No, they don't have organs and organ system.
Cells form tissues, Tissues form organs, Organs forms organ system; Unicellular have their own one cell only. So, it can't possible that they have organs or organ system.
Answer:
A scientific theory refers to the possible explanation of the natural event. It can be tested repeatedly and can be verified by anyone with the help of predefined sets of protocols and scientific experimentation.
Similarly, Darwin proposed the idea of natural selection as the mechanism of evolution.
Various experiments in labs, as well as observations made under natural conditions, proved that natural selection plays a major role in the evolution.
Examples may include industrial melanism of peppered moths, long neck of Giraffe, different shapes and sizes of beaks of Darwin finches et cetera.
This is why natural selection is considered a theory now.
Answer:
Glucose (sugar)
Explanation:
We know that plants take in carbon dioxide and returns it in a form of oxygen. For the plant to be able to make oxygen they need to get power. The power is the sun rays and that is mixed with the CO2, making glucose. Anything that uses photosynthesis is a producer, so it makes its own food.