Question 1:
What Are Sex Chromosomes?
Answers:
- The chromosomes which are responsible for the determination of the sex of a person are called sex chromosomes.
- In humans, X and Y are sex chromosomes.
- The combination of XX chromosomes leads to a female child, whereas XY chromosomes lead to a male child.
Question 2:
How Are Genetic Disorders Transferred in a Family for Generations?
Answers:
- Genetic disorders are transferred along with the passage of genes from one generation to another.
- It is not necessary that every member of the future generation would suffer from the same disease.
- In some cases, the disease stays hidden due to different combinations of genes.
- It may again express itself in the future generation when the combination or pairing of genes changes.
Question 3:
People Living in the Mountains Have High Levels of Haemoglobin in Their Blood. Why? Do You Think It Is a Genetic Trait?People Living in the Mountains Have High Levels of Haemoglobin in Their Blood. Why? Do You Think It Is a Genetic Trait?
Answers:
- Haemoglobin plays a vital role in the transfer of oxygen in our bodies.
- As we go to height or ascend on mountains, the air becomes thinner, which leads to a fall in oxygen level in the air.
- The body compensates for the same by building a large number of red blood cells so that they can work to transport more amount of oxygen.
- The rise in red blood cells leads to an increase in haemoglobin.
- It is a change which occurs due to external factors. Hence, it is an acquired trait.
Question 4:
How the Combination of Genes Plays a Role in the Expression of Dominant and Recessive Traits?
Answers:
- Genes occur in pairs.
- Out of the pair, one gene represents a dominant trait and the other a recessive trait.
- The expression of traits depends on their combination. There are the following possibilities—
Possible combination |
Trait |
One gene of dominant trait, and the other of a recessive trait |
Dominant |
Both the genes of a dominant trait |
Dominant |
Both the genes of recessive traits |
Recessive |
Question 5:
Why Do Acquired Traits Not Pass From One Generation to Another?
Answers:
- Acquired traits do not alter the genetic make-up of an individual.
- For example, the building of muscles is because of exercise, not because of any genetic alteration. Similarly, the piercing of ears has nothing to do with genes.
- Hence, acquired traits do not pass from one generation to another.