Question

Variations appear during meiosis due to
1. Independent assortment
2. Crossing over
3. Linkage
4. Glycolysis
Select the correct code
(a) 1,2,3 correct
(b) 1,2 correct
(c) 2,4 correct
(d) 1,3 correct

Answer 1

Hint: When the progeny shows new characteristics or traits compared to the parent organism, variation occurs. It can be in terms of morphology, physiology, cytology, or even behavioristic traits.

Complete answer:
During meiosis, variation appears due to independent assortment and crossing over. The inheritance of one character is independent of the inheritance of another character during a cross is made between two different individuals. This is known as an independent assortment. On the other hand, crossing over is the exchange of chromatid segments between the non-sister chromatids.
So, the correct answer is ‘1, 2’.

Additional Information: Let us know more about each term in the question:
Independent assortment- This means the assortment of alleles of genes is independent of one another. It was proven by Mendel's experiment of monohybrid crosses of inheritance. In meiosis, the chromosomes are halved. The independent assortment occurs when the maternal and paternal genes are divided randomly.
Crossing over: Exchange of segments between non-sister chromatids of a homologous chromosome. It takes place in the pachytene stage of prophase I. It leads to a new combination of genes and helps in the process of evolution.
Linkage: When two or more genes are linked together and always are inherited together in the same combination to the next generation, such a condition is known as linkage. There are two types of linkage found in genes- complete and incomplete linkage. In complete the characteristics are normally inherited in two or more generations in the original combination. In the incomplete ones, the genes are located at a distance on the chromosome and are attributed to the accidental deconstruction of chromosomal segments during the crossover.
Glycolysis: It is the process of breaking down glucose into two pyruvate molecules. It takes place in the cytosol of the cytoplasm, in the presence or absence of oxygen.

Note: Variation occurs due to crossing over, mutation, recombination, independent assortment, and environmental effects in the gene expressions. This concept is a part of the principle of inheritance and variation proposed by Mendel. Other aspects of this theory are heredity, inheritance, variation, genetics, and genes.