kiahs notes

• Controlled variable

  All variables in the experiment must be made constant so they don't affect the results
• Extraneous/uncontrolled variable


  Any controlled variable that is controlled but actually changes in the experiment, these cause an unwanted effect on the results
• Control group


  A group of individuals/samples that are not exposed to the IV, not tested and used as a comparison
• Personal error

  Mistakes or miscalculations by the experimenter
• Systematic error


  Errors that cause results to differ from the true value by a consistent amount each time, typically due to faulty equipment or calibration, affect accuracy and cannot be minimised by replication
• Random error


  Errors that are caused by unpredictable variations in the measurement process and result in a spread of readings
• Accuracy


  Collected data is close to true value
• Precision

  Collected data is close to each other
• Ethical approaches

  • Consequence-based
  • Duty-based/rule-based
  • Virtues-based
• Ethical concepts

  • Integrity
  • Justice
  • Beneficence
  • Non-maleficence
  • Respect
• Prokaryotic cells


  • Lacks a nucleus
  • Singular loop of circular DNA
  • May contain smaller units of DNA called plasmids
• Both prokaryotic and eukaryotic cells have

  • Plasma membrane
  • Cytosol
  • Ribosomes
  • DNA
• Eukaryotic cells


  • Contain many membrane-bound organelles
  • Multiple linear chromosomes of DNA packed in a nucleus
  • Tend to be larger than prokaryotes
• Eukaryotic cell replication

  1. Somatic cells usually duplicate through mitosis

  2. Germline cells split into 4 individual gametes through meiosis
• Prokaryotic cell replication

  Replicate via a similar process known as binary fission
• Prokaryotes


  A group of single-celled organisms with no nucleus and a circular loop of DNA
• Prokaryotes


  • Bacteria, Archaea
• Eukaryotes


  A group of single and multi-celled organisms with a nucleus and linear strands of DNA
• Eukaryotes

  • Fungi, Animals, Protists
• Characteristics of living things

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Equilibrium
  • Excretion
  • Nutrients
• Cell theory

  All living things are made up of cells, cells are the smallest unit of a living thing and all cells come from pre-existing cells
• Homeostasis


  The maintenance of a relatively stable internal environment in the body despite changes in the external environment
• Organism


  A living thing made up of one or more cells
• Cell organelles and functions

  • Cytosol
  • DNA/deoxyribose nucleic acid
  • Chromosome
  • Nucleus
  • Ribosomes
  • Rough endoplasmic reticulum (RER)
  • Smooth endoplasmic reticulum (SER)
  • Golgi apparatus
  • Lysosome
  • Plasma membrane/cell membrane
• Plasma membrane/cell membrane

  • A phospholipid bilayer that is embedded with proteins, carbs and cholesterol
  • Separates the intracellular environment from the extracellular environment, it is selectively permeable and is studded with many molecules
• Phospholipid


  A singular phospholipid has a polar phosphate head and 2 non-polar hydrophobic fatty acid tails
• Hydrophilic


  Water loving
• Hydrophobic


  Water fearing/ repels water
• Fluid mosaic model


  Molecules that make up the membrane are not held static in one place and various types of molecules are embedded in the plasma membrane
• Hot temperatures

  Cause phospholipids to drift apart
• Cold


  Makes the membrane rigid (hard to transfer substances)
• Cholesterol


  Has large hydrophobic regions which can increase the nonpolar interactions between fatty acid tails in hot environments, keeping them from drifting apart. However, cholesterol also takes up room in the membrane, preventing phospholipids from packing too tightly when it is cold.
• Unsaturated fatty acids


  Have tails with kinks due to double and triple bonds between carbon atoms. The kinks push phospholipids away from each other increasing fluidity in cold environments.
• Saturated fatty acids

  Phospholipids with saturated fatty acids can pack tightly as carbons are bound by single bonds with no kinks.
• Protein structure

  • Integral protein
  • Transmembrane protein
  • Peripheral proteins
• Functions of proteins


  • Transport, channels or pumps that control what enters or exits the cell making the plasma membrane selectively permeable
  • Catalysis, speeding up chemical reactions with the help of a protein group called enzymes
  • Communication, receive signals or recognise cells and molecules. Often attached to the cytoskeleton to transmit signals into the cell
• Carbohydrates structure

  Usually in chains that extend outside of the cell, rooted in the membrane to lipids (glycolipids) or proteins (glycoproteins)
• Carbohydrates functions

  Aid with cell-to-cell communication, signalling, and recognition of self or foreign molecules and adhesion
• Cholesterol functions

  Regulates the fluidity of the membrane. At higher temperatures, the cholesterol keeps the phospholipids bound together, at lower temperatures, cholesterol disrupts the fatty acid tails, stopping phospholipids from becoming a solid boundary.
• Passive transport


  Transport of substances that do not require ATP