CBSE 2023 · Region 3 · Set 1 · Q32 · 5 marks
Protein synthesis requires the services of all three types of RNAs, namely t-RNA, m-RNA and r-RNA. Explain the role of each of them during the process of protein synthesis in prokaryotes.A homozygous tall pea plant with green seeds is crossed with a homozygous dwarf pea plant with yellow seeds.(i)Write the possible phenotype and genotype of $\displaystyle \mathrm{F}_{1}$ generation.(ii)State the laws of Mendel that are proved true by the $\displaystyle \mathrm{F}_{1}$ generation.(iii)Mention the $\displaystyle \mathrm{F}_{2}$ phenotypic ratio along with their possible phenotypes.(iv)Write the genotypes of the male and female gametes produced by $\displaystyle \mathrm{F}_{1}$ progeny.
Protein synthesis requires the services of all three types of RNAs, namely t-RNA, m-RNA and r-RNA. Explain the role of each of them during the process of protein synthesis in prokaryotes.
A homozygous tall pea plant with green seeds is crossed with a homozygous dwarf pea plant with yellow seeds.
(i)
Write the possible phenotype and genotype of $\displaystyle \mathrm{F}_{1}$ generation.
(ii)
State the laws of Mendel that are proved true by the $\displaystyle \mathrm{F}_{1}$ generation.
(iii)
Mention the $\displaystyle \mathrm{F}_{2}$ phenotypic ratio along with their possible phenotypes.
(iv)
Write the genotypes of the male and female gametes produced by $\displaystyle \mathrm{F}_{1}$ progeny.
Marking-scheme solution
tRNA - Act as adaptor molecule, with amino acid binding site and anticodon loop, brings specific amino acid to the amino acid binding site on the ribosome, initiator t-RNA starts the process of translation.
mRNA- Act as a template for protein synthesis, carries information in the form of codon, It has the initiator codon /start codon /AUG to initiate the process, it has the stop codon/UAA/UAG/UGA for termination of the protein synthesis rRNA- rRNA organizes itself into ribosomes, there are two sites in the large subunit in which one site is for binding the incoming t-RNA with the corresponding amino acid second site for peptide bond formation, when the small subunit of rRNA (ribosomes) encounters the mRNA the process of translation begins, ribosome also acts as a catalyst for the formation of peptide bond.
(b)
Phenotype – Tall plant with Yellow seeds
Genotype – TtYy
(ii)
Law of Dominance: Out of two contrasting traits only one trait will appear in F1 generation and is called dominant trait while the one which remain unexpressed is called recessive trait.
Law of segregation: In a hybrid union trait simply remain together and segregate at the time of gamete formation.
(iii)
Phenotypic ratio of F2
Tall yellow : Tall green : Dwarf yellow : Dwarf green
$\displaystyle 9$ : $\displaystyle 3$ : $\displaystyle 3$ : $\displaystyle 1$
(iv)
Male gametes of F1 - TY Ty tY ty
Female gametes of F1 - TY Ty tY ty
Molecular Basis of InheritanceTranslationUnderstandlong_answermedium
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CBSE Class 12 Biology past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.