true pea varieties. One of them is the height of the plant recognized with the allele ‘T’ that represents the dominant condition ‘tall’ and the allele ‘t’ which is ‘dwarf’ and recessive.
![seo images](https://www.vedantu.com/question-sets/0090210c-d179-4ca3-bade-ac4af51520034870061877517161313.png)
Monohybrid phenotypic ratio- \[Tall:{\text{ }}Dwarf\]= \[\;3:{\text{ }}1\]
Monohybrid genotypic ratio –\[\;TT:{\text{ }}Tt:{\text{ }}tt\]= \[1:{\text{ }}2:{\text{ }}1\]
Hence, A pure large plant with a pure, short plant is crossed (tt). In generation \[F2\]the ratio of pure large plants to pure short plants is \[TT:{\text{ }}tt{\text{ }} = {\text{ }}1:1\].
Note:
The ratio of tall: dwarf plants would be\[3:{\text{ }}1\]. But here, in the question it has been asked to find the ratio of pure tall and pure dwarf plants. Out of these \[3\]tall plants, only one is pure homozygous (TT) tall and the other two are heterozygous (Tt) tall. So, the actual genotypic ratio is\[TT:{\text{ }}Tt:{\text{ }}tt{\text{ }}-{\text{ }}1:2:1\].
Additional Information:
Mendel laws:
Law of Dominance: It says that a dominant allele shows its effect in \[{F_1}\]generation in heterozygous condition and recessive allele fails to express itself in presence of dominant allele. It has exceptions of non-mendelian inheritances like codominance, incomplete dominance, etc.
Law of Segregation/ Law of Purity of gametes: According to this law, the alleles present in \[{F_1}\]generation segregate at the time of gamete formation, therefore gametes are pure for a particular trait. This law has no exception.
Law of Independent Assortment: This law cannot be seen in a monohybrid cross. The law states that when two pairs of hybrid features are combined, one pair is separated from another. Exception, connection.
DIHYBRID CROSS
![seo images](https://www.vedantu.com/question-sets/2d4012ea-ef97-4089-a004-e80706c790fb596156021576950759.png)
Phenotypic ratio: Round Yellow: Round green: wrinkled Yellow: wrinkled green
(R Y) : (R_yy) : (rrY) : (rryy)-
Nine : Three : Three : One
Genotypic ratio: RRYY: RRYy: RrYY: RrYy: RRyy: Rryy: rrYY: rrYy: rryy-
One : Two : Two : Four : One : Two : One : Two : One
Recently Updated Pages
Mark and label the given geoinformation on the outline class 11 social science CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
When people say No pun intended what does that mea class 8 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Name the states which share their boundary with Indias class 9 social science CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Give an account of the Northern Plains of India class 9 social science CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Change the following sentences into negative and interrogative class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Advantages and disadvantages of science
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Trending doubts
Bimbisara was the founder of dynasty A Nanda B Haryanka class 6 social science CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Which are the Top 10 Largest Countries of the World?
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
10 examples of evaporation in daily life with explanations
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Give 10 examples for herbs , shrubs , climbers , creepers
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
How do you graph the function fx 4x class 9 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference Between Plant Cell and Animal Cell
![arrow-right](/cdn/images/seo-templates/arrow-right.png)