structure of a compound influences its function in many ways like we take example of phospholipid bilayer 1. The fact that the tails are hydrophobic means that they do not interact with water. When a bunch of phospholipids are floating around in water, they try to arrange themselves in a bilayer that shields the hydrophobic parts from water-based, or aqueous, surroundings.
2. The heads are hydrophilic and can then interact with water and other polar or charged substances on either side of the bilayer. The bilayer acts as a barrier that allows cells to maintain internal conditions that are different from external conditions, which is monumentally important for cells to operate properly.
3. Phospholipids demonstrate the intersection of structure and function in another way, too. We already know that fatty acids can be saturated or unsaturated and that unsaturated fatty acids have bends in their chains. Those bends prevent fatty acids from packing close.
The basics would be that you'd need to find out if they could exchange genetic information. If not, they couldn't be considered part of one species. Set-up 2 artificial environments so both groups would produce pollen at the same time. Fertilise both plants with the other's pollen. Then fertilise the plants with pollen from their own group.
Count the number of offspring each plant produces.
If the plants which were fertilised by the opposite group produce offspring, they are of the same species. You can then take this further if they are of the same species by analysing if there is any difference between the number (and health) of offspring produced by the crossed progeny and by the pure progeny. You'd have to take into account that some of them would want to grow at different times, so a study of the progeny from their first sprout until death (whilst emulating the seasons in your ideal controlled environment). Their success could then be compared to that of the pure-bred individuals.
Make sure to repeat this a few times, or have a number of plants to make sure your results are accurate.
Or if you couldn't do the controlled environment thing, just keep some pollen one year and use it to fertilise the other group.
I'd also put a hypothesis in there somewhere too.
The independent variable would be the number of plants pollinated. The dependant variable would be the number of progeny (offspring) produced.
C. Euglena are likely are obtain nutrition via photosynthesis.
