Heredity and Evolution — Karnataka (SSLC) Class 10 Science Solutions (Free)

Heredity is the transmission of traits from parents to offspring through genes. Mendel's law of segregation states that allele pairs separate during gamete formation, and each gamete receives only one allele of each gene pair. During fertilization, alleles recombine in the offspring.

A gene is a unit of heredity located on a chromosome that controls a specific trait. Dominant traits are expressed when at least one dominant allele (A) is present. Recessive traits appear only when both alleles are recessive (aa). In Aa, the dominant trait shows.

Natural selection is the process where organisms with favorable traits survive and reproduce more successfully. Over many generations, beneficial traits accumulate in populations while unfavorable traits decrease, causing species to change and adapt to their environment, leading to evolution.

Step 1: Cross Aa × Aa Step 2: Punnett square shows: AA (1/4), Aa (2/4), aa (1/4) Step 3: Probability of homozygous recessive (aa) = 1/4 or 25%

Variation refers to differences in traits among individuals due to genes and environment; it's pre-existing. Mutation is a sudden, random change in DNA sequences that creates new genetic material. Mutations are one source of variation in populations.