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Biology · 2026 · 4 marks
CBSE 2026 · Region 1 · Set 1 · Q30
A student performed some crosses in plants and represented the result in the form of bar graphs as shown below. Each graph displays the phenotypic…
A student performed some crosses in plants and represented the result in the form of bar graphs as shown below. Each graph displays the phenotypic proportion of the progeny. Study the graphs and answer the questions:
(a)
What can you infer about the genotype of parents in crosses I and II?
OR
(a)
Which genetic cross is represented by these crosses? $\displaystyle 1$
(b)
Looking at bar graph of cross III, identify the type of cross performed and its importance in genetics.
(c)
What conclusion can you draw from the results of bar graphs of crosses I and II ? Name the genetic principle illustrated.
Marking-scheme solution
(a)
Cross I – Genotypes TT and tt / TT and Tt / TT and TT
Cross II – Genotypes Tt and Tt.
OR
(a)
Monohybrid Cross
(b)
• Test Cross.
• It is done to find the genotype of an organism showing dominant phenotype.
(c)
• It shows that tall trait is dominant over dwarf .
• Genetic principle – Law of Dominance.
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