Answer:
Phosphorus is essential for growth of plants and other organisms. When concentration of phosphorus mostly from high breeding rate e.g., pigs, cattle etc. rise in water it causes severe growth of plants and algae as well as phytoplanktons. As a results layers of phosphorus start to release phosphorus as well due to positive gradient. These reactions in water are iron-redox reactions that are crucial for the release of phosphorus.
When too much phosphorus accumulates, it produces a degrading growth feedback in plants, algae and phytoplanktons that then shift toward excessive nitrogen available from fertilizers and cause a flip from P to N. Cynobacteria now dominates and denitrification as well as nitrification takes place simultaneously.
Severe eutrophication induces hypoxia in water that cause a major damage to plants biodiversity in the environment.
The plasma membrane is the boundary between the cell and its environment. It regulates what enters and exits the cell. Cells must maintain an appropriate amount of molecules to function inside them. They must also have a way to keep things out or to allow things to enter. This is the job of the plasma membrane. The plasma membrane is like the guard at a gated community. The guard must inspect those who enter and those who leave to make sure that only the people and things needed in the community are there.
The cell membrane is a thin semi-permeable membrane that surrounds the cytoplasm of a cell. Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell, while keeping other substances out. It also serves as a base of attachment for the cytoskeleton in some organisms and the cell wall in others. Thus the cell membrane also serves to help support the cell and help maintain its shape.
The correct answer is that the shells of clams and other mollusks dissolve when the pH becomes more acidic.
This is because the shells of clams and other mollusks are made of calcium carbonate that is dissolved in acidic conditions. The pH needs to be low to dissolve calcium carbonate into it. It takes few days to dissolve the shell completely.
Answer:
Unlike inbreeding, hybridization is more likely to cause genetic abnormalities.
Answer:
Density is nearly 3 cabs per hectare
Explanation:
Given -
There are three three intertidal regions.
Area of each intertidal region is 
hectares.
Number of crab in the intertidal regions are as follows -
Intertidal region I - 7
Intertidal region I - 2
Intertidal region I - 6
Sum of crabs in all three regions is equal to
Total area of all three intertidal regions is equal to
hectares
Now density per hectare is equal to total population of crab divided by total area of all the three intertidal regions
Density 
Density is nearly 3 cabs per hectare
