What is the function of yolk sac?

What is the function of lymph ?

What is the function of SER ?

What is the function of lymph?

What is the function of albumin?

What is the function of filiform apparatus in an angiospermic embryo sac ?

The respiratory system includes the respiratory tract, the respiratory organs and air sacs. What are the functions of air sacs ?

What is the function of secondary phloem?

What is the main function of polysome?