Download Name Biology Chemistry of Life What can reduce the effect of a

Name
Biology Chemistry of Life
1. What can reduce the effect of a competitive inhibitor of an enzyme?
A.
Decrease the temperature at which the reaction takes place.
B.
Increase the temperature at which the reaction takes place.
C.
Increase the substrate concentration.
D.
Add a non-competitive inhibitor.
(1)
2. Which molecule represents ribose?
A.
H
C
O
H
C
H
OH H
C
OH C
H
C.
B.
CH 2 OH
C
O
H
C
H
O
C
H
N
OH
H
OH
D.
H
O
H 2C
OH
HC
OH
C
H 2C
OH
H
HOH 2 C
H
C
H
H
C
C
OH
OH
OH
(1)
3. What effect do enzymes have on the
activation energy of exergonic and
endergonic reactions?
Activation energy of Activation energy of
exergonic reactions endergonic reactions
(1)
4. How many ATP molecules (net yield) are
produced per molecule of glucose as a
direct result of glycolysis?
A.
2
B.
4
decreases
C.
10
increases
D.
38
A.
increases
increases
B.
decreases
decreases
C.
increases
D.
decreases
(1)
5. Outline the significance of the properties of water to different organisms.
(Total 5 marks)
6. The diagrams below show various molecular structures.
I.
O
CH 3
(CH 2) n
II.
O
HOH 2 C
H
C
C
C
OH
III.
H
C
H
OH
O
H
H
C
C
OH
OH
IV.
CH 2 OH
C
H H
R
H
H
C
O
N
C
H
H
OH
(a)
C
C
H
OH
OH
C
OH
OH
Identify which of the diagrams represent
(i)
the structure of glucose.
.....................................................................................................................................
(1)
(ii)
the structure of amino acids.
.....................................................................................................................................
(1)
(iii)
the structure of fatty acids.
.....................................................................................................................................
(1)
(b)
Discuss which of the molecules are most similar in structure.
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(3)
(Total 6 marks)
7. State one function for each of the main four elements in organisms.
(Total 4 marks)
8. The diagram below shows possible pathways for the breakdown of glucose in various cells.
Glucose
A
Process Q
(no oxygen present)
B
(a)
C+D
Process R
(oxygen present)
D+E
State the names of processes Q and R.
Q:
..................................................................................................................................
(1)
R:
..................................................................................................................................
(1)
(b)
Deduce the names of substances A and D.
A:
..................................................................................................................................
(1)
D:
..................................................................................................................................
(1)
(c)
State the organelle in which process R takes place.
...............................................................................................................................................
(1)
(Total 5 marks)
Rate of photosynthesis / l CO 2 min –1
9. There are many abiotic factors that affect the rate of photosynthesis in terrestrial plants. Wheat is an
important cereal crop in many parts of the world. Wheat seedlings were grown at three different
concentrations of carbon dioxide (in parts per million) and the rate of photosynthesis was measured at
various light intensities.
50
40
30
key:
20
1300 ppm CO2
500 ppm CO2
280 ppm CO2
10
0
0
5
10
15
20
Light intensity / × 10 3 lumen m –2
[Source: Adapted from J P Kimmins, Forest Ecology, (2nd edition) page 161]
(a)
Describe the relationship between the rate of photosynthesis and light intensity for wheat seedlings
grown at a CO2 concentration of 500 ppm.
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(2)
(b)
Outline the effect of CO2 concentration on the rate of photosynthesis of the wheat seedlings.
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(3)
(c)
The normal atmospheric concentration of CO2 is 370 ppm. Deduce the effect of doubling the CO2
concentration to 740 ppm on the growth of wheat plants.
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(2)
Leaf area and chlorophyll levels were measured in sun leaves and shade leaves of Hedera helix (English Ivy)
and Prunus laurocerasus (Cherry Laurel). Sun leaves developed under maximal sunlight conditions while
shade leaves developed at reduced sunlight levels in the shadow of other leaves.
Species
Leaf Type
Ivy
Laurel
Chlorophyll/
g ml-1
Leaf Area/
cm2
Shade
4.3
72.6
Sun
3.8
62.9
Shade
4.7
38.7
Sun
4.2
25.7
[Source: D Curtis, Plant Ecology independent project, 1990]
(d)
Calculate the percentage increase in the amount of chlorophyll in shade leaves of ivy compared to sun
leaves of ivy
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(1)
(e)
Suggest a reason for the differences in chlorophyll concentration and leaf area in sun and shade leaves
in these two species.
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(2)
(Total 10 marks)
1.
C
[1]
2.
D
[1]
3.
B
[1]
4.
A
[1]
5.
water is transparent
/ allows light to pass through for photosynthesis;
cohesion of water molecules allow transport in plants;
solvent – chemical reactions take place in water;
many substances dissolve in water and can be transported;
high boiling point making liquid water available to organisms / water is liquid over
a range of temperatures;
water is most dense at 4°C so ice floats over water providing winter habitat;
high specific heat capacity so stable environment (internal/external);
high surface tension – supports (near) surface dwelling organisms;
coolant – absorbs heat when it evaporates / changes states;
[5]
6. (a)
(i)
III
(ii)
IV
1
(iii)
I
1
(b)
II and III have the most similarities;
both have ring shaped molecules;
both have one oxygen atom in the ring;
both have the same relative amounts of C, H and O;
both have only –OH and –H linked to the carbon atoms;
both are monosaccharides / sugars / reducing sugars;
I and IV both have a carboxyl / COOH / acid group;
I and IV both are linear;
1
3 max
[6]
7.
Award [1] for each
element and its role.
e.g. C/carbon in forming organic molecules / carbohydrates /
fats / proteins / nucleic acids;
e.g. H/hydrogen in forming organic molecules / carbohydrates / fats /
proteins / nucleic acids / reducing/fixing CO2 in photosynthesis;
e.g. O/oxygen in aerobic respiration;
e.g. N/nitrogen in formation of amino acids / proteins /
nucleotides / ATP / nucleic acids / DNA / RNA;
e.g. P/phosphorus in formation of nucleotides / ATP /
nucleic acids / DNA / RNA;
2+
e.g. Ca/ Ca /calcium in muscle contraction / nerve transmission /
formation of bones / teeth; e.g.. Fe/Fe2+/iron in
formation of hemoglobin /catalase;
+
e.g. Na/Na /sodium in nerve transmission / osmoregulation;
e.g. K/K+/potassium in stomatal opening etc.;
[4]
8. (a)
Q: anaerobic respiration / fermentation;
R: aerobic respiration / Kreb's (citric acid) cycle;
2
(b)
(c)
A: pyruvate / 3-oxopropanoate;
D: carbon dioxide;
2
mitochondrion;
1
[5]
9. (a)
rate of photosynthesis increases (rapidly) /
directly proportional;
rate of photosynthesis levels off /
increases slightly after 10000 lumen m–2;
2
(b)
maximum photosynthetic rate is highest with highest
CO2 concentration;
at low light levels, higher CO2 slightly increases the
photosynthetic rate;
at low CO2 / 280 ppm, the photosynthetic rate reaches its
maximum at low light levels / constant over most light intensity /
at 280 ppm CO2 concentration limits photosynthesis;
at 500 and 1300 ppm CO2 the curve is the same shape
but with different maximum rates /
each higher light intensity requires a higher CO2 concentration
to reach maximum rate;
maximum rate of photosynthesis from 280 to 500 ppm /
increases 5 to 6 times
while 500 to 1300 ppm increases 1.5 times;
3 max
(c)
the rate of photosynthesis will increase (over the rate at 370 ppm);
the photosynthetic rate will at least double (but less than 5–6 times);
not linear;
bigger plants / more growth / more grain / greater yield;
2 max
(d)

(e)
shade leaves receive less light than sun leaves;
to capture sunlight, shade leaves produce more chlorophyll;
to capture sunlight, shade leaves have greater leaf area;
4.3  3.8
 100  13.16% (Accept 13.2%)
3.8
1
2 max
[10]