1. Understand that cells can become specialised and that their structures are related to their specific functions, as illustrated by examples covered in the syllabus
When the cells are specialised
- They do a special job
- They develop a distinct shape
- Special kinds of chemical changes take place in their cytoplasm
Function: involved in electrical communication by the conduction of impulses
Signals are received from the dendritic end and are processed by the cell body and delivered to the axon end
Long enough so that nerves can run to and from different parts of the body to the central nervous system
Dendrites are fibres which branch from the cell body to make contact with other neurons
A long filament of cytoplasm, surrounded by an insulating sheath, runs from the cell body of the neuron. This filament is called a nerve fibre[axon]
The axon is insulated by a fatty sheath [myelin sheath] with small uninsulated sections along it [nodes] This means that the electrical impulse does not travel down the whole axon, but jumps from one node to the next
Function - transport of oxygen
A spherical biconcave disc increases surface area for more efficient diffusion of oxygen
Depression in the centre due to the absence of the nucleus, which gives them the biconcave shape and increases the amount of space available for haemoglobin inside the cell
Elastic in nature can squeeze through capillaries smaller than itself
Spongy cytoplasm which contains a red pigment - haemoglobin, which is iron-containing protein
Present in different linings in our body, like the respiratory tract.
These cells at their surface contain small projections called cilia, which perform the beating or whipping movement to move mucus and trapped particles up to the throat.
These cells contain abundant quantities of mitochondria
Sperms are much smaller than the eggs and are produced in large numbers.
They have a flagellum [which allows the sperm to swim to the egg].
They contain enzymes in the head region - acrosome[secretes enzymes to digest the jelly coat of an egg cell so that the sperm can fuse with the egg nucleus]
The cytoplasm of the midpiece contains many mitochondria[to carry out respiration and provide energy to the flagellum to propel forward]
Surrounded by a jelly coat [which protects the contents of the egg and prevents more than one sperm from entering the cell]
The cytoplasm contains a lot of lipids and proteins [proteins for the growth of the embryo if the egg fertilises - lipids act as energy sources]
Function: absorption of water and mineral ions from the soil. Root hair increases the surface area of the cell to ensure maximum absorption of water and mineral ions.
Walls are thin to ensure water moves through quickly.
No chloroplasts present
Function: conduction of water through the plant; support of the plant.
No top and bottom walls between xylem vessels, so there is a continuous column of water running through them.
Cells are dead without organelles or cytoplasm to allow free passage of water.
Their walls become thickened with a substance called lignin, which means they can help support the plant
Function: the main cells responsible for photosynthesis.
The Palisade layer is the main site for photosynthesis and contains numerous chloroplasts to absorb the maximum amount of sunlight for photosynthesis.
They are long and cylindrical cells closely packed together with fewer intercellular spaces.
Cell: basic functional and structural units in a living organism
Tissue: groups of cells of similar structure working together to perform the same function
Organ: made from different tissues working together to perform specific functions
Organ System: groups of organs with related functions, working together to perform body functions
Organism is an individual animal or plant formed by all the organs and systems working together to produce an independent living thing
Credits: Notes compiled by Manahil Naeem