Answer:
Cell
Explanation:
A cell is the smallest unit of a living thing.
Answer:
Lymphatic: bacteria invade the body but are removed with the help of cells
Endocrine: A chemical message is signaled to help the body relax and sleep
Nervous: The brain signals for the muscles to contract
Explanation:
Lymphatic system is the part in the body that uses the cells in your body to help it.
The endocrine system is about hormones and how the body needs to maintain stable and have homeostasis.
The brain is part of the nervous system and it sends signals to other parts of the body.
There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Yes\.............................................
