Explaining Adaptations in Specialised Cells

Question 1

How are root hair cells adapted for diffusion

Are adapted for the absorption of ………….

Have a specialised ……… (the root ‘hair’) that increases the ………….. so the rate of water uptake by osmosis is greater (can absorb more …………………. than if the surface area was lower)

Have …………… walls than other plant cells so that water can move through easily (due to shorter ……………….distance)

Have a permanent vacuole containing cell sap, which is more………………..than soil water. This ensures a …………….gradient is ………….

Answer 1

water and mineral ions from soil

shape

cell’s surface area water and mineral ions

thinner

diffusion

concentrated

high water potential

maintained

Question 2

Epithelial cells of the small intestine: is adapted for …………

Have ………….. (highly folded sections of the cell membrane), which increases the cell’s surface area so the rate of diffusion of the products of …………. is greater (more particles can be exchanged in the same amount of time)

Each villus of the small intestine has a constant ………………., which continually transports the products of digestion away from the ……… cells.
This maintains a ……………… across the ……………. cell exchange surface (between the…………… of the small intestine and the ….. of the epithelial cell)

Answer 2

diffusion

microvilli

surface area

digestion

blood supply

epithelial

high concentration gradient

epithelial

lumen

interior

Question 3

epithelial transports what molecule

Answer 3

glucose from epithelial high conc to blood stream low conc

Question 4

What are the specialised cells adapted for facilitated diffusion

Answer 4

Neurones, muscle cells and some kidney cells are examples of cells that are adapted for the rapid transport of molecules across their membranes via facilitated diffusion

Question 5

Certain kidney cells:

Have cell …………………… that contain a very high number of aquaporins

Aquaporins …………………….

The aquaporins allow these kidney cells to …… water, stopping it from being ………………..

Answer 5

membrane

are special channel proteins that allow the facilitated diffusion of water through cell membranes

reabsorb

unnecessarily excreted by the body

Question 6

Neurones and muscle cells

Are involved in the transmission of electrical impulses around the body

They have cell membranes that contain channel proteins for ……………….. ions

The opening and closing of these channel proteins (and the resulting facilitated diffusion of these different ions),
as well as the……… of these channel proteins, plays an important role in the speed of electrical transmission, both along the membranes of neurones (during nerve impulses) and in muscle cells (during muscle contraction)

Answer 6

sodium, potassium and calcium ions

number

Question 7

In the case of the kidney cells described above, water is transported across the cell membrane via facilitated diffusion through channel proteins. Don’t forget, however - water can also diffuse through cell membranes (this can occur even though it is a polar molecule because it is a relatively small molecule).