Biology Chapter: Traits and Inheritance

Study Notes

Traits are characteristics passed from parents to offspring. They can be physical (eye color, height) or behavioral (shyness, boldness).
Traits are determined by genes, segments of DNA holding instructions for building and maintaining an organism.
Different gene variations are alleles. The allele combination determines trait expression.
Dominant traits need only one copy for expression; recessive traits require two copies.
Polygenic traits are controlled by multiple genes, resulting in a wide range of expressions (e.g., skin color).
Environmental factors influence trait expression (e.g., nutrition affects height, sunlight affects skin color).
Quantitative traits show continuous variation (height, weight), while qualitative traits display distinct categories (blood type, flower color).

Reproduction is the biological process of producing offspring from parents.
Reproduction is categorized as sexual or asexual.
Asexual reproduction involves a single parent, producing genetically identical offspring.
Sexual reproduction involves two parents, combining genetic material for greater variation.
Sexual reproduction typically involves meiosis, creating gametes (sperm and egg).
Fertilization, the union of gametes, starts development.
Reproduction methods vary across species, adapting to environments and lifestyles.
Factors influencing reproductive success are environmental conditions, resources, and mate availability.
Reproductive strategies differ, impacting survival and gene spread (e.g., parental care, number of offspring).
Mitosis is crucial in asexual reproduction, producing genetically identical cells for growth and repair. This is also involved in some forms of asexual reproduction.
Reproductive cycles differ, controlled by environmental cues and hormonal regulation (e.g., seasonal breeding).
Genetic diversity is maintained through complex mechanisms.
External and internal fertilization are methods for gamete union in sexual reproduction.