Heredity
Question 1: Define Heredity.
Answer:
Heredity refers to the transmission of characters or traits from parents to their offspring. It is the continuity of features from one generation to other.
Question 2: What is the genotype of Human males and females?
Answer:
Genotype is the genetic constitution of an organism. In human beings, there are 23 pairs of chromosomes. Out of these 22 chromosome pairs are called autosomes and the sex chromosome is the last pair of chromosomes that help in deciding the gender of that individual. The genotype of the human male is 44 + XY and the Genotype of the human female is 44 + XX.
Question 3: What is an Allele?
Answer:
Allele is an alternative form of a gene occupying the same position on a chromosome and affecting the same characters but in two alternative ways. It is a variation of the same sequence of nucleotides at the same place on a long DNA molecule. The genomic location of any gene or any genetic material is called a locus and the alternative DNA sequences at a locus are called alleles.
Question 4: State the difference between the dominant trait and the recessive trait.
Answer:
A dominant trait is an inherited character that appears in an offspring if it is contributed by a parent having a dominant allele. A dominant trait overrides the effect of a different variant of the same gene on the other copy of the chromosome.
A trait that must be contributed by both parents in order to appear in the offspring is termed a recessive trait. This trait is expressed only when the genotype is homozygous. When an organism has two recessive alleles it tends to be expressed in the offspring.
Question 5: State the Monohybrid ratio and Dihybrid ratio.
Answer:
Monohybrid Ratio:
- In the F1 generation, the ratio is 100% hybrid type.
- In the F2 generation: the phenotypic ratio is 3:1 and the genotypic ratio is 1:2:1.
Dihybrid Ratio:
- In the F1 generation, the ratio is 100% hybrid type.
- In the F2 generation: the phenotypic ratio is 9:3:3:1 and the genotypic ratio is very complex.
Question 6: Why sexual reproduction produces more variation?
Answer:
In sexual reproduction, two different sets of chromosomes from both parents are mixed resulting in a completely new set of chromosomes. They also undergo crossing over during gamete formation and thus each gamete formed is unique. Hence the progeny has more variation. A large set of characteristics is inherited from both parents and is together passed on to the next generation causing diversity among the individual in the next generation.
Heredity
The transmission of particular characters from parents to offspring is termed Heredity and Evolution. When a living organism is developed or gradually progressed from a simple life form to a complex organism it is termed Evolution. In all living organisms, the rules of inheritance determine the pattern of inheritance. Evolution is due to the inheritance of these variations in a particular organism. When there is reproduction between two genetically diverse organisms it gives rise to variations in any living organisms. Sexual reproduction causes more successful variations as compared to asexual reproduction.
Human beings can be distinguished from one another based on the inherited characteristics that children get from their parents. They reproduce sexually and hence various heredity traits are passed on, which has resulted in such dynamic changes in the later generations over the years. The human body and animals show a variety of changes that occur due to Heredity and Evolution.