<span>An organelle is a functional subunit enclosed by a membrane within a eukaryotic cell. The name "organelle" means little organ and the name comes from the analogy with organs: what an organ is to a body, an organelle is to a cell. So, the organelle is the organ of the cell. There are different types of organelles in cells, such as nucleus, mitochondria, Golgi apparatus, endoplasmic reticulum, chloroplasts, vacuoles, and they all have a different function. For example, the nucleus is the organelle which main function is control of cell activities. Mitochondria are organelles which main function is energy production. </span>
This is called 'controlled' or 'prescribed' burning. Usually fires in the environment are regarded as undesirable and dangerous, but fires actually fulfil an important ecological role, and animals and plants had adapted to a certain frequency and intensity of fires. The seeds of some trees or grasses germinate after forest or grass fires, as the more open conditions after a fire allows the seedlings to compete and avoid being shaded and smothered by more established trees. Unfortunately, farming and forestry practices have in many cases resulted in a reduction of fires. A reduction in the frequency of fires also allows the build up of dead wood, and when a wild fire does occur, the amount of available fuel results in very hot, large and damaging fires. Therefore, management of forests and other environments such as prairies often use controlled burns to avoid the buildup of dead organic mass and to replicate the natural fire cycle.
Plants contain these things called chlorophyll, a green pigment that traps energy from sunlight. It absorbs red and blue light, which gives plants their green color. Hope this helps!
Sexual selection example; The brightness of the feathers of a peacock. You may also see similar traits in other birds, where some dance and show off bright feathers to attract a mate, where other build nests. These specific traits do not increase their chance of survival, and are not learned. They increase their fitness because they increase their chances of reproduction and passing on their genes.
Survival of the fittest = Survival of those who survive, and reproduce
