CIE iGCSE Co-Ordinated Science B6.1 Photosynthesis Exam Style Questions Paper 3
Question
(a) Fig. 4.1 is a photomicrograph of a cross-section through a root.
The boxes on the left show the letters of the parts labelled X and Y in Fig. 4.1.
The boxes on the right show some functions.
Draw lines to link each part with its main function(s).
Draw three lines.
(b) State the function of phloem.
(c) Mineral ions are necessary for plant health.
(i) Explain why nitrate ions are required for growth.
(ii) Magnesium ions are used to make a substance required for photosynthesis.
State the name of this substance.
(d) Table 4.1 shows some of the requirements for the processes of germination and photosynthesis.
Place ticks (✓) in the boxes to show the requirements for each process.
▶️Answer/Explanation
Ans : 4(a)
one mark for each correct line
;;;
4(b) transport of, dissolved sugars / sucrose / amino acids ;
4(c)(i) (nitrate ions) are needed to, synthesise / make, amino acids ;
amino acids make up proteins (which are required for growth) ;
one mark for each correct line
;;;
4(c)(ii) chlorophyll ;
4(d)
1 mark for each correct row ;;
Question
(a) A student investigates the effect of light on an aquatic plant.
The student counts the number of bubbles of gas released in one minute by the aquatic plant kept in the light.
The experiment is repeated with the aquatic plant kept in the dark.
Table 7.1 shows the results.
(i) Complete the sentences to explain the results shown in Table 7.1.
The aquatic plant releases more bubbles of ………………………………………… gas when kept in the light.
This is because the process of ………………………………………… requires energy from light.
This energy is used to react the raw materials ………………………………………… and ………………………………………… .
This process takes place in plant cell structures called ………………………………………… .
(ii) State the name of the response that causes plants to grow towards light.
…………………………………………………………………………………………………………………….
(b) Fig. 7.1 is a photomicrograph of a cross‐section through a leaf.
(i) State the name of the part labelled X in Fig. 7.1.
…………………………………………………………………………………………………………………….
(ii) State the names and functions of the two transport tissues contained in the part labelled Y in Fig. 7.1.
name 1 …………………………………………………………………………………………………………
function ………………………………………………………………………………………………………
name 2 ………………………………………………………………………………………………………….
function ……………………………………………………………………………………………………….
(c) Describe the importance of nitrate ions in the synthesis of proteins.
…………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………….
▶️Answer/Explanation
Ans: 7(a)(i) oxygen ;
photosynthesis ;
carbon dioxide and water ;
chloroplasts ;
7(a)(ii) phototropism ;
7(b)(i) (upper) epidermis ;
7(b)(ii) xylem ;
transports mineral ions / water or xylem is for support (of leaf) ;
phloem ;
transports dissolved sugars ;
7(c) nitrates are required to synthesise, amino acids (which make proteins) ;
Question
(a) Fig. 4.1 shows some different sources of pollution of the water in seas.
(i) Complete the sentences using information from Fig. 4.1.
The two biggest sources of pollution are ………………………………………… and ………………………………………… .
The total percentage of pollution caused by chemical waste is ………………………………………… %.
The percentage of pollution caused by discarded rubbish is ………………………………………… %.
(ii) Suggest one negative impact of untreated sewage on humans.
(b) Polluted water affects the growth of plants.
A scientist measures the height of two pea plants, A and B, for one month.
Plant A is given unpolluted water.
Plant B is given polluted water.
Table 4.1 shows the increase in height for each plant.
(i) Calculate the difference in increase in height between plant A and plant B from Table 4.1.
…………………………………………………………………………………………….. cm [1]
(ii) Water is needed for germination of seeds.
State two other environmental conditions required for germination.
1 ……………………………………………………………………………
2 …………………………………………………………………………..
▶️Answer/Explanation
Ans : 4(a)(i) agriculture and (untreated) sewage ;
41 (%) ;
5 (%) ;
4(a)(ii) any one from:
spread diseases ;
AVP ;
4(b)(i) (29 – 11) = 18 (cm) ;
4(b)(ii) warm / suitable temperature ;
oxygen ;
Question
(a) Fig. 7.1 is a drawing of a cross-section of a leaf.
State the names of the parts labelled A, B and C in Fig. 7.1.
A …………………………………………………………………………
B …………………………………………………………………………
C …………………………………………………………………………
(b) Fig. 7.2 is a cell from the palisade mesophyll layer of the leaf.
On Fig. 7.2:
• Identify the part where photosynthesis takes place with a label line and the correct name.
• Identify the part that contains the genetic material with a label line and the letter X.
(c) Describe the process of photosynthesis.
(d) Plants need nitrate ions to make an important substance.
Circle the name of this substance.
amino acid fatty acid starch
glycogen glycerol
(e) State the name of the cell that absorbs mineral ions in a plant.
(f) State the name of the vessels that transport mineral ions in the stem.
▶️Answer/Explanation
Ans : 7(a) A – cuticle ;
B – (lower) epidermis ;
C – stoma / stomata ;
7(b) one chloroplast with label line ;
with correct name ;
nucleus labelled with an X ;
7(c) (process used in plants / producers) to manufacture glucose ;
from raw materials / carbon dioxide and water ;
using light energy ;
7(d) amino acids circled ;
7(e) root hair (cell) ;
7(f) xylem ;
Question
(a) (i) Define the term enzyme.
(ii) Fig. 10.1 is a graph showing the activity of enzyme A at different pH values.
Describe the trend shown in Fig. 10.1.
Use data in your answer.
(b) Photosynthesis and respiration are both enzyme-controlled reactions.
The table shows some features of photosynthesis and aerobic respiration.
Place ticks (3) in the boxes to show the correct features of each process.
(c) Respiration is one of the characteristics of living organisms.
State three other characteristics of living organisms.
1 …………………………………………………………………………
2 …………………………………………………………………………
3 …………………………………………………………………………
▶️Answer/Explanation
Ans : 10(a)(i) a protein ;
(that functions as) a biological catalyst ;
10(a)(ii) enzyme activity increases then decreases (with increasing pH) ;
optimum / peak / maximum activity, at pH7 ;
10(b) 
10(c) any three from:
movement ;
sensitivity ;
reproduction ;
growth ;
excretion ;
nutrition ;
Question
(a) A student investigates photosynthesis.
The student places four plants A, B, C and D in different conditions and records whether they photosynthesise.
Table 7.1 shows her results.
(i) Use Table 7.1 to state the conditions needed for photosynthesis.
…………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(ii) Each plant is provided with an excess of carbon dioxide.
Explain why.
…………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(iii) State the word equation for photosynthesis.
…………………………………………………………………………………………………………………….
(b) State the name of the cell structure where photosynthesis occurs.
……………………………………………………………………………………………………………………
(c) Magnesium is an essential mineral needed by plants.
Draw three lines to link the boxes and make three correct sentences about magnesium ions in plants.
(d) State the name of the principal ion required to make amino acids in a plant.
………………………………………………………………………………………………………………….
▶️Answer/Explanation
Ans: 7(a)(i) light ;
chlorophyll ;
7(a)(ii) carbon dioxide is required for photosynthesis ;
7(a)(iii) carbon dioxide + water → glucose and oxygen ;;
7(b) chloroplast ;
7(c)
7(d) nitrate ;
Question (a)
State the word equation for photosynthesis.
▶️Answer/Explanation
Answer: The word equation for photosynthesis is:
Carbon dioxide + Water → Glucose + Oxygen
Explanation: Photosynthesis is the process by which plants convert carbon dioxide and water into glucose and oxygen using light energy. This process occurs in the chloroplasts of plant cells, which contain chlorophyll to absorb light.
Question (b)
Fig. 7.1 is a diagram of a cross-section of a leaf.
(i) Identify the area in Fig. 7.1, A, B, C, or D, where most photosynthesis takes place. Give one reason for your answer using evidence from Fig. 7.1.
(ii) On Fig. 7.1, draw one arrow to show the pathway of water during transpiration.
(iii) State the name of part X shown in Fig. 7.1.
▶️Answer/Explanation
Answer:
(i) The area where most photosynthesis takes place is B (palisade mesophyll). This is because it contains the most chloroplasts, which are responsible for photosynthesis.
(ii) The arrow should point from the xylem (in the vascular bundle) to the stomata on the leaf surface.
(iii) Part X is the cuticle.
Explanation: The palisade mesophyll is the primary site of photosynthesis due to its high concentration of chloroplasts. Water moves from the xylem through the leaf and exits via the stomata during transpiration. The cuticle is a waxy layer that reduces water loss from the leaf surface.
Question (c)
A group of pea plants is grown with standard fertiliser and another group is grown with fertiliser containing additional magnesium. The height of the plants is measured and an average calculated. Table 7.1 shows the results.
| Group of pea plant | Average height of plant/cm |
|---|---|
| Standard fertiliser | 27.4 |
| Fertiliser with additional magnesium | 33.0 |
Carbohydrates are needed for plant growth. Explain the results shown in Table 7.1. Include ideas about carbohydrates and photosynthesis in your answer.
▶️Answer/Explanation
Answer:
The plants grown with additional magnesium were taller because magnesium is essential for the production of chlorophyll, which is required for photosynthesis. With more chlorophyll, the plants can produce more carbohydrates (glucose) through photosynthesis, leading to increased growth.
Explanation: Magnesium is a key component of chlorophyll, the pigment that absorbs light for photosynthesis. Without sufficient magnesium, chlorophyll production is reduced, limiting the plant’s ability to photosynthesize and produce carbohydrates. The additional magnesium in the fertiliser allowed the plants to produce more chlorophyll, resulting in more efficient photosynthesis and greater growth.
Question (d)
Fertilisers contain nitrate ions. Describe the importance of nitrate ions to plants.
▶️Answer/Explanation
Answer: Nitrate ions are essential for the synthesis of amino acids, which are the building blocks of proteins. Proteins are required for growth and repair in plants.
Explanation: Nitrate ions are absorbed by plant roots and used to produce amino acids. These amino acids are then used to synthesise proteins, which are vital for cellular functions, growth, and repair. Without nitrate ions, plants cannot produce sufficient proteins, leading to stunted growth.