Overview

This topic covers how organisms are organized, how body systems function together, and how genetic traits are passed from parents to offspring. It examines the relationship between structure and function in biology and explores patterns of inheritance in both simple and complex traits.

Key Systems and Genetic Principles

• Levels of Organization: Cells → Tissues → Organs → Organ Systems → Organism
• Major Organ Systems: Includes circulatory, respiratory, digestive, nervous, musculoskeletal, immune, and reproductive systems. Each has specialized structures and functions.
• Homeostasis: The body's ability to maintain a stable internal environment despite changes in the external environment (e.g., body temperature, blood glucose).
• Hormones and Signals: Endocrine system uses hormones to regulate processes like growth, metabolism, and reproduction.
• Inheritance: Traits are passed through genes. Each individual inherits two alleles per gene (one from each parent).
• Dominant vs. Recessive Alleles: Dominant alleles mask recessive ones. Genotypes can be homozygous (same alleles) or heterozygous (different alleles).
• Complex Inheritance: Includes codominance (e.g., AB blood type), incomplete dominance (blending traits), and polygenic traits (controlled by multiple genes, like height or skin color).
• Sex-Linked Traits: Genes located on sex chromosomes; X-linked traits often affect males more than females (e.g., color blindness).
• Genetic Disorders: May arise from mutations, inherited conditions, or chromosomal abnormalities (e.g., Down syndrome, cystic fibrosis).
• Pedigrees: Family tree diagrams used to track inheritance patterns across generations.

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