Multicellular Organisms: Plant Transport Systems

Question 1

Why do multicellular organisms require transport systems?

Answer 1

Multicellular organisms have a small surface area : volume ratio

Question 2

What do plant organs include?

Answer 2

Roots, stems, leaves

Question 3

What is the function of the upper epidermis?

Answer 3

A transparent layer which allows sunlight to pass through to the cells below

Question 4

What is the function of the lower epidermis?

Answer 4

Underside of the leaf

Question 5

What is the function of the palisade mesophyll?

Answer 5

• Closely packed cells which contain many chloroplasts
• Main site of photosynthesis

Question 6

What is the function of the spongy mesophyll?

Answer 6

• A layer that contains many air spaces where gases diffuse in and out of cells.
• Also carries out photosynthesis.

Question 7

What is the function of the guard cells?

Answer 7

• Two cells which control the opening and closing of the stomata.

Question 8

What is the function of the stomata?

Answer 8

• Pores on the underside of the leaf which allow gas exchange

Question 9

What is the function of the vein (plant)?

Answer 9

• Contains a vascular bundle composed of Xylem and Phloem which are two transport systems

Question 10

How does water enter plants?

Answer 10

• Water enters its plants through its root hair cells by osmosis

Question 11

How are root hair cells specialised?

Answer 11

• Long extensions that increase surface area of the cell
• Allows it to absorb more water and dissolved minerals

Question 12

What is the Xylem made out of?

Answer 12

• Hollow tubes made out of dead cells
• Have rings of lignin which stop the tube closing under pressure of the water

Question 13

What is the definition of transpiration?

Answer 13

Movement of water through plants and its evaporation through the stomata.

Question 14

Describe how water moves in a plant.

Answer 14

• Water travels into root hairs by osmosis
• Water then travels upwards to the leaves in the xylem
• Water then travels to the stomata where it evaporates

Question 15

Describe the factors that change the rate of transpiration.

Answer 15

• Increasing wind speed increases transpiration rate
• Increasing temperature increases transpiration rate
• Increasing surface area increases transpiration rate
• Increasing humidity DECREASES transpiration rate

Question 16

How can rate of transpiration be measured?

Answer 16

A potometer

Question 17

Explain how a mass potometer measures rate of transpiration.

Answer 17

• When water evaporates from the surface of the leaves, the plant loses mass
• The faster the transpiration rate, the more mass the shoot will lose in a certain time

Question 18

Explain how a bubble potometer measures transpiration rate.

Answer 18

• An air bubble moves along the scale giving a measure of the water absorbed by the plant, hence the transpiration rate.

Question 19

Where does sugar in the leaves need to be transported to?

Answer 19

• All parts of the plant (upwards and downwards)
• Provides energy for growth and repair

Question 20

Where is sugar transported?

Answer 20

The phloem

Question 21

What is the phloem made up of?

Answer 21

• Tubes made out of living cells which run along the xylem in the leaf vein
• Have sieve plates and associated companion cells

Question 22

Describe the condition of a flaccid guard cell and when guard cells become flaccid.

Answer 22

• Becomes flaccid when plant is dehydrated or not photosynthesising
• Causes stomata to close

Question 23

Describe the condition of a turgid guard cell.

Answer 23

• Vacuole becomes filled with water and stomata opens allowing water to evaporate