Lipid Bilayer.A plasma membrane is made up of Lipid Bilayers, which consists of polar phosphate heads, which are hydrophilic or water loving, and non-polar fatty acid tails, which are hydrophobic. Proteins are embedded in the membrane as well.Cell membranes are known to have holes, or selective permeable.
I don't know if this helps or not but you would want to know the age of the rock (absolute dating) and from there you will be able to know the age of the fossil and what caused it to die.
One of these principles, now known as Mendel's law of independent assortment, states that allele pairs separate during the formation of gametes. This means that traits are transmitted to offspring independently of one another.