Life sience

• The cell is the basic unit of life of all living organisms
• Structural unit


  All living organisms consist of one or more cells. UNICELLULAR organisms consist of ONE cell. MULTICELLULAR organisms are made up of many cells.
• Functional unit


  Cells are the functional unit because they can perform all the functions that characterise life: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
• Levels of organisation


  • Atoms
  • Molecules
  • Cells
  • Tissues
  • Organs
  • Body systems
• Atom


  Smallest unit of matter made up of protons, neutrons and electrons
• Molecules

  A group of atoms
• Mitochondrion


  • Has a double membrane
  • Inner folds are called cristae
  • Has fluid called the matrix
• Mitochondrion


  • Responsible for cellular respiration
  • Glucose is broken down in the presence of oxygen to release energy
  • Carbon dioxide and water are released as waste products
  • Energy is stored in ATP molecules
  • Referred to as the "powerhouse" of the cell
• Mitochondria are found in animal and plant cells
• Chloroplast


  • Flat, round organelle
  • Contains a green pigment called chlorophyll
  • Chlorophyll traps light energy from the sun during photosynthesis
• Chloroplasts are found only in plant cells
• Vacuole


  • A fluid-filled sac inside the cell
  • Surrounded by a membrane called a tonoplast
  • In plant cells, there is usually one large vacuole
  • Contains a fluid called cell sap
  • In animal cells they are usually absent or small
• Vacuole


  • Stores water, dissolved sugars and salts and waste substances
  • When full, it helps to keep the cell firm/turgid
• Diagram A depicts a plant cell
• Diagram B depicts an animal cell
• Parts of Diagram A and B

  • Cell membrane
  • Nucleus
  • Nuclear membrane
  • DNA
  • Cytoplasm
  • Mitochondrion
  • Vacuole
• Function of parts in Diagram A

  1. Cell membrane

  2. Cytoplasm

  3. Nucleus

  4. DNA
• Function of parts in Diagram B

  1. Cell membrane

  2. Nucleus
• Types of cells


  • Epithelial cell
  • Red blood cell
  • Nerve cell (neurons)
  • Muscle cell
  • Sperm cell
  • White blood cell
  • Skin cell
• Muscle cells


  • Produce power to contract and relax, causing movement
• Red blood cells


  • Have no nucleus and transport oxygen through the body
• White blood cells


  • Protect the blood and organs from infections by fungi, bacteria and viruses
• Egg


  • Contains half (haploid) of the female organism's DNA for reproduction
• Sperm


  • Contains half (haploid) the male organism's DNA for reproduction
• Skin cells


  • Prevent moisture loss and protect the organism against infections
• Stem cells


  • Undifferentiated cells in the human body
  • Able to divide and develop into many different cells
  • Have the ability to become differentiated
• Sources of stem cells

  • Umbilical cord of a newborn baby
  • Human embryos (raises ethical issues)
• Adult stem cells


  • Come from fully developed tissues such as the brain, bone marrow and skin
  • Only generate certain types of cells
  • Induced pluripotent stem cells are adult stem cells changed in the lab to be more like embryonic stem cells
• Uses of harvested stem cells

  • Replace damaged tissues and organs
  • Treat diseases like diabetes, leukaemia, osteoporosis
• Tissues, organs and systems


  • In single-celled organisms, the individual cell performs all life processes
  • In multicellular organisms, cells are specialised to perform specific functions
  • Specialised cells group together to form tissues
  • Groups of tissues that work together form organs
  • Groups of organs that work together form systems
• Organelles


  Structures within individual cells that perform specific functions to keep the cell alive. Examples include the nucleus, mitochondria, and ribosomes.
• Tissues


  Groups of specialized cells that work together to perform a specific function for the entire organism. There are four main types of tissues in the human body: epithelial, connective, muscle, and nervous.
• Stem cells


  Undifferentiated cells in the human body; able to divide and develop into many different cells; have the ability to become differentiated
• Adult stem cells


  Stem cells found in adults; more limited in their ability to differentiate than embryonic stem cells
• What is the primary function of the circulatory system?

  To transport nutrients and oxygen to body cells and waste substances away from cells.
• Why is glucose important for the body?

  It is a necessary nutrient that must be delivered to the cells.
• What are the two main processes of the circulatory system?

  Circulating blood between the heart and lungs, and circulating blood between the heart and body.
• What are the main components of the circulatory system?

  1. Blood
  2. Blood vessels
  3. Heart
• What is blood and what does it transport?

  Blood is the fluid that moves in blood vessels and transports substances around the body.