Transport in flowering plants

Question 1

the phloem and xylem make up the transport system of

Answer 1

vascular plants

Question 2

the role of the xylem is to

Answer 2

transport water and mineral ions from the roots to the shoots of the plant

Question 3

the xylem is formed from

Answer 3

dead cells reinforced by lignin

Question 4

the cell wall in the xylem is

Answer 4

broken down

Question 5

the walls in the xylem are thickened by

Answer 5

lignin

Question 6

the xylem has contents of

Answer 6

continuous column of water

Question 7

role of the phloem is to

Answer 7

transport sucrose and amino acids throughout the plant

Question 8

phloem is formed by

Answer 8

living cells forming a tube with small holes through which substances can move

Question 9

root hair cells contain _____ which releases energy for active transport

Answer 9

mitochondria

Question 10

root hair cells increase ___ ____ of plant roots, increasing the rate at which water and minerals can be taken up

Answer 10

surface area

Question 11

how do root hair cells take up mineral ions and water from the soil

Answer 11

by active transport and osmosis

Question 12

water moves into the root hair cells by

Answer 12

osmosis

Question 13

water moves into the root hair cells through the __ ___ and into the ___

Answer 13

root cortex

xylem

Question 14

once water has gotten into the xylem, it is carried up to the ___ where it enters ____ cells

Answer 14

leaves

mesophyll

Question 15

pathway of water through plants

Answer 15

root hair cells
root cortex cells
xylem
leaf mesophyll cells

Question 16

transpiration is defined as

Answer 16

The loss of water by evaporation from the leaves of plants

Question 17

loss of water occurs through ___ at the surfaces of ___ ____ cells

Answer 17

evaporation

spongy mesophyll

Question 18

after the evaporation of water from spongy mesophyll cells, ___ of water ___ through the stomata happens

Answer 18

diffusion
water vapour

Question 19

functions of transpiration in plants (4)

Answer 19

• transporting mineral ions
• Providing water to keep cells turgid in order to support the structure of the plant
• Providing water to leaf cells for photosynthesis
• Keeping the leaves cool as heat energy is removed from the leaves when water evaporates

Question 20

factors affecting transpiration (4)

Answer 20

• air movement
• humidity
• temperature
• light intensity

Question 21

how does wind affect transpiration rate

Answer 21

As wind speed increases, the transpiration rate increases

When it is windy, water molecules that diffuse out of stomata are quickly blown away from the leaf; this creates a concentration gradient and more water vapour diffuses out of the leaf

Question 22

when it is windy, transpiration rate ____

Answer 22

increases

Question 23

when temperature increases, transpiration rate ___

Answer 23

increases

Question 24

why does rate of transpiration increase when temperature increases

Answer 24

When temperatures are high water vapour molecules have more kinetic energy and move around faster, so they are more likely to move out of the stomata by diffusion

Question 25

when humidity increases, rate or transpiration ___

Answer 25

decreases

Question 26

why does transpiration decrease when humidity increases

Answer 26

Humid air contains a high concentration of water vapour; this reduces the diffusion gradient between the inside of the leaf and the outside air, so less water vapour diffuses out of the leaf

Question 27

when light intensity increases, rate of transpiration ___

Answer 27

increases

Question 28

why does rate of transpiration increase when light intensity increases

Answer 28

Increased light intensity increases the rate of photosynthesis, so the stomata open to allow gas exchange; when this happens, water vapour diffuses out of the stomata

Question 29

PRACTICAL FACTORS AFFECTING TRANSPIRATION

Answer 29

Cut a shoot underwater

To prevent air entering the xylem and place in tube

Set up the bubble potometer, and make sure it is airtight, using Vaseline to seal any gaps

Dry the leaves of the shoot

Wet leaves will affect the results as stomata will be blocked

lift the tube from the beaker of water to allow a single air bubble to form and place the tube back into the water

Allow the plant to adapt to the new environment for 5 minutes

Record the starting location of the air bubble

Leave for 30 minutes

Record the end location of the air bubble

Reset the bubble by opening the tap below the reservoir

Repeat the experiment

Calculate the rate of transpiration by dividing the distance the bubble travelled by the time period

The further the bubble travels in the same time period, the greater the rate of transpiration

Question 30

the lignin that reinforces xylem vessels provides what

Answer 30

a route for the column of water to move through the plant by transpiration

Question 31

root hair cells are

Answer 31

specialised cells found in plants

Question 32

root hair cells are adapted to

Answer 32

absorb water and mineral ions from soil

Question 33

adaptations of root hair cells (2)

Answer 33

root hairs
mitochondria

Question 34

why do root hair cells have root hairs

Answer 34

they increase the surface area for absorption

Question 35

why do root hair cells have mitochondria

Answer 35

they release energy for active transport

Question 36

when minerals are taken up by active transport, how does this allow water to be taken up

Answer 36

because it reduces the water potential in the cell, so water can move in by osmosis

Question 37

how is water lost

Answer 37

evaporation of water through the spongy mesophyll layers into the air spaces

water then diffuses into the surrounding air through the stomata

Question 38

if you wanted to investigate light intensity on rate of transpiration, what would you do

Answer 38

you would just do the same investigation, but change the distance between the potometer and the lamp