Deforestation is not a natural change.
Answer:
B (active transport using ATP)
Explanation:
Movement of substances normally occur in the direction of concentration gradient/difference i.e. the difference in concentration of a substance across a membrane. Letting molecules diffuse or pass down their concentration gradient does not require energy but pumping those molecules against gradient requires energy in form of Adenosine triphosphate (ATP). This process is called Active transport.
In order to perform certain cellular processes, cells need to move substances from their surroundings into the cell across their cell membrane. Moving this substances against the concentration gradient between the cell membrane and its extracellular fluid requires energy (ATP).
An example is the sodium-pottasium pump employed by animal cells in which they expend energy to move K+ molecules into the cell and Na+ molecules outside the cell against the concentration gradient of their cell membrane and extracellular solution.
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Answer:
The Nitrogen Returns into the Soil (Nitrogen Cycle)
Explanation:
After a plant dies it's the job of a decomposer to carry along the nitrogen back to the surface so that it may continue to cycle along, until it eventually returns back to the decomposer through the death of another plant. This part of the cycle is small compared to the whole Nitrogen cycle.
Mitosis is simply a stage in a cells life cycle, which could be broken down further into stages of mitosis. The rest (so not mitosis) is know as Interphase and is where the cell does its normal function, so if it's the cell is in a region of muscle it would contract/relax as normal etc.
Immediately before mitosis (or M phase) is what's know as G2 phase, where the G stands for growth and is where particular gene pathways are expressed to promote growth of the volume of DNA (chromosomes are duplicated, so from 46 to 92). At the end of this stage is a checking process where the DNA is scrutinised for any errors, if all is okay then the cell can proceed to mitosis, if not then the process is stopped so that errors in copying the DNA can be fixed. This is know as a restriction point and the cell must meet the requirements to pass. This is often seen as a way cells can prevent damage being replicated and therefore interfering with normal cell processes. When cells are cancerous they are able to override this and therefore divide and spread the damaged DNA.
