levels of organisation

• What happens to cells in multicellular organisms?


  Cells become specialised.
• What is a tissue?


  A tissue is an aggregation of similar cells working to form a specific function.
• How are organs defined in biological terms?

  Organs are aggregations of tissues working to perform similar functions.
• What are organ systems?


  Organ systems are groups of organs.
• What is the hierarchy of biological organization from organelles to organ systems?

  • Organelles
  • Cells
  • Tissues
  • Organs
  • Organ systems
• What are the three main types of tissues?

  • Epithelial tissues
  • Connective tissues
  • Muscle tissues
• What is the basement membrane in epithelial tissues?

  The basement membrane is an additional layer that epithelial cells sit on.
• Where are epithelial tissues commonly found?


  Epithelial tissues are found covering surfaces and are often sites of absorption.
• What is a characteristic of epithelial tissues regarding blood vessels?

  Epithelial tissues have no blood vessels but may have some nerve endings.
• What is the secretory function of epithelial tissues?

  Epithelial tissues often have a secretory function and are made of collagen and protein.
• What shape do columnar epithelial cells have?

  Columnar epithelial cells are tall and appear column-shaped.
• Where can columnar epithelium be found in the body?

  Columnar epithelium can be found in many areas, including the small intestine.
• What is the function of microvilli on columnar epithelial cells?

  Microvilli increase the surface area for absorption.
• What shape do cuboidal epithelial cells have?

  Cuboidal epithelial cells are cube-shaped with equal height and width.
• Where can cuboidal epithelium be found?

  Cuboidal epithelium can be found in the lining of the proximal convoluted tubules in the kidney.
• What is the role of cuboidal epithelium in the kidneys?

  Cuboidal epithelium reabsorbs useful substances filtered out of the blood.
• What is the characteristic of squamous epithelial cells?

  Squamous epithelial cells are very thin and often line the alveoli in the lungs.
• Why are squamous epithelial cells important for gas exchange?

  Squamous epithelial cells being very thin reduces the diffusion distance for gas exchange.
• What is the function of ciliated epithelial cells?

  Ciliated epithelial cells have cilia that can move and are involved in moving mucus and other substances.
• Where can ciliated epithelium be found?

  Ciliated epithelium is found in the trachea and fallopian tubes.
• What is the role of cilia in the trachea?

  Cilia in the trachea help move mucus out of the lungs.
• What is the role of cilia in the fallopian tubes?


  Cilia in the fallopian tubes set up a current to move an embryo into the uterus.
• What are the types of connective tissues?

  • Loose connective tissue
  • Fibrous connective tissue
  • Adipose tissue
  • Bone tissue
  • Cartilage
  • Blood
• Where is loose connective tissue found?

  Loose connective tissue is found between layers of tissues, such as under the skin.
• What is the function of fibrous connective tissue?

  Fibrous connective tissue is found in tendons and joins muscles to bones.
• What is the role of adipose tissue?

  Adipose tissue stores fat for energy, protection, thermal insulation, and buoyancy.