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Introduction ...................................................................................vii
Biology syllabus .................................................................................................vii
Breakdown of the Leaving Certificate examination .............................................ix
Leaving Cert questions by topic (Higher level)......................................................x
UNIT 1: BIOLOGY: THE STUDY OF LIFE............................................1
1.1
The Scientific Method......................................................................2
Experimentation .................................................................................................3
1.2
The Characteristics of Life ...............................................................5
Definition of life .................................................................................................5
Characteristics of life ..........................................................................................5
1.3
Nutrition ...........................................................................................6
Food...................................................................................................................6
Mandatory activities – Food tests ....................................................................9
1.4
General Principles of Ecology........................................................11
Environmental factors in an ecosystem .............................................................12
Energy flow in an ecosystem.............................................................................12
Factors that affect population numbers in an ecosystem ...................................15
Nutrient recycling .............................................................................................18
Human population ...........................................................................................20
Human impact on an ecosystem .......................................................................21
Conservation ....................................................................................................22
Waste management .........................................................................................23
1.5
A Study of an Ecosystem...............................................................25
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UNIT 2: THE CELL ............................................................................29
2.1 Cell Structure ..................................................................................30
Microscopy .......................................................................................................30
Mandatory activity – Experiment to make slides and observe
under the light microscope ...............................................................................31
Mandatory activity – To prepare a slide of an animal cell ...............................32
Mandatory activity – To prepare a slide of a plant cell....................................32
Cell ultrastructure .............................................................................................33
Movement through cell membranes .................................................................35
Mandatory activity – Conduct any activity to demonstrate osmosis ...............36
Eukaryotic and prokaryotic cells ........................................................................37
2.2 Cell Metabolism .............................................................................39
Enzymes ..........................................................................................................39
Mandatory activity – Investigate the effect of ph on the rate
of enzyme activity.............................................................................................42
Mandatory activity – Investigate the effect of temperature on
the rate of enzyme activity................................................................................43
Mandatory activity – To investigate the effect of heat
denaturation on enzyme activity .......................................................................45
Enzyme immobilisation .....................................................................................46
Mandatory activity – Experiment to prepare an enzyme
immobilisation and examine its application .......................................................47
Photosynthesis..................................................................................................50
Mandatory activity – Experiment to investigate the effect of
light intensity on the rate of photosynthesis......................................................55
Respiration .......................................................................................................58
Mandatory activity – Experiment to prepare and show the
production of alcohol by yeast..........................................................................61
2.3 Cell Continuity................................................................................64
Cell division ......................................................................................................64
Haploid and diploid cells...................................................................................64
Mitosis .............................................................................................................64
Cell cycle ..........................................................................................................66
Cancer .............................................................................................................66
Meiosis.............................................................................................................67
2.4 Cell Diversity ..................................................................................68
Organ systems..................................................................................................68
Tissue culture ...................................................................................................69
v
2.5 Genetics ..........................................................................................70
Gregor Mendel .................................................................................................71
Linkage ............................................................................................................74
Sex chromosomes.............................................................................................75
Sex linkage .......................................................................................................76
DNA .................................................................................................................78
Mandatory activity – To isolate DNA from a plant tissue ................................82
DNA profiling or DNA fingerprinting.................................................................83
Genetic testing and screening...........................................................................84
Genetic engineering .........................................................................................84
Evolution ..........................................................................................................87
UNIT 3: THE ORGANISM.................................................................91
3.1 Diversity of Organisms ..................................................................92
Bacteria (Monera) .............................................................................................93
Fungi................................................................................................................98
Laboratory procedures when handling and culturing micro-organisms ............101
Mandatory activity – To investigate the growth of leaf yeast
using agar plates and controls ........................................................................103
Protoctista (Protista)........................................................................................106
3.2 Organisation and the Vascular Structures .................................107
Organisational complexity of the flowering plant ............................................107
Mandatory activity – To examine microscopically the transverse
section of a dicot stem ...................................................................................111
Organisational complexity of the human circulatory system ............................112
Mandatory activity – To dissect, display and identify an
ox or sheep heart ...........................................................................................117
Mandatory activity – To investigate the effect of exercise on
the pulse rate of a human ..............................................................................118
3.3 Transport and Nutrition...............................................................123
Nutrition in the flowering plant ......................................................................123
Nutrition in the human ...................................................................................127
The digestive system.......................................................................................127
Teeth ..............................................................................................................129
Small intestine ................................................................................................129
Large intestine................................................................................................131
The liver .........................................................................................................131
vi
3.4 Breathing System and Excretion.................................................134
The excretory system in humans .....................................................................139
3.5 Responses to Stimuli....................................................................144
Responses in the flowering plant ....................................................................144
Growth regulators ..........................................................................................145
Adaptations of plants to adverse environmental conditions.............................146
Mandatory activity – To investigate the effect of IAA growth
regulator on plant tissue.................................................................................146
Responses in the human – Nervous system ....................................................148
Sense organs ..................................................................................................154
Endocrine system............................................................................................159
Musculoskeletal system ..................................................................................165
Defence and the immune system....................................................................170
Viruses ...........................................................................................................173
3.6 Reproduction and Growth...........................................................177
Sexual reproduction in the flowering plant .....................................................177
Mandatory activity – To investigate the effect of water,
oxygen and temperature on germination........................................................183
Mandatory activity – Use starch agar or skimmed milk plates to
show digestive activity during germination .....................................................184
Sexual reproduction in the human ..................................................................189
Glossary ........................................................................................201
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LESS STRESS MORE SUCCESS
Thermometer
50
Graduated cylinder
40
30
Water
(25 °C)
20
Boiling tube
Buffer solution
Washing-up liquid
+ boiled celery
10
Hydrogen peroxide
Figure 2.14 Setting up the experiment
Enzyme immobilisation
This describes a procedure to extract useful enzymes, usually from micro-organisms.
● After removal the enzymes are then stabilised so that they can be repeatedly used
to catalyse chemical reactions.
● The enzymes can then produce large quantities of useful products.
Biotechnology
Techniques using microorganisms, or their enzymes, to produce useful products in
medicine or industry.
Advantages of enzyme immobilisation
●
●
●
Easy recovery of enzymes for reuse.
Easy harvesting of products (no enzyme contamination).
Greater enzyme stability.
DEFINITIONS
●
●
Continuous flow bioprocessing involves the regular addition of nutrients to
immobilised enzymes or micro-organisms in a bioprocessor (bioreactor). This
produces a continuous flow of product.
Batch processing is the addition of a fixed amount of nutrients to microorganisms at the beginning of a process. On completion the product and
micro-organisms are separated from the mix.
CELL METABOLISM
47
Applications of enzyme immobilisation
●
●
●
●
●
The production of fructose for use in canned drinks. Fructose is sweeter than
glucose or sucrose, so it is preferred for sweetened drinks. The enzyme glucose
isomerase converts glucose to fructose. This enzyme is difficult to produce, so it is
reused through enzyme immobilisation.
To make lactose-free milk. Many people are lactose intolerant. They cannot
produce the enzyme lactase that breaks lactose down. Immobilised lactase is used
to remove lactose from milk.
Clarification of fruit juices. Fruit juices contain binding carbohydrates called
pectins. These can make the juices more viscous and cause cloudiness. Immobilised
pectinase is used to remove pectins from fruit juices.
Production of vinegar. Bacteria are immobilised to convert ethyl alcohol and
oxygen to acetic acid or vinegar.
Diagnostic reagents. Dipsticks with the immobilised enzyme glucose oxidase can
be used to test for glucose concentrations in blood samples.
Mandatory activity
Experiment to prepare an enzyme immobilisation
and examine its application
1. Add 0.4 g of sodium alginate to 10 cm3 of water.
2. Mix 2 g of yeast in 10 cm3 of distilled water and leave for five minutes.
3. Prepare 1.4 per cent calcium chloride solution and place in a tall beaker.
4. Mix the alginate solution and the yeast suspension and draw the mixture into a
syringe.
5. From a height of about 10 cm, release the mixture from the syringe, one drop at a
time, into the calcium chloride. Each drop will form a bead (see fig. 2.15).
6. Leave the beads to harden for 20 minutes.
7. Filter the beads, wash with distilled water and place into a separating funnel (A)
(see fig. 2.16).
8. Mix another 2 g of yeast with 10 cm3 of distilled water.
9. Pour this mixture into a second separating funnel (B).
10. Make a 100 ml solution of 1 per cent sucrose and heat to 40 °C.
11. Pour 50 cm3 of this solution into each of the separating funnels.
12. Immediately dip Clinstix strips into samples taken from each separating funnel.
13. Remove the strips, leave for ten seconds, and compare both strips with the colour
card supplied.
14. Repeat the test every 30 seconds.
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LESS STRESS MORE SUCCESS
Pores
Yeast cells
Syringe +
alginate and
yeast
Permeable
alginate bead
Calcium
chloride 1.4%
Alginate beads of immobilised
yeast cells
Figure 2.15 Enzyme immobilisation
Free yeast
Retort stand
B
Immobilised yeast
Retort stand
Separating
funnel
A
Separating
funnel
Free yeast
suspension
Sodium alginate
beads with
immobilised yeast
Tap
Tap
Beaker
Beaker
Glucose
solution
Glucose
solution
Figure 2.16 Free and immobilised yeast
Expected results
● The samples released from the separating funnel with the ‘free’ yeast (B) are more
turbid (cloudy) due to the presence of the yeast cells.
● The ‘free’ yeast cells break down the sucrose at a faster rate than the immobilised
cells.
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CELL METABOLISM
Important points to remember
● Enzyme = enzymes in yeast cells, substrate = sucrose, products = glucose.
● Independent or manipulated variable = yeast cells in beads and free yeast cells.
● Dependent variable = rate of glucose formation.
● Controlled variables:
(i) Enzyme concentration: Equal amounts (2 g) of yeast cells.
(ii) Substrate concentration: Equal volumes of the same sucrose solution.
(iii) Temperature: Sucrose solutions at 40 °C.
Note
● The darker pink or more purple the strip, the greater the quantity of glucose
present.
● The use of Clinstix is a quantitative test for glucose. The colour changes indicate
the quantity of glucose present.
● The enzymes in the yeast cells break down the disaccharide sucrose to its
monosaccharides.
2009 Q9 HIGHER LEVEL
9. (a) (i) To which group of biomolecules do enzymes belong?
(ii) Name a factor that influences the activity of an enzyme.
(b) In the course of your practical investigations you prepared an enzyme
immobilisation.
Answer the following questions in relation to that investigation.
(i) Describe how you carried out the immobilisation.
(ii) In the space provided draw a labelled diagram of the apparatus
that you used to investigate the activity of the immobilised enzyme.
(iii) Briefly outline how you used the apparatus referred to in (b) (ii)
above.
LEAVING CERT MARKING SCHEME
9. (a) (i) Proteins
(ii) Temperature or pH
(b) (i) Named enzyme (accept yeast)/mix (or stir)/with alginate/add
to CaCl2 solution/how added/(allow to) harden
(ii) Diagram:
Labels: named substrate/enzyme (accept yeast) or beads/named
product/any one apparatus label
(iii) Add substrate (to immobilised enzyme)/test for named
product/how tested/test at set intervals or control described
(3)
(3)
3(3)
(2)
2(2)
3(3)