SCIENCE STUDY NOTES

1.

Abiotic – refers to all the NON-LIVING chemical and physical factors in an ecosystem. E.G. Temperature, humidity, wind sped, etc.

Biotic – refers to all the LIVING components in an ecosystem. E.G. Plants, Animals

Feature Aquatic TerrestrialViscosity: measure of a resistance to an object moving through it

Has high viscosity, making it harder for organism to move through

Air has low viscosity, easier to move through

Buoyancy: amount of support by an object in a liquid

Supports animals and plants in water, and helps maintain their shape

Don’t experience much buoyancy from air, they need to support themselves

Temperature Variation: Main heat source = sunAnimals & plants can only survive between certain temps

Water heats up slower than air. Different regions temp differs depending on time of the year. Deep water is cold.

Varies more than water. Daily and seasonal variations. Temp under ground doesn’t vary much.

Availability of gasses:Important gasses for organisms:

- Oxygen (O2)- Carbon Dioxide

(Co2)

Availability in water depends on temp. more gas is dissolved at lower temps.

Gasses are freely available in air.

Availability of water Isn’t a problem in aquatic environments.

Availability varies due to rainfall. Water loss may be a problem

Light penetration: light received from sun. The light intensity is greater at the equator than at the poles

Light on water reflects or is absorbed. Light penetration decreases with depth affecting certain organisms

Passes freely through air. Plenty of light is available

Pressure variation: the earths gravitational pull and pressure

Pressure increases with depth. Few organisms live at great depths

Atmospheric pressure decreases with height. This may affect breathing

Availability of shelter Not all aquatic organisms need shelter. Rocks, plants coral reefs do provide shelter for others

Most animals require shelter. Some plants only grow in sheltered environments

Availability of space May restrict numbers in some aquatic environments (due to territory requirements)

May restrict numbers on land for both plants & animals (territory requirements & shelter)

Distribution – where an organism is foundAbundance – number of members of a population

Availability of food Prey Availability of shelter Competition. E.G. for food, mating Availability of water

Short & long term consequences on the ecosystem of the same species competing for resources:

Short Term: as the population increases, there is more competition for resources. Less food is available so the population decreases, it affects the predator population.

Long Term: populations stabilise, as the balance of resource availability and population numbers are reached.

The need for sampling techniques: - Sampling techniques, such as transects, random quadrats and capture

recapture are used to make population estimates when its difficult to count every single member of that population due to time and costs.

2.

Importance of the cycling of materials in ecosystems:

The flow of matter through a natural ecosystem (Carbon/Oxygen and nitrogen cycles):

- Matter is recycled through a natural ecosystem. Dead matter and waste materials are broken down by decomposers and returned to the soil. Plants retrieve the nutrients then herbivores eat the plants and carnivores eat the herbivores and eventually die.

- Nitrogen, carbon, oxygen and water are examples of non-living matter that is recycled through natural ecosystems.

Uses of energy in organisms:

Light energy is used by plants for photosynthesis. = Carbon Dioxide (Co2)+ Water (H20)Sugar (C6H12O6)+Oxygen (O2)

Respiration then converts high energy compounds through a series of biomechanical reactions= Sugar (C6H12O6)+Oxygen (O2) Carbon Dioxide (CO2)+ Water (H2O)+Chemical Energy

Energy released by respiration is used by organisms for: - Growth & Repair- Movement

- Biomechanical reactions- Maintaining the functioning of organs and tissue- Making compounds

Flow of energy through natural ecosystems: Energy flows through in one direction Enters the system as sunlight Producers use the suns energy during photosynthesis This energy is transferred from plants to animals via food chains Through respiration the food is combined with oxygen to release energy

(e.g. heat energy)

3.

Population sizes for plant/animals species in an ecosystem:

Factors that affect numbers in predator and prey populations:

Decomposers: - Decomposers are bacteria and fungi - They breakdown the remains of organisms and their waste products- E.G. breakdown of organic materials into carbon dioxide, which then

enters the carbon-oxygen cycle

Trophic Interactions: Are the feeding relationships between organisms. Examples are food chains, food webs and biomass pyramids.

Food Chains: are flow charts indicating which organism feeds on which organism, if it follows a simple line it’s a food chain.

Food Webs: indicates what organisms feed on in the structure of a diagram.

Simple Food Chain

Biomass Pyramid: is another way to show the transfer of energy in an ecosystem is the biomass and energy pyramid. The total amount of mass is a community is called its biomass. Since matter is lost from the community at each trophic level, the biomass of the producers is the greatest and it decreases at each consecutive level.