Plant Nutrition: IGCSE Biology questions and answers
10 free IGCSE Biology Plant Nutrition questions written in the style of Cambridge Biology papers: 3 multiple-choice and 7 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers Photosynthesis, Leaf structure, Mineral requirements. Work through the questions below, then generate a full Plant Nutrition paper with a fresh set every time.
The rate of photosynthesis is measured at increasing light intensities, first at low and then at high carbon dioxide concentration. At high light intensity the rate is greater at the high carbon dioxide concentration. 1 At high light intensity, carbon dioxide concentration was limiting the rate. 2 At high light intensity, light intensity was limiting the rate. 3 At low light intensity, light was the limiting factor. Which statements are correct?
A 1, 2 and 3
B 1 and 3 only
C 1 only
D 3 only
Show answer
Answer: B
Question 2Multiple choice · 1 markA* challenge
Which row shows why plants need nitrate ions and magnesium ions?
nitrate ions
magnesium ions
A
to make chlorophyll
to make amino acids
B
to make glucose
to make chlorophyll
C
to make amino acids
to make starch
D
to make amino acids
to make chlorophyll
Show answer
Answer: D
Question 3Multiple choice · 1 markA* challenge
A leaf is adapted for photosynthesis. 1 Most stomata are on the upper surface of the leaf. 2 Xylem in the vascular bundle brings water to the leaf. 3 The upper epidermis cells contain many chloroplasts. Which statements are correct?
A 1 and 2 only
B 2 and 3 only
C 1 only
D 2 only
Show answer
Answer: D
Question 4Structured · 3 marksA* challenge
The upper epidermis of a leaf has a waxy cuticle.
(a)
Explain the function of the waxy cuticle.
[1]
(b)
Explain why most stomata are on the lower surface of the leaf.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
reduces water loss
reduces water loss by evaporation B1
1
(b)
cooler, less water loss
the lower surface is cooler and shaded B1 less water is lost by transpiration B1
2
Question 5Structured · 5 marks
Photosynthesis takes place in the chloroplasts of leaf cells.
(a)
Write the word equation for photosynthesis.
[2]
(b)
Describe the role of chlorophyll.
[1]
(c)
State two uses of the glucose made in photosynthesis.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
carbon dioxide + water → glucose + oxygen (light, chlorophyll)
carbon dioxide + water → glucose + oxygen B1 in the presence of light and chlorophyll B1
2
(b)
absorbs light energy
absorbs light energy (to make it available for photosynthesis) B1
1
(c)
respiration; starch; cellulose; sucrose
Any 2 of: respiration; stored as starch; cellulose for cell walls; converted to sucrose for transport B2
2
Question 6Structured · 13 marks
A student investigates the effect of light intensity on the rate of photosynthesis of a water plant by counting the bubbles of gas released per minute. Fig. 6.1 shows the results.
Fig. 6.1
(a)
Describe the effect of light intensity on the rate of photosynthesis shown in Fig. 6.1.
[2]
(b)
Use Fig. 6.1 to find the rate of photosynthesis at a light intensity of 25 units.
[1]
(c)
Calculate the percentage increase in the rate when the light intensity increases from 20 to 40 units.
[2]
(d)
Suggest which factor limits the rate of photosynthesis at light intensities above 80 units. Explain your answer.
[2]
(e)
State two variables, other than light intensity, that the student should keep constant.
[2]
(f)
Suggest why counting bubbles may not give an accurate measure of the rate of photosynthesis.
[2]
(g)
Write the balanced chemical equation for photosynthesis.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
rate increases then levels off
rate increases as light intensity increases (up to about 50–60 units) B1 then levels off / stays constant (allow data quote) B1
2
(b)
29 bubbles per minute
29 ± 1 bubble per minute B1
1
(c)
35 %
(34.5 − 25.5) ÷ 25.5 × 100 C1 35 % (allow ± 5 %, ft their readings) A1
2
(d)
carbon dioxide concentration / temperature
carbon dioxide concentration / temperature B1 increasing light intensity has little or no further effect on the rate (the curve levels off), so light is no longer the limiting factor B1
2
(e)
temperature; CO₂ concentration; plant / species; time
Any 2 of: temperature; carbon dioxide (hydrogencarbonate) concentration; same plant / length of plant; time of counting B2
2
(f)
bubbles different sizes; some O₂ used in respiration / dissolves
Any 2 of: bubbles are not all the same size / volume; some oxygen is used in respiration or dissolves in the water; bubbles hard to count at high rates B2
2
(g)
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
correct formulae B1 balanced (light and chlorophyll may be written over the arrow) B1
2
Question 7Structured · 12 marks
A farmer grows tomatoes in a glasshouse.
(a)
Name the limiting factors of photosynthesis that the farmer can control in a glasshouse.
[3]
(b)
Explain why the farmer burns paraffin in the glasshouse in winter.
[3]
(c)
Explain why increasing the temperature above about 35 °C reduces the rate of photosynthesis.
[2]
(d)
The farmer adds a fertiliser containing nitrate ions. Explain why plants need nitrate ions.
[2]
(e)
Describe the appearance of a plant lacking nitrate ions and of a plant lacking magnesium ions.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
light intensity; carbon dioxide concentration; temperature
light intensity B1 carbon dioxide concentration B1 temperature B1
3
(b)
releases CO₂ and heat; increases two limiting factors; more photosynthesis, higher yield
burning paraffin releases carbon dioxide and thermal energy B1 increasing CO₂ concentration and temperature (both limiting factors) B1 so the rate of photosynthesis and the yield increase B1
3
(c)
enzymes denatured
enzymes controlling photosynthesis are denatured B1 above their optimum temperature B1
2
(d)
to make amino acids / proteins for growth
nitrate is needed to make amino acids B1 which are used to make proteins for growth B1
nitrate deficiency: poor / stunted growth with yellow older leaves B1 magnesium deficiency: yellow leaves (chlorosis) because chlorophyll is not made B1
2
Question 8Structured · 4 marks
Plants need mineral ions from the soil.
(a)
State why plants need nitrate ions and magnesium ions.
[2]
(b)
Describe the symptoms of magnesium deficiency.
[1]
(c)
Describe the symptoms of nitrate deficiency.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
amino acids/proteins; chlorophyll
nitrate: to make amino acids/proteins B1 magnesium: to make chlorophyll B1
2
(b)
yellowing leaves
yellow leaves (chlorosis), especially between the veins / older leaves B1
1
(c)
stunted growth, yellow lower leaves
Any 1 of: stunted growth; yellowing of older leaves B1
1
Question 9Structured · 12 marks
A student places a piece of pondweed in water at different distances from a lamp and counts the bubbles released in one minute.
distance from lamp / cm
10
20
30
40
50
bubbles per minute
45
45
27
15
10
Table 9.1
(a)
Write the balanced chemical equation for photosynthesis.
[2]
(b)
Name the gas in the bubbles.
[1]
(c)
Describe and explain the effect of distance from the lamp on the rate of photosynthesis.
[3]
(d)
At 10 cm the rate does not increase further. Suggest which factor is limiting the rate at this distance, and explain.
[2]
(e)
State two variables the student should keep constant.
[2]
(f)
Explain why counting bubbles is not an accurate way to measure the rate of photosynthesis, and suggest a better method.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
correct formulae B1 balanced B1
2
(b)
oxygen
oxygen B1
1
(c)
closer lamp, more bubbles; higher light intensity; light is the limiting factor
Any 3 of: as distance increases the number of bubbles decreases; light intensity decreases with distance; light is the limiting factor; data quote B3
3
(d)
carbon dioxide concentration or temperature
carbon dioxide concentration / temperature B1 increasing light no longer increases the rate so another factor is in short supply B1
2
(e)
temperature; CO₂ concentration; same pondweed; time
Any 2 of: temperature (use a water bath / heat filter); carbon dioxide concentration (add same mass of hydrogen carbonate); same piece of pondweed; same counting time B2
2
(f)
bubbles vary in size; collect gas in a syringe / measure volume
bubbles are of different sizes / some oxygen dissolves B1 collect the gas in a gas syringe / capillary tube and measure its volume B1
2
Question 10Structured · 14 marks
This question is about photosynthesis.
(a)
Write the balanced chemical equation for photosynthesis.
[2]
A student measures the rate of photosynthesis of pondweed by counting bubbles at different light intensities, at 15 °C and at 25 °C. At low light intensity both temperatures give the same rate. At high light intensity the rate at 25 °C is greater than at 15 °C, and each rate levels off.
(b)(i)
State the limiting factor at low light intensity.
[1]
(ii)
Explain why the rate levels off at high light intensity at 15 °C.
[2]
(iii)
Suggest two variables that the student should keep constant.
[2]
(iv)
Suggest one reason why counting bubbles is not an accurate method.
[1]
(c)
Describe how the structure of a leaf is adapted for photosynthesis.
[4]
(d)
A plant is grown in soil that is short of magnesium ions. State and explain the effect.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
correct formulae B1 balanced B1
2
(b)(i)
light intensity
light intensity B1
1
(ii)
another factor limiting (temperature / CO₂); enzymes working slowly
light is no longer the limiting factor B1 temperature (or carbon dioxide concentration) is limiting / enzymes work slowly B1
2
(iii)
carbon dioxide concentration; size/mass of pondweed; same species; time of counting
Any 2 of: carbon dioxide concentration (amount of hydrogencarbonate); same piece / mass of pondweed; volume of water; time allowed to acclimatise; time of counting B2
2
(iv)
bubbles vary in size
bubbles are different sizes / are hard to count / some oxygen dissolves B1
1
(c)
thin, large surface area; palisade with many chloroplasts near top; air spaces in spongy mesophyll; stomata; xylem and phloem in veins
large surface area to absorb light B1 thin so short diffusion distance for CO₂ B1 palisade mesophyll cells with many chloroplasts near the upper surface B1 air spaces and stomata for gas exchange / veins bring water B1
4
(d)
yellow leaves (chlorosis); magnesium needed to make chlorophyll
leaves turn yellow (between veins) B1 magnesium is needed to make chlorophyll B1
In the 0610 syllabus, Plant Nutrition covers Photosynthesis, Leaf structure, Mineral requirements.
Where can I get Plant Nutrition questions with mark schemes?
This page has 10 Plant Nutrition questions with answers. For more, the free generator on mentorriyaz.in builds a new Plant Nutrition paper with a full mark scheme each time you click.
Want a mentor, not just a paper?
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in