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Corridors and Edges in Ecosystems

• Corridors & Edges:

  • Boundaries between ecosystems present unique physical conditions and species communities.

  • As habitat fragmentation increases, edges become more extensive, and edge-adapted species may dominate.

  • Movement corridors facilitate dispersal and population sustainability but may also promote disease spread.

Fermentation and Cellular Respiration

• Alcohol and Lactic Acid Fermentation:

  • Alcohol Fermentation: Pyruvate converted to ethanol in two steps: releases CO2 to form acetaldehyde, reduced by NADH to ethanol.

  • Lactic Acid Fermentation: Pyruvate directly reduced by NADH to form lactate (no CO2 or acetaldehyde).

• Cellular Respiration:

  • Final electron acceptor is oxygen.

  • Produces more energy (38 ATP) and occurs under aerobic conditions.

Symbiotic Relationships

• Types of Symbiotic Relationships:

  • Parasitism: One organism benefits at the expense of another.

  • Mutualism: Both organisms benefit from the relationship.

  • Commensalism: One organism benefits while the other is neither helped nor harmed.

Cellular Concepts

• Diploid: Organisms with two sets of chromosomes per nucleus.

• Autotrophs: Organisms producing organic food from inorganic substances.

• Climax Community: A stable, persistent community reached through ecological succession.

• Ecotone: Transition zone between two communities or biomes.

Isotopes

• Definition: Atoms with the same number of protons but different neutron counts.

• Radioisotopes: Unstable isotopes that decay, changing elements and used in medical diagnostics (e.g., PET scans).

Reproduction

• Asexual Reproduction: One parent produces genetically identical offspring.

• Sexual Reproduction: Involves two parents contributing unique gene combinations through meiosis.

Buffers in Biological Systems

• Definition: A buffer minimizes changes in H+ and OH- concentrations in solutions, maintaining pH stability (e.g., human blood).

Enzyme Activity Regulation

• Factors Affecting Enzyme Activity:

  • Temperature: Increased temperature can increase reaction rates, but too high can denature enzymes.

  • pH: Optimal pH increases activity; deviations can reduce function.

  • Substrate Concentration: More substrates mean faster reactions to a limit; saturations occur when all active sites are engaged.

  • Cofactors: Assist enzymes by binding to active sites to enhance activity.

  • Enzyme Inhibitors: Chemicals that decrease enzyme activity by binding to active sites, either reversibly or irreversibly.

Properties of Life

• Seven Properties:

  1. Cellular organization

  2. Homeostasis

  3. Metabolism

  4. Responsiveness

  5. Reproduction

  6. Heredity

  7. Growth

Polysaccharides

• Types and Functions:

  • Starch: Formed by glucose monomers (1-4 linkages); serves as a nutrient source for animals.

  • Glycogen: Highly branched polymer of glucose; releases glucose when energy demand is high.

  • Cellulose: Polymer of glucose (β configuration); key structural component of plant cell walls.

  • Chitin: Similar to cellulose but with nitrogen appendages; forms exoskeletons in arthropods and cell walls in fungi.

Cell Structure and Functions

• Key Organelles:

  • Nucleus: Control center of the cell.

  • Plasma Membrane: Regulates material movement in/out of the cell.

  • Vacuole: Stores materials and maintains hydrostatic pressure.

  • Smooth Endoplasmic Reticulum: Site of lipid synthesis.

  • Chloroplast: Enables photosynthesis.

Ribosomes

• Structure & Function:

  • Composed of large and small subunits made of rRNA and proteins, produced in the nucleolus; essential for protein synthesis.

Ecological Interactions

• Predation: Interaction where a predator consumes another organism.

• Herbivory: Herbivores consume plants.

• Parasitism: Parasite derives benefits at the host's expense.

Greenhouse Effect

• Mechanism: Gases like CO2, water vapor, and sulfur dioxide absorb and reflect radiant energy, contributing to global warming.

Threats to Biodiversity

• Four Major Threats:

  1. Habitat Loss: Due to agriculture, urban development, etc.

  2. Introduced Species: Non-native species disrupt ecosystems.

  3. Overharvesting: Species endangered by unsustainable levels of exploitation.

  4. Global Change: Climate and ecological shifts that threaten life sustainability.

Comparison of Mitosis and Meiosis

• Mitosis: One division yielding two identical diploid cells, affects growth and repair.

• Meiosis: Two divisions yielding four haploid gametes, essential for sexual reproduction.

• Cytokinesis in Animals: Cleavage furrow formation splits the cell.

• Cytokinesis in Plants: Forms a cell plate from vesicles that fuse with the plasma membrane.

Distinction of Cell Types

• Plant Cells:

  • Cell wall present.

  • Regular fixed shape.

  • Large central vacuole.

  • Contain chloroplasts.

• Animal Cells:

  • No cell wall.

  • Irregular shape.

  • Small vacuoles if present.

  • Lysosomes present.

  • Centrosomes present.

Autotrophs vs. Heterotrophs

• Autotrophs: Manufacture their own food from CO2.

• Heterotrophs: Depend on other organisms for nutrition using organic compounds.

Chlorofluorocarbons and Ozone Depletion

• Mechanism: Breakdown products rise to the stratosphere, reacting with ozone (O3) and reducing it to O2, leading to a catalytic chain reaction that depletes the ozone layer.