Answer: Option B
Explanation: The thin layer that forms the outer covering of the cell is known as the cell membrane. It is composed of the lipid bilayer which as embedded proteins.
This membrane is selectively permeable which means it allows only specific molecules to pass through them.
The main function of cell membrane is to protect the cell from the outer environment and by the invasion of harmful bacteria and viruses.
Answer: unfavourable ph condition for the pepsin
Explanation: during digestion, enzymes are needed to aid the process.digestive enzymes are biological catalyst that breakdown large food particles into digestible form .
As biological catalyst, enzymes require an optimum temperature and pH condition.outside this temperature or pH,the enzyme is denatured.
In the stomach, hydrochloric acid is required to convert pepsinogen into it's active form,pepsin.the acid also creates an optimum low pH that pepsin needs to function.
As the food moves to the small intestine,the pH is alkaline and is unfavourable for pepsin to function.
Answer:
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
