Transport in Plants

Question 1

What is the function of a root hair cell?

Answer 1

Absorb minerals and water

Question 2

What is the benefit of a palisade cell being located at the top of a leaf?

Answer 2

Lots of light absorption for photosynthesis

Question 3

Compare a palisade cell with a root hair cell

Answer 3

Palisade cell has lots of chloroplasts for photosynthesis whereas a root hair cell has none. Root hair cell has a root hair projection to maximise surface area to volume ratio whereas a palisade cell does not. A palisade cell is located at the top of a leaf whereas a root hair cell is located underground. A palisade cells main function is to undergo photosynthesis whereas a root hair cells main function is to absorb water and mineral ions.

Question 4

How do mineral ions enter a root hair cell

Answer 4

Active transport, from a low concentration of mineral ions in the soil, through the root hair cells partially permeable plasma membrane, to a high concentration of mineral ions in the root hair cell using a protein pump and ATP

Question 5

How does water enter a root hair cell?

Answer 5

Osmosis has occurred. Water has moved from the hypotonic environment in the soil surrounding the root hair cell, through the partially permeable plasma membrane of the root hair cell, to the hypertonic cytosol of the root hair cell. The root hair cell becomes turgid.

Question 6

What is the function of the permanent vacuole?

Answer 6

Stores cell sap (including water in root hair cell)

Question 7

Why do plants need to absorb minerals?

Answer 7

Make other compounds in the plant.

Eg. phosphate ions to make nucleic acids and phospholipids

Question 8

What is xylem tissue?

Answer 8

Continuous transport vessel of a plant with no sieve plates
Transports water and mineral ions in one direction, from roots to leaves
Made of elongated dead cells with no nucleus (make room for more water)
Cell walls strengthened with lignin which adheres to water

Question 9

What is phloem tissue?

Answer 9

Ttransport vessel of a plant with sieve plates
Transports sucrose and other dissolved substances (eg. amino acids and hormones) in both directions of a plant, this is called translocation
Made living cells with no nucleus

Question 10

What is translocation?

Answer 10

Movement of dissolved substances up and down a plant using the phloem.

Question 11

What is a tissue made of?

Answer 11

Many cells

Question 12

What is an organ made of?

Answer 12

Many tissues (which are made from many cells)

Question 13

How are leaves adapted to ensure a short diffusion pathway?

Answer 13

Large surface area and thin

Question 14

What is the function of the stomata?

Answer 14

Allow for gas exchange with the environment

Question 15

Which cells are responsible for opening and closing the stomata?

Answer 15

Guard cells

Question 16

What is transpiration?

Answer 16

The loss of water from the leaves of a plant through the stomata due to evaporation

Question 17

How does transpiration help with water movement in a plant?

Answer 17

It creates a suction pressure which helps to draw water up the xylem from the roots

Question 18

Why do stomata close at night?

Answer 18

Carbon dioxide is not required at night as there is no sunlight for photosynthesis to occur, so closing the stomata reduces water loss

Question 19

What factors affect transpiration?

Answer 19

Humidity, temperature and wind velocity

Question 20

How does increasing humidity affect the rate of transpiration?

Answer 20

As humidity increases, transpiration decreases due to reduction in the water diffusion gradient

Question 21

How does increasing temperature affect transpiration?

Answer 21

As temperature increases, transpiration increases due to the increased kinetic energy of the water molecules

Question 22

How does increasing wind speed affect transpiration?

Answer 22

As wind speed increases, transpiration increases due to maintenance of a steep water diffusion gradient

Question 23

Why does the water that enters a plant not equal to the water that is lost by transpiration?

Answer 23

Some is used for other process like photosynthesis or hydrolysis reactions (eg. breakdown of ATP)

Question 24

What is a potometer?

Answer 24

A device used to estimate transpiration rates

Question 25

How is a potometer used to measure transpiration?

Answer 25

As water moves up through the plant, the air bubble moves along the scale giving a measure of water absorbed by the plant over time and hence transpiration rate.