Companion cells play a vital role in supplying organic solutes to sieve tube elements during translocation. Which of the following is a correct structural or physiological feature of companion cells that enables this function?

A highly folded cell surface membrane to maximize the surface area for co-transporter proteins, and a high density of mitochondria to supply ATP for active proton pumping

Lignified secondary cell walls that provide structural reinforcement to withstand the high hydrostatic pressure generated during active loading

An absence of rough endoplasmic reticulum and ribosomes to minimize resistance to the lateral diffusion of loaded sucrose molecules

A complete lack of plasmodesmatal connections with sieve tube elements to prevent the passive back-diffusion of loaded sucrose down its concentration gradient

A highly folded cell surface membrane to maximize the surface area for co-transporter proteins, and a high density of mitochondria to supply ATP for active proton pumping

Lignified secondary cell walls that provide structural reinforcement to withstand the high hydrostatic pressure generated during active loading

An absence of rough endoplasmic reticulum and ribosomes to minimize resistance to the lateral diffusion of loaded sucrose molecules

A complete lack of plasmodesmatal connections with sieve tube elements to prevent the passive back-diffusion of loaded sucrose down its concentration gradient

2.1 Supplying the cell

Question 74

Markscheme

2.1 Supplying the cell

Question 74

Markscheme

2.1 Supplying the cell

Question 74

2.1 Supplying the cell Questions

2.1 Supplying the cell

Question 74

2.1 Supplying the cell Questions