Types of reproduction of living organisms
Reproduction is the property that keeps life going. In asexual reproduction the new organism develops by mitosis from a somatic cell or cells of one parent, so the offspring are genetically copies of the parent: such a genetically identical group is called a clone. In unicellular organisms: division into two (amoeba, Euglena, Paramecium, bacteria), schizogony — division into many parts (Chlorella, the malaria parasite Plasmodium), budding (yeast) and reproduction by spores. In multicellular organisms: vegetative reproduction (in plants by cuttings, runners, tubers, bulbs, rhizomes and root suckers), budding (freshwater Hydra), fragmentation into parts of the body (planarian, starfish) and spores. Advantages: rapid reproduction, a single organism is enough, good varieties can be kept; disadvantage: little genetic diversity, so if conditions change or disease strikes the whole clone can suffer. Today plants are propagated by tissue culture (micropropagation) and some animals by cloning (the sheep Dolly was cloned in 1996).
“Clone garden”. With an adult’s help (an adult handles the sharp tool) take a cutting from a willow or spiderwort shoot and watch it root in water; record daily changes in a table. Rooted cuttings are genetically alike.