Biology – A Local Ecosystem
1. The distribution, diversity and numbers of plants and animals found in ecosystems are determined by biotic and abiotic factors
Distinguish between biotic and abiotic features of the local environment
Biotic = LIVING FACTORS
Abiotic = NONLIVING FACTOSR
Compare the abiotic characteristics of aquatic and terrestrial environments
Characteristics
Aquatic
Terrestrial
Viscosity : measure of mediums resistance to an object
HIGH – difficult for organisms to move through
LOW – easy to move through
Buoyancy : amount of support
HIGH – support to plants and animals
LOW – plants and animals need to support own body
Temperature
Heats up and cools down more slowly then air
Vary a lot. Daily and seasonal variations can be great
Availability of – gases, water and ions
Gases- depends on temp, diffusion is slower. More gases available at lower temps. O2 decreases with depth
Water – Environment
Ions – saltwater (35% is dissolved ions)
Freshwater = low in ions
Gases – freely available, diffusion is rapid
Water – varies, location is problem,
Ions – vital for plant growth in soil
Light penetration
Decreases with depth
Plent of light, dense plant growth can affect light
Pressure Variation
Varies with depth. Increases depth = increase pressure
Decreases with height above sea level. Little effect on life
Availability and types of substrates ( rocks, soils, sands etc)
Bottom dwellers affects, free swimming etc less affected
Amount and type of soil important to plants. Provides habitats for ground dwellers etc
Strength of natural forces
Tides, currents, waves may vary
Winds and rain can very
Availability of shelter and space
Not required for all organisms, substrate, rocks etc is sufficient
Most animals require shelter.

Identify the factors determining the distribution and abundance of a species in each environment
Distribution
Where organisms if found
Usually uneven
Found where abiotic and biotic factors favour them
Distributed where: SURVIVAL is high, Predation is low, requirements for survival are met

Abundance
How many organisms
Not the same
Changes over time : INCREASES due to births and immigrations DECREASES due to deaths and emigration
Abiotic Factors affecting Distribution and Abundance
Light - Strength of wind
Rainfall - Temp variations
Topography - Tides, currents and waves
Water - Substrate
Space and shelter - Oxygen
Biotic Factors
Availability of food
Number of competitors
Number of mates available
Number of predators
Number and variety of disease causing organisms
Describe the roles of photosynthesis and respiration in ecosystems
Energy needed to sustain ecosystems is obtained fro the sun
Energy is captured through photosynthesis
Photosynthesis uses co2 and water to make food – ALL ORGANISMS rely on this
Respiration is the process by which cells obtain energy
Organic molecules are broken down and energy is produced
ALL RELIES ON SUN
Energy is never recycled – requires CONSTANT input
Photosynthesis POWERS ecosystems
Identify uses of energy by organisms
SYNTHESIS of complex molecules ( lipids, proteins etc)
GROWTH of cells (differentiation, division, elongation etc)
REPAIR and MAINTENANCE of old or damaged cells
ACTIVE TRANSPORT of materials across cell membranes
Functions of SPECIAL CELLS needing extra energy (nerves, muscle, kidney)
TRANSPORT of materials within the ecosystem (phloem, circulatory system etc)
Identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions
Respiration is breakdown of glucose with oxygen to released energy
CO2 + H2O are produced as waste products
GLUCOSE + OXYGEN  CARBON DIOXIDE + Water + ENERGY
Aerobic = requiring oxygen
Energy is held in glucose bonds, when bonds are broken, energy is released
Respiration