What is "work function "?

The threshold wavelength for emission of photoelectrons from a metal surface is 6xx10^(-7) m. What is the work function of the material of the metal surface ?

What are jacobson's organs ? What is their function ?

What are genes? What is their function?

What are guard cells? What is their function?

What are sebaceous glands? What is their function?

What is the part indicated by an arrow mark ? What is its working function ?

What is endostyle ? What is its function ?