Biologically, life cycles define series of changes and developments that members of every species have to undergo within complete generational periods of existence. Ordinarily, this sequence begins at the point of conception and gets terminated when the involved organism manages to produce an offspring of its own. It is referred to as a cycle because every offspring also goes through the same process to reproduce their offspring. All cycles all animal cycles involve pre-productive and reproductive stages. The former is developmental while the latter involves mating. In plants, these get referred to as alternation of generations.
The simplest forms of life like bacteria and protozoa complete their cycles in equally simple formats. This involves the fission of organisms that grow to maturity and ultimately split to form two new organisms. This makes a complete cycle in their lives’ generation. Higher level animals experience more complex life cycles. These begin with sexual relationships that result in conceptions between male and female members of species. When the pregnancies mature into births, the individuals grow to complete their cycles upon reaching reproductive ages and mating to conceive. This marks the onset of another life cycle.
Conversely, plants undergo multigenerational and evolutionary life cycles. The germination of spores marks the onset of this process for different plants. These develop into gametophytes (gamete-producing organisms) which ultimately mature to form gametes. Upon maturity and the attainment of reproductive ages, it is these that get fertilized to form other spore-producing organisms referred to as sporophytes. At this point, the generational life cycle begins again. Because their cycles are multigenerational, they get referred to as alternations of generations. Majorly, such alternations occur in plants as well as in simple life cycles like those of fungi and protists. Notably, different species present outstanding differences in related features of life cycles. These are caused by varied adaptations that enable organisms to survive to maturity and attain reproductive abilities.
In conclusion, biological life cycles of plants and animals define the developments and changes that occur from conception to reproduction within individuals of various plant and animal species. Simple forms of life experience simple life cycles. These involve organisms that split into two to reproduce. However, more complex forms of life experience increasingly complex life cycles. In plants, these get referred to as alternations of generations because they have multigenerational characteristics. Although numerous organisms give birth to multiple offspring, the complete process of a life cycle begins at conception and ends when organisms give rise to offspring.