Natural science

• Scientific Method


  A process used to approach a problem systematically. The aim is to solve it and achieve accurate and reliable results.
• Scientific Method Steps


  1. Investigative question

  2. Hypothesis

  3. Identifying variables

  4. Method

  5. Perform and observe

  6. Results and Interpretation

  7. Conclusion
• Investigative question


  The question must have a question mark. Mention both the independent and dependent variables. The question can't be answered by yes or no.
• Hypothesis


  Your best guess of what the results will be. Mention both variables and the relationship between them.
• Variables


  • Independent variable
  • Dependent variable
  • Controlled/Fixed variables
• Independent variable


  The variable that you control or change.
• Dependent variable


  The variable that changes because the independent variable was changed. This is the one you are going to measure or observe.
• Controlled/Fixed variables


  Aspects that must be kept constant to ensure valid results.
• Method


  A list of apparatus written in list form.
• Perform and observe


  Execute your plan, observe, and collect data.
• Results and Interpretation


  Present your data in appropriate tables and/or graphs. Explain your graphs, tables, and other results in words.
• Conclusion


  Accept or reject your hypothesis and explain the relationship between your variables
• Variables


  Any factor, trait or condition that can exist in varying amounts or types and can change over time.
• Experiment vs Investigation


  • Experiment
  • Investigation
• Experiment


  Questions relationship between two variables – cause and effect, Driven by hypothesis, Follows traditional scientific method
• Investigation


  Answers investigative question, Not always variables, Hypothesis not required
• Experimental control


  The control acts as a comparison to the experiment, Allows scientists to be sure that difference between the results is due to independent variable, The independent variable is absent from the control.
• How to improve validity

  • Validity
  • Reliability
  • Accuracy
• Validity


  Keep all the fixed variables the same.
• Reliability


  Repeat the experiment, Increase the sample size.
• Accuracy


  Measuring the precision, Know how to use the apparatus, Apparatus must work perfectly.
• Tabulation


  Descriptive heading starting the relationship between independent and dependent variable, Independent variable in 1st column, Dependent variable in 2nd column, Content in ink, No units in body of table.
• Graphs


  Heading with both variables, Independent variable on x-axis, Dependent variable on y-axis, Units in brackets after the variable name for the axis, Proper scale on both axes starting at 0 with equal increments, Line graphs are used when both sets of data are continuous and numerical, Bar graphs are used when the independent variable does not represent numerical data, Histograms are used when the independent variable represents groups of continuous data, Pie charts are used to calculate the individual angles with: Amount/Total × 360°.
• Scientific drawings


  Give descriptive heading, Use 10 to 15 lines, Have an accurate shape and perspective, Drawing in pencil, label in pen, No shading or colouring in, Labels must be horizontal and no arrows, Written one below the other, Should be on the right of the drawing, if the isn't enough space, use the left side as well, Lines must be drawn with ruler, Lines must be solid and mustn't cross.
• Indicators


  A quantity that you can measure that illustrates what is happening to the variable, although it never replaces the variable, Indicators are used in the column headings and labels for axes only.
• Cell


  The basic structured and function unit of all living organisms, Microscopic/Unicellular organisms (bacteria) have one cell, Macroscopic/Multicellular organisms (plants) have many cells, Different cell shapes for different functions, All cells have organelles for specific functions.

  
• Cell structure


  • Cell wall (Plants only)
  • Cell membranes
  • Cytoplasm
• Cell wall (Plants only)


  Provides shape and support
• Cell membranes


  Encloses the cell, Allows certain substances into and certain substances out of the cell (Selectively permeable)
• Cytoplasm


  Liquid in which chemical processes take place. Organelles found here

  
• Other organelles


  • Mitochondria
  • Chloroplasts (Plants only)
  • Vacuoles
  • Ribosomes
  • Nucleus
• Mitochondria


  Responsible for cellular respiration (Uses oxygen and glucose to produce energy)
• Chloroplasts (Plants only)


  Responsible for photosynthesis
• Vacuoles


  Stores water, large in plant cells but small in animal cells
• Ribosomes


  Responsible for protein synthesis
• Nucleus


  Surrounded by nuclear membrane, Contains DNA (Hereditary info), Controls the cell functions

  
• Plant cell
• Animal cell
• DNA (Deoxyribonucleic acid)


  Found on our chromosomes in the nucleus of our cells, Made up of two twisted strands called a double helix, The two strands are made up of millions of nitrogen bases that have a unique code, Adenine and Thymine are always linked, and guanine and cytosine are always linked

  
• Uses of DNA


  • To gather evidence in criminal investigations (Forensics)
  • To modify/change/improve plants and animals (Genetic Engineering)
  • To verify people's identity
  • To make vaccines and create hormones like insulin