CBSE 2024 · Region 5 · Set 3 · Q33 · 5 marks
Work out a dihybrid cross upto $\displaystyle \mathrm{F}_{2}$ generation between pea plants bearing violet coloured axial flowers and white coloured terminal flowers using Punnet's square. Give their $\displaystyle \mathrm{F}_{2}$ phenotypic ratio. State the Mendel's law of inheritance that was derived from such a cross.Explain the process of transcription in prokaryotes. How is it different from transcription in eukaryotes ?
Work out a dihybrid cross upto $\displaystyle \mathrm{F}_{2}$ generation between pea plants bearing violet coloured axial flowers and white coloured terminal flowers using Punnet's square. Give their $\displaystyle \mathrm{F}_{2}$ phenotypic ratio. State the Mendel's law of inheritance that was derived from such a cross.
Explain the process of transcription in prokaryotes. How is it different from transcription in eukaryotes ?
Marking-scheme solution
Violet and axial : Violet and terminal : White and axial : White and terminal
$\displaystyle 9$ : $\displaystyle 3$ : $\displaystyle 3$ : $\displaystyle 1$
Mendel’s Law of Independent Assortment, when two pairs of traits are combined in a hybrid segregation of one pair of character is independent of the other pair of characters.
DNA dependent RNA polymerase binds to promoter and initiate transcription on a DNA template, it uses nucleoside tri-phosphate as a substrate and polymerizes in a template dependent fashion following the rule of complementarity, RNA polymerase associates with the initiation/sigma/σ factor(transiently), facilitate opening of the helix, and continue elongation, once the polymerase reaches terminator region, it binds to rho/ρ/termination factor and the nascent RNA falls off, RNA polymerase also falls off once the termination is over.
Transcription
in
Prokaryotes
Transcription
in
Eukaryotes
One type of RNA
polymerase
catalyses
transcription of all $\displaystyle 3$
types of RNA.
Three different RNA
polymerases
are
required for different
$\displaystyle 3$ types of RNA
(RNA
Polymerase–I
rRNA
RNA
Polymerase–II
mRNA
RNA
Polymerase–III
tRNA)
No splicing required
as only exons are
present
splicing is required as
both
introns
and
exons are present
No
processing
of
RNA is required as
hnRNA
is
not
formed
Processing
(capping,
tailing and splicing)
required as hnRNA is
initially formed
It occurs in cytoplasm
of the cell
It occurs in nucleus of
the cell
Principles of Inheritance and VariationInheritance of Two GenesApplylong_answermedium
Practice Principles of Inheritance and Variation →All Principles of Inheritance and Variation questions
More from Principles of Inheritance and Variation
- Using a Punnett square workout the distribution of an autosomal phenotypic feature in the first filial…2025 · asked 3×
- By using Punnett square depict the genotypes and phenotypes of test crosses (where green pod colour (G) is…2023 · asked 3×
- Assertion: In dihybrid crosses involving sex-linked genes in Drosophila generation of non-parental gene…2025 · asked 3×
- The following pedigree chart shows the inheritance of a genetic disorder up to three generations of a family.…2023 · asked 3×
- Write the types and locations of the genes causing thalassemia in humans. State the cause and symptoms of the…2026 · asked 3×
- A person with trisomy of 21^ st chromosome shows (i) Furrowed tongue (ii) Characteristic palm crease (iii)…2024 · asked 3×
- The chromosome number is fixed for all normal organisms leading to species specification whereas any…2023 · asked 3×
- A student performed some crosses in plants and represented the result in the form of bar graphs as shown…2026 · asked 3×
CBSE Class 12 Biology past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.