Temperature is not an agent of chemical weathering.
Viruses are not made out of cells, they can't keep themselves in a stable state, they don't grow, and they can't make their own energy. Even though they definitely replicate and adapt to their environment, viruses are more like androids than real living organisms.
Answer:
Decomposers recycle essential nutrients back into an ecosystem
Explanation:
An ecosystem works thanks to the constant transformation of energy. The role of the decomposers will be to transform energy into something useful in the ecosystem. For example, The bacteria which will rotten the apples that fall from a tree onto the ground are recycling or making available this energy for other organisms to use it. As part of this example, the essential nutrients of the apples will be available to be reabsorved by the roots of the apple tree thanks to the transformation of energy done by the bacteria in the apples.
A. Transpiration is the only force that drives water movement within a plant.
<span>Normally there are two kinds of roots and they are taproot and fibrous roots. In case of taproots the main root goes downwards and smaller roots branches out of it. In case of taproots, it is true that the spread of roots is smaller than the depth of the roots. In case of fibrous roots, the spread of roots is greater than that of the depth of the roots. A wig tree is an example of a plant having taproot. in the wig tree the root can go to a depth of around 120 meters.<span>
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Answer:
Semi-conservative replication
Explanation:
After the double-helix discovery of Watson and Crick, there were three possible models about the DNI replication:
- The Conservative model stated that the two strands of DNI together were the template of another new molecule. The final product was the original double-stranded molecule and the new molecule.
- The semi-conservative model stated that the original DNI molecule separated into two strands, and each of them served as a template for the synthesis of a new complementary strand. The replication product would be two double-stranded DNA molecules, each carrying an original strand a new one.
- The Dispersive moles stated that the replication product would be two molecules made by a mixture of segments of the original and the new molecules.
Meselson and Stahl joined to discover which of the models was the correct one. To do it they used E. coli and Nitrogen isotopes.
- First, they extracted DNI from bacteria grown in a medium with N¹⁴ and got its density band by centrifugation.
- Then they grew bacteria in a medium with N¹⁵, extracted their DNI molecules, centrifugated them, and got the density band, which was heavier than the firsts ones.
- The researchers then transferred bacteria grown in medium with N¹⁵ to a medium with N¹⁴, and they allowed only one replication process to occur. DNI was extracted and centrifugated again, and a new band appeared. This band was an intermediate form between bands of DNI-N¹⁵ and DNI-N¹⁴.
This event <em>eliminated the conservative model</em>. If this model were correct, the expected result would be to get two bands: one corresponding to the density DNI-N¹⁵ and the other corresponding to the density DNI-N¹⁴.
- Bacteria grown in a medium with N¹⁵ and then transferred to a medium with N¹⁴ were finally allowed to replicate twice. Their DNI was extracted and centrifugated. The result was two bands: one of them coincided with the intermediate band, and the other one with the DNI-N¹⁴.
<u>This result was conclusive</u> because if the dispersal model were correct, these two bands should not appear, as all the DNI strands would have part of the original molecule.
With this experiment, Meselson and Stahl proved that the correct replication model was the semi-conservative one.
