Biology – notes 1.Ecosystem: all organisms in an area that interact with each other and with their environment. a) Ecosystems found on dry land are called terrestrial ecosystems. Ex: Tropical forest, deserts, Tundra,… b) Ecosystems found under water are called aquatic ecosystems. Ex: Sea, Lake, River,…

2.Producers: plants that can use photosynthesis to convert radiant energy from the sun into food (chemical energy) for themselves and the animals in their ecosystem. 3.Consumers: animals that feed on plants or other animals in order to get their energy. 4.Primary consumers: animals, such as rabbits and deer, that eat plants. They are also called herbivores.

5.Secondary consumers: animals, such as foxes and wolves, that feed on the plant-eaters. They are either carnivores if they eat meat or omnivores if they eat both plants and meat. 6.The energy source for all ecosystems is the Sun. Sunlight is captured by plants during photosynthesis and is passed through the ecosystems from species to species when herbivores eat plants and carnivores eat herbivores. These interactions form a food chain.

7.Trophic level: feeding levels of the organisms in a food chain or food web. a) 1 st level = plants b) 2 nd level = herbivores c) 3 rd level = carnivores that eat herbivores. d) 4 th level = carnivores that eat carnivores. The amount of energy that is transferred from one trophic level to the next varies from about 5 to 20 percent, with 10% commonly used as an average. Decomposers, such as bacteria and fungi can consume from the 2 nd level on… because they consume any remaining dead plant and animal matter.

8. Scavengers: consumers that feed on the bodies of larger dead animals. 9. Detritivores: consumers that feed on the bodies of smaller dead animals, dead plant matter and animal dung. 10.Carrying capacity: is the largest population of organisms an environment can support. 11.Competition: struggle among individual organisms for access to limited resources such as food or territory. 12.Intraspecific competition: competition among individuals of the same species.

13. Interspecific competition: competition among individuals of different species. 14. Population density: How many individuals can live in an area at the same time. 15. Density-dependant factors: variable that affect a population based on the degree of crowding within the population. Ex: AIDS 16.Density independent factor: variables that affect a population regardless of the density. Ex: forest fire

17.Carbon cycle: (2 phases to provide carbon to all organisms as carbon is the key element of organic compounds) a) Photosynthesis: Producers gather the carbon dioxide (CO 2 )from the air, water(H 2 O) form the soil into their chloroplasts. With the help of sunlight energy, they transform these compounds into carbohydrates(C 6 H 12 O 6 ) and oxygen(O 2 ). b) Cellular respiration: All eukaryotes organisms, in their mitochondria's, get their energy by using these carbohydrates along with oxygen from the air and they return the carbon dioxide back to the atmosphere.

18.Nitrogen cycle: nitrogen is an essential component found in living things. a) Nitrogen-fixing bacteria found in the roots of some legumes take in nitrogen gas and convert it into ammonia or nitrates. b) Decomposers degrade waste and dead matter into ammonia. c) Nitrifying bacteria found in the soil change the ammonia into nitrates that when dissolved into water can be absorbed and used by plants. d) The denitrifying bacteria convert excess nitrates back into nitrogen gas that will be sent back into the atmosphere.