Organisms and environment

03.19.2020
08:48:19
Today’s topic- food chain, food web, producers, consumers, tropic levels an d pyramids of biomass - course book- pages 266 to 269

Nearly all living things depend on the Sun to provide energy. /
This is harnessed by photosynthesising plants and the energy is then passed through food chains.
With the exception of atomic energy and tidal power, all the energy released on Earth is derived from sunlight.
The energy released by animals comes, ultimately, from plants that they or their prey eat and the plants depend on sunlight for making their food.
Photosynthesis is a process in which light energy is trapped by plants and converted into chemical energy (stored in molecules such as carbohydrates, fats and proteins).
Since all animals depend, in the end, on plants for their food, they therefore depend indirectly on sunlight.
Eventually, through one process or another, all the chemical energy in organisms is transferred to the environment.

Food chain: shows the transfer of energy from one organism to the next, beginning with a producer.

Food web: is a network of interconnected food chains.

Producer: is an organism that makes it own organic nutrients, usually using energy from sunlight, through photosynthesis.

Consumer: is an organism that gets its energy from feeding on other organisms.

Herbivore: is an animal that gets its energy by eating plants.

Carnivore: is an animal that gets it energy by eating other animals.

Decomposer: is an organism that gets its energy from dead or waste organic material.

Interdependence means the way in which living organisms depend on each other in order to remain alive, grow and reproduce.

Predator is a carnivore that kills and eats other animals.

Energy is transferred between organisms in a food chain by ingestion.

A food chain shows what eats what in a particular habitat. It shows the flow of energy and materials from one organism to the next, beginning with a producer.
The arrows between each organism in the chain always point in the direction of energy flow from the food to the feeder.
A food web is a network of interconnected food chains. It shows the energy flow through part of an ecosystem.
A pyramid of biomass shows the biomass at each trophic level, rather than the population.
Nearly always the correct pyramid shape.
more accurate indication of how much energy is passed on at each trophic level

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

Energy decreases as it moves up trophic levels because energy is lost as metabolic heat when the organisms from one trophic level are consumed by organisms from the next level.
Energy transfer is inefficient because energy is lost while moving from one trophic level to another. This is because not the entire organism is consumed or digested.
The transfer of energy from primary to secondary consumers of probably more efficient, since a greater proportion of the animal food is digested and absorbed that is the case with plant material.
It is very unusual for food chains to have more than five trophic levels because, on average, about 90% of the energy is lost at each level.

Homework is given on related to population and biomass