paper 1 Flashcards
(173 cards)
1
Q
what are monomers and what polmers do they make
A
amino acids ~> protein
monosaccharide ~> polysaccharide
nucleotides ~> nucleic acids
triglycerides
(3 fatty acids / glycerol) phospholipids
(glycerol / phosphate / 2 fatty acids )
are not polymers
2
Q
what do am acid consist of
A
carboxyl group
nh2
c in middle with 1 h and 1 r
3
Q
name react that form or break poly
A
condensation make water
hydrolysis break use water
4
Q
types of bonds in polymers
A
polysaccharide = glycosidic
ammino acid = peptide
nucleic acid =phosphodiester
triglyceride/ = ester
phosphodiester
4
Q
disacc and their mono
A
lactose = glucose+galactose
maltose =
glucose+glucose
sucrose =
glucose+fructose
4
Q
polymerisation of alpha glucose in plants
A
- chains will coin into alpha helix and form starch
- they are insoluble so wont affect osmosis
- many branches so lots of area for amylase enzyme to break them down quickly for use in respiration
4
Q
2 diff type of glucoise
A
alpha glucose = oh on left and right both on bottom
beta glucose = oh on top on the right and on the left its on bottom
5
Q
test for starch
A
add drops of iodine and if present blue black solution if not then brown orange solution
5
Q
polymerisation of alpha glucose in animal
A
- polymers of glucose form short highly branched chains
- easily broken down by amylose so result in high amount of energy released easily
- insoluble so no affect on osmosis
5
Q
what does
-saturated
-unsaturated
- polyunsaturated
A
-saturated only c-c bonds
-unsaturated some c-c and some c=c
- polyunsaturated many c=c and some c-c
5
Q
test for red sugar
A
- grind sample in pestle and mortar
- put sample in water forming a solution
- 2 cm3 of sugar solution and benedicts
- leave in heated bath for 5 mins
- +ve result is brick red ppt form and -ve result is remain blue sol
5
Q
polymerisation of beta glucose
A
- form cellulose
- long straight unbranched chains that are parallel to each other these are cross linked to eachother
- makes the molecule strong and is used in the cell walls
5
Q
test for non red sugar
A
-grind sample in pestle and mortar and dissolve sample in distilled water filter out debris
- put sample in water forming a solution
- 2 cm3 of sugar solution and benedicts
- leave in heated bath for 5 mins
- -ve result is remain blue sol
- 2cm3 of sugar solution and hydrochloric acid heat for 5 mins
- 2cm3 of sodium hydrognecarbonate
- now add benedicts should be a +ve result is brick red ppt form and -ve result is remain blue sol
5
Q
test for prot
A
- grind and dissolve sample in distilled water filter out debris
- 2cm3 of sample solution and add 2cm3 of biuret reagent
- if +ve then solution turn purple and -ve remain blue
5
Q
test for lipids
A
- dissolve sample in ethanol
-add distilled water and shake more - if present then white emulsion
6
Q
which part of triglyceride and phospholipid is hydrophobic and which is hydrophillic
A
triglyceride - whole thing is hydrophobic
phospholipid - head is hydrophillic and tails are hydrophobic
6
Q
strengths of bonds in protein and factors that affect the strength of these
A
hydrogen - weak
disulfide - strong
ionic - strongest
pH change can weaken these strengths
6
Q
struct of atp
A
adenine base ribose sugar and 3 phosphate groups
6
Q
key struct and funct of nucleus
A
nuclear pores , nuclear envelope , chromasomes
nucleolus (site of rna production)
site of dna replication and transcription
stores genetic info
6
Q
usingf chromatog to sep aa
A
- chromatography used to separate a mixture of amino acids
- A spot of the unknown mixture is placed on a line at the bottom of the chromatography paper
- Spots of known standard solutions of different amino acids are then placed on the line beside the unknown sample spot
- paper is then suspended in a solvent
- Each amino acid will be more or less soluble in the mobile phase
The unknown amino acid can then be identified by comparing and matching them with the chromatograms of the known standard solutions of different amino acids
6
Q
desc mech for enzyme
A
induced fit model
shape of active site changes its tertiary structure slightly to better accomodate the substrate
this then catalyses the reaction and the products are released
6
Q
fact affect rate of enzyme cont reaction
A
enzyme concentration
substrate concentration
concentration of competitive and of non-competitive inhibitors
pH - changes bonds in tertiary structure affects the overall shape denaturing the molecule decrease rate
temperature - changes bonds in tertiary structure affects the overall shape denaturing the molecule decrease rate
6
Q
define what enzyme is
A
an enzyme is a biological catalyst that lowers activation energy for specific reactions
and only create enzyme substrate complexes for specific substrates complementary to the tertiary structure
6
Q
prot hierarchy
A
1° = simple amino acid sequence / peptide chain
2° = h bond form between the backbone of the amino acid chain result in alpha helix / beta pleated
3° = hydrogen, disulfide, ionic bonds form between R groups of the amino acids and result in a
specific structure
4° = many other proteins come and bind to this one and form a large structure
6
type of nucleo and their bases
dna - adenine guanine cytocine thymine
rna - uracil adenine cytocine guanine
6
state both inhib and how they affect rate
competitive inhibitor - similar shape to substrate occupying the active site stopping formation of enzyme substrate complexes may drop off to allow substrate to bind
noncompetitive inhinitors - bind to allosteric site this isnt the active site bot will change the shape of the active site preventing formation of enzyme substrate complex
6
limitations of optical microscopes
- Light has a longer wavelength
- lower resolution
- Lower magnification
6
pro of dna rep
semiconservative replication
1) dna helicase unwinds hydrogen bonds between complementary bases pairs creating two single strands of dna
2) free nucleotides will bind to the open bases on the nucleotide template strands
3) dna polymeraise will form phosphodiester bonds forming the sugar phosphate back bone
4) leads to two identical dna strands being formed
6
key struct and funct of rer
folded membranes called cristae
protein synthesis
6
what enzyme catalyses the hydrolysis of atp and what is formed
atp hydrolase
ATP ~> ADP + Pi
breaking of the unstable bond between phosphate 2-3 releases energy
6
messelson and stahl
1) got sample of ecoli bacteria and grew in both heavy and light nitrogen
2) took sample from heavy generation and mixed with a sample of the light generation
3) got the mixture and spun in centrifuge where samples were separated according to density heavy sank / light at top
4) sample of both mixed together was found to be an intermediate inbetween the two other chains
5) proves that it is semicoservative
6
where is atp used in organism
- active transport
- movement/ muscle contraction
- metabolism
6
key struct and funct of golgi app / ves
folded membranes called cristernae and vesicles surrounding
add carbohydrates to proteins to form glycoproteins
transport / modify lipids
6
how is atp formed
ATP is resynthesised by the condensation of ADP + Pi .
This reaction is catalysed by ATP synthase during photosynthesis, or during respiration.
6
properties of water
- metabolite
used in many metabolic reactions, including condensation and hydrolysis reactions
- solvent
in which metabolic reactions occur
- relatively high heat capacity,
buffering changes in temperature
- relatively large latent heat of vaporisation, providing a cooling effect with little loss of water through evaporation
- strong cohesion between water molecules
this supports columns of water in the tube-like transport cells of plants and produces surface tension where water meets air.
6
viral replication
1. Attachment proteins attach to receptors;
2. Viral RNA (nucleic acid) enters cell;
3. Reverse transcriptase makes DNA from RNA;
4. The DNA is translated (produces) into viral proteins, capsid & enzymes
5. Virus assembled and released from cell
6
key struct and funct of ser
folded membranes called cristae
synthesise lipids and carbohydrates
6
key struct and funct of rer
folded membranes called cristae
protein synthesis
6
key struct and funct of lysosomes
contain enzymes
exocytosis
phagocytosis
6
diff bet prokatyotes and eukaryotes
- prokaryotic are much smaller
- prokaryotic have no membrane bound organelles
- prokaryotic have no nucleus
- prokaryotic smaller ribosome
6
key struct and funct of chloroplast
double membrane
contain thylakoid and many of these make granum thes econtain chlorophyll
fluid surrounding these is called stroma
site of photosynthesis
6
key struct and funct of mitocon
folded membrane called cristae and inner fluid called matrix
site of aerobic respiration
6
define mag
how many times larger the image is in comparison to the origional object
6
struct of virus and why they described as acellular
-capsid
- attachment protein
- viral genetic code
- reverse transcriptase
acellular = no surface membrane
6
define res
minimum distance between two object where they can still be seen as two seperate objects
6
key struct and funct of ribosome
site of protein synthesis
6
limitations of transmission electron microscopes
- samples are in a vacuum
so cant examine living cells
- More complex & time consuming specimen preparation procedure.
may damage the specimen producing artefacts
- Black & white image
6
key struct and funct of vacuole
filled with fluid surrounded by tonioplast membrane
make cell turigid provide support
temporary store of starch and amino acids
6
key struct and funct of cell wall
plants - cellulose
fungi - chitin
prokaryotic - meurin
provide structure and strength
6
limitations of scanning electron microscopes
- samples are in a vacuum
so cant examine living cells
- More complex & time consuming specimen preparation procedure.
may damage the specimen producing artefacts
- Black & white image
7
advantages of using scanning electron microscope
- Electron wavelength is shorter so higher resolution than optical
- can study more detail than optical
- Study 3D structures.
- Higher magnification than optical
7
advantages of using optical microscopes
- view live specimens
- Coloured images
- Preparation rarely damage the specimens
8
advantages of using transmission electron microscope
- Electron wavelength is shorter
- highest resolution
- Study detailed organelles
- Highest magnification
9
conversion from micrometer ( µm ) to milimeter (mm)
µm / 1000 = mm
mm * 1000 = µm
10
why is sample placed into special solution for cell fractionation state the conditions and reasoning
isotonic - prevent movement of water into cells causing lysis
ice cold - prevent destructive enzyme activity
buffer solution - prevent proteins denaturing
10
describe process of cell fractionation
1) cells need to be put into an ice cold isotonic buffer solution
2) solution put in blender to break open cells
3) filter to remove large debris
11
mag eq
i = a * m
11
explain pro of mitosis
1) inter phase
organelles double and dna replicates
2) prophase
chromasomes condense and become visable nucleolus disolve
3) metaphase
chromasomes align in middle of the cell and spindle fibres attach to centromeres on the chromatids
4) anaphase
spindle fibers retract and pull on centromere causing it to split in half
5) telophase
chromasomes uncondense spindle fibres dissapear nucleus reform cytoplasm split via cytokeneisis
12
explain pro of ultra centrifugation
1) after cell fractionation supernatant put in counter balalnced centrifuge and spun at slow speed for short period of time
2) the most dense organles will settle at the bottom and form a pellet filter this out and respin the supernatant at higher speed for longer duration
3) repeat until you have desired thing
13
eq for mitotic index
num cells under go mitosis
------------------------------------
tot num of cells
ans * 100
13
process of binary fission
1) replication of the circular DNA and of plasmids
2) division of the cytoplasm to produce two daughter cells
3) each with a single copy of the circular DNA and a variable number of copies of plasmids.
14
why dont viruses undergo replication
as they are non livivng cells
15
whats the structure of the cell membrane
the phospholipid bilayer consists of hydrophillic phosphate groups and hydrophobic fatty acid tails
15
whats cholesterol and how does it affect movement into cells
Cholesterol may also be present in cell membranes where it restricts the movement of other molecules making up the membrane
16
what are channel pro
they are the tunnels that allow larger molecules through the membrane
16
what are carrier pro
the are proteins that once binded to they take the molecule to the other side
16
whats simple diff
- Diffuse down a diffusion concentration gradient
- high to low concentration
through phospholipid bilayer
- Passive
17
whats act trans
- Ion binds to a specific carrier protein with a complementary tertiary shape
- Ion moves against the concentration gradient
low to high concentration
- Using ATP from respiration
- ATP used to change the protein shape, releasing the ion on the other side
17
whats fac diff
- Substances diffuse through channel proteins, down a diffusion gradient
- high to low concentration
- Passive
- Specific shape channel/carrier protein determines which substances can diffuse through
17
whats osmosis
- diffusion of water
from a higher to a lower water potential (Ψ) (down a water potential (Ψ) gradient
- across a partially permeable membrane
- passive
18
how are cells adapted for rapid trans of substances
- increased surface area
- increased num of channel/ carrier proteins
19
whats co trans
- Energy from ATP actively transports sodium ions out of the cell into the blood
- creating a sodium ion diffusion gradient from the lumen, into the cell
- A glucose molecule is co-transported with sodium ions, using the same carrier protein into the cell
- Glucose diffuses out of the cell into the blood by facilitated diffusion
19
how do lymphocytes distinguish between slef/ non-self cells
each cell has specific molecules on its surface w specific shapes these can be used to identify it
19
how are antigens used in immune response
they are located on surface of pathogen and trigger response from lymphocyte
20
describe process of antigenic variability
mutation occur in specific gene responsible for the antigen
any previous immunity to pathogen will be lost
21
describe the barriers blocking pathogens entering the body
skin is a physical barrier that blocks pathogens
stomach acid is a chemical barrier blocking pathogens
white blood cells are the next defence
21
state non specific immune response
non-specific = phagocytosis
- agglutination of atigens as sntibodues stick them togeather in clumps
- The phagocyte is attracted to the pathogen by non-self ANTIGEN.
- The pathogen is ENGULFED and enclosed in a PHAGOSOME (vesicle).
- LYSOSOMES (made by Golgi) (contain
lysozyme enzymes) fuse with the phagosome.
- Lysozymes enzymes hydrolyse molecules and break down the pathogen
(then exocytosis of products)
21
state the specific immune response
specific = t lymphocyte
the t cells originate i the thymus thats where the t comes from
1) Pathogen enters the body.
2. Phagocyte cells engulf and destroy pathogen and present pathogen’s antigen on their surface.
3. Antigens have a specific tertiary structure. T-cells with a complementary receptor bind. Cytotoxic T cells, kill infected body cells.
4. Helper T-cells stimulate B-cells.
5. B-cells undergo mitosis to clone & make plasma cells.
6. Plasma B cells produce (monoclonal) antibodies.
7. B cells divide (by mitosis) to form Memory B-cells & T-cells divide to form Memory T-cells.
8. More antibodies are produced faster in the secondary immune response. also known as ACTIVE immunity
22
desc struct of ant bod
- Y-shaped
- 2 long polypeptide chains - 2 short polypeptide chains
- constant region
- variable region / antigen-binding site at ends
22
whats passive immunity
antibodies put into organism
no long term immunity
breast milk
22
whats act immunity
antibodies created in response to non self antigens
23
define vaccine
a dead or inactive form of the pathogen that gets injected into the body
23
what happens after vaccine injection
- exposure to antigen activate b cell to differentiate
- b cell undergo mitosis and make large numbers of cells these then differentiate into plasma cells or memory cells
- plasma cells make antibodies
- memory b cells divide rapidly into plasma cells when reinfected by same pathogen these make lots of antibodies rapidly
24
how does hiv result in symptoms of aids
virus replicate in the helper t cell this interferes w normal function of immune system
24
struct of hiv molecule
attachment proteins = on the outside of the molecule
lipid envelope = hold all the stuff
capsid = hold the rna and the reverse transcriptase
24
process of viral replication
1. Attachment proteins attach to receptors;
2. Viral RNA enters cell;
3. Reverse transcriptase makes DNA from RNA;
4. The DNA is translated (produces) into viral proteins, capsid & enzymes
5. Virus assembled and released from cell
25
uses of ant bod for med diag
monoclonala ntibodies could be used to diagnose pregnancy, cancer, covid
25
describe how we can target medication to specific cells by the use of antibody.
- monoclonal antibody created that has binding site complementary to that of an antigen on the outside of the cancer cell these are also attcahed to drugs
- cancer drugs are delivered straight to the cell and are killed this is good as it means that there are lesss negative implications when compared to treatments such as chemotherapy and radiotherapy
25
2 uses of monoclonal antibodies
- targeting medication to specific cell types by attaching a therapeutic drug to an antibody
- medical diagnosis.
25
desc process eliza test
1) add antigens to a well and wash multiple times remove any unstuck antigens
2) add complementary antibody forming antigen-antibody complexes wash removing any unbinded antibody molecules
3) Add a second antibody, with an enzyme attached.
and wash
5) Add a colourless substrate which is complementary to & binds to the enzyme’s active site if present. and produce coloured product
26
describe how we can prevent uncontrolled cell growth of pathogen by the use of antibody.
- monoclonal antibodies binding site complementary to that of an antigen on the outside of the cancer cell
- these attach to cancer cell and prevent chemicals binding that enable the uncontrolled cell division
- these dont damage any other healthy cells only the
27
how is the sa : v advantageous for exchange in organisms
the larger the sa : v is the more efficient the transport
27
adaptations for inc sa : v in humans
villi and micro villi- maximise absorbtion of food
alevoli and bronchi - maximise gas exchange
27
calc sa:v
sa/v
28
adaptations for inc sa : v in insect
spiracles and tracheoles -
maximise gas exchange
29
adaptations for inc sa : v in fish
gill fillaments and lamellae- maximise gas exchange in fish
30
adaptations for inc sa : v in plants
thin wide leaves -maximise gas exchange in plants
31
define breathing
movement of air in and out the lungs
32
define respiration
the chemical reaction happening in the mitocondria releasing energy in the form of atp
33
human gas exchange system breathing in
1) diaphram contract and flatten
2) external intercostal muscles contract and ribs move up and out down pressure gradient
3) volume of thoraxic cavity increases pressure decreases
4) air flows in via trachea down to bronchi then bronchioles and finally to the alveoli where it diffuses into cappillary
34
human gas exchange system breathing out
1) diaphram relax and enlarges
2) internal intercostal muscles contract and ribs move down and in
3) volume of thoraxic cavity decreases pressure increases air goes down pressure gradient
4) air flows out via alveoli then bronchioles and then bronchi and finally trachea where its breathed out
34
how humans have developed to maintain diffusion gradient to aid exchange of substance
the alveoli are wrapped in capillaries and these are constantly taking away the oxygenated blood and bringing deoxygenated blood
35
define pulmonary ventialtion and how is it calculated
total volume of air moving into the lungs in one minute
pul vent = tidal vol * vent rate
36
how humans have developed short diffusion pathway to aid exchange of substance
avleolar epithelium is one cell thick and
36
how have insects evolved to prevent water loss
water proof exoskeleton
37
gas exchange in insects
air flows in through the spiracles to the trachea these branch off to tracheoles these go deeper into the the tissues in the insect and provide oxygen to all of the respiring cells
37
how insects have developed short diffusion pathway to aid exchange of substance
walls of tracheoles are thin
38
method of gas exchange in insects
1) gasses may diffuse in and out
2) muscles in abdomen contract move gasses in and out
3) when in flight muscle cells respire anaerobically this produces lactate lowering water potential of the muscle cells pulls water into the cells form tracheoles via osmosis decrease volume in tracheole resulting in more air being drawn in
38
how insects have developed to maintain diffusion gradient to aid exchange of substance
use of oxygen and production of co2 result in steep diff grad
39
structure of **dicotyledonus** plants
plaisade mesophyll - site of photosynthesis
mesophyll - air spaces
stomata - where gas is taken up
39
how fish have developed to maintain diffusion gradient to aid exchange of substance
counter current flow water flows in opposite direction to blood flow this maximises amount of oxygen intake
40
how plants have adapted to reduce water loss
stomata close at night to reduce water loss by evaporation
40
adaptation of xeraphyte to reduce water loss
curled leaves -
sunken stomata -
small hairs sticking out of plant
thick waxy cuticle
deep / wide spread root system
40
define digestion
large biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membrane
40
deigestion of protein
1) endopeptideases - hydrolyse peptide bond in middle of ammino acid chain
2) exopeptidase - hydrolyse peptide bond at end of ammiino acid chain
3)membrane bound dipeptideases - hydrolyse peptide bonds between dipeptides
40
digestion of carboh
amylase from pancreas and salivary gland hydrolyse polysaccharide into many disaccharides breaking glycosidic bond
sucrase / lactase are membrane bound enzymes that hydrolyse lactase and sucrase into monosaccharides
41
digestion of triglycerides
1) bile salts emulsify lipids into smaller droplets
2) lipase breaks ester bonds in triglyceride and form fatty acids + glycerol
3) micelles formed consist of fatty acids and glycerol and these are taken to the lining of the illeum
42
explain how oxygen is loaded onto haemaglobin
oxygen is loaded in high partial pressure of oxygen and then unloaded in area of low partial pressure
shown on oxyhaemaglobin dissociation curve
42
lipid absorbtion
1) micelles consisting of fatty acids and glycerol are taken to the lining of the illeum
2) fatty acids are non polar so diffuse through phospholipid bilayer leave behind micelle
3) move to smooth endoplasmic reticulum and are made back into triglyceriides
4) moves to golgi and gets a protein added to it forms a chlomicron
5) chylomicronleave via exocytosis and move to the lymph system and they are then transported around the body
43
what are haemaglobin and how do they benefit the transport of oxygen
specific tertiary structure allows for 4 oxygen molecules to bind
cooperative binding
43
whats bohr effect
high co2 conc causes affinity for oxygen to decrease as the acidic nature of the high co2 environment causes the tertiary protein structure to change slightly
44
why do different organisms have diff types of haemaglobin
to cope w demand of environment
44
define double circulatory system
travels through the heart twice in one full circuit
body > heart > lungs > heart > body
44
why does blood flow through lungs at lower pressure
- prevent damage to the alveoli
- blood flow slower speed more time for gas exchange
44
state blood pathway as it enter the heart from body
deoxygenated blood travel into heart via vena cava to the right atrium through atrioventricular valve to the right ventricle through semi lunar valve to pulmonary artery to lungs gets oxygenated comes back into heart via pulmonary artery to the left atrium down through atrioventricular valve to left ventricle through the semi lunar valve to aorta to the rest of body
45
what blood vessel carries blood to and from the kindey
renal atery / vein
45
cardiac output calculation
heart rate * stroke vol
46
structure of veins and how this affects its function
relitively thiin
- no control of the blood flow only carry blood in low pressure
valves
- prevent backflow and unidirectional blood flow
46
what blood vessel carries blood to the heart muscle
what happens if a block occurs here
coronary artery
cardiac arrest heart muscle doesnt have the correct bloodflow
46
two features of the cardiac muscle that are advantageous
myogenic - contract / relax without hormonal stimulation
never fatigues as long as there is a constant supply of oxygen
46
whats the function of valves in the heart
when do they open
- prevent backflow of blood
- maintain unidirectional flow blood
only open when pressure before it exceed pressure after it
46
structure of arteies and how this affects its function
thick muscular cell wall
- constrict and dilate to control blood flow
thick elastic tissue in walls
- maintain the blood pressure stretch and recoil
thick muscle tissue
- prevent vessel from bursting facillitate high pressure
46
structure of capillaries and how this affects its function
many branches
- inc sa:v
one cell thick
- short diff pathway
small lumen
- only one cell goes through at a time maximise diffusion
47
structure of the arteriole
muscle layer
- thicker than artery as constricting the lumen results in reduced blood flow into capillaries
elastic layer
- thinner as the blood pressure is lower than artery
48
desc pro of mass flow hyp
consist of source
( photosynthesisng cell)
sink ( respiring cell )
1) sucrose made by source cells active transport to the sieve tube element via the companion cell
2) water will move into the sieve tube elements from the xylem as there is a high water potential gradient and then out of the sink cell as this creates water from respiration
3) the sucrose will be carried down the hydrostatic pressure gradient to the sink cell
4) sucrose actively transported into the sink cell via the companion cell this decreases the water potential
5) water move from the sieve tube elements back to the xylem via osmosis
48
define stroke volume
amount of blood that leaves the heart each beat
48
formation of tissue fluid
1) capillaries have small gaps called fenestrations
2) as blood enter capilaries from arterioles results in high hydrostatic pressure of the blood
3) water and small molecules are forced out to surroundiing cells this is called ultrafiltration
4) towards venous end hydrostatic pressure has decreased as so much has been forced out pressure within capillary has dropped the water potential has also dropped
5) liquid then re-enter capillary via osmosis
48
how does water move out of plant cells
transpiration is the loss of water through the stomata
49
key points that aid the water moving into root and up plant
cohesion tension theory
- cohesion between water molecules / hydrogen bonds makes them stick togeather create contious water column
-adhesion water molecule stick to walls of xylem thinner the xylem the greater the capillary effect
- root pressure as more water move into root the and therefor increase the pressure within the root forces water up the root
49
what 4 factors affect transpiration and how do they affect it
light
- the more light the more stomata that are open so more water loss
temperature
- hotter water molecules have more kenetic energy move faster / evaporate faster
humidity
- water potential outside of leaf is greater than inside this results in less evaporation
wind
- maintains the water potential gradient
50
process of water moving up plant
1) water evaporate out stomata loss in volume create lower pressure (transpiration)
2) as water is lost more water is pulled up xylem to replace it
3) due to hydrogen bond the water creates continous column via cohesion
4) water molecules stick to walls of xylem via adhesion this further helps the movement of water up the plant
50
whats the process of movement of minerals and organic matter through the plant
translocation
50
investigating translocation
Tracing
- only provide plants with radioactively labeled carbons
- this will be used in photosynthesis to produce sugars
- thin slices of stem placed onto xray film
- this highlights where mass is moving phloem
50
key features of prokaryotic dna
-DNA molecules are short
- circular
- not associated with histone proteins
- dont contain introns
51
key features of ekaryotic dna
-DNA molecules are long
- linear
- associated with histone proteins
- contain introns
51
define locus
exact position of a particular gene occupies on a chromosome
51
define gene
base sequence that may encode for
- amino acid sequence in polypeptide
- functional RNA
51
three features of genetic code that act as an advantage
- degenerate = different sequences code for same thing
- universal = one sequence codes for same thing in all organisms
- non overlapping = base sequences only belong to one triplet dont get shared around
51
what are intorns and exons
exons = useful triplets that code for something
intron = not useful triplet dont code for anything
51
first stage of protein synthesis
- transcription
- DNA helicase attaches at start triplet
- DNA helicase moves along DNA unwinding it and breaking hydrogen bonds
- One DNA strand acts as a template
- RNA nucleotides align with template DNA strand by complementary base pairing.
- RNA polymerase joining adjacent RNA nucleotides with phosphodiester bonds, forming the sugar-phosphate backbone (condensation reaction)
- RNA polymerase meets stop triplet on DNA & falls off from DNA
- DNA rewinds, Hydrogen bonds reform
pre-mRNA is spliced to remove introns, leaving exons forming mRNA. This leaves via a nuclear pore and enters the cytoplasm.
51
define genome
complete set of genes in a cell of an organism
51
define proteome
a full range of proteins that a cell is able to make
51
key fetaures of tRNA
transfer RNA
clover leaf shaped
complementary anticodon
amino acid binding site
51
second stage of protein synthesis
- translation In the cytoplasm
- The start codon of the mRNA enters the ribosome
- The tRNA anticodon binds to complementary mRNA codons
- The tRNA has a specific amino acid attached, which is complementary to the tRNA anticodon
- The amino acid joins by a peptide bond a condensation reaction to an adjacent amino acid, using ATP from respiration.
- The tRNA is released and leaves the ribosome.
Ribosome moves to the next codon and along the mRNA to form the polypeptide, until it reaches the stop codon.
51
define gene mutation
random change in dna base sequence
52
fact inc chance of mutation
exposure to mutagenic agents will increase chance of mutation
high energy radiation
ionising radiation
harmful chemicals
52
types of gene mutation and what is the affect of this
addition - base is added onto the sequence and result in frame shift
deletion - base is removed in sequence and result in frame shift
sustitution - base is swapped out for other base doesnt result in frame shift
52
mutation in chromasome
occurs randomly in mieosis and results in non-disjunction this is when chromasomes dont equally split and result in different num of chromasomes
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variations in meiosis
and what stage they occur
how to calc num of possible combinations in independant segregation
all occur in meiosis 1
- independant segregation
homologous chromasomes line up opposite on the equator and is completely random
these two then further seperate to just one of each pair in the daughter cell
2*n (n=num of homologous chromasome pairs)
- crossing over
homolygous chromasome pairs line up and chromatids twist around eachother form a chiasmata and break off result in new combination of allele
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types of selection
1) directional selection
where extreme advantageous allele is selected for
2) stabilising selection
extreme alleles selected against and the average alleles selected for
3) disruptive selection
both extreme alleles selected for result in speciation
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process of natural selection
1) phenotypic variation
new alleles result from random mutation variety of alleles in the gene pool
2) selection pressure
Competition for light, Disease or Predation
3) those with advantageous alleles are better adapted to the environmental conditions
4) those with advantageous allele outcompete those with disadvantageous alleles, so survive and reproduce therefor passing on the new alleles to the next generation
5) Within the gene pool advantageous alleles increase in frequency
This may lead to SPECIATION
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define genetic diversity
number of different alleles of all genes in a population
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whats the binomial naming system and how is it used
methods of universally identifying the organism
genus species
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what is the sequence of classification
do domain
kinky kingdom
pants phylum
come class
off order
for family
gay genus
sex species
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whats courtship and how are courtship behaviours advantageous
a sequence of behaviours that are specific to certain species
- help identify opposite sex
- help identify potential mate
- increased mating success
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3 key features of atp
1) very unstable bonds between the 2nd and 3rd Pi are easily broken immediately releasing energy, in a single reaction
2) ATP is Easily reformed
easy to reform bond between the 2nd and 3rd Pi
3. ATP is Soluble which means.. ATP is dissolved in the cell, so readily available for biochemical processes e.g. DNA replication
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define index of diversity
An index of diversity describes the relationship between the number of species in a community and the number of individuals in each species.
Calculation of an index of diversity ( d ) from the formula
d=N(N-1)
---------
Σn(n-1)
N = total number of organisms of all species
n = total number of organisms of each species.
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methods of investigating diversity
1) frequency of measurable or observable characteristics
2) the base sequence of DNA
3)the base sequence of mRNA
4)the amino acid sequence of the proteins encoded by DNA and mRNA.
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Farming techniques reduce biodiversity.
1) planting more hedges
Advantages
- Increase biodiversity
- increase in predators of pests so less crop damage - higher yield/income
Increase in pollinators so more yield/income
Disadvantages
- Reduced land area for crop growth/income
- More difficult to farm so less income
2) land clearance for agriculture
Advantages
- Increased yield of food crops.
- Cheaper grazing for cattle and hence cheaper food.
Disadvantage
- Loss of habitat so predator of crop population may increase & more pesticides needed
- Reduced habitat so species diversity reduced
Increased fertilizer use
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define species richness
number of species in a community
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describe process of meiosis
- a cell undergoes 2 rounds of devision creating 4 duaghter cells
- round 1 of division separate homologous pairs of chromasomes to make it hapliod
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define herd immunity
those who are vaccinated provide safety for those who arent vaccinated as they are unable to catch the disease
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what must happen to the sample used in order to better see things in microscope
stain- highlight key structures in the sample
squash- thin layer of cells so light can pass through
single layer of cells- allow light to pass through
add acid - dissolve the cell wall
