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.