Diversity of Living Things

Diversity of Living Things

• Importance of Biodiversity: Essential for ecosystem stability, resilience, and human survival. Provides vital ecosystem services like food, clean water, medicine, and pollination.
• Threats to Biodiversity: Habitat loss, pollution, climate change, invasive species, and overexploitation are major threats.
• Classification System: Organisms are classified using the Linnaean system (DKPCOFGS): Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Binomial Nomenclature: Two-part naming system (Genus species) – e.g., Homo sapiens.
• Dichotomous Keys: Tools used to identify organisms based on their characteristics.
• Domains and Kingdoms:
• Three Domains: Bacteria, Archaea, Eukarya.
• Six Kingdoms: Bacteria, Archaea, Protista, Fungi, Plantae, Animalia.
• Cladograms: Diagrams showing evolutionary relationships based on shared traits.
• Prokaryotic vs Eukaryotic Cells:
• Eukaryotic cells have membrane-bound organelles, including a nucleus.
• Prokaryotic cells lack membrane-bound organelles and have DNA in a nucleoid region.
• Endosymbiotic Theory: Eukaryotic cells evolved from prokaryotic cells engulfing other cells (e.g., mitochondria, chloroplasts).
• Viruses: Non-living entities composed of a protein coat (capsid) and genetic material (RNA/DNA).
• Viral Life Cycles:
• Lytic Cycle: Virus replicates and causes cell lysis.
• Lysogenic Cycle: Viral DNA integrates into host's genome, replicates passively, potentially entering a lytic cycle later.
• Kingdom Overviews:
• Bacteria: Prokaryotic, unicellular organisms that reproduce by binary fission.
• Archaea: Extremophile prokaryotes with unique biochemical features.
• Protists: Eukaryotic, unicellular or multicellular organisms with diverse nutritional strategies (e.g., algae, amoebas).
• Fungi: Eukaryotic, mostly multicellular (except yeasts), heterotrophic decomposers.
• Animals: Multicellular, eukaryotic, heterotrophic organisms with complex organ systems.
• Antibiotic Resistance: Overuse/misuse of antibiotics leads to the evolution of resistant bacteria.
• Biotechnology and Phages: Phages (bacterial viruses) are used in genetic engineering to deliver genetic material.

Genetic Processes

• DNA Structure: DNA consists of nucleotides (phosphate group, sugar, nitrogenous base). Complementary base pairing: A with T, G with C.
• Chromosomes:
• Haploid: One set of chromosomes (gametes).
• Diploid: Two sets of chromosomes (somatic cells).
• Autosomes: Non-sex chromosomes.
• Sex Chromosomes: Determine sex (XX or XY).
• Cell Division:
• Cell Cycle: Interphase (growth, DNA replication) and Mitotic phase (mitosis or meiosis).
• Mitosis: Cell division for growth/repair, producing two identical diploid cells.
• Meiosis: Cell division for sexual reproduction, producing four non-identical haploid cells.
• Karyotypes: Visual representations of an organism's chromosomes, used to detect abnormalities.
• Abnormal Meiosis (Nondisjunction):
• Trisomy: Extra chromosome (e.g., Down syndrome).
• Monosomy: Missing chromosome (e.g., Turner syndrome).
• Heredity:
• Mendel's Laws:
• Segregation: Alleles separate during gamete formation.
• Independent Assortment: Genes for different traits are inherited independently.
• Types of Inheritance:
• Complete Dominance: One allele masks the other.
• Co-dominance: Both alleles are expressed (e.g., AB blood type).
• Incomplete Dominance: Blending of traits (e.g., red + white = pink).
• Sex-linked Inheritance: Genes located on sex chromosomes.
• Autosomal Inheritance: Genes located on autosomes.
• Multi-trait Inheritance: Inheritance patterns involving multiple alleles (e.g., blood types).
• Genetic Engineering: Techniques to modify DNA (e.g. CRISPR).

Animals: Structure and Function

• Circulatory System:
• Blood Components: Red blood cells (oxygen transport), white blood cells (immune function), platelets (clotting), plasma (transport).
• Heart Structures: Atria (receive blood), ventricles (pump blood), valves (prevent backflow).
• Blood Pathway: Right atrium → right ventricle → lungs → left atrium → left ventricle → body.
• Cardiac Output: Volume of blood pumped per minute.
• Heart Sounds and Blood Pressure: Systolic (contracting) and diastolic (relaxing) pressures.
• Respiratory System:
• Structures: Nasal cavity, trachea, bronchi, alveoli (gas exchange).
• Breathing Mechanisms: Inhalation (diaphragm contracts), exhalation (diaphragm relaxes).
• Lung Capacity and Spirometer: Measures volumes (Tidal Volume, Vital Capacity, Residual Volume).
• Disorders: Asthma, COPD, lung cancer.
• Digestive System:
• Organs: Mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, gallbladder.
• Digestion: Mechanical (chewing) and Chemical (enzymes).
• Enzymes: Amylase (carbs), protease (proteins), lipase (fats).
• Disorders: Ulcers, acid reflux, diarrhea, constipation.

Evolution

• Darwin's Observations: Biogeography (species distribution), fossils (historical life forms), bird collections.
• Evidence for Evolution:
• Homologous/Analogous Structures: Homologous (similar structures, common ancestor); Analogous (different structures, similar function).
• Embryonic Evidence: Similar developmental patterns.
• Vestigial Features: Traits that have lost their original function.
• Fossil Record and DNA: Show evolutionary relationships and trends.
• Natural Selection: Differential survival and reproduction of organisms based on advantageous traits.
• Types of Selection:
• Directional: Favoring one extreme phenotype.
• Stabilizing: Favoring the average phenotype.
• Disruptive: Favoring both extreme phenotypes.
• Sexual Selection: Traits increasing reproductive success.
• Artificial and Sexual Selection: Human-driven vs. mate choice.
• Genetic Drift:
• Bottleneck Effect: Drastic reduction in population size due to environmental disruption.
• Founder Effect: Small group establishing a new population, leading to restricted genetic diversity.
• Speciation: Formation of new species, involving reproductive isolating mechanisms.
• Reproductive isolating mechanisms: Pre-zygotic (before fertilization) and Post-zygotic (after fertilization)
• Patterns of Evolution: Adaptive radiation (rapid diversification), divergent evolution (species diverge), convergent evolution (unrelated species develop similar traits), coevolution (species evolve together).