Question

molecular clocks

The image below represents a sediment core that a research team collected from) a lake floor They divided the sediment into five equally sized layers Drag and drop each label onto the image to most accurately descended four of the five layers.

Answer 1

As we know that air in the atmosphere contains the carbon dioxide and this get fully mixed with the unusual carbon 14 atom together with all other carbon dioxide molecules in the lower atmosphere. Plants use this carbon dioxide in photosynthesis to create a host of organic compounds. Those compounds, when formed, have carbon 14 atoms. Animals eat plants and we eat animals flesh and so those one-in-a-trillion carbon 14 atoms get spread around among all living things in the same proportions found in the atmosphere. That means, while we are alive, one in every trillion of the trillions of carbon atoms that make us, is a carbon 14 atom. All the living organisms assimilate carbon. As we know that Carbon 14 atoms are radioactive, and that they decay. They convert themselves into nitrogen 14 atoms and the process is done very slowly as long as we are alive. In our life time we continue to take new carbon 14 and maintain its level. After we die the number of carbon atoms start disintegrating over the time and there will be fewer and fewer carbon 14 atoms remained in us. By measuring the amount of remaining carbon 14 atoms we can determine how long it has been since death.

Similarly, in the core of lake sediment, layers that form will be such as:

• The Shallowest layer will contain the highest carbon 14 to carbon 12 ratio as this is one of the newest layer and contain large amount of living matter,
• The other layer will be the second highest carbon 14 layer that comes at the bottom of the first layer, that has considerably lower proportion of carbon 14 as compared to the first layer
• Then comes the second oldest sediment layer,
• Below the second most sediment layer will lie the first oldest sediment layer which will contain the lowest carbon 14 to carbon 12 ratio.