Advertisements
Advertisements
प्रश्न
Explain the mechanism of hereditary changes.
Advertisements
उत्तर
- Mutation: A sudden change in parental DNA can cause a mutation. This leads to changes in hereditary characters.
- Crossing over during meiosis: During meiosis, crossing over takes place between homologous chromosomes. It produces new combinations of genetic information. As a result, the haploid gametes formed carry altered hereditary characters.
APPEARS IN
संबंधित प्रश्न
Name the information source for making proteins in the cells.
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as:
A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?
A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plants bearing white flowers. What will be the result in F1 progeny?
What constitutes the link between one generation and the next?
What sizes of plants are produced if both parents have genes Tt?
Give the contrasting traits of the following characters in pea plant and mention which is dominant and which is recessive:
Yellow seed
In order to ensure that he had pure-breeding plants for his experiments, Mendel :
(a) cross-fertilised each variety with each other
(b) let each variety self fertilise for several generations
(c) removed the female parts of the plants
(d) removed the male parts of the plants.
Pure-bred pea plants A are crossed with pure-bred pea plants B. It is found that the plants which look like A do not appear in F1 generation but re-emerge in F2 generation. Which of the plants A and B are : (i) tall, and (ii) dwarf? Give reason for your answer.
The farmers have been cultivating a food plant X for over two thousand years and have produced as many as five entirely different looking vegetables A, B, C, D and E from it.
(a) What could the plant X be?
(b) What are A, B, C, D and E?
(c) What is the process of evolution involved in this example known as?
If we pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F1 generation, then we obtain pea plants of F2 generation.
(a) What do the plants of F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation.
(c) State the type of plants not found in F1 generation but appeared in F2 generation, mentioning the reason for the same.
Explain Mendel’s law of independent inheritance. Give one example.
Hereditary characters are transferred from parents to offspring by ______ hence they are said to be structural and functional units of heredity.
In humans, if gene B gives brown eyes and gene b gives blue eyes, what will be the colour of eyes of the persons having combinations
(i) Bb and (ii) BB?
Two pink coloured flowers on crossing resulted in 1 red, 2 pink and 1 white flower progeny. The nature of the cross will be
A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because
Mendel crossed pea plants with two pairs of contrasting characters.
| RRYY | × |
rryy |
| Round, Yellow | Wrinkled, Green |
He observed 4 types of combinations in F2 generation. Which of the combinations were new? Write the conclusion drawn by this experiment.
