October 2020 Component 1 Past Paper

Question 1

Describe the absorption spectrum of chlorophyll a (2)

Answer 1

. Absorption peaks at blue and red
. Less absorption in green
Or (state the nm)

Question 2

Explain the properties of how the position of the head and tail of chlorophyll molecule result in its position in the photosynthetic membrane. Suggest an advantage of the position of the chlorophyll molecule (3)

Answer 2

. Hydrophobic tail + fatty acid hydrophobic regions membrane
. Head hydrophilic
. Holds chloroplast head in optimum position for absorption of light

Question 3

State one element other than carbon hydrogen and oxygen that is found in chlorophyll molecule (1)

Answer 3

Nitrogen / magnesium

Question 4

Explain why cells are found at depth between 150-200m produce chlorophyll b but not chlorophyll a (2)

Answer 4

. No light for chlorophyll a
. Chlorophyll b absorb in blue region of spectrum only light to penetrate this depth

Question 5

With reference to the size of the organism explain how prochlorococcus is able to gain sufficient mineral from nutrient poor water (3)

Answer 5

. Has a very large SA : Vol ratio
. Larger area for nutrient to diffuse
. Small diameter
. Short diffusion distance

Question 6

Explain why this staining technique indicates about the structure of the cell wall of prochlorococcus (1)

Answer 6

. Gram negative + outer lipopolysaccharide layer

Question 7

State 2 features of genetic code (2)

Answer 7

. Linear
. Triplet
. Overlapping
. Degenerate
. Universal code

Question 8

State how many gene code for polypeptide found in RuBisCO molecule (1)

Answer 8

2

Question 9

State the names of 2 substrates that forms an enzyme substrate complex (2)

Answer 9

CO2 and RUBP

Question 10

The first 3-carbon phosphorylated sugar produced by Calvin cycle (1)

Answer 10

Triose phosphate

Question 11

State what is meant by substrate level phosphorylation (2)

Answer 11

. Energy is derived directly from a reaction / break down of substrate
. To combine ADP and Pi

Question 12

Outline the process of chemiosmosis in an animal cell (3)

Answer 12

. H+ flows from intermembrane space to matrix
. through stalked particle
. Energy provide to ATP synthase
. ADP +Pi = ATP

Question 13

Explain how an ATP molecule could act as a non-competitive inhibitor(2)

Answer 13

. ATP binds to allosteric site
. Changes shape of active site

Question 14

Explain how capsaicin reduces ATP production by BAT cells (2)

Answer 14

. Less proton gradient
. Therefore there are less proton to ATP synthetase so produces less ATP

Question 15

Using all the info provided suggest why eating red chilli peppers causes sweating and redding to the neck shoulders and chest (3)

Answer 15

. Pepper increases release of heat energy
. Increased sweating to reduce body temperature
. BAT cells are found in the neck, shoulder and chest
. Increased blood flow causing reddening

Question 16

Explain how the shape of the estimated population graph shown in image 4.1 between the following dates (3)

Answer 16

1850-1950 : stationary phase/ carrying capacity
1970 -1990 : rapid population decline
1990 -2010: population recovery and due to banning of cod fishing

Question 17

Evaluate the effectiveness of using this minimum mesh size allowing the recovery of the cod population (4)

Answer 17

. Would have very little effect
. Bigger mesh size still catches older fish
. Egg production reaches maximum of 12 years
. Older fish produces far more eggs

Question 18

Give 2 method to prevent overfishing (1)

Answer 18

. Reduce number of boats
. Seasonal restrictions
. Fishing quotas
. Having protected areas where no fishing

Question 19

Use ur knowledge of fish farming to conclude how fish farming can impact the ecosystem in the surrounding areas (5)

Answer 19

. More cod in a restricted area
. Results increase level of ammonia because of excretion
. Eutrophication
. Nitrates Increased rate of algae
. Increased CO2 level
. Nutrient impact on number in food chain

Question 20

Following bottom trawling organism populate the area. Identify the type of succession that result in the repopulation and give 2 reason for answer (3)

Answer 20

. Secondary succession
. Organic matter still present
. Seed and roots still present

Question 21

Calculate number of colonies (1)

Answer 21

8.7 *10^6

Question 22

Explain why number of colonies on plates C and E will not be used to calculate the number of bacteria (2)

Answer 22

C - overlapping
E - error in count cause a large percentage error

Question 23

Explain why it is essential that the plates are all cultured using exactly the same culture medium and incubation period (2)

Answer 23

. Different nutrient would affect growth rate
. Differnt incubation period would result in different colony size
. Variation of controlled variables will affect DV

Question 24

At the end of the investigation all plates were autoclaved. State one condition produced by the autoclave which result in sterilisation of plates (1)

Answer 24

. Temperature above boiling point

Question 25

Suggest 2 suitable condition for incubation in order to culture human gut bacteria (2)

Answer 25

. 37C . Anaerobic

Question 26

Explain why the tap is open when the apparatus is assembled (1)

Answer 26

Prevent colour fluid from being pushed out

Question 27

The tap is not closed until 5 min after setting up (1)

Answer 27

Equilibration of pressure inside apparatus

Question 28

Explain why you would expect the meniscus to move in the direction of the arrow (2)

Answer 28

. CO2 levels go up . Pressure goes up / pushes meniscus down

Question 29

Suggest a suitable control experiment and explain why a control is necessary (3)

Answer 29

. Repeated with boiled and cooked Yeast . Keep all other condition the same . Control required to show the effects are being caused by yeast and no other factor

Question 30

State what the standard deviation indicated about the data and comment on the values for 3 sugar in this experiment (3)

Answer 30

. Standard deviation indicates deviation from the mean . Smaller SD more reliable result . Fructose results least reliable + glucose the most

Question 31

Explain why the respiratory rate is much slower when yeast uses sucrose as the respiratory substrate (2)

Answer 31

. Sucrose is a disaccharide . Must be broken down / hydrolysed

Question 32

Predict what would happen to the position of the meniscus if the yeast was only carrying out aerobic respiration (2)

Answer 32

. Would not move . Equal volume of carbon dioxide produced as oxygen is not used / no net change in volume

Question 33

9 marker

Answer 33

A. Energy flow and loss at each trophic level, • Energy from the sun converted into energy in organic molecules by plants/ GPP • Plant breaks down sugars by respiration/ NPP • Energy in form of organic molecules is then passed from one trophic level to the next through the food chain when organisms are eaten. • Energy lost by plants e.g. energy lost by radiation/ reflection (not all wavelengths absorbed/ heat of evaporation. • Energy lost by animals e.g. Respiration/ Excretion/ Egestion; Energy which is left in form of organic molecules are stored or used for growth and available for the next trophic level. B. Efficiency of transfer: • Cellulose and lignin not easy to digest. • Large loss by egestion. • Protein and fats easy to digest, very little energy lost by egestion. • Higher energy lost by excretion ref urea. Egestion bone feathers. • High respiratory rate energy for movement. C- Grow varieties of autotrophs with higher GPP. • Breed animals with higher efficiency; • Animal feeds with less cellulose; • high energy supplements; • Reduce respiration by e.g. Reducing movement/ Warm buildings • Disease free;