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1.4Unit 1: Cells and organisms

Cells tissues and organs

5 min read 5 parts Lesson 4 of 4 1 quiz

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Lesson summary

1.4 Cells tissues and organs — CHECKPOINT BIOLOGY 0893 notes: Describe the levels of organisation from cell to organism and give examples of tissues, organs and organ systems.Cell — the unit every organism is built from.Tissue — a group of similar cells working together on the sa…

  • Plant example
  • Animal example
  • Ciliated epithelium
  • Tissue — a group of similar cells working together on the same job
  • Organ — several tissues working together on a bigger job
  • Organ system — several organs working together

Section 1 of 5Levels of organisation

  • Cell
    • the unit every organism is built from.
  • Tissue
    • a group of similar cells working together on the same job.
  • Organ
    • several tissues working together on a bigger job.
  • Organ system
    • several organs working together.
  • Organism
    • the whole living thing, such as a plant or an animal.

Section 2 of 5Tissues

  • Tissue = a group of similar cells that all work together to carry out a particular function.
  • Most cells in an animal or plant are specialised, and many cells of the same kind are grouped together.
  • Plant example
    • onion epidermis, the tissue that covers the surface of the layers inside an onion.
  • Animal example
    • ciliated epithelium, the tissue lining the tubes leading to the lungs.
    • The cilia all wave together like grass in the wind.
  • Another animal example is muscle tissue, made of muscle cells that contract together.

Section 3 of 5Organs

  • Organ = a structure made of several different kinds of tissue working together.
  • Animal organs include the brain, heart, stomach, intestine, lungs and muscles.
  • Plant organs include leaves, roots and flowers.
  • A brain contains neurones and several other kinds of cell.
  • A plant root contains root hair cells and several other kinds of cell.

Section 4 of 5A leaf as an organ

  • A leaf is a plant organ made of several different tissues.
    • Upper epidermis.
    • Palisade layer.
    • Spongy layer.
    • Lower epidermis.

Section 5 of 5Organ systems

  • Organ system = a set of organs that all work together to carry out the same function.
  • Examples in humans:
    • The digestive system.
    • The circulatory system, made of the heart and blood vessels.
    • The respiratory system.
    • The skeletal system.

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