Sourav Pan is the founder and sole author of Biology Notes Online. He holds a Bachelor of Science (B.Sc.) degree and an M.Sc. in Microbiology from the University of Calcutta. He creates educational resources covering microbiology, immunology, biotechnology, genetics, cell biology, botany, zoology, and other life-science subjects.
His goal is to make complex biological concepts easier to understand through well-structured, student-friendly articles based on academic textbooks, peer-reviewed research, and authoritative scientific sources. In addition to writing new content, he regularly reviews and updates articles to improve their accuracy, clarity, and educational value.
What is Sex Determination? Definition of Sex Determination Sex determination is the biological process that establishes whether an individual will develop as male or female, typically governed by genetic, environmental, or a combination of factors. It involves mechanisms that direct the differentiation of gonads and the subsequent development of sexual characteristics. Methods for Sex Determination … Read more
What is Sex-linked Inheritance? Methods for Sex-linked inheritance Sex-linked inheritance refers to the transmission of genetic traits that are carried on the sex chromosomes, specifically the X or Y chromosome. These traits are inherited differently than those located on the autosomal chromosomes due to the unique nature of sex chromosome behavior. The two main categories … Read more
What is Chromosome? What is Chromosomal Theory of Inheritance? Observations of Chromosomal Theory of Inheritance The Chromosomal Theory of Inheritance provided a clear link between the behavior of chromosomes and Mendel’s laws of inheritance. It was supported by a series of critical observations that connected chromosomal behavior during meiosis with the inheritance patterns Mendel described. … Read more
What is Pleiotropism? Short Definition of Pleiotropism Pleiotropism refers to the phenomenon where a single gene or mutation affects multiple, seemingly unrelated traits or physiological processes. This occurs when one genetic change leads to a range of different effects across various aspects of an organism’s phenotype. Types of pleiotropy Examples of Pleiotropism Significance of Pleiotropism
What is Cytoplasmic or Extra-Nuclear Inheritance? Cytoplasmic inheritance, also known as extrachromosomal or extranuclear inheritance, refers to the transmission of genetic material that is not found within the nucleus but rather in the cytoplasm of a cell. This type of inheritance contrasts with Mendelian inheritance, which involves nuclear genes. In cytoplasmic inheritance, the genetic information … Read more
What is Chi-square Test? Formula of chi-square The Chi-square test is symbolically represented as [latex] \chi^2 [/latex], and the formula for comparing variances is: Where: Similarly, when the Chi-square test is used as a non-parametric test for goodness of fit or testing independence, the following formula is applied: Where: Properties of the Chi-Square Test The … Read more
What is Gene? What is Allele? Differences Between Gene and Allele Understanding the concepts of genes and alleles is crucial in genetics. While both terms are fundamental to the study of heredity, they refer to different aspects of genetic information. Here, we explore the distinctions between genes and alleles, outlining their roles and characteristics in … Read more
Epistasis is the interplay between genes that influence the character. Genes may mask one to the point that one gene is thought to be “dominant” or they can be combined to create a new characteristic. It’s the relation between two genes that could be the basis for a particular phenotype of certain characteristics. Each locus has two alleles that define the phenotypes. They may affect each other in a manner that regardless of the particular allele of one gene it is recessive another dominant variant of. A different expression for epistasis requires a ratio chart, or table.
What is Gene Interactions? Definition of Gene Interactions Gene interactions refer to the relationships between multiple genes where the expression of one gene can influence, or be influenced by, the expression of another gene, collectively determining specific phenotypic traits in an organism. Types of Gene Interaction Gene interactions can be categorized into two primary types: … Read more
What is Linkage? What is Crossing Over? Difference Between Linkage and Crossing Over Here is a detailed comparison of these two genetic phenomena: Aspect Linkage Crossing Over Definition Tendency of genes close on the same chromosome to be inherited together during meiosis. Exchange of genetic material between non-sister chromatids of homologous chromosomes. Relationship of Related … Read more