MCQ Detailed View

Heredity is the process through which traits and characteristics are passed from parents to offspring. This transfer of biological information is controlled by specific units that store instructions for various functions of an organism. The smallest unit of heredity is called a gene.

A gene is a segment of DNA (Deoxyribonucleic Acid) that carries the coded instructions for making proteins and controlling cellular activities. These instructions determine the physical and biochemical traits of an organism, such as eye color, blood type, and metabolic processes. Genes are arranged linearly on structures called chromosomes, which are found inside the cell nucleus. While chromosomes are larger structures containing many genes, the gene itself is the basic hereditary unit responsible for passing a specific trait.

Each gene consists of a sequence of nucleotides (adenine, thymine, cytosine, guanine), which are the building blocks of DNA. Although nucleotides are smaller in size, they are not considered independent units of heredity because a complete gene, made of many nucleotides, is required to express a trait or pass it on to the next generation.

When organisms reproduce, genes are copied and transferred to offspring, ensuring the inheritance of traits. Mutations, or changes in the genetic sequence, can sometimes lead to variations in traits, forming the basis of evolution and diversity in living organisms.

In summary, while chromosomes store many genes, and nucleotides are the chemical components of DNA, the gene is the smallest functional and structural unit of heredity, responsible for carrying and transmitting specific characteristics from one generation to the next.