Organisms and their Environment (4.1-4.9)

**^^Ecosystem: ^^**a unit containing all of the organisms and their environment, interacting together, in a given area

• Food Chain - shows the transfer of energy from one organism to the next, beginning with a producer

• Food Web - A network of interconnected food chains

• Producer - An organism that makes its own organic nutrients, usually from sunlight via photosynthesis

• Consumer - An organism that gains energy by feeding on other organisms. They can be further classified into primary, secondary, tertiary consumers

• Herbivores - Animals that gain energy by eating plants

• Carnivores - Animals that gain energy by eating other consumers

• Decomposers - Organisms that gain energy by breaking down dead, or organic waste material

  

• Light energy from the sun is the source of all energy

• The arrows in a food chain show the transfer of energy from one trophic level to the next

• Energy is transferred from one organism to another by ingestion (eating)

Shows interdependence - how the change in one population can affect others within the food web

Trophic Levels

Trophic Level: the position of an organism in a food chain, food web, pyramid of numbers, or the pyramid of biomass

Primary producers → Primary consumers → Secondary consumers → Tertiary consumers

Energy transfer

At each level, 90% of the original energy is lost

• Respiration – Energy is used to respire

• Movement – Energy is used for movement

• Maintenance of body temperature – Energy is used in homeostasis

• Indigestable material within an organism – Some parts of eaten marterial cannot be digested or used by the consumer

→The higher the trophic level, the smaller the amount of energy transferred

Pyrimads

Food Pyramids: graphical representations that show feeding relationships of organisms at each trophic level

Pyramid of Number - A pyramid of numbers shows how many organisms we are talking about at each level of a food chain.

→The width of the box shows the number of organisms at that trophic level

Could also be irregulary shaped

Pyramid of Biomass - shows how much dry mass the organisms have at each trophic level

→Always pyramid shaped

Nutrient Cycles

Nitrogen Cycle

1. Nitrogen-fixation: Legume plants contain nitrogen-fixing bacteria. These bacteria live in swellings in the plant roots called nodules. Nitrogen-fixing bacteria convert nitrogen gas from air into a form that plants can use to make proteins

2. Production of nitrogenous waste products: Animals cannot store excess protein in their bodies. They break it down and turn it into waste products and excrete them from their bodies.

3. Decomposition: Decomposers break down animal and plant proteins and nitrogenous waste products to into ammonium

4. Nitrification: nitrifying bacteria convert ammonium into nitrates in order to obtain energy.

5. Uptake of nitrates: Plants absorb nitrates from the soil into their roots and use the nitrates to produce their proteins.

Carbon Cycle

Water Cycle:

Population

Population: All the members of a single species that live in a habitat

Community: A combination of all populations of different species in an ecosystem

Ecosystem: A unit containing the community of organisms and their environment, interacting together

Factors Affection population size:

• Food supply

• Predation

• Disease

1. Lag phase

   The population growth begins slowly from a few individuals

2. Log phase

   Exponential growth due to ideal conditions and maximum growth rate is achieved

3. Stationary phase

   The carrying capacity of the environment is reached

   Limitation of resources such as food

4. Death phase

   Sudden environmental change causes an inability of the environment to support the population