1. Units 1 and 2 Cells and the Characteristics of Life

2. What you need to be able to do:
1 List and describe the characteristics of living
organisms.

3. Starter
How can you tell if something is alive?

4. Task
Go to:
station/students/Characteristics_Student.doc
and download the document.
Follow the instructions and complete the sheet.

5. An action by an organism or part of an organism causing a change of position or place
MOVEMENT

6. RESPIRATION The chemical reactions that break down
nutrient molecules in living cells
to release energy
RESPIRATION

7. The ability to detect or sense changes in the environment (stimuli) and to make responses
SENSITIVITY

8. A permanent increase in size and dry mass by an increase in cell number or cell size or both
GROWTH

9. The processes that make more of the same kind of organism
REPRODUCTION

10. The taking in of nutrients which are organic substances and mineral ions, containing raw
materials or energy for growth and tissue repair, absorbing and assimilating them
NUTRITION

11. Characteristics of living things
A mnemonic to help you remember: e
Say what you see!

12. M R S G R E N ovement espiration ensitivity rowth eproduction xcretion
utrition

13. Review and Homework
Match up the pictures and descriptions of the life processes in your booklet.
Complete the Living Things crossword.

14. 2.1 Cell Structure and Organisation
What you need to be able to do:
1 State that living organisms are made of cells.
2 Identify and describe the structure of a plant
cell (palisade cell) and an animal cell (liver
cell), as seen under a light microscope.
4 Describe the differences in structure
between typical animal and plant cells.

15. Starter http://www.kscience.co.uk/animations/animal_c ell.htm
Watch BrainPop video "Cells"

16. Cell Structure

17. Parts common to all cells
Nucleus - contains genetic material which controls the activities of the cell
Cytoplasm - chemical reactions take place here, controlled by enzymes
Cell membrane - partially permeable, controls what comes in and out of the cell
Mitochondria - aerobic respiration occurs here to release energy

18. Plant cells have these extra features
Cell wall - strengthens the cell and provides support
Chloroplasts - contain chlorophyll which absorbs light energy for photosynthesis
Large permanent vacuole - contains cell sap to keep the cell turgid
Note: animal cells may contain small, temporary food vacuoles

19. Looking at animal cells
Preparing a temporary mount of cheek cells
Try the echalk activity - preparing cheek cells

20. Looking at plant cells Preparation of onion skin temporary mount
Look at the echalk activity - preparing onion cells

21. Tasks Review Make biological drawings of each of your slides.
Remember the rules!
Add a title and label the parts you can see.
Answer past paper question 7.
Review
Cells Revision Video

22. 2.1 Cell Structure and Organisation
What you need to be able to do:
3 Relate the structures seen under the light
microscope in the plant cell and in the
animal cell to their functions.
5 Calculate magnification and size of biological
specimens using millimetres as units.

23. Starter
In Biology we study molecules to habitats. The size of these things varies enormously!
Look here:
and here:
In the last lesson we used microscopes to look at cells. You used 10x and 40x lenses to magnify them.

24. Magnification
How much an object is magnified under the microscope is calculated as follows:
total magnification = eyepiece lens x objective lens
So, if we use a 10x eyepiece lens and a 10x objective lens the total magnification is:
10 x 10 = 100x magnification

25. Calculating magnification of biological drawings
The drawing you make of an object under a microscope is usually much larger than the object’s actual size
You need to indicate how much bigger
There are three things involved in magnification calculations;
- the size of the drawing
- the actual size of the object
- the magnification of your drawing
(how much bigger your drawing is compared to the real thing)

26. Magnification formula
To find the magnification of your drawing, the formula is:
magnification = size of drawing (mm)
size of the real thing (mm)
To find the size of your drawing is easy – just measure it with a ruler (in mm)
The size of the real thing is usually given to you. BUT, you must convert to mm to use the formula

27. Estimating Cell Size
We can use a clear plastic ruler to estimate the size of cells.

28. Appearance of ruler at 100x magnification

29. Appearance of onion cells at 100X magnification

30. Estimating the size of cells
Average cell width
12 cells = 1mm
so 1 cell = mm
Imagine the ruler lines! 12
Remember it is only an estimate! 5
Count the number of cells in 1 mm
Average cell length
5 cells = 1 mm
so 1 cell = 0.2 mm

31. 2.2 Movement in and out of cells
What you need to be able to do:
1 Define diffusion as the net movement of
molecules from a region of their higher
concentration to a region of their lower
concentration down a concentration
gradient, as a result of their random
movement.
2 Describe the importance of diffusion of
gases and solutes and of water as a solvent.

32. What substances need to go in and out of a cell and why?
Respiring animal cell:
oxygen
carbon dioxide
glucose
water

33. Photosynthesising plant cell:
carbon dioxide
glucose
water
oxygen
Substances can move in and out of cells in 3 ways
diffusion, osmosis and active transport

34. Diffusion Starter Watch BrainPops "Passive Transport"
Add potassium permanganate to hot and cold water and observe

35. Tasks Can you describe what happens using the following words?
particles, low, concentration, down, high, movement, random, concentration gradient.
Describe and explain how temperature affects diffusion.
Watch the echalk diffusion animation

36. The importance of diffusion
Diffusion is the random movement of particles from a region of high concentration to a region of low concentration down a concentration gradient.
Where in the human body is this important?

37. Watch this video and complete the table in your booklet:

38. Shorter distance = faster rate
Review
Apart from temperature, what other factors affect the rate of diffusion, how and why?
Particle size
Smaller size
= faster rate
Smaller particles move faster than larger ones (less energy needed)
Diffusion distance
Shorter distance = faster rate
Less distance takes shorter time to travel
Concentration
gradient
Bigger difference
= faster rate
Greater net movement down concentration gradient
What other important feature is often seen in parts of the body where dffusion occurs?
A LARGE SURFACE AREA