topic two Flashcards
(247 cards)
1
Q
carbon based compounds found in living organisms incoude
A
lipids
carbohydrates
nucleic acids
proteins
2
Q
how many bodns can carbon form
A
4
3
Q
waht are macromolecules
A
organic compounds. There are four types of macromolecules: carbohydrates, lipids, proteins and nucleic acids. All of them contain carbon, hydrogen and oxygen atoms.
4
Q
carbohydrates are comprised of
A
carbon, hydrogen and oxygen. the ratio of hydrogen to oxygen is 2:1
5
Q
proteins consist of
A
amino acids arranged in long chains
6
Q
function of alpha d glucose
A
Used in the production of ATP in cells.
7
Q
function of beta d glucose
A
Used to build cell walls in plants.
8
Q
function of starch
A
Used as long-term storage in plants.
9
Q
function of ribose
A
Used as a component of DNA and RNA.
10
Q
function of triglycerides
A
Used as long-term storage in adipose tissue in animals.
11
Q
function of steroids
A
Used as chemical messengers in the body, have a distinctive ring shape.
12
Q
function of phospholipids
A
Major component of plasma membranes.
13
Q
function of strutural proteins
A
Proteins such as keratin and collagen form the structural framework of many parts of the body.
14
Q
function of enzymes
A
Metabolic proteins that speed up chemical reactions in the body.
15
Q
function of polypeptides
A
A sequence of amino acids that may make up a protein, or a series of polypeptides can also make up a protein.
16
Q
function of dna
A
Used to store genetic information.
17
Q
function of rna
A
Used to create proteins at ribosomes using the information stored in DNA.
18
Q
basic structures of glucose, amino acids, fatty acids and ribose.
A
19
Q
what implies the monomer is an aminoa cid
A
-COOH
20
Q
what implies the monomer is a fatty acid
A
-COOH attached to a long hydrocarbon chain
21
Q
what detects starch in food
A
iodine solution. will turn blue black
22
Q
waht detects protein in food
A
biuret test. the liquid turns purple.
23
Q
what detects carbs
A
benedict’s solution, reducing sugars. will change from blue to orange or brick red when heated
24
Q
anabolism
A
is the synthesis of complex molecules from simpler molecules; it is a process that requires the input of energy. Anabolism includes the formation of macromolecules from monomers by condensation reactions.
25
catabolism
the breakdown of complex molecules into simpler molecules and includes the hydrolysis of macromolecules into monomers. The breakdown of sugars (including glycolysis) or fats to release energy are all examples of catabolic reactions. Catabolism is a process during which energy is released.
26
Hydrolysis reaction
the breaking of chemical bonds by the addition of water molecules.
27
Condensation reaction refers to
the reaction in which two smaller organic molecules combine to form a larger molecule with the accompanied formation of water or some other simple molecule.
28
define metabolism
the sum of all the enzymatic reactions in a cell or organism.
29
define anabolism
the synthesis of more complex molecules from simpler precursor molecules.
30
define catabolism
the breakdown of complex molecules into simpler molecules.
31
urea formula
CO(NH2)2
32
function of urea
used by body to excrete nitorgen and is also used as a nitrogen fertiliser
33
who synthesised urea and when
Friedrich Wöhler in 1828
34
what contradicted the theory of vitalism
artifical synthesis of urea
35
why is water a polar molecule
the oxygen atom is more electronegative than the hydrogen atoms. this means that oxyen has a greater pull on the electron cloud, acquiring a slightly negative charge whilst the hydrogens are slightly posiitive.
36
polarity of warer allows
important biological properties such as solvency, cohesion and adhesion.
37
what allows the formation of hydrogen bonds
the partial positive hydrogen atoms of one molecule are attracted to the partial negative oxygen atoms of other water molecules.
38
why are fats and oil hydrophobic
they are non polar
39
cohesion
tendancy of wawter molecules to stick to each other due to the hydrogen bonding between them. Each water molecule can potentially form four hydrogen bonds with other water molecules in a tetrahedral arrangement.
40
are the cohesive forces in water strong
yes, Although hydrogen bonds are weak bonds, the presence of a large number of hydrogen bonds in water gives the cohesive forces great strength.
41
what causes high surface tension in water
strong cohesive forces.
42
what is responsible for water droplets adopting a spherical shape, minimising the ratio of area to volume.
high surface tension
43
what is adhesion
the interaction that water molecules have to other molecules, and is why water molecules stick to other polar compounds
44
what causes capillary action
forces of adhesion
45
what creates the unique thermal properties of water inc high specific heat capacity
the hydrogen bonds
46
how much energy is required to turn liquid water into water vapour
a large amount. this means water is a great cooland and has a high latent heat of vaporisation
47
can water dissolve ionic compounds
yes
48
benefit of cohesive properties of water to living organisms
Allows water to be pulled up from the roots to the leaves of plants.
Permits insects, such as pond skaters, to walk/float on the surface of water to catch their prey.
49
benefit of adhesive properties of water to living organisms
Capillary action generated by adhesive forces assists the pumping action of the heart to help blood move through blood vessels.
Adhesion of water molecules to the cell wall of xylem vessels helps water move against gravity from the roots to the leaves.
50
benefit of thermal properties of water to living organisms
Evaporation of sweat from body surfaces involves heat loss, which brings about a cooling effect.
The high specific heat capacity of water makes aquatic ecosystems more stable than terrestrial.
51
benefit of solvent properties of water to living organisms
Water dissolves mineral ions in the soil and transports it along xylem vessels from the roots to all parts of the plant.
Water in blood plasma dissolves a range of solutes and gases, which makes it possible for blood to transport nutrients and gases around the body
Water’s versatility (its ability to exist as a liquid, solid and vapour) makes water a universal solvent and medium for numerous biochemical reactions.
52
What causes water to have a relatively high specific heat capacity?
Hydrogen bonds between hydrogen and oxygen of different water molecules.
53
What property of water makes it an excellent coolant?
Water molecules are dipolar, allowing strong cohesive forces between the molecules.
54
is blood oil based or water based
water based
55
list the biological molecules found in blood
glucose
amino acids
fats
cholesterol
oxygen
sodium chloride
56
why does blood gluclsoe level need to be strictly maintatined
it effects osmolarity
57
what changes the solubility of amino acids
size and r group
58
when will amino acids easily dissolve in water
if they contain a hydrophilic r group. if hydrophobic hey will be transported in lower concentrations
59
how are fats transported in blood
generally insoluble in water so transported in lipoproteins a
60
what are lipoproteins
a single layer of phospholipids with proteins embedded among the molecules surrounding the fat
61
how is cholesterol transported in the blood
lipoproteins are needed
62
how ix oygen transported in the blood
Oxygen is nonpolar, however, due to its small size it is soluble in water to a limited extent. This is why oxygen transported in the blood is bound to the protein called hemoglobin.
63
how is sodium chloride transported in the blood
as Na+ and Cl- ions
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what substances are dissolved in the blood
Amino acids, sodium chloride and carbon dioxide.
65
how is starch transported in theblood
broken down into glucose molecules
66
how is methane produced
a gas produced by anerobic bacteria as a waste product. is also a greenhouse gas
67
physical states of water and methane at 20 degrees
liquid and gas
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polarity of water and methane
polar and non polar
69
water and methane as a solvent
excellent and not
70
boiling temp of water and methane
100 and -161
71
melting point of water and methane
0 and -182
72
specific heat capacity of water and methane
4.2 and 2.2
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latent heat of vap of water and methane
2257 J/g and 760J/g
74
what explains the differences in thermal properties of water and methane
the presence of hydrogen bonding in water
75
how can carbs be classified
monosaccharides, disaccharides and polysaccharides.
the former two are considered sugars; polar
the latter is a macromolecule resulting from polymerisation or condensation of sugars and is not soluble inw ater
76
monosaccharides
the simplest types of carbohydrates. The number of carbon atoms can be from three to seven. The carbons are joined to a hydroxyl group (-OH).
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what happens when monosaccharides link together via a condensaiton reaction
they form a glycosiddic bond producing a disaccharide
78
Condensation reaction refers to the reaction in which
two smaller organic molecules combine to form a larger molecule and a molecule of water or some other simple molecule. The reaction opposite to condensation is called hydrolysis. This is a chemical reaction in which water is used to break down the bonds of big compounds.
79
hydrolysis
is when water ('hydro') is added and used to break up ('lyse') a polymer, a disaccharide or a dipeptide into smaller monomers.
80
glucose exists in two forms:
D glucose and L glucose
81
differences between the alpha de glucsoe and beta d glucose
82
how do animals and fungi store energy
glycogen
83
how do plant sstore energy
starch in their roots and stems
84
what are chitin exoskeletons mad eup of
carbs
85
what is scurose made up of
glucose and fructose
86
waht is maltose made up of
2 glucose units
87
waht is lactose made up of
glucose and galactose
88
what is starch made from
glucose
89
what is glycogen made up of
glucose
90
what is cellulose made up of
glucose
91
How is maltose formed?
By joining two glucose molecules in a condensation reaction.
92
what polysaccharides make up starch
amylose and amylopectin (both of these have glucose as their monomer subunit)
93
structural difference in starch and cellulose
In cellulose molecules, all glucose monomers are oriented in the same direction.
In contrast, starch molecules are made up of glucose monomers that rotate 180 degrees around the backbone chain.
94
is amylose or amylopectin branched
amylopectin
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uses of amylopectin
gives starch its characteristic stickiness. This is very useful in the food, paper and chemical industries, where it is used to make paste, glue (adhesive) or as a lubricant.
makes up 80% of the starch content in potatoes. A genetically modified potato which predominantly produces amylopectin starches (useful for adhesive making), has been produced and approved for cultivation.
96
cellulose fucntion
sturcutral component in plant cell walls
97
amylopectin and amylose are
two differnet forms of starch.
usually in starch glucose monomers rotate 18p degrees around backbone chain.
the arrangement of glucose molecules can be linear, which is called amylose, or branched, which is called amylopectin
98
how are triglycerides formed
by condensation reactions between one glycerol and three fatty acids, creating ester bonds.
99
distinguish between fats and oils
fats are solid at room temp, oils are liquid
100
difference betwen saturated fatty acid and unsaturated fatty acid
A saturated fatty acid has no double bonds between any of the carbon atoms that make up the hydrocarbon chain.
An unsaturated fatty acid can be monounsaturated if it has just one double bond
101
what is a polyunsaturated fatty acid
has two or more double bonds in its hydrocarbon chain
102
cis is when
both hydrogens on one side
103
trans when
hydrogen on either side
104
key features of cis isomers
commonly occur in nature
lower melting point
105
key features of trans isomers
produced artifically when lipids formed by polyunsaturated fatty acids from plants are 'partially hydrogenated' chemically (e.g. when margarine is made from vegetable oil). This process makes plant fatty acids more solid, like saturated fats.
higher melting points
106
phospholipids composition
when one fatty acid in a triglyceride is replaced by a phosphate group
107
whya re steroids lipids
hydrophobic and insoluble in water
108
why do steroids not resemble lipids
they have four fused rings
109
are cis or trans isomers bad
trans
110
Which substances are examples of steroids?
cholesterol and sex hormones
111
why are lipids better for energy storage
higher energy content and can act as thermal insulators
112
a gram of lipid gives
twice the amount of energy as a gram of glycogen
113
each gram of glycogen is stored with
2 grams of water
114
key properties of lipids
more energy per gram
less dnese
non polar but does not affect movement of water
excellent heat insulation
water insoluble
115
The two types of fats that are generally considered to be unhealthy are
the trans fats and those rich in saturated fatty acids.
116
Trans fats, on the other hand, are formed by
the hydrogenation of vegetable oils by adding hydrogen to unsaturated fats under pressure. This process increases the spreadability of vegetable oils and extends the shelf life of certain food products
117
what is the evidence linking the ocnsuption of trans and saturated fats to the incidence of CHD
The hypothesis is that the trans fats and saturated fats contribute to the formation of atherosclerotic plaques in arteries, which in turn lead to heart attack
118
Key questions to consider when doing an evaluation:
Is there a correlation between the lipid and the incidence of the disease under investigation?
Has a statistical analysis been carried out to determine the significance of the data collected?
Is the data collected widely spread? The more widely spread the data, the lower their significance and reliability. Standard deviation and error bars can be used to determine the extent to which the data is widely spread.
Was the sample used for the investigation big enough? Small samples do not provide reliable data.
Was the factor measured as the health indicator valid? For instance, how fast a person can run is not a valid way to measure health.
Were representatives of the whole human population considered? Or only a specific age group, gender, ethnicity, lifestyle, etc.?
Were all important variables effectively controlled?
Were realistic dietary levels of lipids considered?
119
bmi is
weight / height squared
120
health risk classification acording to bi
underweight is under 18.5
normal is 18.5 to 24.9
overweight is 25-29.9
121
how many amino acids are there
20
122
how do two amino acids bind in a condensation reaction to form a depeptide
The carboxyl group and the amino group provide OH and H, respectively, for the formation of a water molecule.
123
Which chemical reaction is taking place when a dipeptide is converted to two amino acids?
hydrolysis
124
Name the bond that forms when two amino acids react together in a condensation reaction.
ester bond
125
genes normally code for how many polypeptides
one
126
what determines the shape and function of the protein
order of rthe amino acids
127
waht determines the types of bonds and itneractions with other molecules aminoa cids can make
r groups
128
A single change in the order of amino acids can cause changes in a protein's conformation, resulting in
a change of shape or loss of function
129
. In sickle cell anemia, the glutamic acid is substituted by ???. This causes severe changes to the structure of hemoglobin.
valine
130
waht is the primary structure
the sequence of amino acids in a protein
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what is the secondary structure
involves the folding of the chains on themselves to form pleated sheets or alpha helixes
132
what is the tertiary structure?
When the polypeptide folds and coils to form a complex three-dimensional shape
133
what is the quaternary structure
A quaternary structure only occurs in proteins that are made up of two or more polypeptide chains and refers to the way the multiple subunits are held together in a multi-subunit complex.
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hemoglobin has which chains
2 alpha 2 beta
135
proteome meaning
each persons unique set of proteins
136
globular proteins
They tend to play active roles in the cell’s metabolism. They consist of complex polypeptide chains that can be linked to other chains to form large complex proteins
137
fibrous proteins
more like a fibre; long and thread-like. Usually, fibrous proteins are made of long polypeptide chains where the hydrophobic R groups are exposed, making the molecule insoluble. They are often found in structural parts of organisms, such as tendons and skin
138
rubisco
globular
An enzyme involved in the fixation of CO 2 in chloroplasts.
139
insulin
globular
A hormone produced by the beta cells of the pancreas, which is involved in glucose uptake from the blood.
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immunoglobin
globular
These are large Y-shaped proteins, also called antibodies, involved in fighting infections by specifically recognising and binding to antigen molecules.
141
rhodopsin
globular
A protein linked to pigment, found on the membrane of rod (photoreceptor) cells of the retina, where it allows very low light intensities to be detected.
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collagen
fibrous
A structural protein, found in muscles, tendons and ligaments, where it gives tensile strength. It also occurs in skin and bones, where it prevents tearing and fractures, respectively.
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spider silk
fibrous
A fibrous protein produced by spiders for their webs. It can be extended and is very resistant to breaking.
144
what is lost via denaturation
secondary and tertiary structures
The hydrogen bonds formed between R-groups of amino acids and amino groups of different amino acids are disrupted. Active sites lose their shape. As a result, the whole enzyme loses its enzymatic properties.
145
how to denature proteins
temp pH
146
what does pH break
the bonds between the non-adjacent amino acids or between the polypeptide chains of quaternary proteins.
147
what is the special area on an enzyme where the actual catalytic reaction takes place
active site
148
what is meant by enzyme–substrate specificity
one enzyme can only catalyse one type of reaction.
149
induced fit
where the enzyme changes shape slightly to fit the substrate more tightly
150
enzymes are
biological catalysts
globular proteins that can speed up a biochemical reactioj
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benefit of the induced fit
the enzyme induces the weakening of bonds within the molecules of the substrate(s), thus reducing the activation energy needed for the reaction. When the enzyme-catalysed reaction is completed, the products are released from the enzyme.
152
How enzymes lower the activation energy.
153
effect of low temp on enezymes
When temperature is low, molecules tend to move slowly. The chance of collision between substrate and enzyme molecules is also low.
154
effect of mid to high temp pn enzymes
When temperature rises, molecules move more rapidly and it is more likely that they will collide with each other. Each enzyme has an optimum temperature in which the rate of enzymatic reaction is the highest. The optimal temperature for human enzymes is around 37 °C.
155
effect of substrate conc on enzyme rate of reaction
When the substrate concentration is low, there are more enzyme molecules available than substrate. The rate of reaction is relatively low. Increasing the substrate concentration causes more chances of collision between substrate and enzyme molecules. Hence, the rate of enzymatic reaction rises gradually. However, this increase is halted when all active sites are occupied by substrate molecules. After this point, adding more substrate does not affect the rate of reaction.
156
stomach pH
2
157
small intenstine pH
7.5
158
what parts of the enzyme are destroyed by denaturation
teritary or quaterynary, maybe even secndary
159
what is immobilisation
a process of attaching an enzyme to a material so that its movements are restricted.
160
adv of immobilising enzymes
if not, they are often present in the final product, which restricts the concentration that can be used to process food for human consumption to avoid adverse effects.
permits higher concentrations of enzymes to be used, allowing a faster rate of reaction.
allows immediate separation of the enzymes from the reaction mixture, which allows them to be recycled, reducing production costs.
161
lactose is broken down into glucose and galactose via which enzyme
lactase
162
The production of lactose-free products has a number of advantages:
no ill effects after consumption
quicker fermentation, for example, in yogurt production as bacteria ferment glucose and galactose more readily than lactose
sweeter tasting milk (glucose and galactose are sweeter tasting than lactose).
163
how are lactoe free products produced
adding the enzyme lactase
immobilsing lactase in alginate beads whilst milk flows past
164
what are dna and rna composed of
three parts; a pentose sugar, phosphate group and nitrogenous base
165
nitrogenous bases in dna
agtc
166
nitrogenous bases in rna
aguc
167
differences in dna and rna
DNA RNA
Contains the sugar deoxyribose.
Bases involved are adenine, thymine, guanine and cytosine.
Is a double-stranded molecule.
Contains the sugar ribose.
Bases involved are adenine, uracil, guanine and cytosine (thymine has been replaced by uracil).
Is a single-stranded molecule.
168
The nucleotide units link together through what
a phosphodiester bond (a covalent bond) to form a single strand, a polynucleotide
169
What is the name of the pentose present in DNA molecules
deoxyribose
170
omplementary base pairing rule
Guanine always pairs with cytosine.
Adenine always pairs with thymine.
171
antiparalel concept
In order for bases to be facing each other, the two strands must run in opposite directions (i.e. they are antiparallel ) to each other. Thus, one strand of DNA runs from 5' to 3', and the opposite strand runs from 3' to 5'. The 3' and 5' refer to the exposed carbon (on the sugar) at the ends of the DNA chains
172
what did crick and watson do
They used the information from the DNA X-ray diffraction patterns produced by Rosalind Franklin and Maurice Wilkins to deduce that the DNA molecule must have a regular double helix structure.
Additionally, they integrated Chargaff’s base ratio, a finding that showed A is always equal to T and C always equal to G in the DNA molecule to work out the complementary base pairing of A to T and C to G. Once they had all the information they built a 6-foot (about 1.8 m) model out of metal scrap and, as expected, everything clicked into place. One very important aspect of using a model is the ability to visualise the molecule and to quickly see how well it fits the available evidence.
173
when does the formation of a new DNA molecule occur
during s phase of the cell cycle
174
what changes during dna rep.
Only the number of DNA molecules changes. It doubles after DNA replication. The chromosome number and genes stay unchanged during DNA replication.
175
summary of dna replication
unwind the coils to make the strands accessible to enzymes. The enzyme helicase then unwinds the double helix and separates the two DNA strands by breaking the hydrogen bonds between the bases. Once the strands are separated and the bases exposed, another enzyme called DNA polymerase can start making new strands of DNA using the two 'old parent' strands as templates.
176
why is dna semi conservative
because each daughter molecule formed contains one original strand from the old molecule and one newly synthesised strand.
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Conservative Model
– An entirely new molecule is synthesised from a DNA template (which remains unaltered)
178
semi conservative model
Each new molecule consists of one newly synthesised strand and one template strand
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dispersive model
New molecules are made of segments of new and old DNA
180
Meselson-Stahl Experiment
Nitrogen is a key component of DNA and can exist as a heavier 15N or a lighter 14N
DNA molecules were prepared using the heavier 15N and then induced to replicate in the presence of the lighter 14N
DNA samples were then separated via centrifugation to determine the composition of DNA in the replicated molecules
The results after two divisions supported the semi-conservative model of DNA replication
After one division, DNA molecules were found to contain a mix of 15N and 14N, disproving the conservative model
After two divisions, some molecules of DNA were found to consist solely of 14N, disproving the dispersive model
181
transcription
the coding information is copied or transcribed into a special molecule called messenger RNA (mRNA). The DNA functions as a template, and the single-stranded mRNA molecule that is made follows the complementary base pairing rules of DNA, with one exception.
the section of DNA that contains the required gene is unwound and separated so that RNA polymerase enzymes can access the DNA bases. The RNA polymerase then transcribes a sequence of DNA bases into mRNA. Hence, the net product of this process is a single-stranded RNA molecule.
182
Which of the following enzymes is responsible for uncoiling and separating the DNA strands during transcription?
RNA polymerase
183
Each set of three consecutive bases in RNA is known as
a codon or triplet .
184
what does the genetic code being degenerate mean
some amino acids encode more than one codon
185
what does the genetic code being universal mean
genetic info in bacteria is translated in the same way as that of elephants, sequoia trees or any other living organisms
186
trna molecuel labelled
187
what is translation
the synthesis of polypeptides on ribosomes according to the genetic code
188
what does trna do
brinds a spefcific amino acid to the mrna
189
what to tran molecules have that paris with the codon of mrna
an anticodon
190
whree does translation take place
in the cytoplasm
191
What is the role of tRNA in translation?
It brings amino acids to the ribosome.
192
what does pcr stand for
polymerase chain reaction
193
what is pcr
a technique that can make billions of copies of one molecule of DNA by repeatedly copying a specific stretch of that DNA.
194
what are plasmids
small circular DNA molecules in some prokaryotic cells that can be used as transfer molecules.
195
waht are transgenic orgnanisms
Placing a gene from one organism into a different organism results in a transgenic organism.
196
how is insulin produced
the human gene for insulin is transgerred to e. coli and results int he production of human insulin
197
how are humans proteins made from plasmids
198
respiration def
the gradual and controlled release of energy by breaking down organic compounds to produce ATP ( A denosine T ri P hosphate).
199
3 main processes of cellular respiration
glycolysis
krebs
etc
200
where does glycolysis take place
cytoplasm
201
where does krebs and oxidative phosphorylation and etc take place
mitocohondria
202
where does krebs take placae
matrix
203
where does the etc take place
the inner membrane of the mitochondrial envelope
204
when is energy produced
when atp is hydrolysed
205
where does Anaerobic respiration take place
the cytoplasm
206
which produces more oxygen
aerobic resp
207
what does anaerobic production produce in yeast
alchol and co2
208
alocholic fermentation formula
Glucose → ethanol + carbon dioxide + 2 ATP molecules
209
lactic acid fermentation
Glucose → lactate + 2 ATP molecules
210
What is the net yield of ATP produced by anaerobic respiration in yeast?
2 ATP molecules
211
which step of aerobic respiration is the only one completed in anaerobic respiration
only glycolysis
212
why is more atp produce in aerobic respiration
6-carbon glucose is systematically and gradually broken down to 6 CO 2 molecules. Each step yields potential energy, which can be converted into ATP in the electron transport chain.
213
what do aerobic and anerobic respiration have in common
glycolysis
both generate in form of ATP
glucose as a substrate
214
how would a respirometer be set up
215
why would you set up the respirometer in a water bath
ensures that temperature does not affect the pressure and hence volume of air in the system
216
what cna be measured with a respirometer
A respirometer can give us a good idea of the respiration rate of germinating seeds, a resting animal or a moving animal, and it allows us to compare different species. It can measure the influence of temperature or, for example, sleep, on respiration. The whole range of tests can be performed with such a simple setup.
217
What is the role of an alkaline solution in the respirometer?
To absorb carbon dioxide
218
why do chloroplasts look green
because chlorophyll a and chlorophyll b , the pigments that capture the photons, reflect green light and absorb most of the other wavelengths in the visible light spectrum
219
cholorophyll absorbes waht most effectively
red and blue light
220
The action spectrum is a good indicator of which wavelengths are most efficient in photosynthesis. Some wavelengths cause a higher photosynthetic rate than others. The action spectrum in Figure 4 shows the different rates of photosynthesis that occur at different wavelengths of visible light.
221
When asked to draw the action spectrum, ensure that the following is included:
The x -axis is labelled light wavelength or frequency and the y -axis is labelled rate of photosynthesis.
The curve increases, decreases and then increases again to decrease again.
One peak is approximately at 425 nm in the blue region.
The second peak is approximately at 670 nm in the red region.
The first peak is higher than the second peak.
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The absorption spectrum of chlorophyll a and b.
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what is photolysis
he stage of photosynthesis in which water is split by light ( photo – light and lysis – splitting). The energy in photons is used to split water molecules.
224
What are the electrons generated from photolysis used for
to generate atp
225
In which process of photosynthesis is light directly involved
The splitting of water
226
What are the products of photolysis?
Hydrogen ions and oxygen
227
is photosynthesis anabolic or catabolic
anabolic
228
which names are interchangeable in photosyntehsis
calvin cycle and light independent reactions
229
Carbon dioxide + water →
→ carbohydrates + oxygen
230
describet he two stages of photosynthesis
Light-dependent reaction which requires light and occurs on the thylakoids of chloroplasts. Photolysis takes place at this stage.
Light-independent reaction that has no light requirement and takes place in the stroma of chloroplasts. It involves carbon fixation to produce carbohydrates.
231
What is needed in photosynthesis to convert carbon dioxide into organic molecules?
ATP and hydrogen from the splitting of water.
232
what is a limiting factor
A limiting factor is a factor that restricts the rate of a reaction when present in a low amount.
233
why does photosynthesis decrease at niht
no sun
234
limiting factors of photosynthesis
CO2
oxygen
Sun
temp
235
how is co2 a limiting factor in photosynthesis
Carbon dioxide is a raw material in the production of carbohydrates, which takes place in the light-independent reaction. Once all the active sites of the enzymes involved in this cyclic process are occupied with a substrate, any further increase in carbon dioxide concentration will not increase the rate (the graph levels off).
236
When designing an experiment to investigate the effect of limiting factors on photosynthesis, consider the following:
Choose a plant material that allows easy control of variables and collection of data. Would it be better to use an aquatic plant or a terrestrial plant?
Finalise your independent variable first (it could be either temperature, light intensity or carbon dioxide concentration), then list all other variables that you have to keep constant throughout the experiment.
After checking the amount of time you have for the experiment, decide on how many levels of the independent variable you will include, as well as the number of repeats for each value. You should have at least 3–5 different levels of the independent variable.
If you have decided to measure the amount of oxygen produced as an indication of rate of photosynthesis, avoid counting bubbles; consider measuring the volume of gas produced, which is more accurate. Alternatively, you may use a data logger and oxygen or carbon dioxide sensor to collect data (if you have them at school).
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what happened when eykaryotes appeared and increased the oxygen conc underwater
Once the oceans and deposits were saturated, the Earth's atmospheric oxygen started to build up. You will see that there is a peak around 300 million years before present – this coincides with the evolution of multicellular organisms and the colonisation of lan
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Which organisms contributed to the rise in oxygen concentration during the first 2 billion years of the Earth's existence?
Cyanobacteria
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Name the process that accounts for the oxygen in the Earth’s atmosphere, oceans and rock depositions over the past 2 billion years.
photosynthesis
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phases of chromatography
mobile phase and a stationary phase
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what are the phasesi in paper hromatography
In the case of paper chromatography, the paper is the stationary phase while the solvent used to develop the chromatogram is the mobile phase. The pigments are commonly separated using an alcohol solvent mixture.
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how does chromatography work
The pigment is first extracted from the leaves by using a suitable solvent that dissolves most plant pigments. A sample of the extract is then placed on chromatography paper and transferred to a container with the chromatography solvent (see Figure 1 ). The pigments move at different rates on the stationary phase, so they separate out to form a chromatogram.
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Rf =
distance travelled by sample/distance travelled by solvent
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how can you deduce the pigments present in a plant from paper chromatography
By comparing the R f value to known R f values of plant pigments, the pigments present in the plant extract can be deduced.
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what is the difference in thin layer chromatographg
the stationary phase is usually silica gel, aluminium oxide or cellulose instead of paper.
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benefit of thin layer chroamtograpt
The good thing about thin layer chromatography is that it gives a better result as well-defined and well-separated spots are obtained.
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Which substance can be used to dissolve pigments in paper chromatography?
Ethanol
