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प्रश्न
Explain the mechanism of hereditary changes.
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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.
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संबंधित प्रश्न
With the help of two suitable examples, explain why certain experiences and traits earned by people during their lifetime are not passed on to their next generations. When can such traits be passed on?
Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors?
Name the first scientist who studied the inheritance of traits from one generation to the next.
A man having blood group O marries a woman having blood group B and they have a daughter. What will be the blood group of the daughter?
Name the scientist who gave the laws of inheritance.
What is the genotype of tall plants which always produced tall offspring
What is the genotype of dwarf plants whose parental cross always produces tall offspring?
A cross between two individuals results in a ratio of 9 : 3 : 3 : 1 for four possible phenotypes of progeny. This is an example of a ______.
For his experiments on heredity, Mendel used :
papaya plants
potato plants
pea plants
pear plants
Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in F1generation are then cross-bred to produce F2 generation of pea plants.
(a) What do the plants of F1 generation look like?
(b) What is the ratio of tall plants to dwarf plants in F2 generation?
(c) Which type of plants were missing in F1 generation but reappeared in F2 generation?
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 person first crossed pure-bred pea plants having round-yellow seeds with pure-bred pea plants having wrinkled-green seeds and found that only A-B type of seeds were produced in the F1 generation. When F1generation pea plants having A-B type of seeds were cross-bred by self-pollination, then in addition to the original round-yellow and wrinkled-green seeds, two new varieties A-D and C-B type of seeds were also obtained.
(a) What are A-B type of seeds?
(b) State whether A and B are dominant traits or recessive traits.
(c) What are A-D type of seeds?
(d) What are C-B type of seeds?
(c) Out of A-B and A-D types of seeds, which one will be produced in (i) minimum numbers, and (ii) maximum numbers, in the F2 generation?
"It is possible that a trait is inherited but may not be expressed." Give a suitable example to justify this statement.
Explain Mendel’s law of independent inheritance. Give one example.
Define Heredity. Give two examples.
A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because
What are the components of the DNA molecule?
In the following figure showing a germinating gram seed, name the parts labelled as A, B and C:
Why is Part 'B' considered to be important during germination?
