June 2018 Component 1 Past Paper

Question 1

State 4 similarities between the processes of ATP synthesis in chloroplast and the bacterium (4marks)

Answer 1

. Both involve proton pump
. Powered by electron energy
. Creation of electrochemical gradient
. Flow of hydrogen ions travel down stalked particles
. Use of atp synthase synthesising atp

Question 2

State conclusion you could draw on graph (3)

Answer 2

. Immediate source is stored atp / only enough atp for 1min
. Anaerobic glycolysis provides ATP / lack of oxygen for 3-4 min
. Aerobic respiration is maintained for 5 hours

Question 3

Describe how the cell wall of gram negative bacteria would differ from archaea (2)

Answer 3

. Absence of protein/ s layer in gram negative
. Layer or lipopolysaccharides

Question 4

What agar plate has lowest water potential

Answer 4

25%

Question 5

Identify species A-C (3)

Answer 5

.A Halobacterium salinarum + lives in a marine environment which has high NaCl conc (1)
.B Staphylococcus aureus + lives on skin which is often high in salt (from sweat) (1)
.C Escherichia coli + in part of gut with low salt (as most has been absorbed)(1

Question 6

Suggest why mean values for the first 2 dilution were so close despite there being a 100times difference in dilution (1)

Answer 6

. Clumping of bacteria
. Overlapping colonies

Question 7

State what the standard deviation or first 2 dilution tells u (1)

Answer 7

. Both unreliable as they have a large SD
. Data range is very large

Question 8

Calculate the number of bacteria in 1cm3 (3)

Answer 8

72 *4 *10^9 =2.88×10¹¹

Question 9

Exaplin how lover levels of nitrate are brought about in these meadows (2)

Answer 9

. Anaerobic conditions
. Nitrates converted to atmospheric nitrogen
OR
. Leaching
. Nitrogen washed out of soil

Question 10

Explain fully how change in agricultural practices has led to the loss of this type of meadow (3)

Answer 10

. Use of fertiliser
. Ploughing increasing aeration/ decreasing anaerobic condition
. Nitrification increases
. More nutrients in the flood water increasing nitrate levels

Question 11

Why the government is encouraging landowners to preserve and re-instate such meadows in certain areas by compensating them for the loss of productive farm land (4)

Answer 11

. Land retains the water
. Which is only released slowly into rivers
. Reducing flood
. Conservation of biodiversity
. Conflicts between loss of farmland and conservation

Question 12

Describe the technique you would use to carry out an assessment of the abundance of these 2 species across a moderately trampled footpath (3)

Answer 12

. Use transect and quadrant
. Estimate number of each species
. Repeat at interval along footpath

Question 13

Predict which species would be found in centre of the trampled footpath and what species will be found at the edge. (4)

Answer 13

. Higher abundance of greater plantain in the centre of the path and higher abundance of ribowort plantain at the edges
. Greater plantain is better adapted to heavily trampled ground.
. Greater plantain is very tolerant of drought
. Greater plantain has seed which germinate best on open ground

Question 14

Why does a food chain usually sustain no more than six energy transfers? Explain
why it would be more energy efficient to produce food in the form of corn, soybeans,
and other crops rather than as meat and other animal products. (3)

Answer 14

. Insufficient energy available to support a further trophic level
. Energy is lost as a metabolic heat/ waste when the organism from one tropic level are consumed by organism from the next
. Fewer trophic levels means more energy available for humans

Question 15

Explain why most warm-blooded organisms have to eat more often than cold-
blooded organisms to get the energy they need for survival. (2)

Answer 15

. Need to maintain body temperature
. Which means they use more food in respiration to produce heat

Question 16

What general name is given to this type of negative feedback mechanism? (1)

Answer 16

Homeostasis

Question 17

explain how the lack of the debranching enzyme causes
low blood glucose (4)

Answer 17

. Glycogen broken down to use in respiration
. Partial hydrolysis of glycogen/ only 30% of glycogen can be hydrolysed
. No removal of 1-6 branch
. Less glucose released

Question 18

Explain what has happened to produce a non-functional glycogen debranching enzyme.
[3]

Answer 18

. Mutation in the gene
. Differnt polypeptide structure
. Active site wrong shape so substrate no longer fit/ fewer enzyme substrate complex

Question 19

How does glycogen differ structurally from the storage polysaccharide starch? [1]

Answer 19

. More branching in glycogen
. More coiling in amylose
. Starch is made up of amylose and amylopectin

Question 20

With reference to the biochemical pathways of photosynthesis and respiration,
explain how a light absorbance of 0 a.u. could be observed in this experiment. [4]

Answer 20

. Rate of photosynthesis and respiration would be equal
. The uptake of CO2 by the plant through light independent reaction is equal
. To it release of CO2 through link reaction and kreb cycle
. At compensate points there is no change in indicator colour

Question 21

State two other variables that should have been controlled in this experiment. (2)

Answer 21

. Temperature
. Size of algal ball
. Concentration of algae

Question 22

How would you predict the compensation points of maize and primrose to differ?(2)

Answer 22

. Compensation point of maize is higher than primrose
. Maize need a lot of sunlight
. Primose grows in shaded environments

Question 23

Using your knowledge of algal growth explain how the area of oxygen-deprived water in
the Gulf of Mexico has occurred. (5)

Answer 23

1. Algal bloom/ or description of (1)
2. Water out of river draining agricultural land (1)
3. contains nitrates/fertiliser/slurry/eq (1)
4. Causes high Nitrate levels in area shown (1)
5. Death and decay of {algae/plants (1)
6. O2 used up by decay organisms(1)

Question 24

Using the data, what conclusions can be drawn about the world fishing stocks since 1974. (4)

Answer 24

. Overfished has increased and fully fished has increased
and underfished has decreased
. Fish stock are decreasing
. Increase in unsustainable fishing and a decrease in sustainable fishing
. within sustainable fishing more fully fished and fewer
underfished stocks

Question 25

Why are the farmed fish more susceptible to infection by lice than wild fish and why is eliminating the lice a problem for fish farms? [2]

Answer 25

.Closely packed so infection can easily spread from fish to fish (1) .Cannot be easily killed as resistant to pesticides (1)

Question 26

Explain three reasons why it is important to the environment that the escape of farmed fish is prevented. (3)

Answer 26

. Foreign species into new areas / decreases biodiversity . Spread disease . Breed with wild fish and reduces genetic diversity /causes wild species to go extinct

Question 27

Describe the role of mitochondria in eukaryotic cells using your knowledge of respiratory pathways. relationship. (9)

Answer 27

Pyruvate transported in from cytoplasm  Correct description of link reaction  Decarboxylation and dehydrogenation to produce 2C Acetyl coenzyme A  Correct description of Krebs cycle  Correct description of 4C + Acetyl coenzyme A giving 6C molecule.  Progressive removal of C as CO2 to reform 4C molecule  Removal of H/use of dehydrogenase/ use of decarboxylase  Formation of Reduced NAD and Reduced FAD Electron transport chain  Correct description of ETC  use of oxygen as final electron acceptor  Use of Reduced NAD and Reduced FAD as source of high energy electrons for ETC  Formation of an EC gradients/ chemiosmosis  subsequent synthesis of ATP by the use of ATP synthase in stalked particles Benefits  Bacteria have a source of pyruvate/oxygen  Constant environment e.g. pH/ water potential  Protection from predation  Eukaryote – increased ATP availability – increased metabolic rate/increased cell division/increased active transport/able to metabolise other respiratory substrates/e.g. fatty acids  Compartmentalisation  Increase in size/ complexity