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Question
What is the peculiarity of the ‘DNA’ structure?
Solution
Peculiarities of the DNA structure:
- DNA is a double helical structure having nucleotides.
- These nucleotides are made of deoxyribose sugar, phosphoric acid and nitrogenous bases such as adenine, thymine, cytosine and guanine.
- The nucleotide sequence of the DNA molecule is called a gene.
- Genes are present on DNA.
- A type of gene is responsible for the synthesis of a particular protein.
- Changes in the gene can alter the characteristics of the organisms.
RELATED QUESTIONS
A homozygous tall plant (T) bearing red coloured (R) flowers is crossed with a homozygous dwarf (t) plant bearing white (r) flowers :-
(i) Give the genotype and phenotype of the plants of F1 generation.
(ii) Mention the possible combinations of the gametes that can be obtained from the F1 hybrid plant.
(iii) State the Mendel’s law of Independent Assortment.
(iv) Mention the phenotypes of the off springs obtained in F2 generation.
(v) What is the phenotypic ratio obtained in F2 generation?
Mention the Phenotype and Genotype ratios of the offspring in F2 generation.
Define the term heredity.
Describe the cross between a homozygous tall, round-seeded pea plant and a dwarf, wrinkled-seeded pea plant. What will be the types of progeny in the F2 generation of this cross and in what proportion will it be?
Name and state the law which is explained by this example.
Give Technical Term:
The hereditary unit, which is responsible for inheritance.
Long answer type question.
Explain with suitable example an independent assotrment.
Identify the percentage of recombinants in F2 generation in the following case.
In Morgan's experiment with Drosophila, the yellow-bodied white-eyed female was crossed with a brown-bodied red-eyed male and their F1 progeny were intercrossed.
Which one of the following traits of garden pea studied by Mendel was a recessive feature?
Genes which code for a pair of contrasting traits are known as ______.
Which of the following crosses will give tall and dwarf pea plants in same proportions?
Which of the following statement is incorrect?
Why did Mendel choose pea plant for his experiments?
In the following crosses write the characteristics of the progeny
| Cross | Progeny |
| (a) RR YY × RR YY | __________________ |
| Round, yellow Round, yellow | __________________ |
| (b) Rr Yy × Rr Yy | __________________ |
| Round, yellow Round, yellow | __________________ |
| (c) rr yy × rr yy | __________________ |
| wrinkled, green wrinkled, green | __________________ |
| (d) RR YY × rr yy | __________________ |
| Round, yellow wrinkled green | __________________ |
An organism with two identical alleles is
A person has to perform crosses for the purpose of studying inheritance of a few traits/characters. What should be the criteria for selecting the organisms?
Assertion: Height in pea plants is controlled by the efficiency of enzymes and is thus genetically controlled.
Reason: Cellular DNA is the information source for making proteins in the cell.
A male plant bearing red flowers was crossed with a female plant bearing yellow flowers. In the F1 generation, all the flowers were orange in colour.
Mention the ratio of red flowers, yellow flowers and orange flowers in the F2 generation.
