This  booklet  belongs  to:  

 

AS  Biology  

 

 

 

 

Plant  Exchange  and  Transport  

 

 

 

 

Work  booklet  

 

 

 

2    

 

 

 

This  workbook  is  designed  to  support  and  supplement  your  

learning.  It  includes  key  diagrams,  experiment  set  ups  and  some  past  paper  questions  for  you  

to  practise.    

 

Keep  it  safe  and  tidy  –  it  should  be  a  revision  asset  if  you  do!  

 

 

 

 

3    

The  leaf  Label  these  diagrams.  Try  and  show  where  each  type  of  cell  is  on  the  micrograph  

as  well  as  on  the  diagram.  

Further  thought  –  what  kind  of  microscopy  does  this  show?    

 

 

 

 

 

 

 

 

 

 

 

 

 

4    

Structure  and  Function  A  typical  AO2  type  question  –  be  clear  what  function  each  of  the  leaf  structures  

has.  Add  in  other  structures  if  you  can  think  of  any  other  relevant  ones.  

 

Structure   Function  Waxy  cuticle    

 

Guard  cell      

Spongy  mesophyll      

Palisade  cells      

Air  spaces      

Xylem      

Phloem      

Upper  epidermis      

Cellulose  cell  walls      

Vacuoles      

 

 

5    

Some  questions    

 

 

1. Flowering plants have stomata in the leaf epidermis and the epidermis of green stems. a) (i) What is a stoma and (ii) what type of cell is associated with each stoma?

……………………………………………………………………………………………

……………………………………………………………………………………….... (2)

b) In relation to photosynthesis, what is the main function of stomata?

…………………………………………………………………………………………

………………………………………………………………………………………… (1)

c) Why is water lost from the gas exchange surfaces of terrestrial organisms?

……………………………………………………………………………………………

………………………………………………………………………………………… (2)

d) The density of stomata varies from 1000 to 100 000 per square centimetre. What would be the density of stomata per square millimetre, if there were 10 000 per square centimetre?

………………………………………………………………………………………… (1)

Think:

- How many marks available? - Do you need to show working/is it a good idea? - Can you tell what the question is from your answer?

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2. A student investigated the rate of transpiration from privet leaves.

• She obtained two sets of ten privet leaves.

• She left the ten leaves in set A untreated. She covered the upper surfaces of the ten leaves in set B with grease.

• She weighed each set of leaves and then tied all the leaves in each set to a separate length of thread. This is shown in the diagram.

• She then weighed each set of leaves every 20 minutes over a period of 2 hours and plotted a graph of her results.

(a) Give two environmental conditions that the student should have kept constant during this investigation.

1 ...................................................................................................................

2 ................................................................................................................... (2)

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(b) The student measured the water loss in milligrams. Explain the advantage of using ten leaves when taking measurements in milligrams.

......................................................................................................................

...................................................................................................................... (1)

(c) Explain the change in mass of untreated leaves in set A shown in the graph.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(d) The results that the student obtained for the leaves in set B were different from those for set A. Suggest an explanation for this difference.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (2)

(Total 8 marks)

 Think:

- What is the action word in each question? - You have been given graphs. Is there any opportunity in the questions to

quote data? - Can you tell what the question is from your answer?

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The  Roots  Label  this  diagram  of  a  root  hair  cell.    

How  does  this  structure  lend  itself  to  the  absorption  of  substances  from  the  soil?  

 

 

 

 

 

 

 

 

 

 

 State  Fick’s  Law:  

 

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How  water  travels  through  the  root  

Use  this  diagram,  along  with  your  own  notes,  to  bullet  point  the  pathway  by  which  water  and  minerals  move  from  the  root  hair  cell  to  the  xylem.  

You  should  aim  to  use  the  following  words  in  your  description:  osmosis,  gradient,  vacuole,  cytoplasm,  apoplastic,  symplastic,  plasmodesmata,  

casparian  strip,    active  transport  

 

 

 

 

 

 

 

 

 

 

 

 

Bullet  point  your  answer  here…  

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A  synoptic  question…  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What  does  a  plant  

use  water  for?  

11    

Movement  in  the  stems  This  is  a  cross-­‐section  through  a  root.  You  should  be  able  to  label  most  of  the  

structures  you  see.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1. What  type  of  microscopy  is  this?    

2. How  can  you  tell?    

 3. What  are  the  two  major  vessels  that  flow  through  the  plant?  

 4. In  which  direction  do  they  flow?  5. What  do  they  carry?  6. Wait,  these  questions  would  be  much  better  tackled  in  a….  

 

12    

Table  of  Comparison  A  really  good  way  to  display  comparative  information.  I  have  included  a  few  

columns  for  you  to  fill  in  –  the  rest  is  up  to  you.  Some  past  questions/textbook  might  help  you  to  put  in  relevant  points  

    Xylem   Phloem  Major  function      

Direction  of  flow  

   

Structure  of  vessels  

   

     

     

     

 

13    

Phloem  statement  sorts  A  good  opportunity  for  you  to  recognise  and  use  statements  that  serve  different  

purposes.  

 Group  the  following  statements  about  phloem  into  the  following  categories  

O   Position  in  plant  organs  

F   Functions  of  phloem  and  processes  that  occur  within  and  between  cells  

P   Pathway  taken  by  substances  within  phloem  tissue  

S   Structure  of  phloem  tissue  including  cell  structure  and  cell  shape  

 

No.   Category

1   phloem  tissue  is  between  ‘arms’  of  xylem  in  vascular  tissue  in  root    

2   transport  of  sucrose  from  roots  to  leaves    

3   movement  of  hydrogen  ions  and  sucrose  into  companion  cell    

4   phloem  sap  moves  through  phloem  tissue  in  root    

5   phloem  sap  moves  through  phloem  tissue  in  stem    

6   sieve  pores  in  sieve  plate    

7   sieve  tube  elements  have  peripheral  cytoplasm    

8   carrier  proteins  in  companion  cell  membranes    

9   sieve  tube  elements  have  thin  cell  walls  that  are  not  lignified    

10   companion  cells  contain  mitochondria    

11   transport  of  amino  acids  from  roots  to  leaves    

12   mitochondria  provide  ATP  for  active  transport  across  companion  cell  membrane    

13   on  outside  of  vascular  bundles  in  stems    

14   on  upper  side  of  veins  in  leaves  of  dicotyledonous  plants    

15   phloem  sap  moves  through  phloem  tissue  in  minor  veins  in  leaf    

16   sieve  tube  elements  are  stacked  end  to  end    

17   movement  of  sucrose  between  companion  cell  and  sieve  tube  element    

14    

18   sieve  tube  elements  are  elongated    

19   phloem  sap  moves  through  phloem  tissue  in  petiole  and  main  vein  of  leaf    

20   phloem  sap  flows  easily,  there  is  little  resistance  to  flow    

21   plasmodesmata  between  companion  cell  and  sieve  tube  element    

22   hydrogen  ions  are  pumped  out  of  companion  cell    

23   sieve  plates    

24   sieve  tube  elements  have  no  nuclei    

25   sieve  tubes  form  continuous  columns    

26   transport  of  sucrose  from  source  to  sink    

 

Match  the  structural  features  (S)  of  phloem  tissue  (sieve  tube  elements  and  companion  cells)  with  the  ways  in  which  those  features  help  the  transport  in  phloem  (F).  Use  the  numbers  from  the  table  above.  You  may  wish  to  use  some  of  the  functions  more  than  once.  

 

Structural  feature  of  phloem  tissue  

                   

How  it  helps  transport  in  phloem  

 

 

                 

 

 

                 

 

 

                 

 

 

 

 

 

15    

Making  the  Grade  These  are  two  perfectly  passable  diagrams.  However,  you  should  be  able  to  

improve  the  labels  on  them  to  bring  them  up  to  an  A  grade  standard.      

 

 

 

 

 

 

 

 

 

 

 

 

16    

The  transpiration  stream  This  diagram  shows  evapotranspiration  at  the  leaf.    The  one  thing  this  doesn’t  

explain  is  the  cohesion-­‐tension  theory.  

Explain  this  first:  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

How  does  water  move  in  at  the  roots?    There  is  more  than  one  theory/explanation  to  this…  

17    

Factors  affecting  the  rate  of  transpiration  

 Factor   How  this  may  affect  transpiration  

 

Number  of  leaves  

 

 

Number,  size  and  position  of  stomata  

 

 

Presence  of  cuticle  

 

 

 

Light  

 

 

Temperature  

 

 

 

Relative  humidity  

 

 

 

Air  movement/wind  

 

 

 

Water  availability  

 

18    

Measuring  transpiration  Label  this  diagram  of  a  potometer  

 

 

 

 

 

 

 

 

 There  are  several  important  steps  to  setting  up  a  photometer.  Name  3  of  them,  and  explain  their  importance:  

1.  

2.  

3.  

 

How  would  you  measure  the  rate  of  water  uptake  (volume)  from  the  leaves  of  the  plant?  

 

19    

Some  questions  (a) Root pressure moves water through the xylem. Describe what causes root

pressure.

.......................................................................................................................

.......................................................................................................................

.......................................................................................................................

.......................................................................................................................

.......................................................................................................................

....................................................................................................................... (3)

(b) A biologist investigated the rate of water movement during the day in different parts of a tree. The results are shown in the graph.

(i) Describe how the rate of water movement in the upper branches changed over the period shown in the graph.

..............................................................................................................

..............................................................................................................

..............................................................................................................

.............................................................................................................. (2)

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(ii) The rate of water movement in the upper branches was different from the rate of water movement in the trunk. Describe how.

..............................................................................................................

..............................................................................................................

..............................................................................................................

..............................................................................................................

.............................................................................................................. (2)

(iii) The results of this investigation support the cohesion tension theory. Explain how

..............................................................................................................

..............................................................................................................

..............................................................................................................

..............................................................................................................

.............................................................................................................. (2)

(Total 9 marks)

 Think:

- This question is asking about a lot of differing processes. Be really sure of your key words and factual knowledge before you attempt them

- “Describe this graph” means a person should be able to draw it from your description

- These are questions where it’s easy to babble. Try and keep your answers concise and factual. Try and visualise the markscheme.

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         Xerophytes  This  is  a  cross  section  of  a  marram  grass  leaf,  taken  with  a  light  microscope.    

Marram  grass  lives  in  sand  dunes  on  windy  coasts.  It  is  therefore  well  adapted  to  dry  conditions  (xerophytic).  Label  the  features  that  allow  it  to  survive  in  theses  

conditions.  

 

 

22    

Some  questions  

 Q1. (a) Figure 1 shows a section through the root of a young plant.

Figure 1

(i) Name the part of the plant labelled R.

............................................................................................................. (1)

(ii) Give the letter which labels a tissue that transports solutes from the leaves.

Answer ...................................... (1)

(iii) Give the letter which labels a tissue that prevents the movement of water through the apoplast pathway.

Answer ...................................... (1)

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(b) Figure 2 shows a single stoma and surrounding cells from the leaf of a xerophytic plant.

Figure 2

(i) Explain how the cuticle reduces water loss.

.............................................................................................................

............................................................................................................. (1)

(ii) Explain how one of the other labelled parts reduces water loss.

.............................................................................................................

.............................................................................................................

.............................................................................................................

............................................................................................................. (2)

(Total 6 marks)

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Q2. (a) The table shows the transpiration rate of a group of plants exposed to different humidities at a temperature of 25°C.

Humidity / % Transpiration rate / arbitrary units

20 26.0

40 21.0

50 16.5

60 11.0

70 9.5

Describe and explain the relationship between humidity and transpiration rate.

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

......................................................................................................................

...................................................................................................................... (3)

(b) The diagrams show a section through a typical leaf and a section through a leaf from a xerophytic plant. The xerophytic leaf has a lower transpiration rate than the typical leaf.

25    

Describe two features shown in the diagram of the xerophytic leaf which reduce transpiration rate. Explain how each of these features contributes to a lower transpiration rate.

Feature 1 ......................................................................................................

Explanation ...................................................................................................

......................................................................................................................

Feature 2 ......................................................................................................

Explanation ...................................................................................................

...................................................................................................................... (4)

(Total 7 marks)

Think:

- Lots of AO2 here – make sure you’re including the “why” as well as the “what”.

- When you are given a table, the most useful thing you can do is to draw a graph to check the trend.

- For the longer answers, make sure you could underline each individual point (for each mark). Again, visualise the markscheme.

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Extra  notes  

 Use  these  last  few  pages  to  make  any  notes  that  you  might  find  useful  for  your  own  

revision  or  understanding    

 

 

 

 

 

 

 

 

 

 

 

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