✓ Board-verified
Biology · 2026 · 3 marks
CBSE 2026 · Region 3 · Set 1 · Q28
(a) Describe the experiment conducted by T.H. Morgan on Drosophila melanogaster involving eye colour and body colour. (b) How did the results deviate…
(a)
Describe the experiment conducted by T.H. Morgan on Drosophila melanogaster involving eye colour and body colour.
(b)
How did the results deviate from Mendelian inheritance pattern ?
(c)
Explain the two genetic terms used by Morgan for his observations.
Marking-scheme solution
(a)
Morgan hybridised yellow bodied white eyed females with brown bodied red eyed males and inter-crossed their progeny.
(b)
He observed that the two genes did not segregate independently of each other as in Mendelian inheritance pattern
The ratio deviated from $\displaystyle 9$:$\displaystyle 3$:$\displaystyle 3$:$\displaystyle 1$ ratio (expected when genes segregate independently)
(c)
• Linkage - He gave this term to describe the physical association of the
two genes present on the same chromosome.
• Recombination - Generations of nonparental gene combinations.
All Principles of Inheritance and Variation questions2026 question paperNCERT solutions: Principles of Inheritance and VariationPractice Principles of Inheritance and Variation →
More from Principles of Inheritance and Variation
- In which of the given chromosomal disorders does the individual have tall stature with feminised character?2024
- In the following figure, two ways of pairing of two homologous pairs of chromosomes are shown. Which of the following phenomena is expressed?2026
- Study the pedigree chart of a family given below and answer the questions that follow: Is the disease in this pedigree chart a recessive or dominant…2023
- Study the figures given below and answer the questions. Cross - A Cross - B Identify in which of the crosses the strength of linkage between the…2026
- Inheritance of which of the following traits is shown in the cross given below? Choose the correct option from the following:2025
- If both the parents are carriers for thalassaemia, the chances of an afflicted child to be born to them is:2024
- Which of the following is correct for the condition when plant YyRr is back crossed with the double recessive parent?2025
- Which of the following features correctly show the mechanism of sex- determination in honey-bees? (i) A zygote formed from the union of a sperm and…2025
CBSE Class 12 Biology past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.