Unit 2: Cells Flashcards
What are all living organisms made up of?
Cells
What features are present in both animal and plant cells?
Cell membrane
Cytoplasm
Nucleus
Vacuoles ( only accept if mention that small vacuoles that do not contain cell sap )
What are the functions of the cell membrane?
Forms a barrier between the cell and its surroundings
Keeps contents of cell inside
Allows simple substances to enter and leave the cell
Controls movement of other substances into and out of cell
Often described as partially permeable
What are the functions of the nucleus?
Controls all activities in the cell
Controls how the cells develop
What are the functions of the cytoplasm?
Place where many chemical reactions take place
What are the functions of the chloroplast?
Photosynthesis
Stores starch
What are the functions of the cell wall?
Stops cells from bursting when they fill with water
Gives shape to cells
Allows water and dissolved substances to pass through freely ( often described as freely or fully permeable )
What are the functions of the sap vacuole?
Full of water to maintain shape and ‘firmness’ of cell
Stores salts and sugars
Define specialised cells
Cells that have a specific structure that enables them to carry out a particular function
What is the special structure of ciliated cells?
They have cilia on the surface => beats back and forth to create a current in the fluid next to the cell surfaces
What is the special structure of root hair cells?
Long extensions => large surface area => absorbs water and ions from the soil
What is the special structure of the xylem vessels?
Cylindrical and empty
Arranged into columns
Cell walls are thickened with bands or spirals of cellulose and lignin
=> allow water and ions to move from the roots to the rest of the plants; provide support for the stem ad leaves
What is the special structure of muscle cells?
Make up fibres that are able to shorten and contract
Some attached to skeleton => move bones at joints
What is the special structure of red blood cells?
Contains haemoglobin => protein that carries oxygen
Shape like flattened discs => large surface area compared to volume => efficient absorption of oxygen
Formula to work out the magnification and actual size
Magnification = image size / actual size
Actual size = image size / magnification
