Key concepts in Biology

• Five kingdoms of living organisms


  • Animals
  • Plants
  • Fungi
  • Protoctists
  • Prokaryotes
• Eukaryotic organisms


  • Animals
  • Plants
  • Fungi
  • Protoctists
• Eukaryotic organisms


  Organisms that are made up of cells that contain a nucleus with a distinct membrane
• Prokaryotic organisms


  Organisms that are always single-celled and do not contain a nucleus, with the nuclear material found in the cytoplasm
• Eukaryotic organisms can be multicellular or single-celled
• Eukaryotic cells


  • Animal cell
  • Plant cell
• Prokaryotic cells are substantially smaller than eukaryotic cells
• Bacteria are prokaryotic organisms
• Main features of animals

  • Multicellular
  • Cells contain a nucleus with a distinct membrane
  • Cells do not have cellulose cell walls
  • Cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
  • Feed on organic substances made by other living things
  • Often store carbohydrates as glycogen
  • Usually have nervous coordination
  • Able to move from place to place
• A typical animal cell
• Main features of plants

  • Multicellular
  • Cells contain a nucleus with a distinct membrane
  • Cells have cell walls made out of cellulose
  • Cells contain chloroplasts (so they can carry out photosynthesis)
  • Feed by photosynthesis
  • Store carbohydrates as starch or sucrose
  • Do not have nervous coordination
• A typical plant cell
• Chromosomes are made up of DNA and proteins
• DNA contains genetic information that determines an organism's characteristics
• The nucleus is the control centre of the cell, containing DNA which controls all activities within the cell.
• DNA is the genetic material that contains instructions for making all the different parts of an organism.
• The structure of DNA consists of two strands twisted around one another, forming a double helix. The bases of these strands pair together according to complementary base pairs - Adenine always pairs with Thymine, and Cytosine always pairs with Guanine.
• Ribosomes are responsible for protein synthesis.
• Proteins act as enzymes, which control chemical reactions within cells.
• The structure of chromosomes is the same in all human body cells but differs between males and females.
• Mitochondria produce energy through respiration.
• Vacuoles store water, waste products, pigments, and enzymes involved in digestion.
• Ribosomes are where protein synthesis occurs.
• Vacuoles store water and other substances such as pigments and waste products.
• Protein synthesis involves transcription (the process by which RNA copies sections of DNA) and translation (the process by which amino acids join together to form polypeptide chains).
• Cell membranes regulate what enters or leaves the cell.
• Protein synthesis involves transcription (the process by which RNA copies sections of DNA) and translation (the process by which ribosomes use mRNA as a template to make amino acids).
• Chloroplasts contain chlorophyll and carry out photosynthesis.
• Amino acids join together through peptide bonds to form polypeptides or proteins.
• Vacuoles store water and waste products.
• Nucleus contains genetic material (DNA) that controls cell activity.
• The nucleus contains genetic material that controls all activities within the cell.
• Mitochondria are responsible for aerobic respiration and energy production.
• Mitochondria produce ATP through aerobic respiration.