Give two reasons for the appearance of variations among the progeny formed by sexual reproduction
Two primary reasons for variations among progeny produced through sexual reproduction are the mixing of parental genetic material and the random assortment of chromosomes during meiosis. The combination of unique genetic combinations from two parents, along with the independent segregation of chromosomes, leads to a wide range of variations within the offspring.
Elaboration:
1. New Combinations of Genes:
In sexual reproduction, each parent contributes half of their chromosomes to the offspring, which are then combined to form a new set of genes. This creates new combinations of genes that were not present in either parent, leading to variation in traits.
2. Random Assortment of Chromosomes:
During meiosis, the chromosomes pair up and are then separated into gametes (sperm and egg cells). This separation is random, meaning that any combination of chromosomes can end up in a single gamete. When these gametes fuse during fertilization, the resulting offspring will have a unique combination of chromosomes from both parents, further contributing to variation.