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Form 1 Chapter 2- Cell as a Unit of Life



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PT3 Science Form 2, Chapter 2 Cell as a Unit of life.

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Form 1 Chapter 2- Cell as a Unit of Life

  2. 2. What is CELL? – BASIC UNITS OF LIVING THINGS Cells All Living Organisms are made out of cells Animals Plants Humans Smallest unit Function and survive on its own Growth, respiration, division and excretion Will die out eventually. All new cells are formed by cell division of other cells (mitosis). Different sizes and shapes Long, short, oval, has tail
  4. 4. WHO ARE THEY? • Theodor Schwann • In 1893, he asserted that plants and animals are made up of cells
  7. 7. MULTICELLULAR ORGANISMS Sporangium contains spores. It is light at first and it be dark and darker as it matures. The spores inside will explode to the surface and it will continue growing.
  10. 10. ORGANS
  11. 11. SYSTEMS
  13. 13. DO YOU KNOW? • Biggest cell in our body is MEGAKARYOCYTE ( a kind of blood cell) , which have a diameter of 0.2mm. They are found in bone narrow to prevent bleeding.
  14. 14. DO YOU KNOW? • The smallest and longest living cell in our body is the brain cell


  • 1. Cells are the basic units of living things 2. cells come in different sizes and shapes. Some are long, short, oval, elongated and got a tail. 3. all living organism are made out of cells. What are living organism? You and I, humans, animals and plants. 4. cell is the smallest unit of living things. 5. it can function on its own. For example, growth, respiration ( breathing), division, excretion. 6. Like all living things, cells will die eventually. All new cells are formed by cell division of other cells which are called mitosis.
  • A microscope makes an object looks bigger than it actually is, it magnifies the object. It used to observe objects which are not visible using naked eyes. Cells of livings things can be observe using a microscope.
    How to use microscope?
    Firstly, when moving your microscope, always carry with both of your hands. One hand you hold on the arm, the other holding the base. So it gives a maximum support on the microscope.
    Turn the revolving nosepiece so that the lowest objective lens is “clicked” on to its position. The shortest lens is the lowest objective lens.
    Your microscope slide should be prepared with a cover slip or a cover glass over the specimen. Place the microscope slide on the stage and fasten it with the stage clips. So why do you need cover the slip with the cover slip? This is because, when you lower your objective lens, it would not touch your specimen. This is to protect your objective lens.
    Look at the objectives lens and the stage from the side and turn the coarse focus knob so that the objective lens move downwards.
    Now look through the eyepiece and adjust the illuminator (or mirror) and diaphragm for the greatest amount of light.
    Slowly turn the coarse focus knob so that the objective lens goes up (away from the slide). Continue until the image comes into focus. Use the fine focus knob, if available for fine focusing.
    Now you should be able to change to the next objective lenses with only minimal use of focusing adjustment. Use the fine adjustment if available. If you can’t focus on your specimen, adjust with the coarse and fine focus knob with higer power objective lens. So not allow objective lens to touch the slide.
    What do you have to keep in your mind when using microscope?
    When moving your microscope, always carry with both your hands.
    Your microscope slide should be prepared with a cover slip. Why? This is to prevent your objective lens touch your specimen and to protect your objective lens.
    Do not allow objective lens to touch the slide
    Look through the eyepiece with one eye and keep the other open. This is to prevent eye strain.
    Remember everything is upside down and backwards. When you move the slide to the right, the images goes to the left.
    Do not touch the glass part of the lenses with your fingers. Use only special lens paper to clean the lenses.
    When finish, raise the tube or lower the stage, click the low power lens in to position and remove the slide. Always leave your microscope in position of the lowest power.
    Always keep your microscope covered when is not in use. Dust is the no1 enemy.
  • -Living things that with only one cell are called unicellular organisms.
    -Unicellular organisms have a very small body size which can only be seen through a microscope.
    -Unicellular organisms usually live in water or in wet place.
    -There are two type of unicellular organisms: (a)Unicellular animals: Amoeba, Paramecium, Plasmodium (b)Unicellular plants: Chlamydomonas, Yeast, Euglena, Pleurococcus
    Example of unicellular organism that we always use is yeast which is use for baking.
    -Unicellular organisms carry out all of the life process such as moving, feeding, reproducing, breathing, and excreting
  • -Living things which made up from various type of cells are called multicellular organisms. Each cell has a different structure and carries out certain body functions.
    -There are a lot of multicellular organisms around us. They are bigger in size because they have large number of cells and therefore, we can see them.
    -There are two type of multicellular organisms: (a) Multicellular animals: Hydra, bird, fish        (b)Multicellular plants: Spirogyra, Mucor (fungus), Grass
    In multicellular organisms, all cells perform their own specialized functions
  • We human body have more than 200 different types of cells. Different type of cells have different shapes and structure to carry out different function. This is known as cell specialization. Cell specialization allows the organisms to perform the various life processes efficiently.
    - Muscle cells enable us to contract and relax our body parts
    -The epithelial cells protects the cells beneath them.
    Red blood cells in our vein carry oxygen in our body. These cells also help to remove carbon dioxide in our body.
    White blood cells kill bacteria inside our body.
    Fat cells store fats
    Connective cells join another type of cells together.
    Nerve cells carry messages around our body.
  • A group of similar cells carry out that carry out the same function will form tissue. For example, a group of muscle cells form muscle tissue. Two or more types of tissue would form an organ. Example like the brain, the heart, the lungs are example of organs.
  • When several type of organs work together, they form a system.
  • The body systems allow us to perform daily activities normally and efficiently. All these function of the systems are control by the brain. When the systems work together, this mean we are complex organisms.
  • Example, we take muscle cell. It start of with one muscle cell, but one cell can’t perform, so many of muscle cells work together. And when they work together, it’ll form tissue. These muscle tissue get help from bone tissue and nerve tissue to make the arm move. Complex organisms have systems that help them to perform in their daily life.
  • MEGAKARYOCYTE is young immature platelet cell. Platelet cell are used for blood clothing.
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