Transport in plants

Question 1

Function of xylem is to

Answer 1

transport water and mineral ions and provide support.

Question 2

Function of phloem is to

Answer 2

transport sucrose and amino acid

Question 3

Xylem have:

Answer 3

thick walls with lignin
no cell contents
cells joined end to end with no cross walls to form a long continuous tube.

Question 4

The large surface area of root hairs increases

Answer 4

the uptake of water and mineral ions.

Question 5

Pathway of water from soil:

Answer 5

root hair cells, root cortex cells, xylem, mesophyll cells.

Question 6

Transpiration is the

Answer 6

loss of water vapour from leaves.

Question 7

Water evaporates from the surfaces of the

Answer 7

mesophyll cells into the air spaces and then diffuses out of the leaves through the stomata as water vapor

Question 8

Water vapour evaporates from the surface

Answer 8

of the mesophyll cell out of the leaf. This
reduces the pressure in the vessels. The pressure of the at the top of the Xylem Vessel is therefore less than the pressure at the bottom in the roots. Due to this pressure difference, water flows upwards. It is called transpiration pull. Because it is caused by loss of water vapour by transpiration.

Question 9

At higher temperature rate of transpiration increases because

Answer 9

at a higher temperature,Molecules have greater kinetic energy, which means the rate of evaporation is higher from the surface of the mass of cells.

Question 10

On a windy day, the air around the leaf – which contains a lot of water vapour that
has just diffused out of the leaf – is quickly moved away

Answer 10

This means that there is
always a diffusion gradient for the water vapour, because there is less of it outsidethe leaf than in the air spaces inside the leaf. So, water vapour
diffuses out of the leaf faster on a windy day than on a day when the air is still.

Question 11

As humidity increase

Answer 11

rate of transpiration decrease because there is a smaller
diffusion gradient for the water between the air and inside leaf.

Question 12

Cells loose water by

Answer 12

transpiration down the water potential gradient by osmosis. The
pressure of water on the cell wall decreases. The turgor pressure decreases. The
leaf become soft and fluffy. This is called wilting.

Question 13

Translocation

Answer 13

movement of sucrose and amino acids in phloem from sources to sinks.

Question 14

Sinks

Answer 14

parts of plants that use or store sucrose or amino acids

Question 15

Sources

Answer 15

parts of plants that release sucrose or amino acids.

Question 16

During summers

Answer 16

when sunlight is available plant photosynthesis, in this case, the
leaves are the source and the roots are the sink as they are the storage of starch.

Question 17

During winters

Answer 17

the plant cannot photosynthesize. In this case, the roots are the
source and leaves are the sink because root contains stored starch, which can be
converted to glucose and used by the leaves.