The graph shows a comparison
between the cells of the algae
and the surrounding water.
By what process could the
obtain more calcium, Ca2+, from the surrounding water?
Plants and algae, like the species
that belong to the
genus pictured here, must obtain many of their
nutrients from their surroundings.
aquatic environments, so they absorb nutrients from the surrounding water.
There are two major ways in which
mineral ions like calcium can be absorbed into the algae cells. Diffusion is the movement of
particles from an area of high concentration to an area of low concentration,
sometimes described as down or along a concentration gradient.
For example, if calcium ions were
in a higher concentration in the surrounding water outside the
they would move into the
cells via diffusion passively without using
an input of energy.
Active transport, however, is the
movement of particles up or against their concentration gradient from an area of low
concentration to an area of high concentration. Active transport, as the name
suggests, is an active process, so it requires an input of energy to occur.
If the concentration of ions is
higher inside the
cells than it is in the surrounding water, these
ions will need to move by active transport into the cell using an input of energy
from the organism itself.
If we take a look back at the
graph, we can see that the concentration of calcium ions is higher within the
cells than it is in the surrounding water.
However, the algae may still
require more calcium ions to carry out essential life processes. To obtain more calcium ions, the
plant would need to move them against their concentration gradient from an area of
low concentration outside the cell in the surrounding water to an area of
comparatively higher concentration inside the cells. As we’ve just seen, the way they do
this is using active transport.
So we’ve deduced that the method
cells could use to absorb more calcium from the surrounding water
is active transport.