Answer:
the third one is correct
explanation
because atomic number and proton &electron number is same . neutron number is solved as atomic mass minus atomic number ( N=atomic mass - atomic number)
Limestone deposits can help researchers learn about what the area was like thousands of years ago as Limestone can contain fossilized plants and animals.
Explanation:
- Limestone often contains fossils of shelled sea creatures. Entire reef formations and communities of organisms are found preserved in limestone.
- The types of fossils found in limestone include coral, algae, clams, brachiopods, bryozoa and crinoids.
- Limestone is a sedimentary rock made almost entirely of fossils.
- Fossils are the remains of ancient plants and animals, like an imprint in a rock or actual bones and shells that have turned into rock. Fossils are found in sedimentary rocks and hold the clues to life on Earth long ago.
- Limestone is composed of the mineral calcite; calcium carbonate. It often has variable amounts of silica in it, as well as varying amounts of clay, silt, and sand. Limestone rocks fall under the category of sedimentary rocks that are made from mineral calcite.
Answer:
increasing extension time
Explanation:
The Polymerase Chain Reaction is a technique widely used in molecular biology laboratories to amplify target DNA regions. The standard steps of a PCR are as follow 1-denaturation, 2-annealing and 3-elongation/extension. These steps are repeated 15-40 times in order to exponentially amplify the linear DNA fragment. It is well known that longer extension times can be used as a strategy to increase the yield of longer PCR products. This is because the extension time depends on the synthesis rate of the DNA polymerase used in PCR technique and the length of the DNA fragment to be amplified.
Answer:
capillaries help the blood containing the things a cell needs
Explanation:
Because it is polar and it is to large to cross the membrane and because the concentration gradients are to strong so they have to be diffused.
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