_Hydrogen_ ...............is the answer.
White snowy place- color of the animals fur. For example white to blend in with the snow
If CO2 was in very small amounts then it would be the limiting factor of photosynthesis, this means the process will take place at a much slower rate because it is lacking one of the raw materials it needs for the process to occur. To find the optimum light intensity you really need all other factors to be at optimum levels or in abundance.
Exocytosis is ana ctive transport method and does not include any transport protein. whereas calcium ions pass through the membrane with the help of trans- membrane protein. These proteins make pores inside hydrophobic membrane and allow the ions to pass though it.