B4 REVISION B4A ECOLOGY Capture-recapture Population size = number in 1st x number in 2nd Number previously marked Assumptions:
no death marking doesnt effect survival sample methods the same Larger sample size means more accurate data 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) B4A ECOLOGY Transect line 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
Question How do you investigate distribution Sample along a transect, draw a kite diagram Question How do you No. In 1st x No. in 2nd calculate No. marked population size
using capture recapture methods 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 (doesnt move or affect water concentration in cells) Make energy
Cellulose for cell walls Proteins for growth Fats for storage B4B PHOTOSYNTHESIS Development of understanding Greek Plants gained mass by taking in minerals from the soil Van
Scientists Helmont Growth not only due to minerals in the soil Priestley Plants make oxygen B4B PHOTOSYNTHESIS Limiting Factors Carbon
dioxide and Light As the factor increases the rate increases Until something else becomes the limiting factor Temperature As the factor increases the rate increases 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) Question What 2 things Water thought are needed for the roots photosynthesis Carbon ? dioxide through leaf pores
Question What is given out by photosynthesis ? Oxygen through leaf pores B4C LEAVES 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) B4C LEAVES Cellular adaptations to photosynthesis Epidermis is transparent
Palisade contains lots of chloroplasts Spongy mesophyll has air spaces Large internal surface area Question ? Locate the parts of a leaf ? ? ?
? ? ? ? ? ? ? Question How are leaves adapted to photosynthesis
? 1. Broad, so large surface area 2. Thin, so short distance for gases to travel 3. Contain chlorophyll to absorb light 4. Have a network of veins for support and transport 5. Stomata for gas exchange B4D OSMOSIS AND DIFFUSION
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 B4D OSMOSIS AND DIFFUSION Osmosis 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 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 dont have cell walls Crenation (water moves out and cell shrivels) Question The exchange of gases in the stomata is by ? Diffusion Question Osmosis is a
type of ? Diffusion Question Explain the term partially permeable A membrane that allows some small molecules to pass through but not larger molecules
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 Living cells (movement of sugars) 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) B4E TRANSPORT IN PLANTS
Uses of water in a plant 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 Question A lack of water can cause? Plants to droop (wilt) Question
Describe how water travels through a plant 1.Absorption from soil through root hairs 2.Transport through the plant to the leaves 3.Evaporation from the leaves (transpiration) Question Describe the
structure of phloem Columns of living cells Question What is transpiration? The evaporation and diffusion of water from inside leaves B4F MINERALS
Mineral Molecule Made Use Nitrate (N) Amino acid & Cell Growth Protein Deficiency Poor growth, yellow leaves
Phosphorus DNA & (P) membranes Respiration & Growth Poor roots, purple leaves (K) Potassium Photosynthesis & Respiration
Poor fruit and flower growth Photosynthesis Yellow leaves Enzymes Magnesium Chlorophyll (Mg) 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 Question Dissolved minerals are absorbed by ?
The roots from the soil Question Why do plants require nitrates? For protein, which are needed for cell growth Question How are minerals taken up into root
hair cells? By active transport 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 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 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 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
Dont forget cooking high temperatures kill bacteria Question What four things are needed in the process of decay? 1. Presence of micro organisms 2. Temperature 3. Oxygen 4. Moisture
Question How can materials be recycled? Materials can decay and can therefore be recycled Question 1. Two samples of soil are collected Describe an experiment to show that decay is caused by
decomposers (bacteria and fungi) 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 Question 1. Breaking down human waste (sewage) Name two things that micro organisms can 2. Breaking down plant waste be used for (compost) Question
Name six food preservation techniques that reduce the rate of decay 1. Canning 2. Cooling 3. Freezing 4. Drying 5. Adding salt / sugar 6. Adding vinegar Question What do
detritivores feed on and give examples? They feed on dead and decaying material (detritus), such as earthworms, maggots, woodlice, etc Question How do detritivores increase the
rate of decay? They produce larger surface area 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
Question Explain how the following food preservation method reduces the rate of decay 2. Cooling The high temperature kills bacteria 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
Question Explain how the following food preservation method reduces the rate of decay 4. Drying Without water, bacteria and fungi cannot feed and grow 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
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 Question Explain the term saprophyte An organism
that breaks down dead organic matter B4H FARMING Disadvantages of using pesticides Bioaccumulation (build up in food chain) Harm organisms that arent pests Some are persistent (dont 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 B4H FARMING
Intensive 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) 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 Question Bioaccumulatio What is a disadvantage n, harm other organisms, of using persistent in pesticides? food chain Question Give an advantage of organic farming
No chemicals
