Animal and plant respiration place carbon into the atmosphere. Plants use carbon dioxide from the atmosphere to make the building blocks of food during photosynthesis. Carbon is found in the hydrosphere dissolved in ocean water and lakes. Carbon is used by many organisms to produce shells.
Scientists combine several well-tested techniques to find out the ages of fossils. The most important are Relative Dating, in which fossils and layers of rock are placed in order from older to younger, and Radiometric Dating, which allows the actual ages of certain types of rock to be calculated.
Relative Dating. Fossils are found in sedimentary rocks that formed when eroded sediments piled up in low-lying places such as river flood plains, lake bottoms or ocean floors. Sedimentary rock typically is layered, with the layers derived from different periods of sediment accumulation. Almost any place where the forces of erosion - or road crews - have carved through sedimentary rock is a good place to look for rock layers stacked up in the exposed rock face. When you look at a layer cake, you know that the layer at the bottom was the first one the baker put on the plate, and the upper ones were added later. In the same way, geologists figure out the relative ages of fossils and sedimentary rock layers; rock layers, and the fossils they contain, toward the bottom of a stack of sediments are older than those found higher in the stack.
Radiometric Dating. Until the middle of the last century, "older" or "younger" was the best scientists could do when assigning ages to fossils. There was no way to calculate an "absolute" age (in years) for any fossil or rock layer. But after scientists learned that the nuclear decay of radioactive elements takes place at a predictable rate, they realized that the traces of radioactive elements present in certain types of rock, such as hardened lava and tuff (formed from compacted volcanic ash), could be analyzed chemically to determine the ages, in years, of those rocks.
Putting Relative and Radiometric Dating Together. Once it was possible to measure the ages of volcanic layers in a stack of sedimentary rock, the entire sequence could be pinned to the absolute time scale. In the Wyoming landscape shown below left, for example, the gray ash layer was found to be 73 million years old. This means that fossils in rock layers below the tuff are older than 73 million years, and those above the tuff are younger. Fossils found embedded within the ash, including the fossil leaves shown below right, are the same age as the ash: 73 million years old. So, there for the relationship between the age of a fossil and the layer of rock in which it was found dates back to about the same time era.
- Got this out of an article, hope it helps! (:
Answer: Chloroplast, endoplasmic reticulum,lysosomes, nucleus, vacuoles.
Explanation:
The cytoplasm can be defined as the fluid that is found inside the cell. This liquid contains various types of salts and minerals dissolved in it.
All the organelles inside the cell is found in the cytoplasm. The organelles like nucleus, chloroplast, vacuoles, lysosomes and other organelles are found in the cytoplasm.
The cytoplasm provides stability, flexibility to the cell. Being the liquid part of the cell it prevents the cell from drying.
Answer:
One possible explanation students can make: Convergent movement between the Jalisco Block and the Rivera Plate best explains the pattern of volcanic activity and earthquakes on the Jalisco Block. ... Even though this seems very slow, plates move very slowly over time, so this is still evidence of convergent movement.
Explanation:
spongy bone is found in the bones of the skull, sternum, vertebrae, the pelvis, the lining of the marrow cavity and the epiphysis.
