.The cell membrane acts like a filter allowing necessary materials in and waste out, while keeping the organelles and cytoplasm in. This means that a cell membrane is selectively

Permeable

Explanation:

The cell membrane is the outermost covering around the animal cells but it is also surrounded by the cell wall in the case of the plant cells. The cell membrane plays an important role in the cell that is it allows the entry of only certain substances like ions, molecules, atoms within the cell and only allows the exist of certain substances out of the cell. This is the selective permeability of the membrane. This process occurs through osmosis in which the desired molecules move from higher to lower concentration. Also it helps in maintaining the balance of nutrients and water within the cell. This helps in getting rid of the waste outside the cell. It provides the protection to the organelles and cytoplasm in the cell against the external injury caused by the external stressor outside the cell like water, pressure, pathogen, and others.

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

→

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.