Answer:
B, A fossil found in rocks from one time period
Explanation:
Fossils are used to determine the ages of rock layers. Index fossils are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in. Hope that this helps you :)
Answer:
Aluminum
Explanation:
The density of Aluminum is 2.7 g/cm3
We know the volume and mass of the unknown metal, as density is mass/volume: 81g/30cm3 = 2.7 g/cm3 which is the density of Aluminum :)
Answer:
Make up the skull and composed of the brain
Explanation:
DNA is nothing more than a sequence of bases (nucleotides) and since DNA is normally double stranded, they can be referred to as base pairs. One could best visualise it like a zipper: two connected strands (that can also be separated). DNA is made up of only four different bases, abbreviated as A, C, G and T. These always form the same pairs: A on one side of the zipper, T on the other side and the same goes for C and G. So, when unzipped, you always know the sequence of the opposite strand.
The sequence of base pairs that make up our DNA should be viewed like a bar code. Every set of three bases code for one building block of a protein. That's all that DNA is for: code for building proteins. A set of three bases is called a codon and tells machinery in the cell (ribosome) to add one specific building block to a forming protein. It's like Lego and DNA is the instructions that tell you which block to add next.
These different blocks give shape and function to the proteins it helps to build.