The dead organic matter are an example of nutrient cycle and can sometimes be buried under sediment, rendering the carbon unavailable to living organisms.
learning
seasons lunar cycles
Orbit changes, axial tilt wobble and change, solar cycles, the sun's position in the galaxy, dust density, positions of other stars, supernovae.
These both are some what better but Hercules cycles are very powerful an strong.
Make a comparison of the life cycles of bugs and insects.
Irregular cycles are not necessarily bad, for example during menstruation this can be normal because it takes time for your body to get into a regular pattern. In general however irregular cycles mean irregular ovulation, this is a major indicator of health because your body will only delay or prevent ovulation if it thinks you cannot cope with pregnancy, or it will only occur if you have some sort of health problem effecting your cycles.
Whales eating salmon.
Whales eating salmon.
For different functions. For example, intestinal cells have short cell cycles because they constantly have to multiply to replace dead or destroyed intestinal cells. Neurons have long cell cycles, because they don't have to multiply and have to last the life of the person.
I assume that you mean menstrual cycles, and no a person cannot have menstrual cycles while pregnant. It is biologically impossible to ovulate and menstruate while pregnant, the body shuts down the menstrual cycles once you're pregnant. People can bleed while their pregnant for various reasons, for example hormonal imbalance or implantation bleeding, but not menstruate.
It varies, but there are short-term cycles that lasts probaly 36 moths or so. But there are long term cycles that some say swing in long about 50 year cycles, but these thing vary.
All cycles are closed e.g. Krebs cycle , Kelvin cycle .