Respiration and Photosynthesis - Worksheets, Questions and Revision

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KS3 · Biology

K3 Respiration and Photosynthesis

AQA KS3 AQA KS3 Science · Calculator allowed · about 65 minutes

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

Photosynthesis is the process plants use to make food. Complete the word equation for photosynthesis:
carbon dioxide + water --(a)--> glucose + (b)

(a)Name the type of energy that should be written above the arrow.(1)

(b)Name the missing product of photosynthesis.(1)

(c)State the green substance found in chloroplasts that absorbs light energy for photosynthesis.(1)

Complete the word equation for aerobic respiration:
glucose + (a) -> carbon dioxide + (b) (+ energy released)

(a)Name the missing reactant.(1)

(b)Name the missing product.(1)

(c)State one place in a cell where most of the reactions of aerobic respiration take place.(1)

Choose the correct letter for each question about cells and gas exchange.

(a)Which organelle is the main site of photosynthesis?(1)

A) Nucleus
B) Mitochondrion
C) Chloroplast
D) Ribosome

(b)Which organelle is the main site of aerobic respiration?(1)

A) Chloroplast
B) Mitochondrion
C) Vacuole
D) Cell wall

(c)Which gas is taken in by a leaf mainly to be used for photosynthesis during daylight?(1)

A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Water vapour

(d)Which structures on the underside of a leaf allow gases to enter and leave?(1)

A) Stomata
B) Xylem
C) Phloem
D) Root hairs

Distinguish between breathing and respiration.

(2)

Complete the missing cells in the table comparing aerobic respiration with anaerobic respiration in human muscle and in yeast.

Feature	Aerobic respiration	Anaerobic respiration (human muscle)	Anaerobic respiration (yeast)
Oxygen needed?	Yes	(a)	(b)
Products (other than energy)	(c)	(d)	(e)
Amount of energy released	(f)	small amount	small amount

(a)Oxygen needed in human muscle anaerobic respiration?(1)

(b)Oxygen needed in yeast anaerobic respiration?(1)

(c)Products of aerobic respiration (other than energy).(1)

(d)Product of anaerobic respiration in human muscle.(1)

(e)Products of anaerobic respiration in yeast.(1)

(f)Amount of energy released by aerobic respiration, relative to anaerobic respiration.(1)

Balanced symbol equations show the same number of atoms of each element on both sides.

(a)Complete the balanced symbol equation for aerobic respiration by writing in the missing number:
C6H12O6 + 6O2 -> ___CO2 + 6H2O(1)

(b)Complete the balanced symbol equation for photosynthesis by writing in the two missing numbers:
___CO2 + ___H2O -> C6H12O6 + 6O2(2)

(c)State why these equations are described as balanced.(1)

Required practical: A student tests a geranium leaf to find out whether it contains starch, using iodine solution.

(a)State why the plant should be left in the dark for 24 to 48 hours before the test (destarching).(1)

(b)Put these four steps of the starch test in the correct order by writing 1 to 4:
Rinse the leaf in cold water
Boil the leaf in ethanol using a water bath
Add iodine solution to the leaf
Boil the leaf in water(2)

(c)Explain why the leaf is boiled in ethanol using a water bath rather than directly over a Bunsen flame.(2)

(d)State the colour change that shows starch is present when iodine solution is added.(1)

(e)A destarched leaf kept in bright light for several hours is compared with a destarched leaf kept in the dark for the same time. Predict and explain the difference in the iodine test result between the two leaves.(2)

A pupil counted the number of bubbles of gas given off by a piece of pondweed in one minute. She repeated the count three times.
Repeat 1: 18 bubbles per minute
Repeat 2: 20 bubbles per minute
Repeat 3: 31 bubbles per minute

(a)Identify the anomalous result.(1)

(b)Calculate the mean number of bubbles per minute, excluding the anomalous result.(2)

(c)Suggest one reason why repeat 3 might be an anomalous result.(1)

(d)Give one disadvantage of counting bubbles compared with measuring the volume of gas produced using a gas syringe.(1)

Required practical: A group of students investigates how the distance of a lamp from pondweed affects the rate of photosynthesis, by counting bubbles of oxygen produced per minute.
Distance from lamp (cm): 10, 20, 40
Rate of bubble production (bubbles/min): 32, 8, 2

(a)Identify two variables, other than distance, that should be controlled in this investigation.(2)

(b)State the independent variable and the dependent variable in this investigation.(2)

(c)Describe the relationship between distance from the lamp and rate of photosynthesis shown in the table.(1)

(d)Show that the rate of photosynthesis is inversely proportional to the square of the distance for the data given.(3)

A gardener grows tomato plants in a heated, well-lit glasshouse in winter. The rate of photosynthesis is measured at three carbon dioxide concentrations, with light intensity and temperature kept constant at optimal levels.
CO2 concentration (ppm): 400, 800, 1200
Rate of photosynthesis (arbitrary units): 10, 18, 19

(a)Describe how the rate of photosynthesis changes as CO2 concentration increases from 400 ppm to 1200 ppm.(2)

(b)Explain, in terms of limiting factors, why the rate of photosynthesis does not keep increasing between 800 ppm and 1200 ppm.(2)

A market gardener grows cucumbers in a glasshouse. She burns a paraffin heater, which releases carbon dioxide, and uses artificial lighting on dull days.
Explain how increasing carbon dioxide concentration and increasing light intensity can each affect the rate of photosynthesis in the cucumber plants, and why increasing carbon dioxide concentration will not always increase the rate of photosynthesis.

(6)

During the day, a green plant photosynthesises and respires at the same time.

(a)Name the gas produced by photosynthesis that is used by respiration.(1)

(b)Name the gas produced by respiration that is used by photosynthesis.(1)

(c)At a certain light intensity, the rate of photosynthesis exactly equals the rate of respiration in the plant. Explain why, at this point, no net gas exchange with the air outside the leaf is measured.(2)

A student measures the dry mass of a young sunflower seedling at the start of an experiment and again 4 weeks later, while it grows in sunlight.
Start dry mass: 0.40 g
Dry mass after 4 weeks: 2.20 g

(a)Calculate the increase in dry mass of the seedling over the 4 weeks.(1)

(b)Calculate the percentage increase in dry mass over the 4 weeks. Give your answer to 1 decimal place.(3)

(c)State the main biological process responsible for this increase in dry mass.(1)

During a 100 m sprint, an athlete's muscles cannot get enough oxygen to meet demand, so they respire anaerobically as well as aerobically.

(a)Name the substance produced in human muscle cells during anaerobic respiration.(1)

(b)Explain why anaerobic respiration cannot continue in muscles for a long period of time.(2)

(c)After the race, the athlete continues to breathe quickly and deeply for several minutes. Explain why.(2)

A group of students investigates how temperature affects the rate of anaerobic respiration (fermentation) in yeast. They mix yeast with a glucose solution in a boiling tube connected to a gas syringe, and measure the volume of gas produced in 5 minutes at different temperatures.
Temperature (deg C): 20, 30, 40, 50
Volume of gas produced in 5 min (cm3): 6, 14, 22, 4

(a)Identify the gas produced by the yeast during fermentation.(1)

(b)Describe the pattern shown by the results as temperature increases from 20 deg C to 50 deg C.(2)

(c)Explain the result at 50 deg C, in terms of enzymes.(2)

(d)Suggest one variable, other than temperature, that should be kept the same in each test tube to make this a fair test.(1)

Choose the correct letter for each question.

(a)Which structure allows carbon dioxide to enter a leaf?(1)

A) Xylem
B) Stomata
C) Phloem
D) Cuticle

(b)Which cells contain the most chloroplasts in a leaf?(1)

A) Epidermal cells
B) Guard cells
C) Palisade mesophyll cells
D) Root hair cells

(c)Which plant tissue transports the glucose made in photosynthesis to other parts of the plant?(1)

A) Xylem
B) Phloem
C) Stomata
D) Cambium

(d)Which statement best describes chlorophyll?(1)

A) A gas used in respiration
B) A green pigment that absorbs light energy
C) A sugar produced by photosynthesis
D) An enzyme that breaks down starch

A gas syringe collected 45 cm3 of carbon dioxide from a fermenting yeast culture in 9 minutes.
Show that the mean rate of gas production was 5 cm3 per minute.

(3)

The rate of photosynthesis of a plant was measured at increasing light intensities, once in normal air (0.04% CO2) and once in air enriched with extra carbon dioxide (0.4% CO2). Temperature was kept constant and optimal throughout.
Light intensity (units): 0, 20, 40, 60, 80
Rate with normal CO2 (units): 0, 8, 14, 15, 15
Rate with extra CO2 (units): 0, 8, 14, 19, 24

(a)Compare the two sets of results at a light intensity of 40 units, and explain what this shows about the limiting factor at this point.(2)

(b)Compare the two sets of results at a light intensity of 80 units, and explain what this shows about the limiting factor for the plant in normal air.(2)

(c)Predict what would happen to the rate of photosynthesis in the extra CO2 condition if the light intensity were increased further beyond 80 units, assuming CO2 remained unlimited.(1)

Describe five ways in which the structure of a leaf is adapted for efficient photosynthesis. For each adaptation, briefly explain its function.

(5)

Aerobic respiration of a given amount of glucose releases approximately 2900 kJ of energy. Anaerobic respiration (lactic acid fermentation) of the same amount of glucose releases only about 150 kJ of energy, because the glucose is only partially broken down.
Calculate the percentage of the aerobic energy yield that is released by anaerobic respiration of the same amount of glucose. Give your answer to the nearest whole per cent.

(3)

Mark scheme · K3 Respiration and Photosynthesis

Question 1

(a) B1 light (energy)
(a) Answer: light energy
(b) B1 oxygen
(b) Answer: oxygen
(c) B1 chlorophyll
(c) Answer: chlorophyll

Question 2

(a) B1 oxygen
(a) Answer: oxygen
(b) B1 water
(b) Answer: water
(c) B1 mitochondria (mitochondrion)
(c) Answer: mitochondria

Question 3

(a) B1 C (Chloroplast)
(a) Answer: C
(b) B1 B (Mitochondrion)
(b) Answer: B
(c) B1 C (Carbon dioxide)
(c) Answer: C
(d) B1 A (Stomata)
(d) Answer: A

Question 4

B1 breathing (ventilation) is the physical movement of air/gases into and out of the lungs
B1 respiration is the chemical reaction inside cells that releases energy from glucose
Answer: Breathing is the physical movement of air in and out of the lungs; respiration is the chemical process in cells that releases energy from glucose.

Question 5

(a) B1 no
(a) Answer: no
(b) B1 no
(b) Answer: no
(c) B1 carbon dioxide and water
(c) Answer: carbon dioxide and water
(d) B1 lactic acid
(d) Answer: lactic acid
(e) B1 ethanol (alcohol) and carbon dioxide
(e) Answer: ethanol and carbon dioxide
(f) B1 a large amount / much more energy (glucose is completely broken down)
(f) Answer: large amount

Question 6

(a) B1 6 (cao)
(a) Answer: 6
(b) B1 6CO2 (cao)
(b) B1 6H2O (cao)
(b) Answer: 6CO2 and 6H2O
(c) B1 the same number of atoms of each element appears on both sides (reactants and products)
(c) Answer: Same number of atoms of each element on both sides.

Question 7

(a) B1 to remove/use up any starch already stored in the leaf, so any starch found later must have been made during the test
(a) Answer: To remove existing starch so results show only new starch made in the experiment.
(b) B1 Boil in water (1) and Boil in ethanol (2) correctly placed
(b) B1 Rinse in cold water (3) and Add iodine (4) correctly placed
(b) Answer: 1) Boil in water 2) Boil in ethanol (water bath) 3) Rinse in cold water 4) Add iodine solution
(c) B1 ethanol is flammable
(c) B1 a water bath heats the ethanol gently without a naked flame nearby, reducing the risk of the ethanol vapour catching fire
(c) Answer: Ethanol is flammable, so a water bath heats it safely without a naked flame that could ignite the vapour.
(d) B1 orange/brown changes to blue-black
(d) Answer: orange/brown to blue-black
(e) B1 the leaf kept in the light turns blue-black because it has photosynthesised and made starch
(e) B1 the leaf kept in the dark stays orange/brown because no photosynthesis occurred without light, so no starch was made
(e) Answer: Light leaf: blue-black (starch made). Dark leaf: orange/brown (no starch made, no photosynthesis).

Question 8

(a) B1 31 (repeat 3)
(a) Answer: Repeat 3 (31 bubbles/min)
(b) M1 (18 + 20) / 2
(b) A1 19 (cao)
(b) Answer: 19 bubbles per minute
(c) B1 e.g. two or more bubbles stuck together and were released/counted at once; miscounted; a change in conditions (light/temperature) during that repeat
(c) Answer: Bubbles may have merged and been counted together, or conditions changed during that repeat.
(d) B1 bubbles vary in size, so counting bubbles is not an accurate measure of the actual volume of gas produced
(d) Answer: Bubbles are not all the same size, so counting them is less accurate than measuring gas volume directly.

Question 9

(a) B1 temperature of the water
(a) B1 concentration/volume of dissolved carbon dioxide (e.g. sodium hydrogencarbonate solution), or species/length of pondweed, or time allowed for counting
(a) Answer: e.g. temperature of the water and concentration of dissolved carbon dioxide
(b) B1 independent variable: distance of the lamp from the pondweed
(b) B1 dependent variable: rate of bubble production (rate of photosynthesis)
(b) Answer: Independent: distance from lamp. Dependent: rate of bubble production.
(c) B1 as distance increases, rate of photosynthesis decreases (the relationship is not linear/proportional)
(c) Answer: As distance increases, the rate of photosynthesis decreases.
(d) M1 calculates distance squared for each distance: 100, 400, 1600
(d) M1 calculates rate x distance² for each row: 32x100=3200, 8x400=3200, 2x1600=3200
(d) A1 cso: all three values equal 3200, showing rate x d² is constant, so rate is inversely proportional to d²
(d) Answer: Rate x distance² = 3200 in every case, so rate is inversely proportional to d².

Question 10

(a) B1 rate increases quickly from 400 ppm to 800 ppm
(a) B1 rate then levels off (little further increase) between 800 ppm and 1200 ppm
(a) Answer: Rate rises from 400 to 800 ppm, then levels off from 800 to 1200 ppm.
(b) B1 carbon dioxide is no longer the limiting factor at this point
(b) B1 a different factor (e.g. light intensity or temperature) is now limiting the rate of photosynthesis
(b) Answer: CO2 is no longer limiting; another factor, such as light intensity or temperature, now limits the rate.

Question 11

Level 1 (1-2): Basic, isolated statements about factors needed for photosynthesis (e.g. light or carbon dioxide is needed), with little or no reference to the idea of a limiting factor. Limited use of scientific vocabulary.
Level 2 (3-4): A clear explanation of how increasing light intensity or carbon dioxide concentration increases the rate of photosynthesis while that factor is limiting, with some reference to another factor eventually becoming limiting.
Level 3 (5-6): A full, logically linked explanation covering both light intensity and carbon dioxide concentration, correctly applying the concept of limiting factors, and clearly explaining why the rate levels off once a different factor becomes limiting, related to the glasshouse context.
Indicative content:
- Photosynthesis requires light energy, carbon dioxide, water and chlorophyll, and produces glucose and oxygen
- Increasing light intensity increases the rate of photosynthesis because more light energy is available to drive the reaction, as long as light intensity is the limiting factor
- Increasing carbon dioxide concentration increases the rate of photosynthesis because carbon dioxide is a raw material, as long as carbon dioxide is the limiting factor
- Whichever factor is in shortest supply relative to what is needed limits the overall rate (the limiting factor)
- Beyond a certain point, carbon dioxide (or light) is no longer limiting, so a different factor, such as temperature or the other resource, becomes limiting and the rate levels off
- A paraffin heater releases both carbon dioxide and heat, so it can raise temperature as well as carbon dioxide concentration, which may allow the rate to increase further if temperature was previously limiting
- Very high temperatures can denature the enzymes controlling photosynthesis reactions, reducing the rate, so there is an optimum temperature
- The market gardener aims to keep all factors (light, carbon dioxide, temperature) close to optimum together, rather than increasing only one, in order to maximise yield

Question 12

(a) B1 oxygen
(a) Answer: oxygen
(b) B1 carbon dioxide
(b) Answer: carbon dioxide
(c) B1 all the carbon dioxide produced by respiration is used up by photosynthesis (and all the oxygen produced by photosynthesis is used up by respiration)
(c) B1 so there is no overall (net) uptake or release of either gas between the plant and the surrounding air
(c) Answer: Respiration and photosynthesis exactly balance, so all gases produced by one process are used by the other, giving no net exchange.

Question 13

(a) B1 1.80 g (cao)
(a) Answer: 1.80 g
(b) M1 correct method: (increase / original mass) x 100
(b) M1 1.80 / 0.40 = 4.5
(b) A1 450.0% (cao, 1 dp)
(b) Answer: 450.0%
(c) B1 photosynthesis (production of glucose/biomass from carbon dioxide and water using light energy)
(c) Answer: photosynthesis

Question 14

(a) B1 lactic acid
(a) Answer: lactic acid
(b) B1 lactic acid builds up in the muscles
(b) B1 this causes muscle fatigue/cramp/pain, reducing muscle function
(b) Answer: Lactic acid builds up in the muscles, causing fatigue and cramp, so the muscle cannot keep working anaerobically for long.
(c) B1 to take in extra oxygen to repay the oxygen debt
(c) B1 the extra oxygen is used to break down (oxidise) the lactic acid that built up in the muscles during the sprint
(c) Answer: The athlete takes in extra oxygen to repay the oxygen debt, which is used to break down the lactic acid produced during the sprint.

Question 15

(a) B1 carbon dioxide
(a) Answer: carbon dioxide
(b) B1 volume of gas produced increases from 20 deg C up to 40 deg C
(b) B1 volume of gas produced then decreases sharply at 50 deg C
(b) Answer: Gas volume rises from 20 to 40 deg C, then falls sharply at 50 deg C.
(c) B1 the high temperature denatures the enzymes in the yeast cells (changes the shape of the enzyme's active site)
(c) B1 denatured enzymes can no longer catalyse the respiration reactions effectively, so the rate of gas production falls
(c) Answer: At 50 deg C the yeast's enzymes denature, so they can no longer catalyse fermentation efficiently and gas production falls.
(d) B1 e.g. concentration/volume of glucose solution, mass/volume of yeast used, or time allowed for gas collection
(d) Answer: e.g. concentration of glucose solution kept the same in each tube.

Question 16

(a) B1 B (Stomata)
(a) Answer: B
(b) B1 C (Palisade mesophyll cells)
(b) Answer: C
(c) B1 B (Phloem)
(c) Answer: B
(d) B1 B
(d) Answer: B

Question 17

M1 rate = volume / time
M1 45 / 9
A1 cso: = 5 cm3/min, matching the value given
Answer: 5 cm3 per minute

Question 18

(a) B1 the rate is the same (14 units) in both normal and extra CO2 conditions
(a) B1 this shows that light intensity, not CO2 concentration, is the limiting factor at this point, since extra CO2 makes no difference
(a) Answer: Rates are identical (14 units), showing light intensity is limiting, not CO2, at this point.
(b) B1 in normal air the rate has levelled off at 15, while with extra CO2 the rate is higher and still rising, at 24
(b) B1 this shows that CO2 concentration is now the limiting factor for the plant in normal air, since adding more CO2 allows a higher rate at the same light intensity
(b) Answer: Normal air plateaus at 15, extra CO2 reaches 24, showing CO2 is now limiting in normal air.
(c) B1 the rate would eventually level off (plateau) as some other factor, such as temperature or enzyme availability, becomes limiting
(c) Answer: The rate would eventually plateau as another factor, such as temperature, becomes limiting.

Question 19

B1 broad/large surface area, to absorb more light
B1 thin, giving a short diffusion distance for gases and allowing light to penetrate to all cells
B1 many stomata (mainly on the lower surface), allowing carbon dioxide to diffuse in efficiently
B1 palisade mesophyll cells packed with chloroplasts near the upper surface, to absorb the maximum amount of light
B1 a network of veins (xylem and phloem): xylem brings water for photosynthesis, phloem removes the glucose produced (accept air spaces in spongy mesophyll allowing gases to circulate, or a transparent waxy cuticle allowing light through)
Answer: Any five of: large surface area, thinness, many stomata, palisade cells packed with chloroplasts, network of veins/xylem and phloem, air spaces in spongy mesophyll, transparent cuticle - each linked to its function.

Question 20

M1 percentage = (150 / 2900) x 100
M1 = 5.17... (or equivalent unrounded value)
A1 awrt 5%
Answer: approximately 5%

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Respiration and Photosynthesis - Worksheets, Questions and Revision

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