Biology A-Level Paper One Overview

Introduction

• Video covers all necessary knowledge for AQA A-level Biology Paper One.
• Resources available for additional help (notes, flashcards).

Biological Molecules

• Monomers and Polymers:
  • Monomers: small units, e.g., glucose, amino acids, nucleotides.
  • Polymers: large molecules formed by monomers, e.g., starch, proteins, DNA.
  • Reactions:
    • Condensation (joining with water release).
    • Hydrolysis (breaking with water addition).

Carbohydrates

• Types:
  • Monosaccharides: e.g., glucose, fructose, galactose.
  • Disaccharides: e.g., sucrose, maltose, lactose.
  • Polysaccharides: e.g., starch, cellulose, glycogen.
• Structure:
  • Difference between alpha and beta glucose.
  • Glycosidic bonds form between monosaccharides.
  • Structural differences lead to functional differences.

Lipids

• Types:
  • Triglycerides
  • Phospholipids
• Structure:
  • Both have glycerol backbones.
  • Triglycerides have 3 fatty acid chains; phospholipids have 2 and a phosphate group.
  • Saturated vs. unsaturated fatty acids.
• Functions:
  • Energy storage, metabolic water source, insulation.

Proteins

• Made of amino acids linked by peptide bonds.
• Structure Levels:
  • Primary: amino acid sequence.
  • Secondary: alpha helices, beta sheets.
  • Tertiary: 3D shape due to interactions.
  • Quaternary: multiple polypeptide chains.

Enzymes

• Proteins in tertiary structure.
• Catalyze reactions by lowering activation energy.
• Specificity due to active site shape.
• Models:
  • Lock and Key
  • Induced Fit

Factors Affecting Enzyme Activity

• Temperature, pH, substrate/enzyme concentration, inhibitors.

Biochemical Tests

• Specific tests for carbohydrates, proteins, lipids.

Nucleic Acids

• DNA & RNA:
  • DNA: genetic material, forms double helix.
  • RNA: single-stranded, involved in protein synthesis.
• Replication:
  • Semi-conservative replication.

ATP

• Structure similar to nucleotides.
• Immediate energy source.

Water

• Essential properties due to polarity and hydrogen bonding.
• Functions in temperature regulation and as a solvent.

Inorganic Ions

• Roles in processes like pH regulation, oxygen transport, co-transport.

Cell Structure

• Key organelles in eukaryotic and prokaryotic cells.
• Differences between eukaryotes, prokaryotes, and viruses.

Microscopy

• Types: optical, electron (transmission and scanning).
• Resolution and magnification differences.

Cell Division

• Mitosis and Meiosis:
  • Mitosis: growth, repair (genetically identical cells).
  • Meiosis: gamete production (genetic diversity).

Membranes and Transport

• Membrane structure: Fluid mosaic model.
• Transport types:
  • Diffusion (simple and facilitated).
  • Active transport, co-transport.
  • Osmosis.

Immunity

• Specific vs. Non-specific responses:
  • Phagocytosis as non-specific.
  • T and B cells in specific immunity.
• Antibodies and Vaccines:
  • Antibody structure and function.
  • Principles of vaccinations and herd immunity.

Exchange and Transport

• Surface area to volume ratio: Importance in gas exchange.
• Ventilation in animals: Human lungs, insect tracheal system, fish gills.
• Plant adaptations: Xerophytes and their adaptations.

Digestion and Absorption

• Enzymatic breakdown of carbohydrates, lipids, proteins.
• Specialized absorption mechanisms in the ileum.

Mass Transport

• In Humans:
  • Circulatory system, heart structure, cardiac cycle.
  • Blood vessels and tissue fluid dynamics.
• In Plants:
  • Transpiration and the cohesion-tension theory.
  • Phloem transport (translocation).

Genetic Information

• DNA and RNA structures, protein synthesis.
• Genetic diversity through mutations and meiosis.

Populations and Evolution

• Natural selection and types of selection.
• Classification:
  • Species, taxonomy, phylogenetic classification.
  • Courtship behaviors in species recognition.

Biodiversity

• Measuring biodiversity, conservation strategies.
• Impact of human activities on biodiversity.
• Calculating index of diversity.

This summary captures key details from the lecture, organized for study and review. Please refer to any additional materials for deeper insights into each topic.