Hello Friends We Are Giving You Important Questions For The Very Important Chapter of 10th Science Namely Heredity And Evolution. These Important Questions Are Providing You By Pcmbnotes4u.com
Heredity And Evolution Important Questions
- In a monohybrid cross between tall pea plants (TT) and short pea plants (tt), a scientist obtained only tall pea plants (Tt) in the F1 generation. However, on selfing the F1 generation pea plants, he obtained both tall and short plants in F2 generation. On the basis of above observations with other angiosperms, can the scientist arrive at a law? If yes, explain the law. If not, give justification for your answer.
- Shweta conducted a study on a tobacco plant. She found that in tobacco plant, the male gametes have twenty four chromosomes. Based on this information, find out the number of chromosomes in:
(a) Female gamets
- In one of his experiments with pea plants, Mendel observed that when a pure tall pea plant is crossed with a pure dwarf pea plant, in the first generation F1, only tall plants appear. What happens to the traits of the dwarf plants in this case? When the F1 generation plants were self-fertilised, he observed that, in the plants of second generation F2, both tall plants and dwarf plants were present. Why it happened? Explain briefly.
- ‘A trait may be inherited, but may not be expressed.’ Justify this statement with the help of a suitable example.
- Seema crossed pure breed of pea plants having round-yellow seeds with wrinkled green seeds and found that only A – B type of seeds were produced in the F1 generation. When in F1 generation, pea plants having A – B type of seeds were crossbred by self pollination, then in addition to the original round yellow and wrinkled green seeds, two new varieties A – D and C – B types of seeds were also obtained.
What are A – B type of seeds?
State whether A and B are dominant traits or recessive traits.
What are A – D and C – B type of seeds?
- Which one will be produced in minimum and maximum number in the F2 generation?
A – B
C – D
- In humans, there is a 50% probability of the birth of a boy and 50% probability that a girt will be born. Justify the statement on the basis of the mechanism of sex-determinants in human beings.
- In humans, the gene for black hair colour is B and gene for brown hair colour is b. What will be the hair colour of person having the genetic constitution?
- ‘Different species use different strategies to determine the sex of a newborn individual. It can be environmental cues or genetically determined’. Explain the statement by giving example for each strategy.
Environmental cue: In some animals, the temperature at which fertilised eggs are incubated determines whether the developing animal in egg is a male or a female. In some animals like snail, individuals can change sex.
Genetic cue: A child who inherits an X chromosome from the father will be a girl and the one who inherits a Y chromosome from the father will be a boy.
- It is possible that a trait is inherited but may not be expressed.” Give a suitable example to justify this statement.
- In a cross between plants with homozygous pink flowers and plants with homozygous white flowers, all the offsprings of F1 generation had pink flowers. When the F1 generation was self-crossed, it was observed in the F2 generation that out of 100, 75 flowers were pink. Make a cross and answer the following questions:
(a) What are the genotypes of the F2 progeny?
(b) What is the ratio of Pink: White flowers in the F2 generation?
- ‘Gene control traits’? Explain this statement with an example.
- Why do all the gametes formed in human females have an X chromosome?
- Write the basic features of mechanism of inheritance.
- Who is regarded as the ‘Father of Genetics’? Name the plant on which he performed his experiment.
- A man with blood group A marries a woman with blood group B. They had 2 children, 1 with AB blood group and other with blood group B.
What could be the genotype of parents?
Briefly discuss multiple allelism.
What all blood group are possible in offspring in the given condition?
- If both parents are homozygous for both blood groups A and B, then what would be the blood group of offspring?
- On crossing two heterozygous tall plants (Tt), a total of 500 plants were obtained in F1 generation. What will be the respective number of tall and dwarf plants obtained in F1 generation?
- How many pairs of contrasting traits were studied by Mendel in pea plant?
- Different species use different strategies to determine sex of a newborn individual. It can be determined by environmental cues or can be genetically determined. Explain the statement by giving examples for each strategy.
- In human beings, the statistical probability of getting either a male or a female child is 50%. Give reasons.
- Shivani tried to cross a homozygous purple flower variety of pea plant (PP) with white flower variety of pea plant (pp). Mention the phenotype and genotype of the F1 generation of offsprings. If the offsprings of the F1 generation are self bred. What will be the phenotypic and genotypic ratios of the F2 generation ? State Mendel’s law of dominance.
- In an experiment by Mendel on a pea plant, the trait of flowers bearing purple colour (PP) is dominant over white colour (pp).
Explain the inheritance pattern of F1 and F2 with the help of a cross following the rules of inheritance of traits.
State the visible characters of F1 and F2 progenies.
- While performing an experiment on pea plants, Mendel crossed tall pea plants and short pea plants and produced F1 progeny through cross fertilisation.
What type of progeny was obtained by Mendel in F1 and F2 generations when he crossed the tall and short plants?
Write the ratio he obtained in F2 generation plants.
- Sahil conducted an experiment on pea plants. In which, pure breeding pea plants with green pods were crossed with pure breeding pea plants with yellow pods. He found that all the F1 generation plants have green pods. Then he interbred the plants from the F1 generation.
(a) What colour of pods will be observed in F2 generation plants? Explain with a cross.
(b) The genotype for the colour of the pod of a pea plant is Gg. What conclusion may be drawn from this?
(c) Why Sahil selected garden peas as his experimental material? Give two reasons.
- If we cross-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant, we will get plants of F1 generation. Now, if we self-cross the pea plant of F1 generation, we obtain pea plants of F2 generation. Based on the given information, answer the following questions:
(a) What do the plants of F1 generation look like?
(b) State the ratio of tall plant to dwarf plants in F2 generation.
(c) State the type of plants not found in F1 generation but appeared in F2 generation. Write the reason for the same.
- A blue colour flower plant denoted by BB is cross bred with that of white colour flower plant denoted by bb.
State the colour of flower you would expect in their F1 generation plants.
What must be the percentage of white flower plants in F2 generation if flowers of F1 plants are self-pollinated?
State the expected ratio of the genotypes BB and Bb in the F2 progeny.
State the type of plants which are not found in F1 generation but reappeared in F2 generation. Write the reason for the same.
- How dominant and recessive traits are different from each other?
- “An individual cannot pass on to its progeny the experiences of its lifetime”. Justify the statement with the help of an example and also give reason for the same.
- How will you justify selection of pea plant by Mendel for heredity experiments?
- A trait A exists in 30% of a population of a species and a trait B exists in 70% of the same population. Which trait is likely to have arisen earlier?
- “It is a matter of chance whether a couple will have a male or a female child.” Justify this statement by drawing a flow chart.
- To study pattern of inheritance, Mendel crossed pea plants with contrasting characters and observed that one of the parental forms of trait was always absent in F1 hybrid but reappeared unchanged in the F2 generation.
Work out a cross upto F2 generation between two pure breed pea plants, one bearing violet flowers and the other white flowers.
Name this type of cross.
State the different laws of Mendel that can be derived from such a cross.
- Plant with round seeds is crossed with plant having wrinkled seeds. All F1 progenies are with round seeds. What percentage of plants would have wrinkled seeds in F2 generations?
- How did Mendel interpret his result to show that traits may be dominant or recessive? Describe briefly.
- In one of his experiments with pea plants Mendel observed that when a pure tall pea plant is crossed with a pure dwarf pea plant, in the first generation, F1 only tall plants appear.
(a) What happens to the traits of the dwarf plants in this case?
(b) When the F1 generation plants were self-fertilized, he observed that in the plants of second generation (F2), both tall plants and dwarf plants were present. Why it happened? Explain briefly.
- If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Name the information source for synthesizing protein in a cell and define it.
What is gene locus?
- List three distinguishing features between monohybrid and dihybrid cross.
- What will happen if both the characters present in F1 generation pass together in F2 generation?
- What do you mean by a true breeding plant?
A true breeding plant is the one that when self fertilised, produces offspring with the same traits. They will be either homozygous dominant or homozygous recessive.
- Mendel performed several experiments that include monohybrid, dihybrid and trihybrid crosses. On the basis of these experiments, mendel formulated laws of heredity. How do Mendel’s experiment shows that traits are inherited independently?
- Differentiate between genotype and phenotype.
- In certain plant, yellow fruit colour (Y) is dominant to green fruit colour (y) and round shape (R) is dominant to oval shape (r). The two genes involved are located on different chromosomes.
What would be genotypic and phenotypic ratio when plant YyRr is back crossed with the double recessive parent?
- Briefly describe multiple allelism?
- Mendel selected Pisum sativum for his experiment to study inheritance of characters. Dihybrid cross involves crossing between parents differing in two pairs of contrasting characters.
(a) Name two contrasting characters related to pod of pea plant.
(b) Which Mendelian law were concluded from monohybrid cross?
(c) What will be the percentage of purple stemmed plants in the F2 generation, when the F1 generation resulted due to cross breeding of green stemmed (GG) tomato plants with purple stemmed (gg) tomato plants, are self pollinated?
- Gregor Johannes Mendel worked on garden pea plant (Pisum sativum) over a period of eight years and contributed in the field of inheritance and expression of such traits.
Why did Mendel chose garden pea for his experiments? Write two reasons.
List two contrasting visible characters of garden pea that Mendel used for his experiment.
Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive.
- Garden pea selected by Mendel for his experiment show several well defined, easily detectable contrasting traits. Mendel performed separate crosses involving one, two or three different contrasting characters. Explain inheritance of character considering only one visible contrasting character.
- What is the difference between genetics and heredity?
- Write the contribution of Gregor Mendel in the modern genetics.
- Name the mode of reproduction that ensures variation in the off-springs. What mechanism, do you think, is actually responsible for variation leading to the survival of the species?
- In mice, black coat colour (allele B) is dominant to brown coat colour (allele b). The offspring of a cross between a black mouse (BB) and a brown mouse (bb) were allowed to interbreed.
(a) Work out cross upto F2 generation for such interaction.
(b) What percentage of the progeny in F2 generation would have black coats?
(c) If a heterozygous black mouse is crossed with a recessive parent then what would be the ratio of their progenies?
If a heterozygous black mouse is crossed with its homozygous parent, then what percentage of the progeny would have black coats? Name the term given to this type of cross.