NEET Biology Principles of Inheritance and Variation
Principles of Inheritance and Variation PDF Notes, Important Questions and Synopsis
- Heredity is the transmission of characters from one generation to another through direct genetic descendants.
- Mendel’s Laws of Inheritance:
- Punnett square is a graphical representation to calculate the probability of all possible genotypes of offspring in a genetic cross.
- Test cross is a cross between the F1 hybrid and its recessive parent. It confirms the purity of the F1 hybrid, whether it is homozygous or heterozygous.
- Back cross is a cross between the F1 hybrid and one of its parents, which may be dominant or recessive.
- Incomplete dominance occurs when two parents are intercrossed with each other, and the hybrid produced does not resemble either of its parents but is mid-way between the parents.
- Multiple allelism occurs when more than two alleles exist at a given locus of a chromosome. In a given individual, only two of these alleles occur, one derived from each parent.
- Co-dominance is the phenomenon when both alleles of a pair are fully expressed in a heterozygote, so the genes and traits are said to be co-dominant.
- Linkage is the tendency of the genes to remain together during the process of inheritance.
- Differences between complete linkage and incomplete linkage:
- Crossing over is the mutual exchange of segments of non-sister chromatids of homologous chromosomes during the process of meiosis.
- Chromosomal Theory of Inheritance was proposed by Walter Sutton and Theodor Boveri. Sutton combined the knowledge of chromosomal segregation with Mendelian principles and called it the chromosomal theory of inheritance.
- Sex Determination in Humans:
- Mutation is an abrupt and discontinuous process where a gene or a chromosome undergoes heritable change in its structure or number.
- Ways of Chromosomal Mutation:
- Mendelian disorders are determined by alteration or mutation in a single gene.
- Aneuploidy is a condition where an organism possesses fewer or extra chromosomes than the normal genome number of the species; e.g. (2N – 1) or (2N + 1), where N is the haploid chromosome number.
- Chromosomal disorders are caused by the absence or excess or abnormal arrangement of one or more chromosomes.
- What type of inheritance is shown by this pedigree?
- Among the seven pairs of contrasting traits of pea as studied by Mendel, the number of traits related to pod and seed respectively are:- (a) 2, 2 (b) 3, 2 (c) 2, 3 (d) 4, 3. Answer given is option (b) 3, 2,,,, but how?
- What is Gene Pool?
- who is the father of genetics
- Term'gamete'was given by Gregor Johann Mendel:--- Is this statement true or false?
- Hi sir, where we are using Dna fingerprinting and what is the use of this technique
- Test cross is between what kind of phenotypes and why is it used
- The minimum weight of tomato obtained from a plant is 20g. The maximum weight of tomato obtained is 120g. What will be the weight of tomato obtained by crossing plant with genotype AAbb x aabb.
- What does the phrase 'unviable in the later stage of life' mean?
- Who gave Agarose gel electrophoresis method?
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