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Biology Leaving Cert HL

Leaving Cert Biology
by

Laush WQ

on 7 June 2014

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Transcript of Biology Leaving Cert HL

Unit 1: The Study of Life
-the scientific method - the characteristics of life - food - ecology - HL ecology - Study of an ecosystem
Unit 2: The Cell
-cell structure - cell diversity - enzymes - enzymes (advanced) & energy carriers - photosynthesis - respiration - diffusion & osmosis - cell division - classification & heredity - DNA & RNA - genetic crosses - variation & evolution - genetic engineering

Units 1 & 2
Biology HL LC
Chapters 13-19
Chapters 7-12
The Study of Life
classification of organisms - monera - fungi - protista - structure of flowering plants - transport, food storage & gas exchange in flowering plants - blood - the heart & blood vessels - the lymphatic system - human nutrition - homeostasis - human breathing - excretion - plant responses - the nervous system - the senses - the endocrine system - the skeleton & muscles - the human defence system - viruses sexual reproduction in flowering plants - vegetative propagation - human reproduction
Unit 3 THE ORGANISM
The Scientific Method
the
scientific method
is a process of investigation in which problems are identified and suggested explanations are tested by means of
experimentation
.
Observation
see/hear/etc or otherwise observe -> recorded, they provide
basis of all facts relating to problem
Hypothesis
a hypothesis is an educated guess based on observations
(a) accounts for all facts observed
(b) leads to the prediction of new information
Experimentation
designed to test the hypothesis

will either support or contradict hypothesis
Collection & interpretation of data
Data, in the form of measurements, observations or information is gathered in the course of experimentation
Conclusion
the data from experimentation is used to reach a result.
Relation
of conclusion to existing knowledge. hypothesis is:
supported if results agree fully
changed if results agree partially
rejected if results contradict
very often, new experiments must be designed to explain conclusions
Reporting
and publishing the results
experiments should be repeatable!
if someone else follows the same procedure and obtains the same results, they are more likely to be valid.
Theories & Principles
a
theory
is a hypothesis supported by many different experiments.
a
principle
or
law
arises from a theory that has been shown valid when fully tested over a long period of time.
1. Careful Planning and Design
A
variable
is a factor that may change in an experiment.
In most experiments, only a single variable is tested. All other factors should be kept constant.
2. Ensure that Experiment is safe
tie back long hair
wear a laboratory coat
wear safety goggles
never place fingers on mucous membranes unless you have washed them
avoid contact between electrical equipment and water
be aware of safety information when handling chemicals
report all accidents to the teacher
Design a control
There should be only one variable between the actual experiment and the control
e.g. no hole for light in box with seedlings
Random Selection
Must be replicable
Others must be able to replicate experiments
Double Blind Testing
neither the tested nor the tester should know who is receiving placebo and who isn't
- the tester can't influence by bias (un/conscious)
1. Sample Size
1. A large sample reduces the risk that results are caused by individual differences, rather than being caused by the factor being investigated.
Principles of Experimentation
Limitations to the value of the scientific method
1. The extent of our knowledge
2. The basis of investigation
If an experiment is badly designed or improperly carried out, it will not yield valid results.
3. Interpreting results
e.g. thalidomide
if the results of an experiment are interpreted incorrectly , faulty conclusions and hypotheses will be drawn
4. changes in the natural world
e.g. antibiotics were thought to kill bacteria
-> found to evolve as resistant
Accidental discoveries
often the most breaking discoveries are accidental
Ethical issues
The Characteristics of Life
is the sum of all biochemical reactions in an organism
Continuity of life
means that living things arise from other living things of the same type. biogenesis
Life
1. Organisation
living things are composed of cells, tissues, organs and organ systems
2. Nutrition
obtain and use food
sun -> plants -> animals
3. Excretion
the removal of waste products of metabolism from the body
4. Behaviour (response)
The way in which an organism reacts to stimuli in their environment
5. Reproduction
asexual or
sexual
e.g. binary fission
The Need for Food
source of energy
make chemicals necessary for metabolic reactions (e.g. enzymes, hormones)
raw material for growth and repair of structures in the organism
elements present in food
commonly:
carbon (C)
hydrogen (H)
oxygen (O)
nitrogen (N)
phosphorous (P)
sulfur (S)
elements present as dissolved salts
sodium (Na)
magnesium (Mg)
chlorine (Cl)
Potassium (K)
calcium (Ca)
trace elements
iron (Fe)
copper (Cu)
zinc (Zn)
Biomolecules
chemicals made inside a living thing
carbohydrates
Cx(H2O)y
always twice as much hydrogen as oxygen
C6H12O6 = glucose
Monosaccharides
smallest
unit carbohydrates
glucose main molecule from which organisms obtain
energy
>
fruit
, chocolate
plants make glucose in
photosynthesis
fructose sweeter, found commonly in fruits
same formula, diff. molecular arrangement
Dissacharides
sweet
to taste and
soluble
in water
two
monosaccharides joined together
sucrose
(table sugar) = glucose+fructose
maltose
(germinating seeds) = glucose+glucose
lactose
(milk) = glucose+glucose
Polysaccharides
insoluble or only slightly soluble in water
many monosaccarides linked
Starch: (amylose) long chains (un/branched) glucose molecules
stored by plants
rice, potatoes, flour, bread
easily digested because glucose arranged in a line
Cellulose
structural carbohydrate in plants
more cross bonding than starch
paper, cotton
more difficult to break - fibre in diet, causing peristalsis
v. strong: cell walls plants
Glycogen
stored by animals
many glucose molecules
more branched than starch
liver and muscles
Sources of carbohydrates
Experiments
To test for Reducing Sugar
Heating Required?
Yes
Chemicals used:
glucose solution, benedict's solution

Positive result:
brick red
control: no glucose - colour: blue
Foods that tested positive:
biscuits, table sugar
To test for Starch
Heating required:
no
Chemicals used:
iodine
Positive result:
black-blue
Control:
no starch
Foods that tested positive:
potato, pasta, bread
Lipids
carbon (
C
), hydrogen (
H
), oxygen (
O
)
no simple ratio
Fats
: solid @ room temperature
Oils
: liquid @ room temperature
Structures of Lipids
GLYCEROL
FATTY ACID 1
FATTY ACID 3
FATTY ACID 2
Triglyceride
Phospholipids
fat-like substances with one fatty acid replaced by phosphate group or phosphate group added
Sources of Lipids
To test for fat
Chemicals used:
fat
Positive result:
brown paper translucent
Control:
water on paper
Foods that tested positive:
butter, cake
Proteins
Elements in Proteins
contain C, H, O and nitrogen (N)
sometimes may contain smaller amounts sulfur, phosphorous etc
no ratio for atoms, but v. complex
often 10s of 1000s of atoms
very large, bulky substances
Structure of Proteins
20 common and several rare amino acids
bonds between amino acids called peptide bonds
made of small nr. amino acids
polypeptide: > 20 amino acids
the way proteins are folded equally important
Fibrous Proteins
little or no folding
long fibres, strong & tough, e.g. hair, n, feathers
structural proteins
Globular Proteins
very folded
rounded shapes, e.g. egg white (albumen) and enzymes
Sources of Proteins
To test for protein (biuret)
Heating required?
No
Positive result:
purple colour change
Control:
water in place of protein
Vitamins
Energy Transfer Reactions
Structural & Metabolic Role of Biomolecules
Minerals
Water
complex carbon-based substances the body cannot make
Water-Soluble Vitamin
VITAMIN C
Fat-Soluble Vitamin
calciferol, found in milk
ultraviolet rays on skin -> vitamin D
Anabolic Reactions
convert smaller molecules into larger ones
e.g. formation of muscle from amino acids
e.g. formation cellulose from glucose
Photosynthesis

CRAP
:
C
atabolic
R
espiration
A
nabolic
P
hotosynthesis
Catabolic Reactions
a complex molecule is broken down into simpler ones.
release energy and require enzymes
e.g. digestion of food
e.g. decay dead plants and animals
Respiration
CRAP
:
C
atabolic
R
espiration
A
nabolic
P
hotosynthesis
Structural Role of Biomolecules
Carbohydrates
cellulose is used to form plant cell walls
7. Cell Structure
8. Cell Diversity
9. Enzymes
10. Enzymes (advances) + energy carriers
11. Photosynthesis (HL)
12. Respiration
13. Diffusion + Osmosis
14. Cell Division
15. Classification + Heredity
16. DNA and RNA
17. Genetic Crosses
18. Variation and Evolution
19. Genetic Engineering
Photosynthesising organisms are
autotrophs
, or
producers
. This means that they create their own food.
6CO2 + 6H2O + light ->chlorophyll-> C6H12O6 + 6O2
Role of photosynthesis:
Life on Earth depends on it, because
Plants use it to make food
Animals obtain their food from plants
Produces oxygen which morganisms need for respiration
Responsible for formation of fossil fuels
The Light Stage
light-dependent
chloroplast
not enzyme-controlled, as involves the (v. fast) flow of electrons
light absorption
light energy transfer
flow of electrons along pathways 1 & 2
1. Light Absorption
Chloroplasts contain many pigments, e.g. chlorophyll
each absorbs different wavelength
i.e. different colour of light
plants absorb all colours of white light
except green
reflected back
why plants appear green
2. Light Energy transferred to Electrons
pigments arranged in cluster
i.e. pigments+strategically placed chlorophyll molecule*+electron acceptor
*reaction centre chlorophyll
there may be many chlorophyll molecules
only one located @ electron acceptor
the diff. pigments absorb light energy of different wavelengths
transfer absorbed energy from one to another
until reaches reaction centre chlorophyll
energy transferred to electrons
become energised/high-energy electrons
flow from electron acceptor alone one of two pathways
a smiling cat
3. Cyclic Photophosphorylation
high-energy electrons pass from chlorophyll to electron acceptor
series of other electron acceptors
back to chlorophyll
in chloroplast
recycle
loss of energy
trapped by ADP+phosphate
forms ATP + water
ADP+E->ATP+H2O
cyclic electron-flow
4. Non-Cyclic Photophosphorylation
in chloroplast
eventually 2e- combine with NADP+ to temporarily form NADP-
(NADP+)+2e- -> NADP-
the chlorophyll molecule is now short of e-
gains new electrons from splitting of H2O
WHEN 2 WATER MOLECULES ARE SPLIT:
4 protons (4H+)
4 electrons (4e-)
oxygen (O2)
Two of these e- replace the e- lost by chlorophyll
protons formed stored in pool of protons in chloroplast
now attracted to NADP-
combine to reduce to NADPH
NADP-+H+ -> NADPH
as a result, e- (2 at a time) pass from H2O molecule to chlorophyll
energised by light and flow to e- acceptor
eventually used to form NADPH
as they flow, some energy converts ADP to ATP
e- do not recycle: non-cyclic electron flow
2e- (two high-energy electrons) at a time passed
from chlorophyll to electron acceptor
along another series electron acceptors
e- do not return to chlorophyll
lose some energy passing from acceptor to acceptor
ADP+Energy+P->ATP+H2O
End Products of the Light Stage
oxygen (O2)
made when H2O is split
can be used for respiration
or released into atmosphere
glucose (C6H12O6)
ATP
-> will supply energy for Calvin Cycle reactions
NADPH
-> supplies protons and electrons for Calvin Cycle reactions
The Calvin Cycle
or Dark Stage
6CO2+6H2O+light->chlorophyll->C6H12O6+6O2
in Stroma of chloroplast
discovered by Melvin Calvin 1961
enzyme-controlled
->affected by temperature
CO2 from air/respiration enters chloroplast
CO2
molecules combine with
H+
and
e-
to form
glucose
H+ comes from
NADPH -> NADP+ + 2e- + H+
i.e. carbon dioxide is reduced to glucose
as
addition of electrons = reduction
energy to form glucose comes from conversion ATP to ADP and phosphate
ATP + water -> ADP + P + energy
all NADP+ and ADP molecules made in Calvin Cycle reused in light stage
NADPH\__/NADP+
CO2 ---------------------------------> C6H12O6
ATP/ \ADP+P
Introduction
Aerobic Respiration
Anaerobic Respiration
To prepare and show the production of alcohol by yeast
Krebs Cycle + Electron Transport Chain
Micro-Organisms in Industrial Fermentation
a
tissue
is a group of similar cells adapted to carry out the same function(s)
Plant Tissues
Animal Tissues
Tissue Culture
Organs & Organ Systems
Dermal Tissue
single layer cells surrounds different parts plant
Location
: Epidermis found as
covering
on leaves, stems, roots
Description
: living, rectangular cells
often slightly thickened cell wall
sometimes epidermis has waterproof cuticle on outer surface
Function
:
protects
plant
where cuticle present:
secondary function preventing water loss
find the words "epidermis" and "cuticle!" <3
Vascular Tissue
PHLOEM
XYLEM
Description
: hollow tubes that run continuously from roots up stem and into leaves
Function
: mainly to transport water (+ dissolved minerals) throughout plant
secondly
to provide support in woody plants as xylem forms the wood in trees
Description
: Phloem also a series of tube-like structures. found in leaves, stem, roots
Function
: transport of food from leaves to rest of plant
Connective Tissue
Description
: a number of cells spread out in a matrix (or material) that is produced by connective cells
joins and supports other body structures
e.g. adipose tissue (stores fat) cartilage, bone, blood
Example
blood is a connective tissue as it consists of red cells, white cells and platelets suspended in a matrix (plasma)
Red cells carry oxygen, white cells defend the body and platelets clot blood
Nervous Tissue
Description
: composed of neurons (nerve cells)
Function
: adapted to carry electrical impulses to and from the brain and spinal cord
the growth of cells in or on a sterile nutrient medium
called in vitro (glass) cultivation
a sample tissue is removed from the plant or animal
grown in glassware, bath or bioreactor
under v. carefully controlled conditions
sterile fluid containing nutrients (+ commonly hormones & other substances to enhance growth)

important to prevent micro-organisms from growing in the bioreactor
as they consume nutrients and produce toxic waste
e.g. bacteria and yeasts
nutrients:
energy source such as glucose
chemicals to stimulate growth (e.g. growth regulators or hormones)
vitamins & minerals
Applications Tissue Culture
Plant Breeding
the growth of large of plants from small pieces of plant

a desirable plant is cut into many small pieces (1-k cells)
cells grown or cultured in a laboratory on a suitable medium
in time form a clump of similar cells called a callus

growing conditions changed so that callus continues to grow

after some time forms a young plant embryo and then a young plant
when young plants are sufficiently large they may be planted out as normal small plants
The formation of a new plant from single cells in this way shows that each nucleus has all the genes necessary to form an adult plant
Benefits of Micropropagation
production of a large number of plants in a short time
plants grown this way are genetically identical
inexpensive way to produce large nrs of plants
Cancer Research
using tissue culture it is possible to produce special antibodies (monoclonal antibodies / MABs) that react to cancer antigens
vast range of other antigens
Benefits of monoclonal antibodies
may change colour when they react with cancer antigens
used to test whether a cell in cancerous
if toxic drugs attached to monoclonal antibodies it is
delivered only to cancer cells
->the MABs do not join to normal cells
Skin Grafts
tissue culture can be used to grow new skin for patients who have been badly burned
previously it had to be removed from elsewhere on the body and relocated
very often grown from stem cells
originally taken from embryos, also found in bone marrow + umbilical cords
An organ is a structure composed of a number of tissues which work together to execute one or more functions
An organ system consists of several organs working together to carry out one or more functions
Organs
An Example of a Plant Organ
:
1. Dermal tissue in epidermis
2. Vascular tissue as xylem & phloem in vascular bundles
3. Ground tissue as palisade and mesophyll cells
An Example of an Animal Organ:
the heart
1. the walls of the heart are made of cardiac muscle
2.the heart is enclosed in a membrane called the pericardium
3. blood and numerous blood vessels are present
4. the heart is controlled by nervous tissue
Organ Systems
animals, e.g. humans consist of
10 organ systems
: epilethial, skeletal, muscular,
digestive
,
circulatory
, respiratory, urinary, nervous, reproductive, endocrine
Circulatory System
heart, blood vessels & blood
includes lymph vessels & lymph
functions: transport materials, fight infections
Digestive System
mouth, oesphagus, stomach, small intestine, large intestine, anus (in association with liver and pancreas)
functions: take in food, break it down and transfer nutrients to circulatory system
Classification of Organisms

Monera (bacteria)
Fungi
Protista
Human Nutrition
Homeostasis
Human Breathing
Structure Of Flowering Plants
Transport, Food Storage & Gas Exchange in Flowering Plants
Blood
The Heart & Blood Vessels
The Lymphatic System
Excretion
Plant Responses
The Nervous System

The Senses
The Endocrine System
The Skeleton & Muscles
The Human Defence System
Viruses
Sexual Reproduction in Flowering Plants
Vegetative Propagation
Human Reproduction
The Nephron
Temperature Regulation in Humans
Excretion in Plants
The Urinary System (OL)
The Kidneys
2 fist-sized organs just below diaphragm
in small of back
bean - shaped
depression in each kidney =
hilium
blood in aorta contains waste products
some of this enters kidneys through 2
renal arteries
per minute ca. 20% of our blood passes through kidneys
Filtration
incoming blood is filtered
in outer cortex of kidney
results in small particles (useful + waste) being forced out of bloodstream into kidney
Reabsorption
some of useful materials taken back into blood
-> reabsorption
in cortex + medulla
Secretion
some substances secreted from the blood into the cortex
e.g. potassium & hydrogen ions (H+) [too much potassium in the body
prevents nerve impulses travelling correctly
reduces the strength of muscular contraction]
by controlling H+ concentration in blood, kidneys control blood pH
only unwanted waste & toxic products left in kidney
Urine
typically
96% water
,
2.5% nitrogenous waste
(mostly urea)
1.5% salts
urea formed in liver when excess proteins
de-aminated
purified blood leaves through
renal veins
to vena cava
urine flows from medulla into
renal pelvis
>shaped like funnel, collects waste & carries it to ureter
then carried by 2 ureters to bladder
Bladder
adult: up to 800ml urine
not under voluntary control
2 sphincter muscles @ junction to bladder and urethra
emerges through penis in males and close to vagina in females
control of urination through control of sphincter reflex
from ~2 years of age
Functions of the Kidneys
Excretion
Osmoregulation
pH Control
remove waste products from the bloodstream & convert to urine
sent to bladder & excreted through urethra
Water Content
: kidneys control water content of body by varying water content of urine
Salt Concentration
: again, contr by varying salt concentration of urine
-> ensures that blood plasma (i.e. all body fluids) has same concentration as normal body
cells
this means that cells bathed in these fluids do not have problems gaining/losing water by osmosis
-> kidneys are osmoregulatory/regulate osmosis
by producing urine either more or less acidic
-> hydrogen ions ~ allows blood to remain @ normal value of 7.4
don't need this detail ;)
Receptacle: over stem - supports floral parts

Sepals: green, leaf-like; protect budding flower

Petals: attract animals (esp) insects in animal-pollinated plants
in wind-pollinated, petals small (& green) or absent
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