Resumen biologia ib
2.1.1 Outline the Cell Theory * Living organisms are composed of one or more cells * Cells are the smallest unit of life * Cells must come from pre-existing living cells
2.1.2 Discuss the evidence for the cell theory
The cell theory has amassed tremendous credibility through the use of the microscope in the following: * Robert Hooke- studied cork and found little tiny compartments that he called cells * Antonie Van Leeuwenhoek- observed the first living cells, called them 'animalcules' meaning little animals * Schleiden- stated that plants are made of 'independent, separate beings' called cells * Schwaan- made a similar statement to Schleiden about animals
2.1.3 State that …ver más…
State that a virus is a non-cellular structure consisting of DNA or RNA surrounded by a protein coat. * Viruses are not cells. They are simple particles consisting of DNA and RNA wrapped in a protein coat. Viruses are not considered alive because they have no metabolism and they require a host to live. Viruses do not carry out all the functions of life, therefore they are not living.
Explain three advantages of using light microscopes.
Light microscopes * Display color instead of monochrome (black and white) images. * Provide a large field of view. * Facilitate preparation of sample material. * Allow for the examination of living material and the observation of movement. * Cheap in comparison to electron microscopes
Outline the advantages of using electron microscopes.
Electron microscopes: * Provide images of higher resolution and magnification than light microscopes. * Resolution refers to the ability to distinguish two objects as separate entities. * Magnification refers to the ability to increase the size of a viewed object.
Scanning Electron Microscopes (SEM) provide images of the specimen's surface while Transmission Electron Microscopes (TEM) provide images of a sample's interior. The resolution of an SEM is approximately half that