<span>d. sporangia.
is a structure that can be found in unicellular and multicellular organisms that encloses spores. Organisms that form sporangia in their life cycles are plants, fungi and algae among others.</span>
An endoskeleton of calcified cartilage
<span>Modern humans have been around for a very short period of time. There are differences in race, asian people tend to be smaller, stuff like that. The problem is different races marry and those genes mix. If Asians only married pure blood Asians, Africans only married and procreated with other Africans thanks in hundreds of thousands of years different sub species would most likely start to occur. Seeing as how human population is all connected today, that won't happen.</span>
Genetic variation<span> is essential for </span>natural selection<span> because </span>natural selection can only increase or decrease frequency of alleles that already exist in the population.Genetic variation<span> is caused by: mutation
i pulled this off of the site i got the information from i hope this helps you out if not sorry
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