Biology

Cards (333)

  • Cells
    The basic unit of life that can be found in every living thing, including humans, animals, plants and bacteria
  • Cells
    • Small in structure, 0.1 to 5.0 μm in diameter for prokaryotic cells, 10 to 100 μm in diameter for eukaryotic cells
    • Have general structures that allow them to be self-regulating, such as producing energy, movement, removing wastes etc.
  • Unicellular organism

    Living things that are made of a single cell, such as bacteria
  • Multicellular organism

    More complex organisms like humans, animals and plants
  • All known living things are made up of one or more cells
  • All living cells arise from pre-existing cells by division
  • The cell is the building block of structure and function in all living organisms
  • The activity of an organism depends on the total activity of independent cells
  • Cells are the site of all chemical reaction of life (metabolism and energy flow)
  • Cells contain hereditary material (DNA), the blueprint for their cell growth, development and behavior
  • All cells are basically the same in chemical composition in organisms of similar species
  • Prokaryotes
    Earliest organisms on earth, mostly unicellular, lack well-defined nuclei and membrane-bound organelles, have a single circular chromosome, classified into Bacteria and Archaea
  • Eukaryotes
    More complex and evolved organisms, can be unicellular (algae, protozoa) or multicellular (animals, plants, fungi), have a nucleus wrapped in a nuclear membrane and membrane-bound organelles
  • Similarities between prokaryotes and eukaryotes

    • Ribosome
    • DNA
    • RNA
    • Cytoplasm
  • Differences between prokaryotes and eukaryotes
    • Circular DNA (prokaryotes) vs Complex and extensive DNA (eukaryotes)
    • No nucleus (prokaryotes) vs Have nucleus (eukaryotes)
    • Mostly unicellular (prokaryotes) vs Can be uni- or multicellular (eukaryotes)
    • All have cell wall (prokaryotes) vs Some do contain cell wall (eukaryotes)
    • Few organelles (prokaryotes) vs Have membrane bound organelles (eukaryotes)
    • Small in size (prokaryotes) vs Larger in size (eukaryotes)
  • Similarities between plant and animal cells
    • Mitochondrion
    • Golgi apparatus
    • Rough and smooth endoplasmic reticulum
    • Nucleus
    • Cytoplasm
    • Ribosomes
  • Differences between plant and animal cells
    • Cell wall (plants) vs No cell wall (animals)
    • Large vacuole (plants) vs Small or no vacuole (animals)
    • Chloroplasts (plants) vs No chloroplasts (animals)
    • Flagella only in gametes (plants) vs Flagella (animals)
  • Theoretically it is possible to build a living organism from cells
  • Applications of prokaryotic cells

    • Cleaning up oil spills
    • Decompose organic matter into sludge
    • Produce vitamins, antibiotics, hormones (e.g. insulin)
    • Amplify DNA, cloning and genetic manipulation
  • Applications of eukaryotic cells

    • Mammalian cell biology - DNA replication, gene expression, cell division etc.
    • Drug discovery and screening
    • Transgenic crop plants - make corn resistant to specific insect pest
    • Transgenic animals - production of pharmaceutically important protein
  • The seven characteristics of life are: cells and organisation, metabolism, responsiveness and movement, growth and development, reproduction, homeostasis, and evolution
  • Levels of organisation in the human body

    • Atoms and molecules
    • Cells
    • Tissues
    • Organs
    • Organ systems
    • Organism
  • Types of stem cells
    • Totipotent stem cells
    • Pluripotent stem cells
    • Multipotent stem cells
  • Examples of cells adapted to their function

    • Muscle cells with myofilaments to contract and relax
    • Nerve cells with axons and dendrites to produce and move nerve impulses
    • Red blood cells with biconcave shape and haemoglobin to carry oxygen
    • Intestinal epithelial cells with microvilli to increase surface area for nutrient absorption
  • My Healthy Plate

    Recommended diet for average Singaporean to maintain a balanced diet
  • Tim adjusted his diet in order to lose weight
  • Alan, Marilyn and her friends are aspiring athletes wanting to achieve their goals in weightlifting and marathon running respectively
  • Adhesion
    The attraction between unlike molecules or surfaces
  • Cohesion
    The attraction between like molecules or surfaces
  • Density
    The mass per unit volume of a substance
  • Hydrophobic
    Having a tendency to avoid or repel water
  • Hydrophilic
    Having a tendency to attract or be attracted to water
  • Inter-molecular

    Occurring between molecules
  • High specific heat capacity
    The amount of heat required to raise the temperature of a substance by one degree
  • Intra-molecular

    Occurring within a molecule
  • Non-polar

    Having no permanent electric dipole moment
  • Polar
    Having a permanent electric dipole moment
  • Solvent
    A liquid that dissolves a solute, forming a solution
  • Solutes
    A substance dissolved in a solvent to form a solution
  • Surface tension

    The cohesive force between the surface molecules of a liquid that causes the surface to behave like an elastic sheet