Maybe immune system and respiratory system
<span>An increase in hours of television viewing leads to increases in the sales of snack foods. This is an example of a correlation hypothesis.</span>
They create DNA molecules by assembling nucleotides. (Brainliest please) :)
The double membrane. It's theorized that chloroplasts used to be their own single-celled organism in the environment (and therefore with its own membrane). Then, the theory states, a larger cell took in the chloroplast by endocytosis, which involves surrounding the chloroplast in the large cell's own membrane. The chloroplast would then have two membranes surrounding it. This is similar to the thinking for mitochondria becoming an organelle as well. Hope this helps! :)
