4 bioenergetics higher (import) class: date: · €€€€€€€€€ plants are grown in...

4 Bioenergetics higher (import)

Name: ________________________

Class: ________________________

Date: ________________________

Time: 56 minutes

Marks: 56 marks

Comments:

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Plants are grown in glasshouses to protect them from the weather or extend the growing season.

Plants make food by photosynthesis.

6CO2 + 6H2O energy from C6H12O6 + 6O2

light glucose

In winter, when days are shorter, glasshouses are heated to keep the enzyme reactions in plantsat optimum rates.

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What else should a grower do to make sure that the plants are photosynthesising at the optimumrate? Give a reason for your answer.

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A young athlete trains and this makes her heart work harder. The table shows part of her trainingrecord.

Time measured in weeksfrom the start of training

0 8 16 24 32 40

Resting pulse rate measuredin pulses per minute

75 69 66 63 61 60

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(i) Give two changes to her heart resulting from this training.

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(ii) The graph shows a smooth curve drawn to match the data from her training record.

Use the graph:

(A) to estimate her resting pulse rate, in pulses per minute, after 18 weeks of training;

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(B) to predict her resting pulse rate, in pulses per minute, if she continues her traininguntil the end of the year.

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(Total 4 marks)

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The graph shows the concentration of carbon dioxide in the air in a greenhouse full of tomatoplants, measured over a period of 24 hours.3

(a) Explain why the concentration of carbon dioxide in the air in the greenhouse increasedbetween X and Y.

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(b) Explain why the concentration of carbon dioxide in the air in the greenhouse decreasedbetween Y and Z.

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(Total 4 marks)

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Some students investigated the effect of light intensity on the rate of photosynthesis.

They used the apparatus shown in Diagram 1.

Diagram 1

The students:

• placed the lamp 10 cm from the pondweed

• counted the number of bubbles of gas released from the pondweed in 1 minute

• repeated this for different distances between the lamp and the pondweed.

(a) The lamp gives out heat as well as light.

What could the students do to make sure that heat from the lamp did not affect the rate ofphotosynthesis?

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(b) The table shows the students’ results.

Distance in cm

Number of bubblesper minute

10 84

15 84

20 76

40 52

50 26

(i) At distances between 15 cm and 50 cm, light was a limiting factor for photosynthesis.

What evidence is there for this in the table?

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(ii) Give one factor that could have limited the rate of photosynthesis when the distancewas between 10 cm and 15 cm.

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(c) In this question you will be assessed on using good English, organising information clearlyand using specialist terms where appropriate.

Diagram 2 shows a section through a plant leaf.

Diagram 2

Describe the structure of the leaf and the functions of the tissues in the leaf.

You should use the names of the tissues in your answer.

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(Total 9 marks)

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(a) Respiration is a process which takes place in living cells. What is the purpose ofrespiration?

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(b) (i) Balance the equation for the process of respiration when oxygen is available.

C6H12O6 + O2 → CO2 + H2O(1)

(ii) What is the name of the substance in the equation with the formula C6H12O6?

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(c) Oxygen is absorbed through the alveoli in the lungs.

(i) How are the alveoli adapted for this function?

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(ii) Name the gas which is excreted through the alveoli.

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(d) (i) What is the name of the process of respiration when oxygen is not available?

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(ii) Describe the process of respiration which takes place in human beings when oxygenis not available and give an effect.

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(Total 10 marks)

The graph shows the effect of temperature on photosynthesis.6

(a) Between which temperatures is the rate of photosynthesis fastest?

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(b) Suggest why the rate of photosynthesis stays the same between these two temperatures.

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(c) A greenhouse owner wants to grow lettuces as quickly and cheaply as possible in winter.

At what temperature should he keep his greenhouse in order to grow the lettuces asquickly and cheaply as possible?

.......................... °C

Explain your answer.

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(Total 6 marks)

The graph shows how the rate of photosynthesis is affected by different conditions.7

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(a) What patterns can you find from this graph?

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(b) How useful could this information be to a grower using glasshouses? Give reasons foryour answer.

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(Total 7 marks)

Marathon runners are recommended to have a high carbohydrate diet prior to a race. Threeathletes tried out three dietary regimes prior to a marathon race.8

These three dietry regimes were as follows.

Athlete A Up to 7 days before the race - Normal mixed diet

7 days before the race - Prolonged extreme physical activity

6-3 days before the race - Protein and fat diet; no carbohydrate

2 and 1 days before the race - Large carbohydrate intake

Athlete B Up to 5 days before race - Normal mixed diet

5 days before the race - Prolonged extreme physical activity

4-1 days before the race - Large carbohydrate intake

Athlete C Up to 4 days before the race - Normal mixed diet

4-1 days before the race - Large carbohydrate intake

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The graph below shows the effect of each of these dietary regimes on glycogen levels in theathletes’ muscles

(a) (i) What is the immediate effect of extreme physical activity on the glycogen content ofmuscles?

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(ii) Describe how this effect occurs.

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(b) (i) Evaluate the three regimes as preparation for a marathon race.

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(ii) Suggest a possible explanation for the different effects of the three regimes.

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(Total 9 marks)

The graph shows the effect of increasing the carbon dioxide content of the inhaled air on:

• the number of breaths per minute;

• the total volume of air breathed per minute.

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(i) Describe the effect of increasing the percentage of carbon dioxide in the inhaled air on thetotal volume of air breathed.

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(ii) Suggest why the total volume of inhaled air is not directly proportional to the number ofbreaths per minute.

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(Total 4 marks)

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Mark schemes

ideaprovide (more) lightprovide (more) CO2 provide (plenty of) waterif any one of these is low it will limit the reaction[Do not allow answers referring to temperature,as optimum is specified in question 3)

any three for 1 mark each[3]

1

(i) any two from

* (heart) more muscular

accept bigger

* (heart) more powerful

accept more efficient

accept stronger2

2

(ii) * pauses longer between (heart) beats

accepts beats more slowly

accept heart rate decreases

* less fast around the heart

recovers more quickly not just ‘heart healthier’

do not credit pulse rate slower2

[4]

(a) respiration

reject start respiring / respire only at night1

no photosynthesis because no light1

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(b) photosynthesis rate greater than respiration rate1

reject no respiration / photosynthesis only

photosynthesis since light1

[4]

(a) any one from:

ignore ‘check temperature’

• add a water bath

• heat screen

• use LED

• low energy bulb / described1

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(b) (i) rate / number of bubbles decreases

accept converse with reference to increasing light or shorterdistance

or

less oxygen / gas released

ignore reference to rate of photosynthesis1

(ii) temperature / CO2 (concentration)

accept ‘it was too cool’ or not enough CO2

accept number of chloroplasts / amount of chlorophyll

allow heat

allow CO2

do not allow CO2

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(c) Marks awarded for this answer will be determined by the Quality of WrittenCommunication (QWC) as well as the standard of the scientific response. Examinersshould also refer to the information in the Marking guidance, and apply a ‘best-fit’approach to the marking.

0 marksNo relevant content.

Level 1 (1-2 marks)There is a brief description of at least 1 tissue or at least 1 function of an indicatedpart of the leaf.

The account lacks clarity or detail.

Level 2 (3-4 marks)There is a clear description which includes at least 1 named tissue and at least 1correct function described for an indicated part of the leaf.

Level 3 (5-6 marks)There is a detailed description of most of the structures and their functions.

Examples of responses:

• epidermis

• cover the plant

• mesophyll / palisade

• photosynthesises

• phloem

• xylem

• transport.

The following points are all acceptable but beyond the scope of thespecification:

• (waxy) cuticle – reduce water loss

• epidermis – no chloroplasts so allows light to penetrate

• stomata / guard cells – allow CO 2 in (and O2 out) or controls water loss

• palisade (mesophyll) – many chloroplasts to trap light

– near top of leaf for receiving more light

• spongy (mesophyll) – air spaces for rapid movement of gases6

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(a) to transfer / provide / give release energy

or production of ATP / adenosine triphosphate (molecules)

accept to give heat1

(b) (i) C6H12O6 + 6O2 → 6CO2 + 6H2O

accept any other

n : 6n : 6n : 6n ratio

do not credit if any other changes have been made1

(ii) glucose

do not credit sugar / sucrose1

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(c) (i) any two from

large surface

thin (surface)

moist (surface)

(with a good) blood supply2

(ii) carbon dioxide

accept water vapour

do not credit just water1

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(d) (i) anaerobic (respiration)1

(ii) any three from

in mitochondria

glucose decomposes / breaks down / reacts

or glucose → lactic acid for (2) marks

to give lactic acid

or breathing hard

or lactic acid → CO2 + water

causing pain

(leaving an) oxygen debt

(quick) source of energy

(but) less efficient than aerobic respiration

accept less efficient than with oxygen3

[10]

(a) 21.5 – 22 and 27 – 27.5

for 1 mark1

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(b) ideas oflimiting factor / shortage ofe.g. light / carbon dioxide / water / chlorophyll

each for 1 mark(allow 1 for ‘maximum / optimum rate of enzyme activity if noreference to limiting factors) (ignore denaturation)

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(c) 21.5 – 22° C

(allow first figure from answer to (i) so that no ‘double-penalty butonly if this first answer is 20 or greater)

maximum rate of photosynthesis / highest / fastest

but related to flat part of curve

most economical heating / cheapest related to heating

must relate to the temperature the candidate has given

each for 1 mark3

[6]

(a) + light = + photosynthesis+ light = + photosynthesis to a limitlimit depends on temp/CO2 levels+ CO2 = + photosynthesis+ temp = + photosynthesis

each for 1 mark5

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(b) need to raise optimum levelswhen one other raisedto get max/economic yield

each for 1 mark2

[7]

(a) (i) reduced sharply

for 1 mark1

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(ii) converted to glucose which is respired to produce energy

(allow answers in terms of glucagon)

gains 3 marks3

(b) (i) athlete A’s was most effectivesince resulted in highest muscle glycogen level on day of racefor energy release during race

for 1 mark each3

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(ii) e.g. excess carbohydrate stored as glycogen rather than fat in short termparticularly if glycogen stores depleted

for 1 mark each2

[9]

(i) increase in CO2 concentration leads to increase in volume of air inhaledincrease of % carbon dioxide has little effect over most of range / largeincrease when % carbon dioxide > 5.6 %

each for 1 mark2

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(ii) idea thatdepth of breathing changes at low % carbon dioxide, in crease in % CO2

results in volume of each breath increasing without increase / little increasein number of breaths

each for 1 mark2

[4]

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4 bioenergetics higher (import) class: date: · €€€€€€€€€ plants are grown in...

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