Unit 1: Cells and organisms
Cells, tissues and organs — HIA International - Grade 6 Revision Notes & Topical Questions
5 min read 8 parts Lesson 5 of 5 3 quizzes
Lesson summary
1.4 Cells, tissues and organs — HIA INTERNATIONAL notes: Describe the levels of organisation in living organisms from cell to organism, with examples of tissues, organs and organ systems.Order — cell, then tissue, then organ, then organ system, then organism.Organism — a living t…
- Specialised cells
- Definition
- Plant example
- Animal example
- Other examples
- Animal organs
Part 1 of 6Levels of organisation
Order
- Order cell, then tissue, then organ, then organ system, then organism.
Organism
- Organism a living thing such as an animal or a plant.
Specialised cells
- Specialised cells most cells in an organism are specialised for a particular activity.
Part 2 of 6Tissues
Tissues
Definition
- Definition a group of similar cells that all work together to carry out a particular function.
Grouping
- Grouping usually many cells of the same kind are grouped together.
Plant example
- Plant example onion epidermis covers the surface of the layers inside an onion.
Animal example
- Animal example ciliated epithelium lines the tubes leading to the lungs, and its cilia wave together to move mucus.
Other examples
- Other examples muscle tissue and xylem tissue.
Part 3 of 6Organs
Definition
- Definition a structure made of several different kinds of tissue working together.
Animal organs
- Animal organs the brain, heart, stomach, intestine, lungs and muscles.
- The brain contains neurones and several other kinds of cell.
Plant organs
- Plant organs leaves, roots, stems and flowers.
- A root contains root hair cells and several other kinds of cell.
Part 4 of 6Tissues in a leaf
Leaf
- Leaf a plant organ made of several tissues.
Upper epidermis
- Upper epidermis the layer covering the top surface.
Palisade layer
- Palisade layer cells packed with chloroplasts for photosynthesis.
Spongy layer
- Spongy layer cells beneath the palisade layer.
Lower epidermis
- Lower epidermis the layer covering the underside.
Part 5 of 6Organ systems
Organ systems
Definition
- Definition a set of organs that all work together to carry out the same function.
Digestive system
- Digestive system organs that break down and absorb food.
Circulatory system
- Circulatory system the heart and blood vessels.
Respiratory system
- Respiratory system organs for gas exchange such as the lungs.
Skeletal system
- Skeletal system bones that support the body.
Part 6 of 6History of the cell idea
| Year | Discovery |
|---|---|
| 1625 | Galileo builds the first microscope |
| 1665 | Robert Hooke sees cork cells and names them cells |
| 1670 | Leeuwenhoek sees living cells in pond water |
| 1833 | Robert Brown discovers the nucleus in plant cells |
| 1838 | Schleiden and Schwann propose that plants and animals are made of cells |
| 1845 | Braun proposes that cells are the basic unit of all life |
| 1855 | Virchow says that all cells arise from other cells |
Key terms
| Term | Meaning |
|---|---|
| Tissue | A group of similar cells that work together to do one function. |
| Organ | A structure made of different tissues working together. |
| Organ system | A set of organs that work together for the same function. |
| Organism | A living thing, made of one or more organ systems. |
| Ciliated epithelium | Tissue lining the airways that moves mucus with cilia. |
| Epidermis | The outer covering layer of cells. |
Avoid these mistakes
1
Saying a tissue contains different cell types — a tissue is a group of similar cells.
2
Thinking an organ and an organ system are the same — an organ system is several organs working together.
3
Forgetting plants have organs — leaves, stems, roots and flowers are plant organs.
4
Mixing up the order of organisation — it goes from cell to tissue to organ to organ system to organism.
Marked practiceQuizzes for this lesson
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