An ecosystem is all the different organisms living together in a particular environment.
There are two types of ecosystems, artificial and natural. A natural ecosystem is one where humans don't control the processes going on within it. An artificial ecosystem is one where humans deliberately control the growth of certain living organisms and get rid of others which threaten their well-being.
Humans affect (deliberately) artificial ecosystems as there is less biodiversity. Humans can also affect natural ones (not on purpose). Artificial ecosystems can be used for making money - farmers may use pesticides on unwanted insects and feed the animals for slaughtering so more profit is made when it is sold.
Examples of ecosystems - woodlands and lakes are natural whereas greenhouses are artificial.
Many ecosystems are still unexplored around the world. In areas of forests, the ground is so dense that it is difficult to penetrate. Some species are yet to be discovered in the sea and land!
Classification is organising living organisms into groups. We classify organisms into groups based on genetic similarities, for example whales and humans have a similar bone pattern. Classification reflects these similarities.
Living things are divided into kingdoms, they are then divided into smaller groups like a genus. Members of the plant kingdom - must contain chloroplasts. Members of the animal kingdom - must have compact bodies (ability to move freely) and should be able to search/hunt for food. Fungi and bacteria are classified into other kingdoms, and some single-celled organisms have features of both plants and animals like euglena.
The animal kingdom is divided into vertebrates and invertebrates. Vertebrates are divided into five groups called classes - fish, amphibians, reptiles, birds and mammals.
- Fish → have scales and gills, use side of head for gas exchange
- Amphibians → exchange gas through skin (it is permeable and moist)
- Reptiles → dry scaly skin (lose less water)
- Birds → most can fly, have a beak (which is hard, easy for catching food)
- Mammals → have fur (keep them warm), give birth to young, produce milk