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Questions
Using height (tallness/dwarfness) of a plant as an example, show that genes control the characteristics or traits in an organism.
Explain with an example, how genes control the characteristics (or traits).
Solution
A gene is the section of DNA on a chromosome that codes the formation of a protein controlling a specific characteristic of the organism. Suppose, a plant progeny possesses gene for the characteristic called 'tallness'. The gene for tallness will give instructions to the plant cells to generate many plant-growth hormones due to which the plant will grow tall. On the other hand, if the plant has the gene for shortness, less plant-growth hormones will be produced, due to which the plant will not grow much and remain a dwarf plant.
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RELATED QUESTIONS
A pea plant with blue colour flower denoted by BB is cross-bred with a pea plant with white flower denoted by ww.
(a) What is the expected colour of the flowers in their F1 progeny?
(b) What will be the percentage of plants bearing white flower in F2 generation, when the flowers of F1 plants were selfed?
(c) State the expected ratio of the genotype BB and Bw in the F2 progeny.
What is a gene?
List any two contrasting characters other than height that Mendel used in his experiments in pea plants.
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?
What constitutes the link between one generation and the next?
In the human blood grouping, the four basic blood types are type A, type B, type AB, and type O. The blood proteins A and B are :
(a) simple dominant and recessive traits
(b) incomplete dominant traits
(c) codominant traits
(d) sex-linked traits
Which of the following statement is incorrect?
(a) for every hormone there is a gene
(b) for every protein there is a gene
(c) for production of every enzyme there is a gene
(d) for every type of fat there is a gene
What are the possible blood groups likely to be inherited by children born to a group A mother and a group B father? Explain your reasoning.
"It is possible that a trait is inherited but may not be expressed." Give a suitable example to justify this statement.
In the following Question, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
Assertion: When pure breed tall plants are crossed with pure breed short plants, all the plants in F1 progeny are tall. When the tall plants of F1 progeny are crossed, short plants re-appear in F2 progeny.
Reason: Traits are independently inherited.
