GCSE BIOLOGY REVISION: CELL SPECIALISATION
Students should be able to, when provided with appropriate information, explain how the structure of different types of cell relate to their function in a tissue, an organ or organ system, or the whole organism.
Cells may be specialised to carry out a particular function:
• sperm cells, nerve cells and muscle cells in animals
• root hair cells, xylem and phloem cells in plants.
Specialisation- the process by which cells develop into specific cells that are meant to carry out the correct function.
Tissue- a group of cells which work together to perform a particular function, for example epithelial tissue in animals and mesophyll tissue in plants.
Organ- a group of tissues which work together to perform a specific function. The lungs are an example of an organ in animals, and the stem is a plant example.
Organ system- a group of organs working together to perform a particular function for example the circulatory system and the respiratory system.
Often examiners will ask a rather vague question about being able to describe a specialised cell, explaining how it is well adapted. Sperm cells and root hair cells are the perfect examples to use when answering these types of questions. The question might be more specific, as the specification clearly states which cells to learn, you must learn all of them! Additionally, they could ask for two examples, in this case it is your choice which two specialised cells you talk about. But there are plenty of other specialised cells you could choose to learn about if you are interested. However, learning unique examples will not give you any extra marks.
The acrosome (the head) contains digestive enzymes which penetrate through the egg
The middle piece is filled with lots of mitochondria for energy release to help propel the cell towards the egg
The tail allows the cell to swim efficiently
Nerve cells extend to reach various parts of the body so that communications can be sent to and from the central nervous system
Extra branches allow further extension and so that the cell can communicate with other nerve cells, muscles and glands
Covered in a fatty myelin sheath which provides insulation, this speeds up the rate of action potentials. The name for this is called salutatory conduction.
Contain protein filaments that slide over one another to cause contraction
Contain many mitochondria to provide energy for contraction
Skeletal muscle merges for contractions to be in unison
Root hair cells
Found in the root of plants
They have the role of absorbing water and minerals found in the soil
They have a large surface area (hair-like projections) allowing easier and efficient uptake
Each root hair cell contains a large number of mitochondria, this provides more energy for active transport.
Absence of end walls to allow easy flow of water
Walls are thick and contain a woody substance called lignin to provide support and prevent collapse
Assimilates can be transported up and down the stem
Has a companion cell to provide energy for transport