chapter 3: the cell what do you know about cells?
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Chapter 3: The CellChapter 3: The Cell
What do you know about cells?
Objectives:
1. To define the term cells
2. To look at the basic structure of the cell
3. To identify the main parts of the cell
4. To distinguish between plant and animal cells
5. To identify the main parts of a microscope
6. To use a light microscope to examine plant and animal cells under low and high power
All living things are made of cells.
Cell Structure
Cells are made up of 3 main parts:
1. Cell Membrane
2. Cytoplasm
3. Nucleus
Parts of the cell and their function (job)
Part Function
Cell Membrane
Cytoplasm
Nucleus
Chloroplast
Cell Wall
Vacuole
Part Function
Cell Membrane Protects the cell
Controls what enters & leavest the cell
Cytoplasm Place where chemical reactions take place
Nucleus Controls the cells activities
Chloroplast Carries out photosynthesis
Cell Wall Gives shape to the cell
Vacuole Stores materials in the cell
Parts & Functions of the Cell
Plant cells have all the features present in animal cells.
In addition, they have:– A cell wall for
strength– Chloroplasts– Large vacuoles
Differences between Plant & Animal Cells
Plant Cells Animal Cells
Cell wall present
No chloroplasts
Large vacuoles
Plant Cells Animal Cells
Cell wall present No cell wall
Chloroplasts present No chloroplasts
Large vacuoles Small vacuoles or no vacuoles
Differences between plant & Animal Cells
Is this a plant cell or an animal cell?
Give 2 reasons for your answer
Identify the main parts of the plant cell
A
B
D
C
E
E
A microscope is used to view small objects in detail.
Identify the main parts of the microscope
A
B
C
D
E
The parts of a microscope and their functions are as follows:
Part Function
Eye piece lens
Objective lens
Coarse Focus Wheel
Fine Focus Wheel
Stage
Mirror or light source
Magnification using a light microscope
• The total magnification is calculated by multiplying the power of the eyepiece by the power of the objective lens being used.
Total magnification = eye piece lens X objective lens
• To examine animal or plant cells under a microscope:– Make sure there is light passing through the
opening in the stage.– Use the lowest power lens on the nosepiece.– Clip the slide onto the stage.– Turn the coarse focus knob to bring the stage
close to the slide.
CHAPTER 2CELLS AND THE
MICROSCOPE
– Turn the coarse focus knob to bring the lens away from the slide.
– Move the slide so that the cells of interest are in the centre.
– Adjust the amount of light passing through the slide.
– Change the objective lens to a higher power and re-focus using the fine focus knob.
– Draw labelled diagrams of the cells at each magnification.
CHAPTER 2CELLS AND THE
MICROSCOPE
• To prepare a slide from plant tissue:– Cut an onion and remove
a thin layer of cells.– Place the onion cells in
water on a microscope slide.
– Place a cover slip over the onion cells.
Mandatory Experiment To prepare a slide from plant tissue and draw a diagram of the cells under magnification
CHAPTER 2CELLS AND THE
MICROSCOPE
• Draw a few drops of iodine solution across the cells using absorbent paper.
CHAPTER 2CELLS AND THE
MICROSCOPE
Definitions
TissuesA tissue is a group of similar cells with the
same function e.g. muscle tissue OrganAn organ is made of many different tissues
working together e.g. the heartSystemsA system is a group of organs working
together e.g. the circulatory system
Plants Animals
Tissue Storage tissue
Organ Flower
System Shoot System
Quiz
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