Biology

• An organism is any contiguous living system such as an animal, plant, fungus, protist, archaeon, or bacterium.
• A unicellular organism is an organism that consists of one cell.
• A multicellular organism is made up of many cells.
• A microscopic organism cannot be seen by the human eye without the use of microscope. (E.g. euglena)
• A macroscopic organism can be seen by the plain human eye. (E.g. multicellular organism like animals)
• A microscope in an instrument used to magnify a tiny object.
• The Romans discovered the first lens.
• It was derived from the Latin word lentil - as it resembled the shape of the lentil bean.
• Zacharias Janssen made the first compound microscope.
• Robert Hooke is known to built his own microscope. He used thin slice of cork as a specimen in his microscope.
• Cellula means small compartment. It eventually became the word cell.
• Micrographia is one of the first detailed handbook on microscopy ang imaging
• Anton Van Leeuwenhoek is a scientist who studied the bacteria, blood cell, and protists. He made a microscope which had more powerful magnification than what Hooke built.
• Matthias Jakob Schleiden a professor of botany in Germany. He stated that all plants are composed of cells.
• Theodor Schwann is a professor of physiology at the University of Belgium. He studied several slides of animal tissues in which he stated that animals are composed of cells.
• Postulates of Cell Theory

  • All organisms are made up of cells
  • The basic unit of life is cell
  • All cells come from pre-existing cells.
• Rudolf Ludwig Karl Virchow postulated the idea of Omnis cellula e cellula (All cells come from cells).
• Theory of Spontaneous Generation states that organisms came from non-living things.
• Francesco Redi - was able to disprove the theory that maggots could be spontaneously generated from meat using a controlled experiment.
• John Needham - believed that life can arise spontaneously. He repeated Redi's experiment but yielded different result because he was not successful in killing all microbes while boiling broth.
• Lazzaro Spallanzani - disagreed to the theory of spontaneous generation after observing absence of small organisms in some chicken broth placed in sealed flasks heated for 30 minutes.
• Louis Pasteur - disproved spontaneous generation through an experiment where beef broth was sterilized through boiling in two flasks, one that was exposed to air and another that was protected from it.
• Testosterone - derived from the cholesterol of testes