12 - Energy & Respiration

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1. Outline the need 1) anabolic reactions (synthesis of complex substances

for energy in from simpler ones)
living organisms. 2) active transport (transport of substances against con-
[2] centration gradient)
3) movement e.g. muscle contraction / cilia movement /
locomotion
4) bioluminescence, electrical discharge, temperature
regulation, etc

2. anabolic reac- synthesis of complex substances from simpler ones e.g.

tions polypeptides from amino acids

3. examples of ana- 1) DNA replication

bolic reactions 2) Protein synthesis
3) Active transport
4) Movement
5) Maintenance of body temperature

4. Examples of an- 1) protein synthesis

abolic reactions 2) making polysaccharides
in a mammal that 3) making triglycerides
require ATP as an 4) making polynucleotides / DNA / RNA
energy source. 5) phosphorylation
(2)

5. Describe how the 1) small

structure of ATP 2) water-soluble
is related to its 3) easily transported around the cell
role as energy 4) easily hydrolysed to release energy
currency. [3] 5) relatively large quantity of energy released (30.5 kJ
mol-1)
6) rapid turnover rate

6. ATP synthesis 1) process is called chemiosmosis

2) ATP is generated using electrical potential energy, this
is energy from the transfer of electrons by electron carriers
in the ETC
3) protons are allowed to flow down their concentration
gradient via facilitated diffusion through ATP synthase

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4) transfer of 3H+ allows production of 1 ATP molecule pro-
vided that ADP and Pi are available inside the organelle
5) as protons travel through ATP synthase, it drives down
part by rotation force provided by electrochemical gradient
that produces ATP

7. respiration process whereby chemical potential energy from the

breakdown of organic molecules is used to synthesise
ATP

8. Outline the 1) glucose is phosphorylated (substrate-level phosphory-

process of gly- lation) using 2 ATP molecules
colysis in a mam- 2) this results in the formation of fructose biphosphate
malian cell. [6] /hexose bisphosphate (6C)
3) this raises energy level of glucose / lowers activation
energy of reaction
4) fructose biphosphate is lysed to produce 2 triose phos-
phate (3C) molecules, 5) (6C --> 2 * 3C)
6) hydrogen atoms and phosphate groups are removed
from triose phosphate by coenzyme NAD
7) this produces 2 molecules of pyruvate and
8) NADH
9) removed phosphate groups are added to ADP to pro-
duce 4 ATP, however since 2 were used there's a net gain
of 2 ATP

9. where does gly- cytoplasm

colysis occur?

10. number of ATP 4 produced but 2 used in substrate-level phosphorylation

molecules pro- therefore net gain of 2 ATP
duced during gly-
colysis

11. Link reaction 1) pyruvate is decarboxylated (CO‚ is removed)

2) then it's dehydrogenated (H is removed and picked up
by NAD), this converts pyruvate into a 2C compound
3) then it's combined with coenzyme A (CoA) to produce
acetyl coenzyme (ACoA)
4) coenzyme transfers acetyl group with 2C to Krebs Cycle
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12. where does the mitochondrial matrix; pyruvate enters by active transport
link reaction oc- from cytoplasm into the mitochondrial matrix
cur?

13. number of ATP 0

molecules pro-
duced during the
link reaction

14. Krebs cycle 1) ACoA combines with oxaloacetate (4C) to form citrate
(6C)
2) citrate is decarboxylated and dehydrogenated
3) 1 FADH, 3 NADH and 2 CO‚ are produced
3) oxaloacetate is regenerated and can recombine with
ACoA

15. where does the mitochondrial matrix

Krebs cycle oc-
cur?

16. number of ATP 2 molecules of ATP from every pyruvate molecule

molecules pro-
duced during
Krebs Cycle

17. Outline how ATP (electron transport chain & chemiosmosis)

is synthesised by 1) reduced NAD and FAD are
oxidative phos- 2) passed to ETC in the
phorylation. [8] 3) inner mitochondrial membrane (cristae)

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4) hydrogen released from reduced NAD and FAD
5) splits into electrons and protons
6) as these electrons pass along electron carriers from a
higher to lower energy level, energy is released
7) energy released pumps H+ into intermembrane space
creating a
8) proton gradient across the crista
9) protons diffuse back through channel proteins which
have, 10) ATP synthase associated with them into the
matrix
11) 1 ATP produced from ADP and Pi when 3H+ pass
down via the electrochemical gradient
12) oxygen is the final electron acceptor at the end of ETC
in the matrix
13) protons combine with electrons and oxygen atoms to
form water

18. where does ox- inner mitochondrial membrane (cristae)

idative phospho-
rylation occur?

19. number of ATP .

molecules pro-
duced during ox-
idative phospho-
rylation

20. types of anaero- alcoholic fermentation and lactic acid fermentation

bic respiration

21. where does cytoplasm

anaerobic respi-
ration occur?

22. Describe respira- 1) pyruvate formed by glycolysis

tion in yeast cells 2) reduced NAD formed by glycolysis
in anaerobic con- 3) pyruvate decarboxylated by
ditions. [7] 4) pyruvate decarboxylase producing
5) ethanal
6) ethanal is the hydrogen acceptor
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7) from reduced NAD
8) ethanol formed, this reduction is catalysed by
9) alcohol dehydrogenase
10) irreversible (so chemical potential energy of ethanol is
wasted)
11) NAD regenerated so can accept more hydrogen atoms
12) so glycolysis can continue

23. lactate pathway 1) pyruvate itself accepts the hydrogen and is converted
(mammals) to lactate by lactate dehydrogenase
2) again NAD is released and allows glycolysis to continue

24. extra oxygen af- 1) converting lactate to glycogen

ter anaerobic res- 2) reoxygenation of Hb
piration need to 3) high metabolic rate

25. Explain why less 1) glucose is not completely broken down and only glycol-
ATP can be syn- ysis occurs
thesised from the 2) pyruvate still contains energy
same mass of 3) ETC stops
glucose in anaer- 4) because there's no oxygen to act as final electron
obic respiration acceptor
than in aerobic 5) so oxidative phosphorylation stops, Krebs Cycle (no
respiration. [3] NAD or FAD to accept H) and link reaction pause

26. energy value of 15.8

carbohydrates

27. energy value of 39.4

fats

28. energy value of 17.0

proteins

29. Explain why 1) lipids contain relatively more hydrogen atoms

more ATP can 2) more reduced NAD and FAD are produced
be synthesised 3) more electrons are passed along ETC
in aerobic respi- 4) more hydrogens pumped across inner mitochondrial
ration from one membrane
gram of lipid than
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from one gram of
glucose.

30. respiratory quo- measures the ratio of CO‚ to O‚ given out and taken in by
tient (RQ) an organism

RQ = vol. of CO‚ ÷ time / vol. of O‚ ÷ time

RQ = moles of CO‚ / moles of O‚

31. RQ when respir- e.g. 2/0 =

ing anaerobically *high values of RQ indicate alcoholic fermentation

32. structure of a mi- 1) 0.5-1.0 ¼m

tochondrion 2) double-membrane; inner one is folded inwards to form
cristae
3) cristae increase surface area for reactions (mitochodria
from more active cells have more densely packed cristae)
4) outer membrane more permeable than inner
5) inner membrane has lower pH than matrix due to H+
released due to ETC
6) matrix contains enzymes for link reaction & krebs cycle,
+ 70S ribosomes and circular DNA

33. adaptation of rice .

for wet environ-
ments

34. Suggest the 1) DNA for transcription (codes for mRNA)

functions of the 2) ribosomes for translation
DNA and ribo- 3) synthesis of respiratory enzymes and inner membrane
somes in a mito- proteins
chondrion. [3]

35. State two ways in contains ribose not deoxyribose and has three phosphate
which the struc- groups not one
ture of ATP dif-
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fers from the
structure of an
adenine nu-
cleotide in a DNA
molecule. [2]

36. RQ (respiratory the ratio of carbon dioxide molecules produced to oxygen

quotient) molecules taken in during respiration

37. RQ value of car- 1.0

bohydrate

38. RQ value of lipid 0.7

39. RQ value of pro- 0.9

tein

40. mechanism of re- 1) dehydrogenation happens regularly throughout the dif-

dox indicators ferent stages of aerobic respiration
when determin- 2) the hydrogens that are removed from substrate mole-
ing respiration cules are used in oxidative phosphorylation and are trans-
rates ferred by NAD and FAD
3) when DCPIP and methylene blue are present, they
can also take up hydrogens and get reduced (blue ->
colourless)
4) faster the rate of respiration, the faster the rate of
hydrogen release and faster the dyes get reduced and turn
colourless
5) therefore the rate of colour change can correspond to
the rate of respiration in yeast
5) rate of respiration (sec^-1) = 1 / time (sec)

41. effect of temper- 1) add a redox dye such as DCPIP or methylene blue to a
ature on the rate suspension of yeast cells
of respiration of 2) add the test tubes to a temperature-controlled water
yeast using a re- bath
dox indicator 3) record the time taken for a colour change to occur once
the dye is added (& repeat across a range of tempera-
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tures)
4) when reduced, the blue dyes become colourless (rate
of change from blue to colourless is a measure of the rate
of respiration of the yeast)

42. effect of sub- 1) add different concentrations of a substrate to the sus-

strate concentra- pension of yeast cells (e.g. 0.1%, 0.5% glucose)
tion on the rate 3) record the time taken for a colour change to occur once
of respiration of the dye is added (& repeat across a range of tempera-
yeast using a re- tures)
dox indicator 4) when reduced, the blue dyes become colourless (rate
of change from blue to colourless is a measure of the rate
of respiration of the yeast)

43. variables to be 1) volume of dye added

controlled in re- 2) volume of yeast suspension
dox indicator ex- 3) type of substrate
periment to in- 4) concentration of substrate
vestigate respira- 5) temperature
tion rate in yeast

44. using a respirom- 1) organisms to be investigated are placed in one tube and
eter to investi- non-living material (glass beads) of the same mass in the
gate the rate of other tube
uptake of oxygen 2) soda lime is placed in both tubes to absorb carbon
dioxide
3) coloured fluid is poured into the manometer reservoir
and allowed to flow into the capillary tube (ensure that
there are no air bubbles and volume of liquid is the same
in both tubes)
4) rubber bungs are fitted on both tubes, spring clips are
closed and the manometer is then attached to the bent
glass tubing (ensure that it's airtight)
5) open spring clips (to allow pressure throughout the
apparatus to equilibrate with atmospheric pressure)
6) as organisms respire, oxygen is taken from air in the
tube, reducing the volume and pressure, causing the
manometer fluid to flow towards the organisms
7) carbon dioxide is removed by the soda lime which

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ensures that distance moved by the fluid is only affected
by oxygen uptake
8) distance moved by the manometer fluid can be calcu-
lated using pi*r^2*h
9) volume of oxygen taken up can be calculated if the
diameter of the tube is known

45. using a respirom- 1) respirometer is placed in water baths at different tem-

eter to measure peratures
the effect of tem- 2) rate of respiration is represented by gradient of the
perature on res- graph
piration rate

46. using a respirom- 1) set up a respirometer

eter to determine • control tube must contain an equal amount of inert ma-
the RQ of ger- terial (glass beads) to the volume of organism used
minating seeds • it should not contain any soda lime (therefore carbon
or small inverte- dioxide given out by respiring organisms is not absorbed)
brates 2) use the manometer reading to calculate change in gas
volume within a given time (x cm^3 min^-1)

• x -> oxygen consumed (distance moved by fluid in exper-

imental tube)
• y -> distance moved by fluid in control tube
• x - y -> carbon dioxide given out
• RQ = (x-y/x)

47. change in RQ in- substrate being respired has changed

dicates

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 13 - Photosynthesis
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1. 3 basic steps of 1. light-dependent

photosynthesis energy capture, chemiosmosis/generation of ATP

2. light-independent
carbon fixation; enzyme-catalysed reactions using ATP
formed in light reactions to fix CÓ into sugars (CH2O)

3. pigment regeneration
electron replacement from the splitting of H2O in oxygenic
photosynthesis

2. reaction site thylakoid (membrane)

of light-depen-
dent stage

3. reaction site stroma

of light-indepen-
dent stage

4. light energy is re- 1. photolysis (only in photosystem II)

quired for 2. produce ATP in photophosphorylation (for the reduction
of CO2 to carbohydrate in light-independent stages)

5. types of pho- primary pigments and accessory pigments

tosynthetic pig-
ments

6. primary pig- act as reaction centres e.g. chlorophyll a

ments

7. accessory pig- - several hundred surround a primary pigment molecule

ments - light energy absorbed passed onto primary pigment mol-
ecule

8. photosystem pigments arranged in light-harvesting clusters in the thy-

lakoid membrane

9. what wavelength 700 nm, bacteria as well as plants

of light does pho-
tosystem I ab-
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sorb and where
is it present

10. what wavelength 680 nm, plants only

of light does pho-
tosystem II ab-
sorb and where
is it present

11. stages of light 1. photolysis of water (in photosystem II only)

dependent reac- 2. photophosphorylation of ADP to ATP (of two types;
tions cyclic in photosystem I and both cyclic and non-cyclic in
photosystem II)

12. photolysis of wa- chemical decomposition of water induced by light

ter H‚O ’ 2Hz + 2e{ + ½O‚
- in photosystem II
- oxygen is the waste product

2Hz + 2e{ + NADP ’ NADPH

- hydrogen ions combine with electrons from photosystem
I and NADP to produce NADPH

13. cyclic only involves photosystem I, no reduction of NADP

photophosphory- 1. light is absorbed by photosystem I and is passed to
lation primary pigment
2. photoactivation: an electron in the chlorophyll molecule
is excited to a higher energy level and is emitted from the
chlorophyll molecule
3. excited electron is captured by an electron acceptor and
passed back to chlorophyll molecule via a chain of electron
carriers
4. energy released from this is used to synthesise ATP
(from ADP and Pi by chemiosmosis)
5. ATP then passes to light-independent reactions

14. non-cyclic involves both photosystems, NADP is reduced

photophosphory- 1) light is absorbed by both photosystems and excited
lation electrons are emitted from primary pigments of both re-
action centres
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2) electrons are absorbed by electron acceptors and pass
along electron carriers
3) photosystem I's primary pigment absorbs the electron
from photosystem II
4) photosystem II receives replacement electron from the
photolysis of water
5) ATP is synthesised as electrons lose energy passing
carrier chain

15. Outline the main 1) RuBP (ribulose bisphosphate), a 5C compound

features of the 2) combines with carbon dioxide
Calvin Cycle. [9] 3) this is catalysed by the enzyme rubisco and
4) an unstable 6C compound is formed
5) which splits to form two molecules of GP (glycer-
ate-3-phosphate) / PGA (phosphoglyceric acid)
6) PGA is reduced using ATP as an
7) energy source
8) and NADPH
9) to form TP (triose phosphate)
10) TP used to form glucose/carbohydrates/lipids/amino
acids
11) 5/6 of TP produced is used in regeneration of RuBP
12) this requires ATP
13) light-independent

16. differences .
between cyclic
and non-cyclic
photophosphory-
lation

17. types of pig- .

ments in chloro-
plasts

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18. limiting factor factor that has the greatest effect in reducing rate

19. 3 factors affect- 1) light intensity & wavelength

ing photosynthe- 2) temperature
sis 3) carbon dioxide concentration

20. C3 plants C3 plants are plants that doesn't have photosynthetic

adaptations to reduce photorespiration

RuBP + CO‚ ’ unstable intermediate

intermediate splits forming a 3C compound (GP)

21. C4 plants - the light-dependent reactions and the Calvin cycle are
physically separated, with the light-dependent reactions
occurring in the mesophyll cells and the Calvin cycle oc-
curring in bundle-sheath cells

- CO2 is fixed in the mesophyll cells to form oxaloacetate

(4C) by PEP carboxylase that has no tendency to bind to
O2

- oxaloacetate is then converted to malate which is trans-

ported to bundle-sheath cells. Malate breaks down here
releasing a CO2 molecule

- the CO2 molecule released is fixed by rubisco and made

into sugars via the Calvin cycle

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22. photorespiration reaction in which rubisco attaches oxygen instead of car-

bon dioxide to ribulose bisphosphate

23. Explain the role 15) it's a coenzyme

of NADP in pho- 16) when reduced
tosynthesis. [6] 17) carries protons
18) and (high energy) electrons
19) from photosystem light stage
20) on thylakoid membrane grana
21) to stroma / Calvin cycle~

24. Describe how .

you would car-
ry out an inves-
tigation into the
effect of wave-
length of light on
the rate of pho-
tosynthesis of a
plant, using a
redox indicator
such as DCPIP.
[8]

25. Outline the reac- 1) Carbon dioxide binds to RuBP

tions occurring 2) this is catalysed by rubisco
in the stroma that 3) and results in the formation of an unstable 6C com-
lead to the pro- pound which
duction of a poly- 4) splits into two molecules of GP (glycerate-3-phosphate)
saccharide, such 5) GP reduced to TP (triose phosphate)
as alginate. [4] 6) using reduced NADP and ATP

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7) TP used to form glucose
8) formation of glycosidic bonds

26. Describe how 1) spot extract on base line

chromatography 2) concentrate spot
is used to 3) suspend base of chromatogram in solvent
identify 4) calculate the Rf value using Rf value = distance moved
chlorophyll a in by spot ÷ distance moved by solvent front
an extract from 5) compare with known Rf value to identify chlorophyll a
chloroplasts. [4] pigment
6) detail of method; e.g. cover to stop evaporation of sol-
vent, remove chromatogram before solvent front reaches
top

27. Rf value formula Rf value = distance moved by spot ÷ distance moved by

solvent front

28. State features of 1) stomata number/size

a dicotyledonous 2) number/size of chloroplasts
leaf that can af- 3) leaf surface area/thinness of lamina
fect the rate of 4) number/size of intercellular airspaces
photosynthesis. 5) rubisco concentration
6) age/senescence

29. State precise- stroma

ly where in
the chloroplast
RuBP and GP are
located.

30. Explain what is tendency of water molecules to move from one region to
meant by the another / potential energy of water / ability of water to do
term water poten- work
tial. [1]

31. Name precise- non-cyclic photophosphorylation

ly the process
that produces re-
duced NADP.

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32. The optimum pH 1) excited electrons leave chlorophyll a/photosystem
for the activi- 2) and pass along the ETC
ty of rubisco is 3) protons present from photolysis
pH8. Explain why 4) pumped into intermembrane space
the illumination 5) rubisco is in stroma
of chloroplasts 6) protons leaving stroma raises pH
leads to optimum
pH conditions for
rubisco. [3]

33. Describe how 1) enters via stomata

carbon dioxide 2) by diffusion down a concentration gradient
reaches the in- 3) passes through air spaces
side of a pal- 4) dissolves in film of water on cell surface
isade mesophyll 5) diffuses through cell wall / surface membrane of pal-
cell from the isade cells
external atmos-
phere. [3]

34. Outline the role 1) absorb light energy

of the accessory 2) at wavelengths not readily absorbed by chlorophyll
pigments in pho- a/primary pigment
tosynthesis. [3] 3) pass energy to chlorophyll a/primary pigment
4) in reaction centre

35. action spectrum graph of the rate of photosynthesis at different wave-

lengths of light

36. absorption spec- graph of absorbance of different wavelengths of light by a

trum pigment

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 14 - Homeostasis
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1. define homeosta- maintenance of a constant internal environment

sis [1]

2. negative feed- mechanism that keeps changes to a factor within narrow

back limits

3. positive feed- enhances or accelerates the output created by an activat-

back ed stimulus

4. cells that detect thermo-receptors in hypothalamus

changes in core
temperature

5. cells that detect thermo-receptors in skin

changes in exter-
nal temperature

6. thermoregula- vasodilation & vasoconstriction

tion by smooth e.g. in vasoconstriction, muscles in walls of arterioles that
muscles in supply blood to capillaries near skin surface contract de-
arterioles creasing the lumen size; blood supply is reduced so less
heat is lost from it

7. thermoregula- shivering
tion by skeletal involuntary contraction of skeletal muscles generate heat
muscles

8. thermoregula- skin hairs stand up when they contract, traps air (not very
tion by erector effective in humans)
pili muscles in
skin

9. thermoregula- both increase metabolic rate (more heat produced)

tion by adrenal
and thyroid gland when environment temperature decreases gradually:
1) hypothalamus secretes a hormone which activates an-
terior pituitary gland to release TSH (thyroid stimulating
hormone)
2) TSH stimulates thyroid gland to secrete thyroxine into
blood
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3) thyroxine increases metabolic rate which increases
heat production, especially in the liver
4) when temperature starts to increase again, hypothal-
amus responds by reducing release of TSH by anterior
pituitary gland

10. excretion removal of unwanted products of metabolism

11. deamination extra proteins can't be stored but to make use of amino
acids in it, it's deaminated by removing -NH‚ and H

amino acid ’ keto acid + ammonia

ammonia + CO‚ ’ urea

*keto acids (enter Krebs Cycle) are respired, or converted

to glucose, glycogen or fat

12. creatinine nitrogenous waste excreted in the urine formed from cer-
tain amino acids
*creatine used in the form of creatine phosphate as energy
store in muscles, some of this is excreted out out as
creatinine

13. uric acid nitrogenous waste excreted in the urine formed from the
breakdown of purines from nucleotides

14. factors affecting solute potential (water potential is lowered) and pressure
water potential potential (water potential is raised)

15. substances that 1) all glucose

have to be re-ab- 2) vitamins
sorbed 3) much of water
4) some inorganic ions e.g. Na and Cl ions
5) amino acids

16. lining of prox- single layer of cuboidal epithelial cells

imal convoluted
tubule

17.
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adaptations of 1) microvilli present to increase surface area of inner-sur-
cuboidal epithe- face facing lumen
lial cells [4] 2) tight junctions that hold adjacent cells together so fluid
doesn't pass between cells (all substances reabsorbed
must go through cell)
3) many mitochondria to provide energy for Naz/Kz pump
4) co-transporter proteins in the membrane facing lumen

18. re-absorption in 1) Naz/Kz pumps in basal membranes of cells lining proxi-

the proximal con- mal convoluted tubule pump out Naz out of cell via active
voluted tubule [5] transport into the blood
2) this lowers Naz inside the cell, so that more Naz diffuses
from fluid in lumen of the tubule via co-transporter mole-
cules in the membrane
3) passive movement of Naz provides energy to move
glucose (even against a concentration gradient); example
of indirect/secondary active transport
4) once glucose is inside the cell, it diffuses via transport
proteins in the basal membrane into the blood
5) removal of solutes increases water potential of filtrate;
a water potential gradient is established so water moves
down this gradient

19. osmoregulation control of water potential in body fluids

20. monitoring wa- 1) water potential of blood is constantly monitored by

ter potential of osmoreceptors in hypothalamus
blood 2) when a decrease is detected, nerve impulses are sent
along neurones to the posterior pituitary gland
3) they stimulate the release of ADH
4) ADH reduces water loss in urine by making kidneys
absorb as much as possible

21. how ADH affects 1) ADH acts on the cell surface membrane of the collecting
kidneys [4] duct cells, making them more permeable to water
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2) ADH binds to receptor proteins on cell surface mem-
brane which activates enzymes (ends with the production
of an active phosphorylase enzyme)
3) phosphorylase causes ready-made vesicles containing
aquaporins to move to cell-surface membrane
4) vesicles fuse with the membrane, increasing permeabil-
ity
- water moves out of tubule into tissue fluid
- as tissue fluid in medulla has very low pH
- volume of urine is smaller and more concentrated

22. z-cells of islets of secrete glucagon when blood glucose concentration is low
Langerhans

23. ²-cells of islets of secrete insulin when blood glucose concentration is high
Langerhans

24. GLUT 4 muscle and adipose

25. GLUT 2 liver cells (always have GLUT proteins present in their cell
surface membranes)

26. GLUT 1 brain cells (always have GLUT proteins present in their cell
surface membranes)

27. Describe the role 1) insulin binds to receptors on X cells

played by in- 2) GLUT(X) added to membrane of cells
sulin in the con- 3) glucokinase phosphorylates glucose in liver cells
trol of blood glu- 4) faster respiration of glucose
cose concentra- 5) activates glycogen synthase
tion. [5] 6) causes lipid synthesis
7) blood glucose concentration decreases

28. effects of insulin 1) stimulates cells with receptors for it to increase glucose
[4] absorption rate, convert it to glycogen and use it in respi-
ration
2) when insulin binds to receptors on muscle cells, vesi-
cles with GLUT4 proteins are moved to the cell surface
membrane and fuse with it
3) stimulates the activation of enzyme glucokinase which
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phosphorylates glucose (traps it inside as phosphorylated
glucose can't pass through transporters in membrane)
4) stimulates enzymes phosphofructokinase and glyco-
gen synthase which add glucose molecules to glycogen,
increasing their size

29. how glucagon in- 1) z-cells respond by secreting glucagon, ²-cells stop insulin
creases blood secretion
glucose [9] 2) glycogen binds to receptor molecules in cell surface
membrane of liver cells
3) receptor changes conformation
4) G-protein is activated (because of binding)
5) adenylyl cyclase is activated (enzyme that catalyses
conversion of ATP to cyclic AMP)
6) cyclic AMP is second messenger
7) cyclic AMP binds to kinase enzymes that activate other
enzymes by phosphorylating them
8) this enzyme cascade amplifies original signal from
glucagon
9) glucose phosphorylase (at the end of cascade) is acti-
vated
10) it catalyses breakdown of glycogen to glucose by
removing glucose from 1,6 branches
11) concentration of glucose increases in cell so it diffuses
out via GLUT2 into blood
12) can stimulate gluconeogenesis (producing glucose
from amino acids and lipids)

30. cell that doesn't muscle cells; they're stimulated by adrenaline which in-
have glucagon creases glucose by activating the same enzyme cascade
receptors as glucagon
*glucose produced remains in muscle cell where it's re-
quired for respiration

31. Name the struc- basement membrane

ture that acts as
this filtration bar-
rier during ultra-
filtration

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32. After leaving 1) sodium potassium pumps in basal membrane
the Bowman's 2) pumping of Na+ out of cells into blood
capsule, the 3) Na+ concentration decreases inside cells
glomerular fil- 4) so Na+ enters epithelial cells from lumen
trate passes 5) by facilitated diffusion
through the prox- 6) Na+ co-transports glucose into cell
imal convoluted 7) this is secondary / indirect active transport
tubule, where se- 8) then facilitated diffusion of glucose out of cells into blood
lective reabsorp- 9) via GLUT proteins
tion occurs. De-
scribe and ex-
plain how all
of the glucose
in the glomeru-
lar filtrate is reab-
sorbed back into
the blood. [5]

33. Name the part of posterior pituitary gland

the body that re-
leases ADH into
the blood.

34. where is ADH produced in hypothalamus but stored in the posterior pitu-
produced? itary gland

35. ureter

36. pelvis

37. medulla

38. cortex

39. collecting duct

40. loop of henle

41. distal convoluted

tubule
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42. proximal convo-

luted tubule

43. Bowman's cap-

sule

44. Explain how dip 1) stick has a pad containing the immobilised enzymes
sticks function to 2) glucose oxidase and
test for glucose 3) peroxidase
in a sample of 4) stick dipped in urine
urine. [8] 5) glucose reacts to give hydrogen peroxide (catalysed by
glucose oxidase)
6) hydrogen peroxide reacts with a colourless substance
(chromogen)
7) to give a coloured substance
8) compare with colour chart
9) more glucose gives darker colour

45. Outline how a 1) pad contains glucose oxidase

glucose biosen- 2) glucose oxidase reacts with glucose in the blood
sor works. [3] 3) oxygen detected
4) electric current generated
5) detected by electrode
6) gives numerical value of blood glucose concentration

46. Outline how a 1) change in factor away from set-point

negative feed- 2) detected by receptor
back mechanism 3) hormone released or nerve impulse sent
works. [4] 4) hormone / impulse reaches effector
5) effector performs corrective action
6) factor returns to set-point

47. presence of glu- indicates that a person may have diabetes. If the con-
cose and ke- centration for these rises above the renal threshold, then
tones in urine not all glucose has been absorbed from the filtrate in the
proximal convoluted tubule --> so will be present in the
urine

48.
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stomata open 1) increasing light intensity
due to 2) low carbon dioxide concentrations in the air spaces
within the leaf

49. stomata close 1) darkness

due to 2) high carbon dioxide concentrations in the air spaces in
the leaf
3) low humidity
4) high temperature
5) water stress, when the supply of water from the roots is
limited and/or there are high rates of transpiration.

50. explain how Opening during the day maintains the inward diffusion of
stomata have carbon dioxide and the outward diffusion of oxygen. The
daily rhythms closure of stomata at night when photosynthesis cannot
of opening and occur reduces rates of transpiration and conserves water.
closing

51. explain the 1) ATP-powered proton pumps in the cell surface

mechanism by membrane actively transport H+ out of the guard cell
which guard cells 2) the low H+ concentration and negative charge inside
open and close the cell causes K+ channels to open; K+ diffuses into the
stomata cell down an electrochemical gradient
- the removal of hydrogen ions has left the inside of
the cell negatively charged compared with the outside,
and as potassium ions have a positive charge, they are
drawn down an electrical gradient towards the negatively
charged region
- they also diffuse into the cells down a concentration
gradient
- such a combined gradient is an electrochemical gradient
3) the high concentration of K+ inside the guard cell lowers
the water potential (È)
4) water moves in by osmosis, down a water potential
gradient through aquaporins
5) the entry of water increases the turgo of the guard cells,
so they expand; the thin outer wall expands most, so the
cells curve apart

52.
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structure of - wall adjacent to the pore is very thick
guard cells - the wall furthest from the pore is thin
- bundles of cellulose microfibrils are arranged as hoops
around the cells so that, as the cell becomes turgid, these
hoops ensure that the cell mostly increases in length and
not diameter
- the thin outer walls bend more readily than the thick inner
walls, the guard cells become curved, opening the pore
between two cells

53. abscisic acid a stress hormone that is released if a plant is subjected to

(ABA) difficult environmental conditions (e.g., very high temper-
atures, reduced water supplies) and triggers the closure
of stomata to reduce transpiration and prevent water loss

54. role of abscisic 1) ABA binds to cell surface receptors on guard cells
acid (ABA) in the 2) inhibits the proton pumps to stop hydrogen ions being
closure of stoma- pumped out
ta during times of 3) ABA also stimulates the movement of calcium ions into
water stress the cytoplasm through the cell surface membrane and the
tonoplast
4) Ca2+ acts as a second messenger to activate channel
proteins to open that allow negatively charged ions to
leave the guard cells
5) this stimulates the opening of channel proteins which
allows the movement of potassium ions out of the cells
6) Ca2+ also stimulate the closure of the channel proteins
that allow potassium ions to enter
7) the loss of ions raises the water potential of the cells,
water passes out by osmosis, the guard cells become
flaccid and the stomata close

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1. reflex arc pathway along which impulses are transmitted from a re-
ceptor to an effector without involving 'conscious' regions
of the brain

2. reflex arc path- 1. stimulus

way 2. receptor
3. sensory neurone
4. synapses
5. relay neurone
6. synapses
7. motor neurone
8. effector
9. automatic response

3. reflex action an immediate response by an effector to a specific stimu-

lus without involving conscious regions of the brain

4. resting potential difference in charge across the membrane when a neu-

rone is not firing, typically -70mv

5. how resting po- by keeping more +ve ions outside the cell than inside
tential is main-
tained 1) done by using a Na+/K+ pump; it uses ATP to pump
3Na+ out and 2K+ in
- results in a neurone with a more +ve charge outside than
inside creating a -ve resting potential

2) membrane also has more protein channels for K+ than

Na+, and due to the concentration of K+ being higher
inside, it diffuses out of the neurone, making the resting
potential even lower

3) many -vely charged molecules are also present inside

the cell, and the membrane is impermeable to them 4
neurone is more -ve inside

6. action potential rapid change in potential difference across the membrane

caused by changes in permeability of cell surface mem-
brane to Na+ & K+

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7. generator/recep- - weak stimulus

tor potential - some Na+ channels open
- some Na+ diffuses in
- does not reach threshold potential
- Na+/K+ pump restores resting potential

8. depolarisation 1) electric current used to stimulate the axon causes Na+

voltage-gated channels to open
2) Na+ diffuses into the axon, the membrane depolarises
(meaning resting potential of cell decreases)
3) more Na+ voltage gated channels open if threshold
potential is reached (-50mv)
4) inside reached a potential of +30mv
5) e.g. of positive feedback

9. repolarisation 1) once +30mv is reached, Na+ voltage gated channels

close and K+ ones open
2) K+ diffuses out
3) restores potential difference back to -70mv

10. hyperpolarisa- - when membrane potential becomes more negative than

tion resting potential
- caused by K+ channels being slow to close

11. refractory period - a period of inactivity after an action potential, sodium

voltage gated channels are shut
- makes action potentials discrete (don't overlap) and
- unidirectional

12. saltatory con- 1) action potential 'jumps' from node to node

duction 2) local circuits are set up between nodes
3) conduction velocity / speed of impulses becomes faster

13. Explain how 1) action potential reaches synaptic knob (pre-synaptic

a cholinergic membrane)
synapse func- 2) it stimulates opening of Ca²z voltage-gated channels
tions. [7] 3) Ca²z diffuses into cytoplasm of pre-synaptic neuron
4) this causes vesicles containing ACh to move towards
pre-synaptic membrane and fuse with it

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5) ACh is released via exocytosis and diffuses across
synaptic cleft
6) it binds to receptors on post-synaptic membrane
7) this causes ligand-gated/chemically-gated Naz channels
to open and Na+ enter post-synaptic neuron
8) Naz depolarizes the membrane; an action potential is
generated
9) ACh is recycled; via acetylcholinesterase forming ac-
etate and choline
10) choline + acetyl coezyme A ’ ACh (transported back to
pre-synaptic vesicles)

14. role of synapses 1) one-way transmission

2) interconnection of nerve pathways
3) integration of impulses

15. Explain what is 1) open or closes when voltage changes due to the arrival
meant by a volt- of an action potential
age-gated chan- 2) specific to an ion, have hydrophilic pores, transmem-
nel. [2] brane protein

16. Outline the bi- 1) contain synthetic hormones

ological basis 2) as they do not get broken down quickly so act for longer
of contraceptive 3) oestrogen/progesterone blood concentrations remain
pills containing high
oestrogen and 4) this suppresses FSH
progesterone. [8] 5) by the anterior pituitary gland (via negative feedback)
6) Graafian follicle does not develop
7) LH is not secreted
8) ovulation prevented
9) cervical mucus thickens which decreases ability of
sperm to penetrate through it
10) prevents implantation / endometrium less well devel-
oped

17. Explain the 1) breaks down acetylcholine

role of acetyl- 2) so acetylcholine leaves binding site
cholinesterase in 3) depolarisation stops in post-synaptic membrane
a synapse. [3] 4) stops continuous action potentials in post-synaptic

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membrane
5) ACh is recycled

18. anatomy of
venus flytrap

19. Describe how the 1) action potential reaches lobe of leaf

production of ac- 2) H+ pumped across surface membrane into cell wall
tion potentials in 3) cell wall loosens / cross-links broken
the leaf cells 4) calcium pectate breaks down in middle lamella
of the Venus fly 5) Ca2+ ions enter cells
trap can result in 6) water enters by osmosis
the leaves clos- 7) midrib cells expand and become turgid
ing and trapping 8) leaves / lobes become concave
an insect. [5]

20. Explain why the 1) amylase enters endosperm

aleurone layers 2) hydrolyses starch
of barley seeds 3) glucose needed by embryo for
need to produce 4) for ATP production
amylase during 5) for growth of embryo
germination. [3]

21. Le dominant allele results in the production of active gib-

berellin (GA1) which stimulates stem elongation

22. explain how the dominant allele codes for an enzyme that converts inactive
dominant allele gibberellin to active gibberellin (GA1)
for height in a
pea plant results
in the produc-
tion of active gib-
berellin

23. Active gib- 1) cell division

berellin stimu- 2) cell elongation
lates stem elon- 3) increase in internode length
gation by caus-
ing the break-
down of DEL-
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LA protein re-
pressors so that
growth genes
can be ex-
pressed. Sug-
gest the effects
of the expression
of these growth
genes.

24. DELLA proteins inhibit the cell division and expansion that drives the
growth of plant organs, plant growth is stimulated via
destruction of DELLA proteins

25. receptor poten- increase in positive charge inside a cell

tial

26. chemoreceptors 1) Na+ diffuse through channel proteins in cell surface

detecting salt membrane of microvilli
2) membrane gets depolarised (in the sensory zone)
3) sufficient stimulation by Na+ causes Ca2+ voltage-gat-
ed channels to open
4) entry of Ca2+ into cytoplasm stimulates exocytosis of
vesicles containing neurotransmitters from basal mem-
brane
5) if stimulation of action potential in sensory neurone is
above threshold, impulses travel to taste centre in cerebral
cortex of the brain

27. chemoreceptors 1) cell sensitive to sweet have protein receptors that stim-
detecting sweet ulate a G-protein
2) G-protein activates an enzyme that produces cyclic
AMP
3) cyclic AMP acts as a 2nd messenger, activating a
cascade to amplify the signal that leads to K+ channels
closing
4) this depolarises the membrane

28. syncytium multinucleate cell, typically formed by the fusion of many

smaller cells during development e.g. muscle fibre
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29. sarcolemma cell surface membrane

30. sarcoplasmic endoplasmic reticulum; membranes of SR have lots of

reticulum (SR) protein pumps that transport Ca2+ to the cisternae of SR

31. transverse sys- infolding/invagination of sarcolemma

tem tubules - formed from the inward extension of sarcolemma
(T-tubules) - allows impulses from sarcolemma to pass to the SR
- maintains Ca2+ store in SR

32. sarcoplasm cytoplasm; lots of mitochondria present between myofib-

rils

33. structure of stri- .

ated muscles

34. myofibril (any of the elongated contractile threads found in striated

muscle cells)

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35. structure of a my- each myofibril is made of two filaments; thick (myosin) and
ofibril thin (actin)

A-band: centre of sarcomere appears darker due to over-

lap of both actin and myosin filaments

H-band: within the A-band, only myosin present

I-band: only actin present

Z-line/disc: provides attachment for actin filament, disc

separating one sarcomere from another

M-line: attachment for myosin filaments

36. sarcomere part of a myofibril between two Z lines

37. structure of - made of myosin (a fibrous protein with a globular head)

thick filaments - fibrous protein anchors molecule to thick filament
(myosin) - globular heads point away from M-line

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38. structure of thin - made of actin (a globular protein)

filaments (actin) - many actin molecules link to form a chain
- 2 chains twist to form an active filament

tropomyosin (fibrous): twisted around 2 chains/filament

troponin: attached to actin chain at regular intervals, Ca2+

binding site

39. sliding filament 1) Ca2+ is released from stores in SR and binds to tro-
model of muscle ponin, changing it's shape
contraction 2) troponin and tropomyosin move to different positions on
thin filament, exposing myosin binding sites on the actin
chain
3) myosin binds to exposed binding sites, forming
cross-bridges between thick and thin filaments
4) myosin heads tilt, pulling actin filaments towards centre
of sarcomere
5) each myosin head is an ATPase; ATP is hydrolysed to
ADP and Pi which remain bound to the myosin head (actin
has been let go)
6) the energy is used to carry out the power stroke (myosin
head attaching to binding sites on actin while ATP and Pi
remain bound)
7) ADP and Pi are replaced by a new ATP
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8) this causes release of the myosin head which goes back
to its original position

40. power stroke action of myosin pulling actin inward (toward the M line)

41. Describe the ef- 1) cell wall pH decreases/becomes more acidic

fects on the cell 2) expansins are activated by decrease in pH
wall of many hy- 3) they loosen non-covalent bonds / cross-links
drogen ions mov- 4) between cellulose and hemicellulose OR between cel-
ing into the cell lulose microfibrils
wall. [3] 5) cell wall expands
6) due to turgor pressure on wall

42. Name the loca- ²cells / pancreas / islets of Langerhans / hypothalamus

tion of the recep-
tors in a non-dia-
betic person that
detect a change
in blood glucose
concentration.

43. Discuss the bi- .

ological, ethical
and social im-
plications of us-
ing this contra-
ceptive pill. [9]

44.
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Describe how an
action potential
is transmitted
along a senso-
ry neurone in a
mammal. [5]

45. Suggest how 1) compresses nerve

a tumour on 2) damages myelin sheaths / Schwann cells
the optic nerve 3) prevents the setting up of local circuits / saltatory con-
could prevent the duction
transmission of 4) stops Na+ / K+ pumps from working
nerve impulses 5) blocks blood supply
to the brain. [3] 6) oxygen supply / glucose supply / ATP production is
reduced

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1. homologous a pair of chromosomes in a diploid cell that have the same

chromosomes structure and genes at the same loci, and pair during the
meiotic division to form a bivalent

2. locus position a particular gene is found on a particular chromo-

some
*the same gene is always found at the same locus

3. gene length of DNA that codes for a particular protein or

polypeptide

4. allele an alternative form of a gene / particular variant of a gene

5. autosomes any chromosome that is not a sex chromosome

6. haploid (n) cells that contain a single set of chromosomes

7. diploid (2n) cell that contain two sets of chromosomes

8. explain why there 1) number of chromosomes would double every genera-

is a need for re- tion
duction division 2) introduces genetic variation
(meiosis)

9. meiosis I

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division that halves the number of chromosomes and re-
sults in haploid cells
*step that results in genetic diversity

10. prophase I early

1) chromosomes condense
2) mitotic spindle begins to form
3) centrosomes move to opposite poles

middle
4) synapsis occurs (homologous chromosomes pair up,
each pair is called a bivalent)

late
5) nuclear envelope and nucleolus disappear
6) crossing over may occur

11. synapsis the pairing of homologous chromosomes during prophase

I

12. crossing over crossing over is the exchange of the genetic materi-
al/gene loci between homologous chromosomes/between
maternal and paternal chromatids during synapsis (during
prophase I)

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13. synapsis vs 1) synapsis refers to the pairing of homologous chromo-

crossing over somes during prophase 1; crossing over is the exchange
of genetic material during synapsis

2) synapsis always occurs, crossing over may not

3) synapsis ensures the proper segregation of homolo-

gous chromosomes and allows recombination by crossing
over; crossing over allows the variation of alleles in a
population through genetic recombination

14. bivalent paired homologous chromosomes, also called a tetrad

because it consists of four chromatids

15. chiasma point where crossing over occurs

16. metaphase I bivalents line up across the equator of the cell

17. anaphase I

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homologous chromosomes move to opposite poles of the
cell, centromeres first, pulled by microtubules
*sister chromatids stay together

18. telophase I nucleolus and nuclear envelope reform, cytokinesis

19. meiosis II sister chromatids separate

20. prophase II 1) nuclear envelope and nucleolus disperse

2) centrosomes and centrioles replicate and move to op-
posite poles of the cell
3) the duplicated chromosomes and spindle fibers reap-
pear in each new cell

21. metaphase II chromosomes line up across the equator of the spindle

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22. anaphase II centromeres divide, chromatids separate and spindle mi-

crotubules pull the chromatids to opposite poles

23. telophase II the spindle fibres disappear, and a nuclear membrane

forms around each set of chromosomes forming 4 haploid
cells

24. number of chro- chromosomes are counted by the number of centromeres

mosomes dur- present so 46
ing meiosis (hu- when they duplicate and get sister chromatids, there are
mans) still 46 centromeres so 46 chromosomes but 92 chro-
matids

25. where does sper- seminiferous tubules of the testes

matogenesis oc-
cur?

26. steps of sper- 1) diploid cells divide by mitosis to produce spermatogonia

matogenesis (2n)
2) spermatogonia grow to form primary spermatocytes

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(2n)
3) primary spermatocytes undergo meiosis I forming 2
secondary spermatocytes (n)
4) secondary spermatocytes undergo meiosis 2 forming
spermatids (n)
5) spermatids mature into spermatozoa (n)

27. where does oo- ovaries

genesis occur?

28. steps of oogene- 1) diploid cells divide via mitosis to form oogonia (2n)
sis during foetal development
2) oogonia undergo growth till they're large enough to
undergo meiosis becoming primary oocytes (2n)
3) primary oocytes begin meiosis but are stopped at
prophase I and remain in prophase I till puberty (so remain
diploid)
4) FSH triggers the division of primary oocytes every
month (post/during puberty), they complete meiosis I,
forming 2 haploid cells (secondary oocyte which gets most
of the cytoplasm and a polar body)
5) secondary oocyte starts meiosis II but is stopped at
metaphase II and is released into the oviduct
6) if it's fertilised, it completes meiosis II, forming an ovum
and polar body

29. where does the anthers

formation of male
gametes (pollen)
take place in
flowering plants?

30. steps in the for- 1) diploid mother cells divide by meiosis forming 4 haploid
mation of male cells
gametes (pollen) 2) nucleus of each haploid cell divides by mitosis (forming
a tube nucleus and a generative nucleus), no cytokinesis
takes place
3) these cells develop into pollen grains, each surrounded
by a protective wall made of tough exine and thinner intine

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31. where does the ovules
formation of fe-
male gametes
(egg cells) take
place in flower-
ing plants?

32. steps in the for- 1) a large, diploid mother cell develops and divides by
mation of fe- meiosis producing 4 haploid cells; 3 degenerate leaving
male gametes 1
(egg cells) 2) surviving haploid cell develops into embryo sac which
grows larger, then its nucleus divides by mitosis 4x to form
8 haploid nuclei
3) 6 nuclei move to the sides (3 to each side); the ones
opposite the micropyle are the antipodal cells while out of
the 3 at the top, the middle one becomes the egg cell
4) 2 nuclei called polar nuclei present at the middle of the
embryo sac fuse together

33. double fertilisa- 1) pollen is released into the embryo sac

tion in an- 2) one of the nuclei fertilises the egg cell
giosperms (extra 3) the other nucleus fuses with the central nuclei forming
info no need to a triploid cell
learn) 4) the triploid cell develops into endosperm and is the
embryo's food supply during early development

34. causes of genet- crossing over, independent assortment, random fertiliza-

ic variation tion

35. independent as- Mendel's law of independent assortment states that the
sortment alleles of two (or more) different genes get sorted into
gametes independently of one another

in other words, the allele a gamete receives for one gene

does not influence the allele received for another gene

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36. cause of inde- independent assortment is due to the random orientation

pendent assort- of homologous chromosomes during metaphase I
ment of chromo- - the orientation of each homologous pair is random and
somes is not affected by the orientation of any other homologous
pair
- the number of combinations possible when chromo-
somes assort independently into gametes is 2• where n is
the haploid number

37. when does inde- independent assortment will not occur if two genes are
pendent assort- located on the same chromosome (linked genes)
ment not hap-
pen?

38. dominant an allele whose effect on the phenotype of a heterozygote

is identical to it's effect on a homozygote // an allele that
is always expressed if present

39. recessive the allele that is expressed when no dominant alleles are
present // an allele that is masked when a dominant allele
is present

40. codominant alleles that both have an effect on the phenotype of a

heterozygous organism

41. linkage the presence of 2 genes on the same chromosome so

that they tend to be inherited together and do not assort
independently

42. test cross genetic cross in which an organism showing a charac-

teristic caused by a dominant allele is crossed with an
organism that's homozygous recessive; the phenotypes of
the offspring can be a guide to whether the first organism
is homozygous or heterozygous
//
the crossing of an individual of unknown genotype with
a homozygous recessive individual to determine the un-
known genotype

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43. F1 offspring resulting from a cross between an organism
with a homozygous dominant genotype and one with a
homozygous recessive genotype

44. F2 the offspring resulting from a cross between two F1 (het-

erozygous) organisms

45. phenotype an organism's characteristics, often resulting from an in-

teraction between its genotype and its environment

46. genotype the alleles possessed by an organism

47. homozygous having 2 identical alleles of a particular gene

48. heterozygous having 2 different alleles of a particular gene

49. monohybrid in- inheritance of 1 gene

heritance

50. multiple alleles when a gene has more than 2 alleles for one trait e.g. blood
group

51. sex linkage a sex-linked gene is a gene that is present on the X

chromosome and not the Y chromosome

52. dihybrid inheri- the inheritance of two characteristics which are controlled
tance by different genes, at once

53. finding gamete .

combinations in
dihybrid inheri-
tance

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54. epistasis (no the interaction between 2 non-linked genes which causes
need to know the one gene to mask the expression of the other phenotype
word)

55. interactions be- cases where different loci interact to affect one phenotypic
tween loci character e.g., alleles on 2 separate loci both affect feather
colour on a bird

56. autosomal link- gene loci present on the same autosome that are often
age inherited together and do not assort independently

57. Dzchi-square)
( used to determine whether the difference between an
test observed and expected result is statistically significant //
to test if there's linkage or epistasis

once the Dzresult is found, this needs to be compared

to a critical value table using the degree of freedom.,
interpreting the result:
- if above the critical value, then accept the hypothesis
- if below the critical value, then reject the hypothesis

58. degree of free- number of classes - 1

dom

59. if Dz >critical value more than 95% confident that there's a significant differ-
at p = 0.05 ence between observed and expected frequencies 4 link-
age occurred

60. if Dz <critical value more than 95% confident that there is not a significant
at p = 0.05 difference between observed and expected frequencies 4
linkage did not occur, results are what were expected

61. mutation unpredictable change in the structure of a DNA molecule

62. gene mutation

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change in the structure of DNA molecule, producing a
different allele of a gene

63. mutagen a substance that increased the chance of a mutation oc-

curing

64. causes of muta- can be random or due to environmental factors (ionising

tions & UV radiation, chemicals, etc.)

65. chromosome changes in the structure or number of whole chromo-

mutation somes in a cell

66. types of muta- substitution, addition, deletion

tions

67. frameshift - caused by a base addition or deletion

- affects all codons after the point of mutation
- protein made may be useless
- may introduce a STOP codon, so complete protein may
never be made

68. silent mutation mutations in DNA that do not significantly alter the pheno-
type of the organism or has no apparent effect

base substitutions are often silent mutations as many

amino acids have more than 1 triplet code

69. mutation that a base substitution occurs in the gene coding for amino
causes sickle cell acid sequence in ²-globin
anaemia
CTT (glumatic acid) ’ CAT (valine)
Hb, ’ Hbâ

70. effects of sickle 1) haemoglobin becomes less soluble

cell anaemia on 2) molecules stick together and form long fibres inside red
phenotype blood cells
3) red blood cells become sickle shaped
4) distorted cells cannot transport oxygen, and get stuck in
small capillaries and block unaffected cells from passing

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71. 'classic' form of - autosomal recessive mutation, individuals that are ho-
albinism mozygous for the recessive allele show the mutation
- mutation occurs in the gene for the enzyme tyrosinase
resulting in absent or inactive of tyrosinase in melanocytes

72. other form of al- sex-linked and affects the eyes only
binism

73. structure of ty- - a trans-membrane protein found in organelles called

rosinase melanosomes in melanocytes
- it's an oxidase and has 2 Cu atoms in the active site which
bind an oxygen
- occurs in plants as well as animal tissues

74. albinism pheno- 1) melanin totally/partially missing from eyes, skin and hair
type 2) eye pupils appear red
3) poor vision by rapid, jerky eye movement by a tendency
to avoid bright light

75. Huntington's dis- 1) mutation is inherited as a dominant allele

ease 2) the mutation is an unstable segment in a gene on
chromosome 4 coding for the protein huntingtin
3) in people who do not have HD, the segment is made up
of a small number of repeats of the triplet of bases CAG,
people with HD have a large number of repeats called
'stutters'
4) more stutters ’ earlier age of onset
5) age of onset is usually middle-age

76. effects of Hunt- 1) neurological disorder resulting in involuntary move-

ington's disease ments (chorea) and progressive mental deterioration
2) brain cells are lost
3) the ventricles of the brain become larger

77. structural genes genes that code for proteins needed by a cell; they may
form a part of the cellular structure or have different roles
such as behaving as an enzyme

78. regulatory gene

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genes that code for proteins that regulate the expression
of other genes; by making proteins such as repressors
that inhibit operator genes or control the transcription of
another gene

79. repressor en- The synthesis of a repressible enzyme can be prevented

zyme by binding a repressor protein to a specific site, called an
operator, on a bacterium's DNA.

80. inducible en- The synthesis of an inducible enzyme occurs only when its
zyme substrate is present. Transcription of the gene occurs as a
result of the inducer (the enzyme's substrate) interacting
with the protein produced by the regulatory gene.

81. transcription fac- 1) proteins that may bind to the promoter region of a gene
tors are 2) may increase or decrease the transcription of the gene
3) their role is to make sure that genes are expressed in
the correct cell at the correct time and to the correct extent

82. operon a length of DNA making up a unit of gene expression in a

bacterium; consists of one or more structural genes and
also control regions of DNA that are recognised by the
products of regulatory genes

83. structure of the - consists of a cluster of three structural genes (lacZ, lacY,
lac operon lacA) and a length of DNA including operator and promoter
regions which control lactose metabolism in E. coli
- close to the promoter, but not actually part of the operon,
is its regulatory gene
- genes within an operon will always be expressed togeth-
er or not at all because they're under the control of a single
promoter

84. promoter a specific nucleotide sequence in DNA that binds RNA

polymerase and indicates where to start transcribing

85. operator segment of DNA to which a repressor protein binds (in-

hibits transcription by obstructing RNA polymerase)
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86. sequence of 1) the regulatory gene codes for a protein called a repres-
events when sor
there is no lac- 2) the repressor binds to the operator region, close to the
tose in the medi- gene for ²-galactosidase
um in which 3) in the presence of bound repressor at the operator, RNA
the bacterium is polymerase cannot bind to DNA at the promoter region
growing 4) no transcription of the three structural genes can take
place

87. lacY encodes lactose permease (allows lactose to enter cell)

88. lacA encodes transacetylase (with unknown function)

89. lacZ encodes ²-galactosidase (hydrolyses lactose to glucose

and galactose)

90. sequence of 1) lactose is taken up by the bacterium

events when lac- 2) lactose binds to the repressor protein, distorting its
tose is present shape and preventing it from binding to DNA at the
in the medium in operator site
which the bac- 3) transcription is no longer inhibited and messenger
terium is growing RNA is produced from the three structural genes. The
genes have been switched on and are transcribed togeth-
er

91. why the lac oper- 1) This mechanism allows the bacterium to produce ²--
on mechanism is galactosidase, permease and transacetylase only when
useful lactose is available in the surrounding medium and to
produce them in equal amounts
2) avoids the waste of energy and materials in producing
enzymes for taking up and hydrolysing a sugar that the
bacterium may never meet

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92. function of tran- 1) form part of the protein complex that binds to the pro-
scription factors moter region of the gene
in gene expres- 2) activate appropriate genes in sequence
sion in eukary- 3) determination of sex in animals
otes 4) allow responses to environmental stimuli
5) regulate cell cycle, growth and apoptosis
6) give hormones their effect

93. how gibberellin stimulates the synthesis of amylase

controls seed 2) DELLA protein inhibits the binding of a transcription
germination in factor such as PIF to a gene promoter
plants 3) gibberellin causes the breakdown of DELLA protein
4) gibberellin allows PIF to bind to its target promoter
5) transcription of the gene can then take place, resulting
in an increase in amylase production

94. consequences of 1) silent: same amino acid; a mutation that has no appar-
a gene mutation ent effect on the organism
on a protein 2) missense: different amino acid; no apparent effect
3) nonsense: introduce a 'stop' triplet
4) frame shift: protein that is made becomes totally useless

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1. genetic variation 1) independent assortment

among individu- 2) crossing over
als in a popula- 3) random mating between organisms
tion is caused by 4) random fertilisation
(5) 5) mutation
*1-4 reshuffle existing alleles and produces phenotypic
variation

2. what type of mu- gene mutations, however the alleles formed are often
tation produces recessive and do not show up frequently in populations
new alleles?

3. mutations in so- cannot be passed onto offspring by sexual reproduction

matic cells but is passed to all other somatic cells derived from it
*however, mutations in somatic cells of the gonads may be
inherited if the mutated cell divides to form gametes

4. discontinuous the variation in phenotypic traits in which types are

variation grouped into discrete categories with few or no interme-
diate phenotypes 4 qualitative differences with no interme-
diates
e.g., blood group, the inheritance of haemophilia or sickle
cell anaemia

5. genetic basis 1) different alleles at a single gene locus have large effects
of discontinuous on the phenotype
variation 2) different genes have quite different effects on the phe-
notype

6. continuous varia- variation in which many alleles have small effects on the
tion phenotype, quantitative differences with many intermedi-
ates
e.g., height, weight

7. genetic basis of 1) different alleles at a single locus have small effects on

continuous varia- the phenotype
tion 2) different genes have the same/additive effect on the
phenotype

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3) a large number of genes may have a combined effect
on a particular phenotype (polygenes)

8. polygenes a gene whose individual effect on a phenotype is too small

to be observed, but which can act together with others to
produce observable variation

9. factors that tend 1) dominance

to reduce pheno- 2) gene interaction
typic variation

10. t-test - a statistical test used to determine if the means of 2

groups are significantly different
- a t-test might be used to calculate whether or not differ-
ences seen between the control and each experimental
group are a factor of a manipulated variable or simply the
result of chance

- data collected should be continuous data

- data should be from a population that is normally distrib-
uted
- standard deviations should be approximately equal

11. null hypothesis a statement that there is no association or difference

(H0) between two sets of data

"there is no significant difference between the two means

we are comparing"

12. degrees of free- df = (n• + n‚) - 2

dom (df) in t-test

13. if calculated t > any difference between the two data sets is less likely to
critical t at p = be due to chance and the difference is significant, so the
0.05 null hypothesis is rejected

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14. if calculated t < the difference between the means is insignificant and the
critical t at p = null hypothesis is accepted, the small difference in them is
0.05 due to chance (e.g., sampling error) and can be neglected

15. importance of - genetic variation provides the raw material on which

genetic variation natural selection can act
in selection - variation within a population means that some individuals
have features that give them an advantage over other
members of that population

16. why natural se- 1) populations have the capacity to produce many off-
lection occurs springs
2) offsprings compete for resources
3) individuals best adapted to survive breed and pass on
their alleles

17. types of environ- biotic & abiotic

mental factors

18. biotic factors caused by living organisms e.g., food competition, preda-
tion, infection by pathogens

19. abiotic factors caused by non-living components of the environment

20. selection pres- factors that contribute to selecting which variations will
sures provide the individual with an increased chance of surviv-
ing over others

selection pressures control the chances alleles being

passed onto the next generation

21. natural selection effects of selection pressures on the frequency of alleles

in a population

natural selection raises the frequency of alleles that are

advantageous and reduces the 'disadvantageous' ones

22. types of selec- directional, stabilizing, disruptive

tion

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23. stabilising selec- - favours the mean of the distribution; frequency of mean
tion phenotype increases as the organisms are already adapt-
ed to the environment
- acts against extremes
- e.g., birth weight

24. directional selec- - occurs when natural selection favors one of the extreme
tion variations of a trait, causing the allele frequency to contin-
uously shift in one direction
- e.g., the beak size in a population of finches

25. disruptive selec- - occurs when conditions favour both extremes of a phe-
tion notype
- different phenotypes (polymorphism) is maintained in the
population
- e.g., Galapagos flinches

26. X do not affect X = changes in environmental factors

the likelihood of *changes in environmental factors only affect the likeli-
an allele arising hood of an allele surviving in a population
by mutation

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27. factors affecting 1) genetic drift
allele frequency 2) the founder effect
in a population 3) natural selection

28. genetic drift a change in the allele frequency of a population which

occurs by chance (as only some organisms of each gener-
ation reproduce), it's most noticeable in small populations

29. the founder ef- an example of genetic drift that occurs when a small
fect group of individuals break off from a larger population to
establish a colony
- alleles in the founding population may be present at
different frequencies or missing altogether
- evolution of this population may take a different direction
from the larger parent population

30. how natural se- causes changes in allele frequencies with fitness-increas-
lections affects ing alleles becoming more common in the population
allele frequency
in a population

31. Hardy-Weinberg principle that states that a population's allele and genotype
Principle frequencies are constant unless there is some sort of
evolutionary force acting upon them
*formula used to calculate allele, genotype, or phenotype
frequencies in a population when certain criteria are ful-
filled

32. when the 1) no mutation (no change to type of alleles in a popula-

Hardy-Weinberg tion)
Principle applies 2) no natural selection (environmental factors do not
favour an allele over others)
3) population is infinitely large (as it's not possible for allele
frequencies to be maintained in a small poplation)
4) no non-random breeding (all members with different
characteristics have equal chance to breed)
5) no migration (no change in population size)

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33. artificial selec- humans purposefully applying selection pressures to pop-

tion ulations in order to breed 'desirable' traits from the natural
variation among organisms

34. process of artifi- 1) selective breeding - individuals with desirable features

cial selection are chosen to interbreed
2) some of these desirable features are chosen to inter-
breed
3) this is repeated over many generations (over time,
alleles deemed as 'desirable' increase in frequency while
the disadvantageous ones may completely disappear)

35. 'desirable' fea- 1) docility (the trait of being agreeably submissive and
tures when se- manageable)
lectively breed- 2) fast growth rate
ing cattle 3) high milk yields

36. problems asso- 1) the animals are large

ciated with se- 2) they take a long time to reach maturity
lectively breed- 3) the gestation period is long
ing cattle 4) the number of offspring produced is small

37. progeny testing testing the bull for the production of desirable character-
istics (e.g. milk production as it's a sex-limited trait) by
checking the performance of their female offspring to see
if it should be used in future crosses

38. background all alleles of genes within each organism's genotype that
genes adapt it to its environment, these have to also be consid-
ered by the breeder

39. examples of crop 1) the introduction of disease resistance to varieties of

improvement wheat and rice
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2) the incorporation of mutant alleles for gibberellin syn-

thesis into dwarf varieties so increasing yield by having a
greater proportion of energy put into grain

3) inbreeding and hybridisation to produce vigorous, uni-

form varieties of maize

40. why is disease to reduce the loss of yield resulting from infections
resistance intro-
duced to vari-
eties of wheat
and rice?

41. why are mutant 1) most dwarf varieties carry mutant alleles for 2 reduced
alleles for gib- height (Rht) genes
berellin synthe- 2) these genes code for DELLA proteins which reduce the
sis incorporated effect of gibberellin on growth
into dwarf vari- *another mutant allele of a different gene has its dwarfing
eties? effect as the plant cells don't have receptors for gibberellin
3) mutant alleles increase yield by having a greater pro-
portion of energy put into grain

42. why is inbreed- - when maize plants are inbred, the plants in each gener-
ing and hybridis- ation become progressively smaller and weaker (inbreed-
ation done to pro- ing depression)
duce vigorous, - this occurs because homozygous plants are less vigor-
uniform varieties ous than heterozygous plants
of maize? - challenge when growing maize: heterozygosity and uni-
formity
- solution: hybridisation
1) using maize seeds that produce homozygous plants
2) these different homozygous varieties are crossed, pro-
ducing F1 that are all the same genotype

43. ideal maize char-

acteristics
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1) high yields
2) resistance to more pests and diseases
3) good growth in nutrient-poor soils / short water supply

44. state the general organisms have changed overtime

theory of evolu-
tion

45. how evolution 1) organisms produce more offspring than are needed to
occurs replace the parents
2) natural populations tend to remain stable in size over
long periods
3) there is competition for survival / struggle for existence
4) there is variation among the individuals of a given
species
5) the best adapted variants will be selected for by natural
conditions operating at the time / natural selection occurs
/ survival of the fittest

46. comparing when the amino acid sequence of a particular protein is

amino acid compared in different species, the number of differences
sequences of gives a measure of how closely related the species are
proteins

47. comparing nu- differences in the nucleotide sequences of mtDNA can be

cleotide se- used to study the origin and spread of our own species
quences of mito-
chondrial DNA

48. human mtDNA 1) inherited through the female line

2) a zygote contains mitochondria of ovum and not sperm
3) mtDNA is circular so can't undergo any form of crossing
over 4 changes in nucleotide sequence can only occur by
mutation
4) different human populations show differences in mtDNA
sequences; these provide evidence for the origin of differ-
ent populations

49. molecular clock a technique that uses the mutation rate of biomolecules to
hypothesis deduce the time in prehistory when two or more life forms
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diverged
- assumes a constant rate of mutation overtime
- the greater the number of differences in nucleotide se-
quence, the longer ago those individuals shared a com-
mon ancestor
- 'clock' can be estimated from fossil evidence

50. speciation the formation of new species

51. define species a group of organisms with similar morphological, physio-

logical, biochemical, and behavioural features, which can
interbreed to produce fertile offspring and are reproduc-
tively isolated from other species

52. types of specia- allopatric (geographical separation) and sympatric (eco-

tion logical & behavioural separation)

53. allopatric specia- speciation that occurs when 2 populations are separated
tion from each other geographically
1) population of species splits and movies to different
areas
2) each new population experiences different selective
pressures causing morphological, physiological & behav-
ioural features to change
3) when the different populations are re-introduced, they
can no longer interbreed

54. sympatric speci- the formation of a new species in populations that live in
ation the same geographic area as a result of a genetic change
that produces a reproductive barrier between the changed
population (mutants) and the parent population
*speciation will result if the polyploid offspring are viable
and fertile but cannot interbreed with the original parent
population
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*usually occurs through a polyploidy which occurs e.g.,
when meiosis goes wrong

55. polyploidy or- has more than 2 complete sets of chromosomes in its cells
ganism

56. tetraploid (4n) when 2 diploid gametes fuse (2+2=4) and zygote gets 4
complete sets of chromosomes
- often sterile as it's difficult for 4 pairs of chromosomes to
pair during meiosis I
- fertile polyploid offspring will typically require two poly-
ploid parents (unless allopolyploidy occurs) as reproduc-
tion with the original parent population results in offspring
with an uneven number of chromosome sets
- tetraploid cell may grow and reproduce asexually
- occurs often in plants but rarely in animals

57. triploid (3n) when a tetraploid's gametes (diploid/2n) fuses with a nor-
mal, haploid gamete (n) 4 2+1=3
- may be able to grow normally but always sterile as ga-
metes cannot be formed (3 sets of chromosomes cannot
be shared equally among daughter cells)

58. kinds of polyploi- autopolyploid and allopolyploid

dies

59. autopolyploid all sets of chromosomes from the same species

autopolyploidy occurs when a polyploid offspring is de-
rived from a single parental species (usually via self fertil-
isation)

60. allopolyploid

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different sets of chromosomes from a different but related
species
- meiosis happens more easily in an allotetraploid than in
an autotetraploid as chromosomes are not quite identical
- allotetraploid can be fertile and produce gametes

61. reproductive iso- the inability of 2 organisms of the same species to in-
lation terbreed due to geographical separation of behavioural
differences

62. when can repro- pre-zygotic or post-zygotic

ductive isolation
occur?

63. pre-zygotic isola- - individuals not recognising one another as potential

tion mates or not responding to mating behaviour
- animals being physically unable to mate
- incompatibility of pollen and stigma
- inability of male and female gametes to fuse

64. post-zygotic iso- - failure of cell division in zygote

lation - non-viable offspring
- viable but sterile offspring
*post-zygotic isolation is more wasteful of energy

65. causes of extinc- 1) climate change

tion 2) competition (from better adapted species)
3) habitat loss
4) killing by humans

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1. recombinant DNA made by joining pieces from two or more different

DNA (rDNA) sources

2. organism that transgenic organism or genetically modified organism

expresses the (GMO)
genes that have
been attained
from another or-
ganism as a re-
sult of rDNA

3. difference be- in selective breeding, whole sets of genes are involved

tween selective whereas genetic engineering often results in the transfer
breeding and ge- of one gene
netic engineering

4. origin of genes extraction of genes from one organism or the synthesis of

that can be genes
placed in an or-
ganism such that
they express the
gene product

5. overview of gene 1) identification of the desired gene

transfer 2) isolation of the desired gene by
- cutting from a chromosome using enzymes (restriction
endonucleases)
- using reverse transcriptase to make a single strand of
complementary DNA (cDNA) from mRNA
- creating the gene artificially using nucleotides
3) multiplication of the gene (using polymerase chain re-
action - PCR)
4) transfer into the organism using a vector (e.g. plasmids,
viruses, liposomes)
5) identification of the cells with the new gene (by using a
marker), which is then cloned

6. restriction endonucleases, ligase and reverse transcrip-

tase

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enzymes used in
genetic engineer-
ing

7. plasmid small, circular pieces of double-stranded DNA

8. properties of 1) they occur naturally in bacteria

plasmids that al- 2) can be transferred between different bacterial species
low them to be 3) can be produced artificially
used in gene 4) double stranded so genes from prokaryotes and eu-
cloning karyotes can be inserted
5) replicate independently in bacteria

9. transferring plas- 1) the plasmids and bacteria are bathed in an ice-cold

mids to host cells calcium chloride solution (high conc. of Ca ions) and then
(bacteria) heat shocked, making the bacteria's cell surface mem-
brane more permeable
2) only a very small proportion of bacteria take up the
plasmids with the gene (1%), those that do so are said to
be transformed

10. vector used to deliver genes into a plasmid

11. markers genes coding for easily identifiable substances that can be
transferred with the desired gene and identify which cells
have been successfully altered and now contain recombi-
nant DNA

12. examples of 1) antibiotic resistant genes (the gene for antibiotic re-
gene markers sistance is replaced, therefore the 'transformed' bacteria
would not be able to grow in a medium with an antibiotic
present)
2) GFP (green fluorescent protein) which fluoresces under
UV light
3) GUS (²-glucuronidase enzyme) which transforms
colourless or non-fluorescent substrates into products that
are coloured or fluorescent

13. disadvantages 1) risk of antibiotic resistance genes spreading to other

of using bacteria, producing pathogenic (disease-causing) strains
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antibiotic-resis- that can't be killed by antibiotics
tant genes as 2) if the resistance spread to other bacteria this could
marker genes make antibiotics less effective

14. use of fluores- the GFP gene, along with the desired gene, are linked to
cent genes as a specific promoter and once this promoter is activated,
markers and the protein is expressed, the recombinant bacteria
are detected when they glow green under exposure to
ultraviolet light

15. advantage of us- 1) they are easier to identify (all that is required is the
ing fluorescent ultraviolet light)
genes as mark- 2) more economical (do not need to grow the bacteria on
ers plates of agar infused with antibiotics)
3) no risk of antibiotic resistance being passed onto other
bacteria
4) there are antibiotics that are no longer effective and
therefore would not stop any bacteria from growing

16. vectors that can plasmids, viruses & liposomes

be used in gene
cloning

17. promoters the region of DNA that determines which gene will be
expressed as it's the region of DNA to which RNA poly-
merase binds as it starts transcription

18. role of promoters 1) ensures that RNA polymerase recognises the template
strand
2) transcription start-point
3) the promoter is used to regulate gene expression be-
cause only if it is present will transcription and therefore
the expression of the gene occur

19. explain why pro- if the gene being inserted into the bacterium is to be
moters and oth- expressed, then an appropriate promoter also needs to be
er control se- inserted
quences may 1) e.g., when bacteria were first transformed to produce
have to be trans- insulin, the gene for it was inserted next to to ²-galactosi-
dase so they shared a promoter
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ferred as well as 2) the promoter switched on the gene when the bacteria
the desired gene were in a medium with lactose but no glucose, and they
produced the ²-galactosidase as well as human insulin

20. restriction en- an enzyme that binds to a specific target area on DNA and
donucleases cuts it at the site

21. role of restric- 1) isolate the desired gene

tion endonucle- 2) separate the DNA strands (at the same base sequence)
ases (restriction in a vector so the desired gene can be inserted
enzymes) in the
transfer of a gene
into an organism

22. why are many they bind to a specific restriction site (specific sequences
different restric- of bases) on DNA, eg. HindIII will always bind to the base
tion endonucle- sequence AAGCTT
ases required

23. how restric- restriction enzymes either cut straight across the sug-
tion endonucle- ar-phosphate backbone to give blunt ends or they cut in
ase work a staggered fashion to give sticky ends

24. sticky ends short lengths of unpaired bases, make it easier to insert
the desired gene into another organism's DNA or into
a vector as they can easily form hydrogen bonds with
complementary sequences of bases on other pieces of
DNA cut with the same restriction enzyme

25. blunt ends fragment ends of a DNA molecule that are fully base
paired

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26. reverse tran- an enzyme encoded by retroviruses that uses an RNA

scriptase strand as a template for DNA synthesis (produces 1 DNA
strand)

27. role of reverse produce a single-strand complementary DNA molecule

transcriptase in (cDNA) that contains the code for the desired character-
the transfer of a istic, this will then be inserted into a vector (after being
gene into an or- converted into a double-stranded DNA molecule)
ganism

28. source of reverse retroviruses

transcriptase en-
zymes

29. advantage of us- easier for scientists to find mRNA with the specific charac-
ing reverse tran- teristic because specialised cells make very specific types
scriptase en- of mRNA (eg. ²-cells of the pancreas produce many insulin
zymes mRNA) and mRNA does not contain introns

30. (DNA) ligase catalyses the formation of phosphodiester bonds in the

DNA sugar-phosphate backbone

31. role of ligase in enables the isolated desired gene to be spliced into a
the transfer of a vector (generally a plasmid) so that it can be transferred
gene into an or- to the new organism
ganism

32. polymerase method for the rapid production of a very large number of
chain reaction copies of a particular fragment of DNA
(PCR)

33. each PCR reac- 1) DNA (or RNA) sample being amplified
tion requires 2) primers
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3) free nucleotides - used in the construction of the DNA
or RNA strands
4) buffer solution - to provide the optimum pH for the
reactions to occur in
5) DNA polymerase

34. three stages of 1) denaturation - the double-stranded DNA is heated to

PCR 95°C which breaks the hydrogen bonds that bond the two
DNA strands together
2) annealing - the temperature is decreased to 65°C so
that primers can attach to the ends of single-stranded DNA
molecules
3) elongation - the temperature is increased to 72°C as this
is the optimum temperature for Taq polymerase to build
the complementary strands of DNA to produce the new
identical double-stranded DNA molecules

35. primers short sequences of single-stranded DNA that have base

sequences complementary to the 3' end of the DNA or
RNA being copied and define the region that is to be
amplified by identifying to the DNA polymerase where to
begin building the new strands

36. Taq polymerase a heat-stable form of DNA polymerase extracted from ther-
mophilic bacteria (Thermus aquaticus), found in places
such as hot springs, that is used in PCR

37. features of Taq 1) not destroyed in the denaturation step, so it does not
polymerase that have to be replaced each cycle
enable it to be 2) its high optimum temperature means the temperature
used in PCR for the elongation step does not have to be dropped below
that of the annealing process so efficiency is maximised

38.
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variable number regions of repeating sequences of bases found in the
tandem repeats non-coding part DNA that contain variable numbers of
(VNTR) repeated DNA sequences and vary between different peo-
ple (only identical twins share all their VNTR sequences)

39. gel electrophore- a technique used for separating and analysing nucleic
sis acids or proteins on the basis of their size and electrical
charge

40. outline how 1) DNA sample placed in well (at end of gel)
gel electrophore- 2) electric field is passed through the gel
sis is carried out 3) negatively charged DNA attracted to anode
to confirm which 4) shorter fragments move further in unit time
species a partic- 5) compare band positions to identify species
ular sample is
from [3]

41. factors affecting 1) net (overall) charge - -vely charged molecules move to
the movement of anode (+), +vely charged molecues move to cathode (-),
charged mole- highly charged molecules move faster than those with less
cules in gel elec- overall charge
trophoresis 2) size - smaller molecules move faster than larger ones
3) composition of gel - size of pores within gel (e.g.,
agarose for DNA has different pore size than polyacry-
lamide for proteins) determines speed with which mole-
cules move

42. electrophoresis 1) the charge on proteins is dependent on the ionisation of

of proteins the R groups of amino acids - the charge of the R groups
depends on the pH and therefore buffer solutions are used
during the separation of proteins to keep the pH constant.

2) gel electrophoresis is used to separate polypeptide

chains produced by different alleles of the same gene e.g.,
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the haemoglobin variants (±- globin, ²-globin and the sickle
cell anaemia variant of ²-globin)

43. alloenzymes (no variant forms of enzymes produced by different alleles of

need to learn) the same gene

44. electrophoresis 1) DNA quantity is increased using PCR

of DNA 2) restriction enzymes cut the DNA into fragments (dif-
ferent restriction enzymes cut the DNA at different base
sequences, so enzymes that will cut close to the VNTR
regions need to be used)
3) electrophoresis is carried out on the DNA sample
4) the fragments are not visible so must be transferred
onto absorbent paper which is then heated to separate the
two DNA strands
5) probes are then added, after which an X-ray image
is taken or UV-light is shone onto the paper producing a
pattern of bands

45. probes short sequences of single stranded DNA that have base
sequences complementary to a particular VNTR region,
they also contain a means by which to be identified -
1) a radioactive label (eg. a phosphorus isotope) which
causes the probes to emit radiation that makes the X-ray
film go dark, creating a pattern of dark bands
2) a fluorescent stain/dye which fluoresces when exposed
to UV light, creating a pattern of coloured bands

46. microarrays laboratory tools used to identify the genes present in an

(DNA chips) organism's genome, find out which genes are expressed
within cells, and compare the genes present in 2 different
species
a microarray consists of a small (usually 2cm²) piece of
glass, plastic or silicon (also known as chips) that have
probes attached to a spot (called a gene spot) in a grid
pattern, there can be 10,000 or more spots per cm²

47. how microarrays 1) DNA is collected from the species that are going to be
are used in compared
2) restriction enzymes are used to cut the DNA into frag-
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the analysis of ments
genomes 3) the fragments are denatured to form single-stranded
DNA molecules
4) the DNA is labelled with fluorescent tags (the fragments
from the different sources are tagged different colours,
usually red and green)
5) the labelled DNA samples are mixed together and
allowed to hybridise with the probes on the microarray
6) any DNA that has not bound to the probes is washed
off
7) the microarray is inspected using UV light, causing the
tags to fluoresce
8) the presence of colour indicates that hybridisation has
taken place (as the DNA fragments are complementary to
the probes)
# red and green: DNA from one species has hybridised with
probes
# yellow: DNA from both species hybridised (the two
species have DNA with exactly the same base sequence)
# no colour/blue: no hybridisation, gene not present in either
species
9) the microarray is scanned so data is read by a computer
and stored

48. how microarrays microarrays are used to compare which genes are active
are used in de- by identifying the genes that are being transcribed onto
tecting mRNA in DNA
studies of gene 1) mRNA is collected from 2 types of cells and reverse
expression transcriptase is used to convert mRNA to cDNA
2) PCR may be used to increase quantity of cDNA as
mRNA quantity is quite low at any one time
3) cDNA is labelled with fluorescent tags and denatured to
give single stranded DNA
4) single stranded DNA is allowed to hybridise with probes
on the microarray
5) UV light is shone; spots that fluoresce indicate the
genes that were being transcribed in the cell
# intensity of light emitted by each spot indicates the level
of activity by each gene
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# high intensity: indicates many mRNA molecules are pre-
sent in sample

49. bioinformatics bioinformatics is the collection, processing and analysis of

biological information and data using computer software

50. role of bioinfor- 1) comparisons can be made with other known genomes
matics following using the many databases available; sequences can be
the sequencing matched and degrees of similarity calculated
of genomes 2) human genes such as those associated with develop-
ment can be found in other organisms e.g, Drosophila; 4
Drosophila could be used in experiments as a model for
humans
3) ways to control Plasmodium and gene sequencing is
helping in the development of vaccines for malaria

51. why are most eukaryotic cells will carry out the post-translational mod-
recombinant hu- ification (due to presence of Golgi Apparatus / enzymes)
man proteins that is required to produce a suitable human protein
produced us-
ing eukaryotic
cells (eg. yeast,
or mammalian
cells in culture)
rather than using
prokaryotic cells

52. advantages of 1) cells have simple nutritional requirements

producing hu- 2) large volumes of product are produced
man proteins 3) production facilities do not require much space and
by recombinant the processes can be carried out anywhere in the world;
DNA techniques reliable supply available
4) few practical and ethical problems as proteins do not
have to be extracted from animal sources or by
5) the proteins are engineered to be identical to human
proteins or have modifications that are beneficial

53. producing re- factor VIII is a blood-clotting protein that haemophiliacs

combinant factor cannot produce
VIII 1) kidney and ovary hamster cells have been genetically
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modified to produce factor VIII
2) once modified, the cells are cultured in fermenters
3) due to the optimal conditions in the fermenter, the
hamster cells constantly express factor VIII which can
then be extracted and purified, and used as an injectable
treatment for haemophilia

54. advantages of 1) fewer ethical, moral or religious concerns (proteins are

using recombi- not extracted from human blood)
nant factor VIII 2) less risk of transmitting infection (e.g. HIV) or disease
3) greater production rate

55. producing #the enzyme adenosine deaminase is used to treat se-

recombinant vere combined immunodeficiency (SCID) while patients
adenosine are waiting for gene therapy or when gene therapy is not
deaminase (ADA) possible
# the larva of the cabbage looper moth has been genetically
modified (using a virus vector) to produce ADA

56. severe com- #a crippled immune system due to the inability to make
bined immunod- adenosine deaminase (ADA)
eficiency (SCID) # sufferers may die at infancy due to normal infections
# T-lymphocytes of sufferers are removed and normal alle-
les of the ADA gene are introduced into them using a virus
vector however this is not a permanent cure

57. producing re- 1) bacteria plasmids are modified to include the human in-
combinant in- sulin gene; restriction endonucleases are used to cut open
sulin plasmids and DNA ligase is used to splice the plasmid and
human DNA together
2) recombinant plasmids are then inserted into Es-
cherichia coli, transforming the cells
3) once the transgenic bacteria are identified (by the mark-
ers), they are isolated, purified and placed into fermenters
that provide optimal conditions
4) they multiply by binary fission, and express the human
protein - insulin, which is eventually extracted and purified

58. 1) identical to human insulin, unless modified to have

different properties (eg. act faster, which is useful for taking
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advantages of immediately after a meal or to act more slowly)
using recombi- 2) there is a reliable supply available to meet demand (no
nant insulin need to depend on availability of meat stock)
3) fewer ethical, moral or religious concerns (proteins are
not extracted from cows or pigs)
4) fewer rejection problems or side effects or allergic reac-
tions
5) cheaper to produce in large volumes
6) useful for diabetics who have animal insulin tolerance

59. genetic screen- the analysis of a person's DNA to check for the presence
ing of a particular alleles (can be done in adults, an in vitro
embryo, or an embryo or foetus in a uterus)

60. how a sample 1) taking tissue samples from adults or embryos produced
of DNA to be by in-vitro fertilisation
analysed (from 2) chorionic villus sampling or amniocentesis of embryos
adult, embryo, and fetuses in the uterus
foetus) can be
obtained

61. chorionic villus a small sample of part of the placenta called the chorion
sampling is removed by a needle

62. amniocentesis needle puncture of the amniotic sac to withdraw amniotic

fluid for analysis

63.

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genetic screen- #Brca-1 and Brca-2 are genes that produce tumour sup-
ing for the faulty pressor proteins and thus they play an important role in
alleles of Brca-1 regulating cell growth
and Brca-2 # faulty alleles of these particular genes exist (can be in-
herited from either parent) which increase the risk of an
individual developing breast cancer
# advantages of screening:
1) preventative measures can be taken e.g., an elective
mastectomy (breast removal) to reduce the risk of devel-
oping cancer
2) screening for breast cancer may begin from an earlier
age or more frequently
3) enables the person to participate in research and clini-
cal trials

64. genetic screen- #haemophilia is a sex-linked recessive inherited disease

ing for where the body does not produce a blood protein (either
haemophilia factor VIII or factor IX) that is required for the blood to clot
# advantage of genetic screening for women:
1) can determine whether they are carriers or not (as
haemophilia is a recessive disease)
2) can help the women (and their partners) make deci-
sions about future pregnancies (if they're carriers)
3) help the doctors take special precautions during the
pregnancy (if a carrier)
4) women can use pre-implantation genetic diagnosis
(PGD) during IVF to choose an embryo that is carrying
the allele for the relevant blood clotting factor as opposed
to embryos carrying the recessive alleles

65. genetic screen- #sickle cell anaemia is an autosomal recessive disease

ing for sickle cell that results in the haemoglobin molecule being less solu-
anaemia ble if oxygen is not present, causing red blood cells to form
a sickled shape
# this sickled shape reduces the ability of the red blood cell
to carry oxygen and the cells are less flexible, and more
prone to getting stuck in small capillaries
# advantage of genetic screening:
1) people with a family history of the disease or African

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ancestry may get tested to determine if they are a carrier
2) if the person is determined to be a carrier they can
discuss with a genetic counsellor their options so they can
make informed decision
3) if the person is undergoing IVF, they could use PGD to
select an embryo that does not have the recessive alleles

66. genetic screen- #Huntington's disease is a late-onset neurodegenerative

ing for Hunting- disease caused by an austosomal dominant allele
ton's disease # advantage of genetic screening:
1) people to plan for the future (how they will live and be
cared for)
2) couples to make informed reproductive decisions (as
the risk that their children may inherit the disease is 50%)
3) people to participate in research and clinical trials

67. cystic fibrosis #cystic fibrosis is an autosomal recessive genetic disorder

that is caused by a deletion mutation of 3 bases (AAA) of
the gene that codes for a transporter protein called CFTR
# it is a progressive disease in which abnormally thick
mucus is produced in the lungs and other parts of the body
(pancreatic duct, ducts in the reproductive system)
# CFTR sits in the cell surface membranes of cells and
allow chloride ions to pass out of the cells; the high con-
centration of chloride ions outside cells reduces the water
potential causing water to flow out via osmosis mixing with
the mucus outside making it easier for cilia to remove it
# in cystic fibrosis, the faulty CFTR protein no longer trans-
ports chloride ions across the cell surface membrane and
therefore water does not move by osmosis across the
membrane
# there is no cure for cystic fibrosis, although there are many
different treatments that help alleviate symptoms

68. advantage of ge- 1) t enables couples to make informed reproductive deci-

netic screening sions (as both may be carriers and therefore not display
for cystic fibrosis any symptoms)
2) people can participate in research and clinical trials

69.
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therapeutic abor- terminating pregnancies for a medical reason rather than
tion for any other reason

70. gene therapy the insertion of 'normal' alleles of a gene into the cells of
a person with a genetic disorder in an attempt to cure the
disorder

71. most common viruses (retrovirus, lentivirus, HIV, adeno-associated

vectors that are virus), liposomes, naked DNA is sometimes used
used to carry
normal alleles to
host cells (in
gene therapy)

72. retroviruses in #retroviruses insert their genes into the host's genome
gene therapy however do so randomly
# this means they may insert their genes within another
gene or into the regulatory sequence of a gene (which may
then activate a nearby gene causing cancer)

73. lentivirus #a virus characterized by a long incubation period (e.g.,

HIV)
# inserts genes randomly into host's genome, but this virus
can be modified to not replicate

74. adeno-associat- #this virus does not insert its genes into the host genome
ed virus (AAV) and so they are not passed on to daughter cells when a
cell divides
# this is a problem when cells are short-lived e.g. lympho-
cytes but can be used successfully with long-lived cells
such as liver cells and neurones

75. Leber congenital #a form of hereditary blindness caused by retinal cells

amaurosis dying off gradually from a young age in males
# doctors injected adeno-associated viruses into the retina
that contained the normal alleles of one of the genes that
caused damage to the photoreceptors, improving their
eyesight

76. removes problems associated with using vector

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advantage of us-
ing naked DNA in
gene therapy

77. social & eth- 1) the potential for side effects that could cause death
ical considera- (eg. the children who were treated for SCID developed
tions of using leukaemia)
gene therapy 2) whether germ cell gene therapy should be allowed
3) genetic conditions where treatments already exist
4) the expense of treatments as multiple injections of the
genes may be required if the somatic cells are short-live;
this may make the cost of gene therapy accessible to a
limited number of people
5) who has the right to determine which genes can be
altered and which cannot

78. germ cell gene attempts to alter alleles in cells involved in sexual repro-
therapy duction

79. use of PCR and 1) electrophoresis of DNA is used in genetic profiling

DNA testing in (fingerprinting) in forensic science
forensic medi- 2) PCR is used in forensic science to solve crimes: used
cine and criminal to amplify DNA from small tissue samples
investigations

80. crop plants have 1) resistant to herbicides - increases productivity / yield

been genetically 2) resistant to pests - increases productivity / yield
modified to be 3) enriched with vitamins - increases the nutritional value

81. benefits of us- 1) organisms with the desired characteristics are pro-
ing genetic en- duced more quickly
gineering rather 2) all organisms will contain the desired characteristic
than traditional (there is no chance that recessive allele may arise in the
selective breed- population)
ing techniques to 3) the desired characteristic may come from a different
solve the global species / kingdom
demand for food

82. consequences of 1) the development of resistance for the genes that have
using genetical- been introduced
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ly engineered or- 2) the risk of the gene spreading to wild relatives
ganisms to solve 3) the modified organism may become a pest
the global de- 4) the reduction in biodiversity
mand for food 5) potential ecological effects (e.g. harm to non-targeted
species)

83. disadvantages of 1) the development of resistance for the genes that have
using genetical- been introduced
ly engineered or- 2) the risk of the gene spreading to wild relatives
ganisms to in- 3) the modified organism may become a pest
crease the pro- 4) the reduction in biodiversity
ductivity of the 5) potential ecological effects (e.g. harm to non-targeted
crop species)
6) possible risk to human health as an allergy (there are
no long-term studies on the effect on human health)

84. describe how the 1) vitamin A is found in the aleurone layer of rice
vitamin A con- 2) white rice does not contain the aleurone layer
tent of rice can 3) genes that code for vitamin A are extracted from
be enhanced by 4) bacteria
genetic modifica- 5) and daffodils
tion [9] 6) the genes are inserted into plasmids
7) and promoters are added
8) the plasmids are put into Agrobacterium tumefaciens
9) Agrobacterium tumefaciens is mixed with rice embryos
10) some embryos take up bacteria and the vitamin A
gene
11) the plants grow into adult plants
12) and produce seeds with vitamin A
13) in the endosperm
this variety of rice is called Golden Rice

85. vitamin A #vitamin A is a fat-soluble vitamin found in oily fish and

animal products such as eggs, milk, cheese & liver
# also made in human bodies from carotene (orange
carotenoid pigment)
# deficiency can cause blindness and immune deficiency
syndrome

86.
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genes for daffodils and a common soil bacterium called Pantoea
carotene produc- ananatis
tion is taken from

87. ethical implica- some organisations condemn Golden Rice saying it is the
tions of Golden wrong way to solve poverty; solving political, cultural and
Rice economic issues will help lower poverty, and people can
afford to have a more varied diet

88. GM salmon 1) growth-hormone regulating genes from Pacific Chinook

salmons and promoters from ocean pout are injected into
the fertilised egg of an Atlantic salmon
2) this enables the salmon to produce growth hormone
throughout the year and therefore grow all year instead of
just the summer and spring
3) they reach market size in 18 months as opposed to 3
years of an unmodified fish
4) to prevent the GM salmon from reproducing in the wild,
all the salmon are female and sterile

89. genetically modi- 1) a source of vegetable oil which is used as a biodiesel

fied oil seed rape fuel and lubricant
2) modified oil seed rape is resistant to the herbicide
glyphosphate (inhibits the synthesis of 3 amino acids:
phenylamine, tyrosine, trytophan which are required for
producing essential proteins) and contains lower concen-
trations of erucic acid glucosinolates
3) the gene transferred into crop plants came from a strain
of the bacterium Agrobacterium

90. genetically modi- tobacco has been made resistant to 2 different herbicides
fied tobacco (sulfonylurea & dinitroaniline) and in both cases the genes
were taken from other species of plant, also has been
made insect-resistant against the tobacco bud worm

91. detrimental ef- 1) the genetically modified plant will become an agricultur-
fects on al weed
the environ- 2) pollen will transfer the gene to wild relatives, producing
ment of growing hybrid offspring that are invasive weeds

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a herbicide-resis- 3) herbicide-resistant weeds will evolve because so much
tant crop of the same herbicide is used

92. detrimental ef- 1) the evolution of resistance by the insect pests

fects on the envi- 2) a damaging effect on other species of insects (however,
ronment of grow- less pesticide is used, less risk of spray carrying and
ing an insect-re- affecting non-target species in other areas)
sistant crop 3) the transfer of added gene to other species of plant

93. genetically modi- protected against boll weevil

fied cotton

94. Bt maize 1) maize has been genetically modified with a gene for Bt
toxin
2) gene for Bt toxin is taken from the bacterium Bacillus
thuringiensis
3) Bt toxin is lethal to insects that eat it but harmless to
other animals
4) genetically modified crop plants with Bt toxin gene
produce their own insecticides
5) maize is protected against corn borers
6) Bt resistance in corn borers is a recessive allele; adult
corn borers in refuges (non GM maize) are homozygous
dominant or heterozygous and supply the dominant alleles
to counteract the resistance when adult corn borers from
fields and refuges mate

95. social implica- 1) modified crop plants may become agricultural weeds or
tions of using invade natural habitats
genetically modi- 2) the introduced genes may be transferred by pollen to
fied organisms in wild relatives whose hybrid offspring may become more
food production invasive
3) the introduced genes may be transferred by pollen to
unmodified plants growing on a farm with organic certifi-
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cation
4) the modified plants may be a direct hazard to other
animals and humans by being toxic or producing allergies
5) the herbicide that can now be used leaves toxic resides
on the crop
6) genetically modified seeds and herbicides are expen-
sive and their cost removes any advantage of growing a
resistant crop
7) growers need to buy new seeds every season, keeping
costs high
8) danger of losing traditional varieties with their desir-
able background genes and possibly unknown traits which
might be useful

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1. species a species is a group of organisms with similar morpholo-

gy and physiology, which can breed together to produce
fertile offspring and are reproductively isolated from other
species

2. ecosystem an ecosystem is a relatively self-contained, interacting

community of organisms, and the environment in which
they live and with which they interact

3. habitat a habitat describes the place where a species lives within

an ecosystem

4. niche a niche is the role of an organism in an ecosystem

5. biodiversity the degree of variation of life forms in an ecosystem

6. the three dif- 1) variation in ecosystems or habitats

ferent levels at 2) the number of species and their relative abundance
which biodiversi- 3) genetic variation within each species
ty is considered

7. species richness the number of species in a community

8. the number of species richness and a measure of the evenness of abun-

species and their dance of different species
relative abun- - the more species there are and the more evenly the
dance (species number of organisms are distributed among the different
diversity) species, the greater the species diversity
- ecosystems with high species diversity are more stable
and able to resist changes
- some ecosystems are dominated by a few types of
species
- the tropics are important centres for diversity (living con-
ditions not extreme, high light intensity all year, animals
don't have to expend energy keeping warm)

9. genetic diversity the diversity of alleles within the genes in the genome of
a single species

10.
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how can genet- by finding out
ic diversity within 1) what proportion of genes have different alleles
a species be as- 2) how many alleles there are per gene
sessed?

11. collecting organ- 1) dichotomous key

isms and making 2) drawings or photographs with identification
species lists 3) timed research throughout the area being studied
4) photograph and label species that are unidentified
'species A', 'species B', etc.

12. pooter apparatus that is used to collect small animals such as

beetles

13. the two types of random sampling and systematic sampling

sampling

14. when should ran- 1) when an area looks reasonably uniform

dom sampling be 2) no clear pattern to the way the species are distributed
used? *samples must be taken randomly to avoid bias

15. quadrat square frame that marks off an area of ground, or water,
where you can identify the different species present and/or
take a measurement of their abundance

16. random sam- a sample that fairly represents a population because each
pling member has an equal chance of inclusion

17. random sam- species frequency and density

pling results can
be used to calcu-
late

18.
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species frequen- measure of chance of a particular species being found
cy within any one quadrat

19. species density measure of how many individuals there are per unit area
e.g. per square metre

20. percentage cover the percentage of area inside the quadrat that is occupied
by each species
- if you have 100 little squares in 1 quadrat, then you count
the squares in which the plant species is present - you
count a square only when it is half or more covered by the
plant
- so if the plant is in about 25 squares within the quadrat
you can say the plant covers 25% of the area
- not always equal to 100%; can be less or more

21. Braun-Blanquet .
scale

22. methods to as- 1) frame quadrats

sess the distrib- 2) line transects
ution and abun- 3) belt transects
dance of organ- 4) mark-release-recapture
isms in a local
area

23. systematic sam- systematic sampling is used investigate species distribu-

pling tion where physical conditions change e.g., altitude, soil
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moisture content, soil pH, exposure/ light intensity
*investigated using line and belt transects

24. mark-release-re- method of estimating the population size of mobile organ-

capture isms
1) as many individuals as possible are caught
2) each individual is marked, in a way that will not affect
its future chance of survival
3) marked individuals are counted
4) marked individuals are returned to their habitats to mix
randomly with their population
5) after enough time has elapsed, a large sample is recap-
tured
6) number of marked and unmarked individuals are count-
ed

25. line transect a line is marked along the ground and the identity of the
organisms that touch the line at set distances (e.g., every
x metre) is recorded
- gives qualitative data that is represented as a drawing

26. belt transect place a quadrat at regular intervals along the line and
record the abundance of each species within the quadrat
- data plotted as bar chart or kite diagram

27. kite diagram a kite diagram can be used to show density and distribu-
tion of species along a transect line or other environmental
gradient

28. correlation a measure of the extent to which two factors vary together,
and thus of how well either factor predicts the other
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- plot a scatter graph or calculate correlation coefficient (r)
- strength of correlation = how close the points are to the
straight line

29. Spearman's rank - Spearman's rank correlation determines whether there

correlation is correlation between variables that don't show a normal
distribution

use when data:

1) data points are independent of each other
2) data is correlated, but not linear (draw scatter diagram
first)

1) make a null hypothesis that there is no correlation

between the percentage cover of the two species
2) draw a scatter graph to see if it looks as if there is a
correlation between the abundance of the two species
3)

if the value calculated for Spearman's rank is greater than

the critical value at p=0.05, then the null hypothesis can
be rejected, meaning there is a correlation between two
variables

30. Pearson's linear - Pearson's linear correlation is a statistical test that de-
correlation termines whether there is linear correlation between two
variables
- data must be quantitative and show normal distribution

1) create a scatter graph of data gathered and identify if a

linear correlation exists
2) state a null hypothesis
3) if the correlation coefficient r is close to 1 or -1 then it can
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be stated that there is a strong linear correlation between
the two variables and the null hypothesis can be rejected

31. Simpson's Index a measure of biodiversity between 0 and 1 that takes into
of Diversity account both species richness and species evenness
- values near 1 indicate high levels of biodiversity
- values near 0 indicate low levels of biodiversity
- used to quantify the biodiversity of an area

*n: total number of organisms in one species

*N: total number of organisms of all species

32. taxonomic hier- domain ’ kingdom ’ phylum ’ class ’ order ’ family ’ genus ’
archy species

Kings Play Chess On Fancy Gold Squares

33. the three do- bacteria, archaea, eukarya (protists, fungi, plants, ani-
mains mals)

BAE

34. characteristic 1) unicellular prokaryotes

features of 2) DNA exists as a circular 'chromosome' and does not
bacteria have histone proteins associated with it
3) smaller circular molecules of DNA called plasmids are
often present
4) no membrane-bound organelles are present
5) ribosomes (70 S) are smaller than in eukaryotic cells
6) cell wall is always present and contains peptidoglycans
(not cellulose)

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7) cells divide by binary fission, not by mitosis
8) usually exist as single cells or small groups of cells.

35. characteristic 1) unicellular prokaryotes

features of 2) similar size range as bacteria
archaea 3) no membrane-bound organelles
4) DNA exists as a circular 'chromosome' and does have
histone proteins associated with it
5) ribosomes (70S) are smaller than in eukaryotic cells,
but they have features that are similar to those in
eukaryotic ribosomes, not to bacterial ribosomes
6) smaller circular molecules of DNA called plasmids are
often present
7) cell wall always present, but does not contain
peptidoglycans
8) cells divide by binary fission, not by mitosis
9) usually exist as single cells or small groups of cells

36. characteristic 1) all organisms classified have cells with nuclei and mem-
features of brane-bound organelles
eukarya 2) DNA in the nucleus arranged as linear chromosomes
with histone proteins
3) ribosomes (80S) in the cytosol are larger than in
prokaryotes; chloroplasts and mitochondria have 70S
ribosomes, like those in prokaryotes
4) chloroplast and mitochondrial DNA is circular as
in prokaryotes
5) a great diversity of forms: there are unicellular, colonial
and multicellular organisms
6) cell division is by mitosis
7) many different ways of reproducing - asexually and
sexually.

37. characteristic 1) encompasses all eukaryotic cells that do not belong to

features of the the other three eukaryotic kingdoms
kingdom 2) some are protozoa: have animal-like cells (no cell walls)
Protoctista 3) some are algae: have plant-like cells (cellulose cell wall
and chloroplasts)

38.
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characteristic 1) heterotrophic (obtain energy and carbon from dead
features of the and decaying matter or by feed as parasites on living
kingdom Fungi organisms)
2) none contain chlorophyll so does not photosynthesise
3) reproduce by means of spores
4) cells have cell walls made of chitin or other substances,
not cellulose
5) never have cilia or flagella
6) simple body form, which may be unicellular or made up
of long threads called hyphae (mycelium) and large fungi
such as mushrooms produce large compacted masses of
hyphae known as 'fruiting bodies' to release spores

39. characteristic 1) multicellular eukaryotes with cells that are differentiated

features of the to form tissues and organs
kingdom Plantae 2) few types of specialised cells
3) some cells have chloroplasts and photosynthesise
4) cells have large, often permanent vacuoles for support
5) autotrophic nutrition
6) cell walls are always present and are made of cellulose
7) cells may occasionally have flagella - e.g. male gametes
in ferns
8) complex body forms with branching systems above and
below the ground

40. characteristic 1) multicellular eukaryotes with many different types of

features of the specialised cells
kingdom 2) cells that are differentiated to form tissues and organs
Animalia 3) cells do not have chloroplasts and cannot photosynthe-
sise (although some, such as coral polyps have photosyn-
thetic protoctists living within their tissues)
4) cell vacuoles are small and temporary (for example,
lysosomes and food vacuoles)
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5) heterotrophic nutrition
6) cells do not have cell walls
7) communication is by the nervous system
8) cells sometimes have cilia or flagella

41. explain why viruses have none of the features that are traditionally
viruses are not used for classification
included in the
three domain
classification

42. characteristics of 1) acellular (no cellular structure or metabolism)

viruses 2) can only be seen using an electron microscope
3) hijack the DNA replication machinery in host cells to
make proteins and replicate
4) energy need for such processes is provided by respira-
tion in the host cell

43. taxonomic sys- is based on:

tem for classify- 1) the diseases which they cause
ing viruses 2) the type of nucleic acid they contain (DNA or RNA)
3) whether the nucleic acid is single-stranded or dou-
ble-stranded (in humans DNA is always double-stranded
and RNA is usually always single-stranded however in
viruses DNA and RNA can be either single-stranded or
double-stranded)

44. four groups of 1) DNA single-stranded viruses

viruses 2) DNA double-stranded viruses
3) RNA single-stranded viruses
4) RNA double-stranded viruses

45. five major threats 1) habitat loss and the degradation of the environment
to biodiversity 2) climate change
3) excessive use of fertilisers and industrial and domestic
forms of pollution
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4) the overexploitation and unsustainable use of resources
5) the effects of invasive alien species on native species,
especially endemics

46. habitat fragmen- many species of plant and animal either lose their habitats
tation completely or their habitats become divided into small
areas

47. species at most endemic species on small islands

risk of extinction

48. threats to the 1) overfishing (very difficult to know whether fish stocks
biodiversity of are sustainable), example of overexploitation of resources
aquatic ecosys- 2) fishing further down the food chain taking smaller fish
tems that other animals depend on influences their populations
too
3) non-biodegradable plastic is a major marine pollutant
4) fertilisers that have not been absorbed by crop plants
drain into aquatic ecosystems causing the overgrowth of
producers such as algae faster than herbivores can feed
on them
5) algae producing toxic substances and affecting coral
reefs
6) acidification of marine ecosystems due to acid rain
reducing the biodiversity as few animals are able to sur-
vive/breed in waters of low pH
7) coral bleaching due to increase in water temperature
due to increase in greenhouse gases

49. keystone species a species that influences the survival of many other
species in an ecosystem

50. threats to the bio- 1) global warming (cattle and rice farming, breakdown of
diversity of ter- organic waste in landfills under anaerobic conditions in-
restrial ecosys- creasing methane emissions) is likely to produce changes
tems in the distribution of terrestrial ecosystems
2) when organisms migrate to cooler areas, competition
would occur between migrating organisms and species in
existing communities
3) some ecosystems will become even more restricted in
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their range due to global warming causing problems for
coastal ecosystems

51. discuss the rea- 1) moral and ethical

sons for the need 2) aesthetic
to maintain biodi- 3) ecological
versity 4) social and commercial

52. moral and ethical humans share the planet with millions of others species
reasons to main- and they have no right to cause the extinction of other
tain biodiversity species

53. ecological rea- 1) the higher the diversity of an ecosystem, the less likely
sons reasons to it is to be unbalanced by changes in conditions or threats
maintain biodi- such as pollution
versity 2) ecosystems are of direct value to humans; many of the
drugs that we use originate from living organisms

54. aesthetic rea- 1) people gain pleasure from studying or just appreciating
sons reasons to the natural world
maintain biodi- 2) wildlife is a source of income for many countries as eco-
versity tourism has increased in popularity; this form of tourism
provides employment and contributes to the economies of
these nations

55. social and com- 1) wild varieties of cultivated crops can provide the genetic
mercial reasons resources we might need to widen the genetic diversity
reasons to main- of cultivated maize if it is affected by disease or other
tain biodiversity catastrophes
2) microorganisms are a source of useful products e.g.,
Taq polymerase used for PCR in forensic and DNA analy-
sis

56.
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endangered an endangered species is one that is threatened with
species extinction

57. protecting 1) zoos

endangered 2) botanic gardens
species 3) conserved areas (national parks and marine parks)
4) 'frozen zoos'
5) seed banks

58. zoos 1) provide enjoyment and interest for visitors

2) provide protection for endangered and vulnerable
species
3) have had success with captive breeding programmes,
often with the long-term aim of reintroducing the animals
to their natural habitat
4) contribute to research (trying to gain a better under-
standing of breeding habits, habitat requirements and
ways to increase genetic diversity)

59. problems associ- the major goal of captive breeding is to reintroduce ani-
ated with captive mals to their natural habitat
breeding pro- 1) inbreeding due to small population size
grammes 2) some animals simply refuse to breed in captivity
3) often it is not possible to create suitable habitats for
animals so they cannot be returned to the wild
4) some captive-bred animals do not know how to avoid
predators, find food or rear their own young

60. national parks conservation areas with strict limits on human activity to
protect wildlife and the environment
1) tourism brings in money to pay for maintenance of such
parks
2) raises awareness if people are involved in conservation
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efforts
3) alien animal species are removed; invasive plants are
dug up and destroyed
4) marine parks: conserve fragile ecosystems and areas
at risk of overfishing, dredging, pollution

61. botanic gardens seeds or cuttings are collected from species in the wild and
then used to build up a population of plants from which,
one day, some plants may be reintroduced to their natural
habitats
1) protect endangered plant species
2) research methods of reproduction and growth
3) research conservation methods
4) reintroduce species to habitats
5) educate the public (roles of plants in the cosystem;
economic value)

62. how a sample of carried out in sterile conditions

cells could be 1) cells divide by mitosis to give a mass of cells that can
grown on agar be cloned by subdividing them
2) 2hen the cells are transferred to a medium contain-
ing an appropriate mixture of plant hormones, they grow
stems and roots and can then be transferred to grow in
soil
3) these techniques of tissue culture and cloning are used
to produce large numbers of plants from a few original
specimens

63. frozen zoos holds genetic resources for endangered species in the
form of eggs, sperms and embryos until they're needed
- holds more genetic diversity than a normal zoo
- genetic material is kept for longer periods of time
*eggs are more difficult to freeze as they are more likely
damaged by freezing and thawing (ice crystals may form
which damage internal membranes)

64. seed banks seeds of the same species are collected from different
sites, so that the stored samples contain a good proportion
of the total gene pool of that species so genetic diversity
is not lost
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- seeds can be stored for a long time with little mainte-
nance, anywhere in the world
- seeds are germinated every few years to:
1) check if seeds are still viable produce new plants to
collect new seeds
2) find conditions for breaking seed dormancy

65. ways to keep these are seeds cannot be dried and frozen, such as
the genetic diver- seeds of economically important tropical species e.g.,
sity of species rubber, coffee, cocoa
with recalcitrant 1) collect seeds and grow successive generations of
seeds plants
2) keep as tissue culture

66. methods of as- 1) in vitro fertilisation (IVF)

sisted reproduc- 2) artificial insemination (AI)
tion 2) embryo transfer
3) surrogacy

67. why assisted re- 1) it's a solution to the problem of inbreeding

production is 2) solve the problem of males and females who do not
useful show any courtship behaviour and will not mate
3) movement of large mammals is difficult, expensive and
breeding does not always happen so sperm is collected
which can then be used in assisted reproduction

68. sperm bank a storage facility that holds supplies of semen that's frozen
for future use
*samples are collected from males, checked for sperm
activity and then diluted with a medium containing a buffer
solution and albumen
*small volumes of semen are put into straws (thin tubes)
and are stored in liquid nitrogen at -196°C

69. artificial insemi- a straw is placed into warm water so that sperm become
nation (AI) active and then put into a catheter, which is inserted into
the vagina, through the cervix and into the uterus
*may happen when the female is naturally ovulating or
may follow hormone treatment so she superovulates to
produce a large number of follicles at the time of AI
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*following AI, the resulting embryos may be 'flushed out'
of the uterus and transferred to other females (surrogate
mothers) that have had hormonal treatment to prepare
them for pregnancy
*protects endangered animals from pregnancy
*the endangered female becomes the source of many
offspring

70. in vitro fertilisa- 1) oocytes are collected by inserting a needle into the
tion (IVF) ovaries and withdrawing some mature follicles
2) he oocytes are kept in a culture medium for a short time
and then mixed with semen
3) the resulting zygotes divide to form embryos, which are
cultured for several days and then placed into the mother
or into several females of the same or different species
4) these embryos can also be stored in 'frozen zoos'

71. zona pellucida the region surrounding the layer of glycoproteins around
an egg cell

72. problems of suc- - organisms that have been saved from extinction has in-
cessful conser- creased in numbers beyond the capacity of the ecosystem
vation to sustain such numbers
- therefore culling is used to reduce numbers

73. culling reduction of an animal population by selective slaughter

1) transferring animals to places where there are small

populations (expensive and not easy over large distances)

2) birth control
- sedating male wild mammals and cutting their sperm
ducts (vasectomy)
- chemical contraceptives: vaccine is used which targets
the zona pellucida which stimulates an immune response
that produces antibodies against these glycoproteins and
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attaches to the glycoproteins around the female¼s own
eggs, so blocking sperm from fertilising the egg (90%
success rate)

74. alien species alien or invasive species are those that have moved from
one ecosystem to another where they were previously
unknown

75. causes of alien 1) humans trading animals and plants or unwittingly car-
species rying them on ships
2) introduced as biological control agents to control pests
3) escapees
4) animals introduced for sport

76. effects of alien 1) successful predators with few controls (no natural
species predators of it in new environments)
2) may compete effectively with native organisms that
occupy the same niche, pushing them to extinction
3) may also introduce diseases that spread to similar
organisms that have never been exposed to the pathogens
4) outcompete native species simply by reducing the
space where they can grow

77. red lionfish - native to the seas of South-East Asia

(Pterois volitans) - invading the waters of the Caribbean (likely to have
escaped from aquaria in the US)
- eating its way through many local species on coral reefs
- no natural predator in its new environment

78. water hyacinth - a floating aquatic plant that spreads rapidly when intro-
(Eichhornia cras- duced to new habitats
sipes) - blocks sunlight from reaching native aquatic plants and
reduces the oxygen concentration of the water, so killing
fish
- provides a habitat for mosquito larvae
- its control is important for the sake of human health

79. non-governmen- 1) the World Wide Fund for Nature (WWF)

tal organisations 2) the Convention on International Trade in Endangered
involved in local Species of Wild Fauna and Flora (CITES)
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and global
conservation

80. CITES (Conven- a signed agreement to control trade of endangered

tion on In- species and their products e.g.: fur, skin, ivory
ternational Trade 1) considers evidence presented to it about endangered
in Endangered species and assigns to 1 of 3 appendices with given
Species) criteria and trading regulations
2) sometimes CITES listings don't benefit the species:
species trade becomes illegal, the price for products in-
creases causing more trade occurs

81. WWF (World largest and most well-known NGO for conservation
Wildlife Fund for 1) funds conservation projects
Nature) 2) publicises environmental issues
3) campaigns to save ecosystems from degradation and
species from extinction

82. outline how de- 1) small scale - farmer plants trees on land that is no longer
graded habitats needed for food production
may be restored 2) e.g., mangrove forest is being replanted in many parts
of the world to provide protection against storm damage,
flooding and rising sea levels; mangrove forests are also
important nursery grounds for young fish

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