Movement among cells against concentration gradient is called

What is meant by influx and efflux?

Choose the correct sentences for diffusion:
$(1)$ In diffusion,molecules move in a random fashion.
$(2)$ Diffusion rates are affected by the gradient of concentration.
$(3)$ Diffusion is a slow process and is dependent on a 'living system'.
$(4)$ Movement by diffusion is passive.

Movement and accumulation of ions across a membrane against their concentration gradient can be explained by

Read carefully the following statements and choose the right answer from the options given below.
$I$. Diffusion is a slow process and it does not depend upon the living system.
$II$. Usually,the process of diffusion does not need energy.
$III$. Diffusion can occur from one part of a cell to another part of the same cell,or from one cell to another,and from one tissue to another tissue.
$IV$. Diffusion is a rapid process over short distances,but extremely slow over long distances.

Which of the following does not require a carrier molecule during transport through cell membranes?