1. ENVIRONMENTS Read 199-207

2. SIZES OF ENVIRONMENTS SMALLEST LARGEST ORGANISM MICRO-HABITAT HABITAT BIOME BIOGRAPHICAL REGION BIOSPHERE

3. ECOSYSTEMS BIOTIC – living ABIOTIC – (A)non-living Examples: Abiotic factors that influence tolerance (worksheet) BIOTICABIOTIC

4. COMPARISONS FACTORSAQUATIC HABITATTERRESTRIAL HABITAT Water availability Dissolved minerals Temperature Light Buoyancy/Density Viscosity (resistence to movement) Gas availability Pressure

5. COMPARISONS FACTORSAQUATIC HABITATTERRESTRIAL HABITAT Water availabilityReadily availableVaries in availability Species have special features to transport it Dissolved mineralsIons in water Fresh water – low solute Salt water – high solute Ions in soil Variable in amounts TemperatureLess variationGreater variation LightLimited – depends on clarityReadily available Buoyancy/DensityMore dense = more supportLess dense = less support Viscosity (resistence to movement) Very viscoseNot very viscose Gas availabilityO 2 not readily available CO 2 readily available O 2 readily available CO 2 not readily available PressureIncreases with depthDescreases with altitude

6. ECOLOGICAL NICHE An ecological niche describes how an organism or population responds to the distribution of resources and competitors. The way of life of a species. The optimum range refers to the abiotic factors at which the organisms functions best. Physiological stress refers to outside the preferred niche/optimum range. Looking at niches (worksheet)

7. PLANTS & TROPISMS Read 219-228

8. TROPISMS Tropism is the directional growth response of a plant to an environmental stimulus. Positive tropism – growing toward a stimulus Negative tropism – growing away from a stimulus Complete the table: TropismStimulusResponse Phototropism Geotropism Hydrotropism Thigmotropism Chemotropism

9. TROPISMS Tropisms (worksheet) Leaves can tell a story (worksheet) TropismStimulusResponse PhototropismLightPositive: shoots grow towards the light Negative: roots (if responsive) grow awy GeotropismGravityPositive: roots grow downwards Negative: shoots grow upwards HydrotropismWaterRoots grow towards water ThigmotropismTouch, contactStems and tendrils grow round or against points of contact with solid objects (eg other plants) ChemotropismChemicalsPositive: pollen tubes of some plants are attracted to the stigma of same species, enabling fertilisation. Ovary releases chemicals to produce response.

10. PLANTS IN DEFFERENT ENVIRONMENTS CategoryDescriptionCharacteristics HydrophytesAquatic plants: floating or living in water Have little or no cuticle on stems and leaves. Stomata (specialised pores for gas exchange) are found on the upper surface of the leaves. Small amount of transport tissue (xylem). XerophytesDry conditionsFleshy, succulent plants OR hard-leaved sclerophylls. Thick waxy cuticle, hair covering leaves, few stomata, reduced leaf surface area, leaf orientation away from sun. HalophytesSalt tolerantMany are succulents. Usually have high osmotic pressure in cytoplasm, control salt levels in shoots. If excess salt enters via the leaves they cannot control osmotic concentration so stomata close reducing transpiration and CO 2 uptake. MesophytesMoist conditionsPerennials – survive underground as bulbs, tubers. Annuals survive with dormant seeds. Stomata control water loss. EpiphytesAerial: growing on branches or trunks. Not parasitic.

11. Which is which?

12. Know the definitions of these: Epicormic bud Lignotubers Phytohormones Gibberellins Cytokinins Abscisic acid Ethylene Auxins Life of Plants (video) Phytochromes Photoperiodism Dormancy Taxis Nastic Nutation