1. Biology 2
warm up session:
Higher tier

2. Remember, you have learnt all the information on the following slides in your lessons. This is just to refresh your memory of the essentials

3. Animal Cells Nucleus - controls cell’s activities
Cytoplasm - where chemical reactions take place
Cell membrane - controls what enters and leaves cell
Mitochondria - where energy is released during aerobic respiration
Ribosomes - where proteins are made

4. Plant Cells Plant cells also have:
A rigid cell wall - for strength and support
Chloroplasts - absorb light to make energy for photosynthesis
Vacuole filled with cell sap

5. These are cells adapted to carry out different functions
Specialised cells
These are cells adapted to carry out different functions

6. Different types of cells
Yeast cells have a nucleus, cytoplasm and a membrane surrounded by a cell wall
A bacterial cell have a cytoplasm, cell membrane and a cell wall
But the genes are not in a distinct nucleus

7. Diffusion and concentration gradients
high
concentration
low
Diffusion is the spreading of the particles…
…from a higher concentration to a region of lower concentration...
…the greater the difference in concentration, the faster the rate of diffusion.
Diffusion happens in gas exchange in the lungs and in leaves

8. Enzymes and their structure
normal
denatured
heat pH
Enzymes are biological catalysts –they speed up reactions in living things
Enzymes are protein molecules - made up of amino acids
The shape of the enzyme is vital to its function.
Temperature and pH affect enzyme activity
1.) High temperatures can destroy the enzymes ‘special shape’ so it becomes denatured.
2.) Different enzymes work best at different pH values.

9. Enzymes in digestion Enzyme: Produced in Job Where Amylase
- Salivary glands
- Pancreas
- Small intestine
Catalyses the breakdown of starch into sugars
Mouth
Small intestine
Protease
Stomach
Pancreas
Catalyses the breakdown of proteins into amino acids
Lipase
Catalyses the breakdown of lipids (fats and oils) into fatty acids and glycerol

10. Making use of enzymes

11. Enzymes in industry Type of enzyme Proteases Carbohydrases Isomerases
Use
To ‘pre-digest’ protein in baby foods
To turn starch into sugar syrup for making chocolates and cakes
To turn glucose syrup into fructose syrup to use in slimming foods
Why is it used?
The baby may not be able to digest all the protein itself
Sugar syrup is sweet and makes the food ‘taste nice’
Fructose is twice as sweet as glucose so it can be used in smaller amounts in slimming foods

12. Body organisation The body is made of cells
A group of cells that work together are called a tissue
A group of tissues that work together are called an organ
A group of organs that work together are called an organ system

13. Types of animal tissue
A tissue is a group of cells with similar structure and function.
There are 3 examples of tissue:
Muscular tissue, which can contract to bring about movement
Glandular tissue, which can produce substances such as enzymes and hormones
Epithelial tissue, which covers some parts of the body

14. Types of plant tissue include
Palisade layer – where photosynthesis happens
Spongy mesophyll layer – allows gases to reach palisade layer
Xylem – transports water and nutrients
Phloem – transports food (e.g. sugars)
Xylem and Phloem

15. The digestive system includes

16. Aerobic respiration can be summarized by this equation: +
oxygen
carbon dioxide
water
glucose
energy
Mitochondria are the energy-producing part of the cell.
The energy that is released during respiration is used:
For GROWTH
MOVEMENT
MAINTAINING A CONSTANT TEMPERATURE (in mammals and birds)
MAKING PROTEINS
Teacher notes
See the ‘Animal and Plant Cells’ presentation for more information about mitochondria and respiration.

17. Aerobic respiration during exercise
During exercise the heart rate increases and the rate and depth of breathing increases...
…this increases the supply of sugar and oxygen to cells and
increases the rate of removal of carbon dioxide
Circulation

18. Anaerobic respiration
During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid.
As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration.

19. Inheritance recap – Inside the cell

20. Mitosis Mitosis is the division of body cells
Produces new identical cells for growth and repair
Before cell division, genetic information on the chromosomes is copied so new cells have the same genes as the parent cells

21. Meiosis (Higher)
Cells in reproductive organs (testes and ovaries) divide to form sex cells (gametes)
Before division a copy of each chromosome is made.
The cell now divides twice to form 4 gametes – each new cell has half a set of chromosomes
Sexual reproduction results in variation as the new individual gets half a set of chromosomes from each parent

22. ? Alleles Different forms of genes are called alleles
allele for blue eyes
allele for brown eyes ?
Some characteristics are controlled by a single gene.
Different forms of genes are called alleles
Eg, for eye colour, skin colour, hair colour etc

23. Inherited disorders Polydactyly
A disorder causing extra fingers or toes
Caused by dominant allele of a gene
Can be passed on by only one parent who has the disorder
50% chance of inheriting disease

24. Inherited disorders Cystic fibrosis
A disorder which affects cell membranes in many organs of the body particularly the lungs and the pancreas
Caused by recessive allele so must be inherited by both parents

25. Embryo screening
Unborn embryos can be checked for the alleles that cause these and other genetic disorders…
…some people think this leads to more abortions and so they think it’s unethical

26. Carbon dioxide + water (+ light energy)
Photosynthesis
Carbon dioxide + water (+ light energy) 
Glucose + Oxygen
Photosynthesis is when green plants use light energy to make their own food
The rate of photosynthesis may be limited by 3 things: ) carbon dioxide
2) light intensity
3) temperature

27. Limiting carbon dioxide levels
Increasing carbon dioxide levels increases the rate of photosynthesis up to a point.
Eventually one of the other factors (temperature and light) becomes limiting
If there is too little carbon dioxide the rate will slow down.
Carbon dioxide maybe limited in an enclosed space eg, a greenhouse on a sunny day or in a rapidly photosynthesising rain forest

28. Limiting light intensity
Increasing light intensity increases the rate of photosynthesis up to a point
When a certain light intensity is reached the rate of photosynthesis stays constant
Eventually one of the other factors becomes limiting

29. Limiting temperature
If it is cold then enzymes do not work effectively slowing down the rate.
The rate of photosynthesis increases steadily with a rise in temperature up to a certain point (35-40ºC = optimum temp)
After this the enzymes are destroyed and the reaction stops completely.

31. Healthy plant growth Stunted growth Yellow leaves
Plant roots absorb mineral ions
needed for healthy growth
For healthy growth plants need
mineral ions including
Nitrates and
Magnesium
Mineral ions:
Nitrates
Magnesium
Needed for:
Nitrates used to make proteins for growth
Needed for chlorophyll production
Symptoms shown by plants if deficient in mineral
Stunted growth
Yellow leaves

32. Populations The factors that effect population size are: Temperature
Availability of nutrients
Amount of light
Availability of water
Availability of oxygen and carbon dioxide
Limits of Population

33. There are 2 methods for collecting environmental data
To sample randomly:
Choose area to sample
Place quadrat randomly onto area
Count number of species within quadrat
Repeat 5 times
To sample along a transect:
Choose a straight line through the area
Place quadrat at one end of the line
Repeat at 5 set intervals along the line

34. Fossils and exctinction
Fossils are the remains of dead plants and animals which lived millions of years ago.
Fossils show us how much or how little different organisms have changed as life developed on Earth.
Many early life forms were soft-bodied... which means that they have left few traces behind....what traces there were have been mainly destroyed by geological activity.

35. Fossils and exctinction
Extinction may be caused by:
- changes to the environment
- new predators, diseases or more successful competitors
- a single catastrophic event, eg massive volcanic eruptions or collisions with asteroids

36. Fossils and exctinction
New species arise as a result of:
isolation – two populations of a species become separated, eg geographically
HT only:
genetic variation – each population has a wide range of alleles that control their characteristics
natural selection – in each population, the alleles that control the characteristics which help the organism to survive are selected
speciation – the populations become so different that successful interbreeding is no longer possible.

37. Some scientific terms... Reproducible
Would another scientist be able to repeat it and get the same results?
Valid
Keep everything the same except the independent & dependent variables
Precision
Smaller scale division on equipment
Range
From the smallest to biggest
Interval
What the values go up by
Claims
You decide if it is true or false by looking at evidence, independent organisations avoid bias

38. What is the questions asking you to do?
Describe a graph
Refer to the pattern
e.g. as……...increases………increases etc
Explain
Describe & give a reason “because…….”
Evaluate
For & against
Compare
What is the same & what is different
Calculate
Show calculations & give units
Suggest a reason
This should be scientific

39. Things to think about when evaluating a situation...
Economical aspect - money
Environmental – pollution/ greenhouse gases/ global warming/ acid rain/ carbon dioxide/ habitat destruction
Health risks – body rejection/damage
Availability/accessibility
Ethical – suffering/human rights
Religious

40. Some final tips...
Read the whole Q – 33% of the Qs can be answered from information given to you in text, diagrams, graphs & tables
Follow instructions – “tick a box” “tick two boxes” “use info from the table”
Don’t write “it” – “the concentration increases” NOT “it increases”

41. And remember...
1 mark per minute – you have 60 minutes to answer 60 marks
Use bullet points for short questions –
e.g. 3 marks should mean 3 bullet points
Write in ‘good English’ for the 6 mark question
Check your answers – read over your answers at the end

42. Good luck 