1. B4 revision

2. B4a Ecology Capture-recapture
Population size = number in 1st x number in 2nd
Number previously marked
Assumptions:
no death
marking doesn’t effect survival
sample methods the same
Larger sample size means more accurate data

3. B4a Ecology
Key Terms
Ecosystem (living and non living factors in an area)
Can be self supporting
Habitat (area where an organism lives)
Population (number of individuals in one species)
Community (all the populations)
Zonation (gradual change in distribution of species across a habitat)
Due to an abiotic factor e.g. Rocky shore
Biodiversity (number of species in an area)

4. B4a Ecology Transect line Kite diagram Natural ecosystems
Used to measure distribution
Kite diagram
Shows distribution
Natural ecosystems
E.g. Native woodlands and lakes
Higher biodiversity
Artificial ecosystems
E.g. Forestry plantations and fish farms
Lower biodiversity

5. Question How do you investigate distribution
Sample along a transect, draw a kite diagram

6. How do you calculate population size using capture recapture methods
Question
How do you calculate population size using capture recapture methods
No. In 1st x No. in 2nd
No. marked

7. B4B Photosynthesis Balanced symbol equation
6CO2 + 6H2O  C6H12O6 + 6O2
Isotope experiments have shown us
Oxygen made comes from water
Photosynthesis has 2 stages
Light splits water to make oxygen and H ions
Carbon dioxide + H makes glucose
Uses of glucose
Stored as starch (doesn’t move or affect water concentration in cells)
Make energy
Cellulose for cell walls
Proteins for growth
Fats for storage

8. B4B Photosynthesis Development of understanding Greek Scientists
Plants gained mass by taking in minerals from the soil
Van Helmont
Growth not only due to minerals in the soil
Priestley
Plants make oxygen

9. B4B Photosynthesis Limiting Factors Plants respire all the time
Carbon dioxide and Light
As the factor increases the rate increases
Until something else becomes the limiting factor
Temperature
Until the enzymes denature
Plants respire all the time
Day: take in carbon dioxide and give out oxygen (as also doing photosynthesis)
Night: do opposite (only repiring)

10. Question What 2 things are needed for photosynthesis?
Water thought the roots
Carbon dioxide through leaf pores

11. Question What is given out by photosynthesis?
Oxygen through leaf pores

12. B4C Leaves

13. B4C Leaves General leaf adaptations for photosynthesis
Broad (large surface area)
Thin (short diffusion distance)
Different photosynthetic pigments e.g. Chlorophyll a & b, carotene, xanthophyll (absorb different wavelengths of light)
Vascular bundles (support and transport)
Guard cells (open and close stomata)

14. B4C Leaves Cellular adaptations to photosynthesis
Epidermis is transparent
Palisade contains lots of chloroplasts
Spongy mesophyll has air spaces
Large internal surface area

15. Locate the parts of a leaf
Question ? ?
Locate the parts of a leaf ? ? ? ? ? ? ? ? ?

16. How are leaves adapted to photosynthesis?
Question
Broad, so large surface area
Thin, so short distance for gases to travel
Contain chlorophyll to absorb light
Have a network of veins for support and transport
Stomata for gas exchange
How are leaves adapted to photosynthesis?

17. B4D Osmosis and Diffusion
Net movement of particles from an area of high concentration to an area of low concentration as a consequence of random movement
Increase diffusion by
Short distances
Greater concentration gradient
Larger surface area
Diffusion of carbon dioxide and oxygen in leaves
Large surface area (air spaces in mesophyll)
Stomata

18. B4D Osmosis and Diffusion
Net movement of water from an area of high water concentration to an area of low water concentration across a partially permeable membrane as a consequence of random movement
Partially permeable: let small particles through
Turgor Pressure
Water pressure acting against cell walls
Wilting is due to lack of turgor pressure

19. B4D Osmosis and Diffusion
Key Terms
Plant cells have cell walls
Flaccid (water moved out of cells)
Plasmolysed (so much water has moved out the cell membrane has pulled away from the cell wall)
Turgid (water moved in, cell swells and vacuole increases in size)
Animal cells don’t have cell walls
Crenation (water moves out and cell shrivels)
Lysis (water moves in and cell bursts)

20. The exchange of gases in the stomata is by ?
Question
The exchange of gases in the stomata is by ?
Diffusion

21. Question
Osmosis is a type of ?
Diffusion

22. ‘partially permeable’
Question
A membrane that allows some small molecules to pass through but not larger molecules
Explain the term
‘partially permeable’

23. B4E Transport in Plants Vascular bundles: xylem and phloem Xylem
Transpiration (movement of water and minerals)
Thick cell wall, hollow and dead cells
Phloem
Translocation (movement of sugars)
Living cells

24. B4E Transport in Plants Transpiration
Evaporation and diffusion of water from inside the leaves
Pulls other water molecules up
Happen due to open stomata for gas exchange
Factors that effect transpiration rate
Increased light (more photosynthesis)
Increased temperature (more evaporation)
Increased wind (steeper concentration gradient)
Decreased humidity (steeper concentration gradient)

25. B4E Transport in Plants Uses of water in a plant Reducing water loss
Cooling
Photosynthesis
Support
Movement of minerals
Reducing water loss
Change in guard cell turgidity to open/close stomata
Number and distribution of stomata
Waxy cuticle
Root hair cells
Increased surface area for osmosis

26. A lack of water can cause…?
Question
A lack of water can cause…?
Plants to droop (wilt)

27. Describe how water travels through a plant
Question
Absorption from soil through root hairs
Transport through the plant to the leaves
Evaporation from the leaves (transpiration)
Describe how water travels through a plant

28. Question
Describe the structure of phloem
Columns of living cells

29. The evaporation and diffusion of water from inside leaves
Question
What is transpiration?
The evaporation and diffusion of water from inside leaves

30. B4F Minerals Mineral Molecule Made Use Deficiency Nitrate (N)
Amino acid & Protein
Cell Growth
Poor growth, yellow leaves
Phosphorus (P)
DNA & membranes
Respiration & Growth
Poor roots, purple leaves
(K) Potassium
Enzymes
Photosynthesis & Respiration
Poor fruit and flower growth
Magnesium (Mg)
Chlorophyll
Photosynthesis
Yellow leaves

31. B4F Minerals Minerals are present in soils in low concentrations
Root hair cells also used to take up minerals by active transport
Move substances from low concentrations to high concentrations using energy

32. Dissolved minerals are absorbed by …?
Question
Dissolved minerals are absorbed by …?
The roots from the soil

33. Question Why do plants require nitrates?
For protein, which are needed for cell growth

34. How are minerals taken up into root hair cells?
Question
How are minerals taken up into root hair cells?
By active transport

35. B4F Decay: Specification
Understand what causes decay and why decay is useful.
What conditions speed up decay.
Explain the role of detritivores and saprophytes
How food preservation works
Different methods of food preservation

36. Detritivores
A detritivore is an organism that feeds on detritus (dead/decaying things – eg leaves)
Earthworms, maggots and woodlice are detritivores. They:
Speed up the rate of decay by breaking down the detritus are creating a larger surface area for other microorganisms to work.
Reintroduce essential nutrients back into food chains.
Warm temperatures, good supply of water and oxygen also speed up decay.
Compost is warm because of respiration by microorganisms in it and so this speeds up decay

37. Saprophytes
A saprophyte is an organism that gains nutrients from dead organic matter. This is usually the first stage of decay.
Saprophytes produce enzymes that break down dead matter. They can then absorb the released nutrients.
Bacteria and fungi feed saprotrophically by extracellular decay

38. Food Preservation Salt: draws water out of savoury food
Vinegar: denatures bacterial enzymes
Sugar: draws water out of sweet food
Freezing: suspended animation
Canning – kills bacteria, prevents contamination
Drying – removes water and stops bacterial growth

39. Don’t forget cooking – high temperatures kill bacteria

40. Question What four things are needed in the process of decay?
1. Presence of micro organisms
2. Temperature
3. Oxygen
4. Moisture
What four things are needed in the process of decay?

41. Question How can materials be recycled?
Materials can decay and can therefore be recycled

42. Question
Two samples of soil are collected
2. One sample is heated but not burned
3. Both samples are weighed and then put in sealed flasks containing limewater
4. After two days the soil samples are re-weighed
5. Only the fresh soil sample loses mass
6. The limewater in the flask containing the fresh soil turns from clear to milky.
7. This shows that carbon dioxide is produced
Describe an experiment to show that decay is caused by decomposers (bacteria and fungi)

43. Question Name two things that micro organisms can be used for
1. Breaking down human waste (sewage)
2. Breaking down plant waste (compost)
Name two things that micro organisms can be used for

44. Name six food preservation techniques that reduce the rate of decay
Question
1. Canning
2. Cooling
3. Freezing
4. Drying
5. Adding salt / sugar
6. Adding vinegar
Name six food preservation techniques that reduce the rate of decay

45. What do detritivores feed on and give examples?
Question
What do detritivores feed on and give examples?
They feed on dead and decaying material (detritus), such as earthworms, maggots, woodlice, etc

46. Question How do detritivores increase the rate of decay?
They produce larger surface area

47. Question
Explain how the following food preservation method reduces the rate of decay …
1. Canning
The food is heated to kill bacteria. The food is then put into cans and sealed while it is still hot. This forms a vacuum and prevents the entry of oxygen and bacteria

48. The high temperature kills bacteria
Question
Explain how the following food preservation method reduces the rate of decay …
2. Cooling
The high temperature kills bacteria

49. Question
Explain how the following food preservation method reduces the rate of decay …
3. Freezing
Freezing kills and slows down the growth of others. Freezing food stops bacteria from reproducing

50. Without water, bacteria and fungi cannot feed and grow
Question
Explain how the following food preservation method reduces the rate of decay …
4. Drying
Without water, bacteria and fungi cannot feed and grow

51. This is an example of osmosis
Question
Explain how the following food preservation method reduces the rate of decay …
5. Adding salt or sugar
A high concentration of sugar or salt solution kills some bacteria and fungi and stops the growth of others.
This is an example of osmosis

52. Question
Explain how the following food preservation method reduces the rate of decay …
6. Adding vinegar
Vinegar is an acid. Very few bacteria can grow in acid conditions.
Food such as pickled eggs and chutney are preserved in this way

53. An organism that breaks down dead organic matter
Question
Explain the term
‘saprophyte’
An organism that breaks down dead organic matter

54. B4H Farming Disadvantages of using pesticides Hydroponics
Bioaccumulation (build up in food chain)
Harm organisms that aren’t pests
Some are persistent (don’t break down)
Hydroponics
Growing plants without soil, in a mineral solution
E.g. In greenhouses, areas of poor soil
Advantages
Better control of minerals and disease
Disadvantages
Requires fertilisers and support

55. B4H Farming Intensive farming Organic Farming
More efficient by reducing energy transfer
Remove pests
Remove weeds
Keep animals indoors
Reduce amount animals can move around
Organic Farming
Use manure and compost
Crop rotation to include nitrogen fixing crops
Weeding
Advantages (no chemicals)
Disadvantages (more labour and time consuming)

56. B4H Farming Biological Control Using other animals to eat pests
Advantages
No need for chemical pesticides
No need for repeat treatment
Disadvantages
Predator may not eat the pest
Predator may eat useful species
May increase out of control
By removing something from the ecosystem you may effect the food chain

57. Question What is a disadvantage of using pesticides?
Bioaccumulation, harm other organisms, persistent in food chain

58. Give an advantage of organic farming
Question
Give an advantage of organic farming
No chemicals