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CAIE IGCSE Biology 6.1 Photosynthesis Questions

Practise defining photosynthesis, writing its equations and analysing investigations involving light, chlorophyll, carbon dioxide, oxygen production and limiting factors.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • state that plants use light energy to synthesise carbohydrates from carbon dioxide and water
  • write the word equation or balance 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ with correct reactants and products
  • interpret gas, starch-test or indicator data and identify the factor limiting photosynthesis rate

Covered syllabus points

6.1.1—Photosynthesis as the process by which6.1.2—Word equation for photosynthesis6.1.3—Chlorophyll is a green pigment that is6.1.4—Chlorophyll transfers energy6.1.10—Photosynthesis equation6.1.5—Subsequent use and storage6.1.6—Importance of: (a) nitrate ions6.1.7—Need for chlorophyll, light and carbon6.1.8—Effects of varying light intensity6.1.9—Effect of light and dark conditions on6.1.11—Explain the limiting factors

Question 1

[Maximum number: 1]

Which substance is used up in photosynthesis?

A

chlorophyll

B

light

C

oxygen

D

water

Question 2

[Maximum number: 4]

Scientists investigated the effect of cuticle thickness on water loss from the leaves of the balsam fir tree, Abies balsamea.

The leaves were divided into three groups:

A - thick cuticle

B - medium cuticle

C - thin cuticle Samples of leaves from each group were weighed. The leaves were placed on a tray in dry air at 20∘C20^{\circ} \mathrm{C}. The samples of leaves were reweighed, at intervals, over 15 hours. The scientists calculated the mass of each sample of leaves as a percentage of the initial mass. mass of the leaves as a percentage of the initial mass

Fig. 5.1 shows the results.

Fig. 5.1 shows the results.

Question (a)

(a)

Water is one of the raw materials needed for the production of sugars in photosynthesis.

[ 4 ]

Question (i)

(i)

State the name of the other raw material needed for photosynthesis.

[ 1 ]

Question (ii)

(ii)

State three ways a plant uses the sugars produced in photosynthesis.

[ 3 ]

Question 3

[Maximum number: 1]

Which structure contains the pigment that transfers energy from light into chemical energy?

A

chloroplast

B

mitochondrion

C

nucleus

D

ribosome

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