If you cross dominant genotype PV/PV male Drosophila with double recessive female and obtain F 1 hybrid. Now you cross F 1 male with double recessive female. i) What type of linkage is seen? ii) Draw a cross with correct genotype. iii) What is the possible genotype in F 2 generation?

i) Again if you cross F 1 male with double recessive female a complete linkage can be seen and it occurs due to the absence of chiasma or crossing over in between the linked genes present on homologous chromosomes. Crossing over will not present in male drosophila. ii) Correct cross over is shown in the below diagram and In F1 generation it shows only two gametes due to lack of crossing over iii) F 2 hybrid exhibits only parental genotype due to complete linkage and Test cross failed to produce 1:1:1:1 ratio & instead produced 7:1:1:7. PV Pv PV pv PV PPVV PPVv PPVV PpVv Pv PPVv PPvv PPVv Ppvv PV PPVV PPVv PPVV PpVv pv PpVv Ppvv PpVv ppv

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 6

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Due to incomplete linkage in maize, the ratio of parental and recombinants are

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Important Questions on Chromosomal Basis of Inheritance

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12th Tamil Nadu Board

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 7

Genes G S L H are located on same chromosome. The recombination percentage is between L and G is 15%, S and L is 50%, H and S are 20%. The correct order of genes is

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 8

The point mutation sequence for transition, transition, transversion and transversion in DNA are

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 9

If haploid number in a cell is 18. The double monosomic and trisomic number will be.

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 10

Changing the codon AGC to AGA represents

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 11

Assertion (A): Gamma rays are generally used to induce mutation in wheat varieties.
Reason (R): Because they carry lower energy to non-ionize electrons from atoms.

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 12

How many map units separate two alleles A and B if the recombination frequency is 0.09?

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12th Tamil Nadu Board

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 13

“When” two different genes came from the same parent they tend to remain together.
i) What is the name of this phenomenon?
ii) Draw the cross with a suitable example.
iii) Write the observed phenotypic ratio.

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Biology Botany Standard 12>Chapter 3 - Chromosomal Basis of Inheritance>Evaluation>Q 14

If you cross dominant genotype PV/PV male Drosophila with double recessive female and obtain F₁hybrid. Now you cross F₁male with double recessive female.

i) What type of linkage is seen?

ii) Draw a cross with correct genotype.

iii) What is the possible genotype in F₂generation?