Test: Genetics - SSC CGL MCQ

Gregor Mendel is known as the Father of Genetics for his pioneering work with pea plants, which laid the foundation for the fundamental principles of genetic inheritance. Mendel's experiments on pea plants led to the discovery of basic laws of genetics, which are still fundamental to our understanding of heredity today.

Gregor Mendel introduced the term "factor" to describe what we now refer to as genes, the functional units of DNA. This conceptualization was a crucial step in understanding how traits are passed down from one generation to the next.

Genes existing in pairs of similar forms are called alleles. Alleles are different versions of the same gene that can result in different traits or characteristics in an organism. Understanding alleles is key to comprehending how genetic traits are inherited and expressed.

Mendel's Law of Dominance states that one allele can be dominant over another, and this dominant allele will be expressed in the offspring. This concept is fundamental in understanding how certain traits are expressed in organisms based on their genetic makeup.

Mendel's Law of Segregation explains that during gamete formation, alleles separate so that each gamete carries only one allele for each trait. This principle helps us understand how genetic information is passed down from parents to offspring in a predictable manner.

Mendel's Law of Independent Assortment explains that allele pairs separate independently during gamete formation, meaning the inheritance of one trait does not affect the inheritance of another. This principle is crucial in understanding how different traits are inherited independently of each other.

Humans typically have 46 chromosomes, with 44 forming 22 pairs called autosomes, and the remaining 2 being sex chromosomes. In females, the sex chromosomes are identical and are known as X chromosomes (XX), while in males, they differ, with one X and one Y chromosome. This genetic setup determines the biological sex of an individual.

During reproduction, females produce gametes with 22 autosomes and one X chromosome. On the other hand, males produce two types of gametes: one with 22 autosomes and an X chromosome, and the other with 22 autosomes and a Y chromosome. This process is crucial for genetic diversity and the transmission of genetic information from one generation to the next.

Males produce two types of gametes: one with 22 autosomes and an X chromosome, and the other with 22 autosomes and a Y chromosome. The presence of either an X or a Y chromosome in the gametes determines the biological sex of the offspring. This process is essential for sexual reproduction and the inheritance of genetic traits.

Gene is described as a small segment of DNA on a chromosome that codes for a polypeptide. This means that genes are responsible for carrying the instructions for making proteins, which play various critical roles in the functioning of living organisms.

The one gene-one polypeptide theory was proposed by Lederberg and Tatum. This theory suggests that each gene in an organism is responsible for producing a single polypeptide, which can then contribute to the formation of specific proteins essential for various biological processes.

In genetics, "linkage" refers to the phenomenon where genes tend to stay together during inheritance. This means that certain genes located close to each other on a chromosome are more likely to be inherited together, rather than undergoing independent assortment.

Gregor Mendel discovered that some alleles are dominant over others. Dominant alleles are represented by capital letters, while recessive alleles are represented by lowercase letters. This discovery was fundamental in establishing the principles of genetic inheritance and how traits are passed down from parents to offspring.

The 9:3:3:1 ratio in the F2 generation of a dihybrid cross demonstrates the principle of independent assortment, where genes for different traits segregate independently of each other during gamete formation. This ratio is a classic example of how two different traits can be inherited independently, without influencing each other's inheritance.

In females, the sex chromosomes are identical and are both X chromosomes (XX), while in males, the sex chromosomes differ, with one X and one Y chromosome (XY). This difference in sex chromosome composition between females and males is what leads to the development of distinct biological characteristics and gender-specific traits.