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Practice each question, then open the answer or worked solution.
How do genes and chromosomes share similarity from the point of view of genetical studies?
Ans: Genes and chromosomes share similarity from the point of view of genetical studies as:
They are found in pairs.
They segregate at the time of gamete formation and only one of the pair is transmitted to a gamete.
Independent pairs segregate independently of each other.
What is recombination? Discuss the applications of recombination from the point of view of genetic engineering.
Ans: The gene combination which is different from parental genes is called recombination.
This can happen naturally during meiosis. This can also be artificially induced through genetic engineering. Genetic engineering has been applied in creating recombination for various species to produce useful products for humAns: For example; Bt cotton and Bt brinjal have been produced through genetic engineering. Some vaccines are also being produced through this process, e.g. hepatitis B vaccine.
What is artificial selection? Do you think it affects the process of natural selection?
How?
Ans: Artificial selection is the selective breeding of plants and animals to include beneficial traits in them. This is also called selective breeding. While some selective breeding can be purely artificial, many others are natural breeding done in a controlled environment. From the point of ethics, it may be wrong to go for artificial selection. But if we follow the law of natural selection and survival of the fittest, then it can be safely assumed the even in case of artificial selection only those varieties are going to survive which are fit to survive. Hence, it can be inferred that artificial selection is not going to affect the process of natural selection.
With the help of an example differentiate between incomplete dominance and codominance.
Ans:
Incomplete dominance | Co-dominance |
Phenotypes from both the parents are partially manifested in F1 generation. | Phenotypes from both the parents are completely manifested in F1 generation. |
Example: When snapdragon plants with red flowers were crossed with flowers, the F1 generation produced pink flowers. | Example: ABO blood grouping in humans shows co-dominance. |
It is said, that the harmful alleles get eliminated from population over a period of time, yet sickle cell anaemia is persisting in human population. Why?
Ans: The sickle cell anemia is controlled by a single pair of allele; HbA and HbS. If both the parents are heterozygous (HbAHbS) then the offspring can suffer from this disease. The offspring should be homozygous (HbSHbS). Heterozygous individuals are carriers of this of this disease. Heterozygous individuals are advantageous in terms of adaptation. Due to this, sickle cell anemia is persisting in human population.