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PRINCIPLES OF INHERITANCE AND VARIATION
Study Material
PRINCIPLES OF INHERITANCE AND VARIATION
Very Short Answer Questions
Q1. What is the cross between the F progeny and the homozygous recessive parent called? How is it useful?
Q2. Do you think Mendel's laws of Inheritance would have been different if the characters that he chose were located on the same chromosome?
Q3. Who proposed the Chromosome Theory of Inheritance?
Q4. Define true breeding. Mention its significance.
Q5. Explain the terms phenotype and genotype.
Q6. What is point mutation? Give an example.
Q7. What is the genotype of wrinkled phenotype of pea seeds?
Q8. What will be the phenotypic ratio in the offsprings obtained from the following crosses.(a) Aa x aa(b) AA x aa(c) Aa x Aa(d) Aa x AA Note: Gene 'A' is dominant over gene 'a'
Q9. In garden pea, the gene T for tall is dominant over its allele for dwarf. Give the genotypes of the parents in the following crosses.(a) tall x dwarf producing all tall plants.(b) tall x tall producing 3 tall and 1 dwarf plants
Q1. Mention the advantages of selecting pea plant for experiment by Mendel.
Q2. Differentiate between the following:(a) Dominant and Recessive(b) Homozygous and Heterozygous
Q3. Explain the Law of Dominance using a monohybrid cross.
Q4. Define and design a test-cross.
Q5. Explain the Co-dominance with example.
Q6. Explain the Incomplete dominance with example.
Q7. Write a brief note on chromosomal mutations and gene mutations.
Q8. Define Law of Segregation and Law of Independent Assortment.
Q1. Explain the dihybrid cross with the help of punnet square board by taking contrasting traits, seed colour and seed shape
Q1. Mendel crossed pea plants producing round seeds with those producing wrinkled seeds. From a total of 7324 F2 seeds, 5474 were round and 1850 were wrinkled. Using the symbols R and r for genes, predict the:(a) the parental (p) genotypes(b) the gametes(c) F, progeny(d) the cross between F1 hybrids(e) genotypes. phenotypes. genotypic frequency. phenotypic ratio of F2 progeny
Q2. The following data was obtained from an experiment on peas. The grey coloured seed is dominant over white coloured seed. Use the letter G for grey and g for white traits. Predict genotypes of the parents in each of the following crosses.Parent Progeny Grey white (a) Grey x white 164 156 (b) Grey x grey 59 19 (c) White x white 0 100 (d) Grey x grey 180 0
Q3. In tomatoes red fruit colour (R) is dominant to yellow (r). Suppose a tomato plant homozygous for red is crossed with one homozygous for yellow. Determine the appearance of the following:the off (a) the F1 (b) F2 (c) spring of a cross of the F1 back to the red parent. (d) the offspring of a cross of the F1 back to the yellow parent.
Q4. In pea, axillary position of flowers (1) is dominant over its terminal position (t). Coloured flowers (C) are dominant to white flowers (c). A true breeding plant with coloured flowers in axils is crossed to one with white terminal flowers. Give the phenotyes, genotyes and expected ratios of F1 , F2 back cross and test cross progenies. What genotypic ratio is expected in the F2 progeny?
Q5. In summer squash, a plant with white flowers and disc-shaped fruits is crossed to a plant with yellow flowers and sphere-shaped fruits. The F1 hybrids had white flowers and disc-shaped fruits. Which phenotypes are dominant? Give the genotypes of the parents and the hybrids. If these hybrids were selfed and 256 progeny were obtained, what what would be the frequencies of the various phenotypes?
Q6. Give the ratios of the following:(a) Monohybrid test cross,(b) Dihybrid test cross(c) F2 phenotypic ratio of mono- hybrid cross(d) F2 phenotypic ratio of dihybrid cross (e) F2 Genotypic ratio of monohybrid cross and 10 F2 genotypic ratio of dihybrid cross
Q7. A diploid organism is heterozygous for 4 loci. How many types of gametes can it produce?
Q8. What is crossing over? In which stage of cell division crossing over occurs? What is its significance?
Q9. Genes contain the information that is required to express a particular trait. Explain.
Q10. For the expression of traits genes provide only the potentiality and the environment provides the opportunity. Comment on the veracity of the statement.
Q11. Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross?
Q12. In peas, tallness is dominant over dwarfness and violet colour of flowers is dominant over the white colour. When a tall plant bearing violet flowers was pollinated with a dwarf plant bearing white flowers. different phenotypic groups were obtained in the progeny in numbers mentioned against them: Tall, Violet = 138 Tall, White = 132 Dwarf, Violet = 136 Dwarf, White = 128 Mention the genotypes of the two parents and of the four offspring types.
Q13. How do genes and chromosomes share similarity from the view point of genetical studies?