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Comprehensive Overview of Biology Concepts

May 29, 2025

Biology Lecture Notes

Introduction to Cells

  • Ribosomes help build proteins.
  • Eukaryotic Cells: Have a nucleus.
    • Example: Animal and plant cells.
  • Prokaryotic Cells: Lack a nucleus (e.g., bacteria).
    • Small, colorless, require staining to be seen.
    • Types of DNA: Chromosomal, Plasmid.

Specialised Cells

  • Examples: Muscle, red and white blood cells, sperm, egg, root hair cells.
  • Humans are multicellular with specialised cells.
  • Resolution: Ability to distinguish between two separate points.

Microscopy

  • Magnification: Eyepiece lens x objective lens.
  • Scale bars show real length of magnified images.

Enzymes

  • Proteins crucial for digestion.
  • Denaturation: Change in enzyme's shape due to heat or pH.
  • Factors Affecting Enzyme Activity: pH, temperature, substrate concentration.

Calorimetry

  • Measures energy in food (in joules).
  • Energy transferred = mass x specific heat capacity x temperature rise.

Transporting Substances

  • Diffusion: Movement from high to low concentration.
  • Semi-permeable membranes allow selective diffusion.
  • Osmosis: Movement of water particles from high to low concentration.
  • Active Transport: Movement against the concentration gradient, requires energy.

Growth and Stem Cells

  • Growth: Increase in number of cells via mitosis.
  • Stem Cells: Undifferentiated, can become various cell types.
  • Embryonic vs Adult Stem Cells: Differ in differentiation potential.

Nervous System

  • Stimulus: Change detected by receptors.
  • Receptor Cell: Converts stimulus into electrical impulse.
  • Reflex actions are automatic, involve the spinal cord.
  • Synapse: Gap between neurons, neurotransmitter transmission.

Genetics

  • Alleles: Different forms of the same gene.
  • Homozygous/Heterozygous: Allele pair configurations.
  • Mutations: Changes in DNA sequence affecting protein structure/function.

Evolution

  • Natural selection drives adaptations.
  • Antibiotic resistance as an example of evolution in bacteria.

Classification

  • Organisms classified to produce fertile offspring.
  • Five Kingdoms: Animals, Plants, Fungi, Protists, Prokaryotes.

Health and Disease

  • Wellbeing includes physical, mental, social aspects.
  • Cardiovascular Disease: Leading cause of mortality, influenced by lifestyle.
  • Immune System: White blood cells, lymphocytes, phagocytes.

Photosynthesis

  • Equation: Carbon dioxide + water → glucose + oxygen.
  • Affected by light intensity, CO2 concentration, temperature.

Transport in Plants

  • Xylem: Water/mineral transport.
  • Phloem: Sugar transport.
  • Transpiration and translocation processes.

Homeostasis

  • Maintenance of optimal internal conditions.
  • Endocrine System: Hormones regulate body functions.

Human Reproductive System

  • Hormones involved: Adrenaline, oestrogen, thyroxine.
  • Menstrual cycle regulated by FSH, LH, oestrogen, progesterone.

Diabetes

  • Blood sugar regulation via insulin and glucagon.
  • Differences between Type 1 and Type 2 diabetes.

Ecology and Biodiversity

  • Human impacts: Deforestation, fish farming.
  • Preservation of biodiversity with non-indigenous species management.

The Carbon and Nitrogen Cycles

  • Carbon cycled through atmosphere via photosynthesis, respiration.
  • Nitrogen Cycle: Essential for DNA and protein formation.

Fieldwork Techniques

  • Quadrats: Estimate biodiversity in fields.
  • Belt Transects: Analyze variation across habitats.