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Secondary 3 Biology Plant Biology Quiz
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Questions
Secondary 3 Biology Quiz - Plant Biology
Name: _________________________ Class: _________________________ Date: _________________________ Score: ______ / 40
Duration: 45 minutes Total Marks: 40
Instructions:
- Answer ALL questions in the spaces provided.
- Write your answers clearly and legibly.
- Marks are indicated in brackets [ ].
- Where diagrams are referenced, use the information provided to answer the questions.
- Use precise biological terminology in your responses.
Section A: Multiple Choice (5 marks)
Choose the most appropriate answer for each question. Write the letter (A, B, C, or D) in the box provided.
1. Which of the following is the correct word equation for photosynthesis?
A) Glucose + Oxygen → Carbon dioxide + Water + Light energy B) Carbon dioxide + Water → Glucose + Oxygen (in the presence of light and chlorophyll) C) Carbon dioxide + Glucose → Water + Oxygen + Light energy D) Oxygen + Water → Carbon dioxide + Glucose + Light energy
[1 mark]
Answer: [ ]
2. A student placed a potted plant under a bell jar with a chemical that absorbs carbon dioxide. After 24 hours in sunlight, which of the following would be observed?
A) The plant produced more oxygen than normal. B) The plant produced less glucose than normal. C) The plant's leaves turned blue-black with iodine test. D) The plant's stomata closed permanently.
[1 mark]
Answer: [ ]
3. The diagram below shows a cross-section of a leaf.
[W] ---------------------
| [X] | [X] |
| [X] | [X] |
[Y] | [X] | [X] |
| |
[Z] ---------------------
O O O O O
Which labelled part contains the most chloroplasts?
A) W B) X C) Y D) Z
[1 mark]
Answer: [ ]
4. In an experiment, a leafy shoot was attached to a potometer. The air bubble moved 60 mm in 30 minutes. What is the rate of water uptake?
A) 0.5 mm per minute B) 2.0 mm per minute C) 30 mm per minute D) 60 mm per minute
[1 mark]
Answer: [ ]
5. Which of the following best explains why most land plants have more stomata on the lower surface of their leaves?
A) To increase water loss through transpiration B) To allow more carbon dioxide to enter for photosynthesis C) To reduce water loss by avoiding direct sunlight D) To prevent pathogens from entering the leaf
[1 mark]
Answer: [ ]
Section B: Structured Questions (25 marks)
Answer all questions in the spaces provided.
6. The diagram below shows two cells found in a leaf.
Cell A: Cell B:
( ) ( ) | |
( ) ( ) <-- chloroplasts | () |
( ) ( ) | () | <-- chloroplasts
( ) ( ) | () |
\ / | |
\__/ \______/
(bean-shaped) (rectangular)
(a) Identify Cell A and Cell B. [2]
Cell A: _________________________
Cell B: _________________________
(b) State one function of Cell A. [1]
(c) Explain how Cell B is adapted to maximise photosynthesis. [2]
7. A student investigated the effect of light intensity on the rate of photosynthesis in an aquatic plant. The apparatus is shown below.
Lamp [Beaker with water]
| | |
|----------| Aquatic plant |
| | producing |
| | bubbles |
| |__________________|
Distance (cm)
The student counted the number of oxygen bubbles produced per minute at different distances of the lamp from the plant. The results are shown in the table.
| Distance of lamp (cm) | Number of bubbles per minute |
|---|---|
| 10 | 45 |
| 20 | 38 |
| 30 | 28 |
| 40 | 18 |
| 50 | 10 |
(a) State the independent variable in this experiment. [1]
(b) State two variables that must be kept constant to ensure a fair test. [2]
(c) Describe the trend shown in the results. [1]
(d) Explain why the number of bubbles decreases as the lamp is moved further away. [2]
(e) Suggest why counting bubbles may not be the most accurate method for measuring the rate of photosynthesis. [1]
8. The diagram below shows a cross-section of a root.
[Soil particle] [Root hair]
| |
| <--Water--> |
| <--Ions---> |
| |
[Soil particle] [Root hair]
(a) Name the process by which water enters the root hair cell from the soil. [1]
(b) Explain why water moves from the soil into the root hair cell. [2]
(c) Mineral ions are also absorbed by root hair cells. Name the process by which mineral ions are absorbed when their concentration in the soil is lower than in the root hair cell. [1]
(d) Explain why this process requires energy. [1]
9. The diagram below shows a section through part of a plant stem.
[P] [P] [P] [P] [P]
[Q] [Q] [Q] [Q] [Q]
[P] [P] [P] [P] [P]
[Q] [Q] [Q] [Q] [Q]
(a) Identify tissue P and tissue Q. [2]
Tissue P: _________________________
Tissue Q: _________________________
(b) State the function of tissue P. [1]
(c) Explain how tissue P is adapted to carry out its function. [2]
(d) Name the process by which dissolved sugars are transported in tissue Q. [1]
10. A student placed a celery stalk in a beaker of water containing red dye. After 2 hours, the student cut a cross-section of the celery stalk and observed red-stained areas.
(a) Name the tissue that became stained red. [1]
(b) Explain how water moves from the roots to the leaves of a tall tree against the force of gravity. [3]
Section C: Data-Based Question (10 marks)
11. A farmer wanted to investigate the effect of carbon dioxide concentration on the rate of photosynthesis in tomato plants grown in a greenhouse. The farmer measured the rate of photosynthesis at different carbon dioxide concentrations while keeping light intensity and temperature constant. The results are shown in the graph below.
Rate of photosynthesis
(arbitrary units)
^
50 | ____________
| ____/
40 | ____/
| ____/
30 | ____/
| ____/
20 |____/
|
10 |
|
0 +----+----+----+----+----+----+----+---->
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Carbon dioxide concentration (%)
(a) Describe the relationship between carbon dioxide concentration and the rate of photosynthesis between 0% and 0.3% carbon dioxide. [2]
(b) Explain why the rate of photosynthesis increases as carbon dioxide concentration increases from 0% to 0.3%. [2]
(c) State what happens to the rate of photosynthesis at carbon dioxide concentrations above 0.4%. [1]
(d) Explain why the rate of photosynthesis does not increase further at carbon dioxide concentrations above 0.4%. [2]
(e) The farmer wants to maximise tomato yield. Suggest and explain two ways, other than increasing carbon dioxide concentration, that the farmer could increase the rate of photosynthesis in the greenhouse. [3]
Suggestion 1: _________________________________________________________________________
Explanation: _________________________________________________________________________
Suggestion 2: _________________________________________________________________________
Explanation: _________________________________________________________________________
12. The diagram below shows a cross-section of a leaf as seen under a microscope.
[A] ---------------------
| [B] | [B] |
| [B] | [B] |
[C] | [B] | [B] |
| |
[D] ---------------------
O O O O O
(a) Identify the layer labelled B. [1]
(b) State one function of the air spaces in layer C. [1]
(c) Explain why the cells in layer B are packed tightly together. [2]
(d) Name the structure labelled O and state its function. [2]
Structure: _________________________
Function: _________________________________________________________________________
13. A student set up an experiment to investigate the effect of temperature on the rate of transpiration. The results are shown in the table below.
| Temperature (°C) | Rate of transpiration (cm³/hour) |
|---|---|
| 10 | 2 |
| 20 | 5 |
| 30 | 12 |
| 40 | 8 |
| 50 | 1 |
(a) Describe the trend in the rate of transpiration between 10°C and 30°C. [1]
(b) Explain why the rate of transpiration increases between 10°C and 30°C. [2]
(c) Suggest a reason for the decrease in the rate of transpiration at 40°C and 50°C. [2]
14. The diagram below shows a potometer, an apparatus used to measure the rate of water uptake by a leafy shoot.
[Reservoir]
|
| [Air bubble]
| |
[Leafy shoot]--|--[Capillary tube]--[Beaker of water]
(a) State the purpose of the reservoir in the potometer. [1]
(b) Explain why the leafy shoot must be cut under water before being placed in the potometer. [2]
(c) A student using the potometer recorded that the air bubble moved 45 mm in 15 minutes. Calculate the rate of water uptake in mm per minute. [1]
15. The diagram below shows a stoma on the lower surface of a leaf.
[Guard cell] [Stoma] [Guard cell]
( ) | ( )
( ) | ( )
( ) | ( )
( ) | ( )
(a) Name the cells that control the opening and closing of the stoma. [1]
(b) Explain how these cells open the stoma during the day. [2]
(c) State one advantage to the plant of closing its stomata at night. [1]
Section D: Extended Questions (10 marks)
16. A student investigated the effect of different colours of light on the rate of photosynthesis in an aquatic plant. The student placed the plant in water and exposed it to red, green, and blue light of the same intensity. The number of oxygen bubbles produced per minute was recorded.
| Colour of light | Number of bubbles per minute |
|---|---|
| Red | 30 |
| Green | 5 |
| Blue | 25 |
(a) Explain why the plant produced the most bubbles in red light. [2]
(b) Explain why the plant produced very few bubbles in green light. [2]
(c) Suggest why blue light also resulted in a high rate of photosynthesis. [1]
17. The diagram below shows a cross-section of a stem from a dicotyledonous plant.
[E] [E] [E] [E] [E]
[F] [F] [F] [F] [F]
[E] [E] [E] [E] [E]
[F] [F] [F] [F] [F]
(a) Identify the tissues labelled E and F. [2]
Tissue E: _________________________
Tissue F: _________________________
(b) State one structural difference between the cells in tissue E and tissue F. [1]
(c) Explain how the structure of tissue E helps it to perform its function. [2]
18. A farmer noticed that plants in a waterlogged field were wilting even though there was plenty of water in the soil.
(a) Explain why the plants were wilting. [2]
(b) Suggest one way the farmer could prevent this problem in the future. [1]
19. The diagram below shows a root hair cell.
[Soil water] --> [Cell wall] --> [Cell membrane] --> [Vacuole]
(a) Explain how the root hair cell is adapted for its function of absorbing water and mineral ions. [2]
(b) Name the process by which water moves from the root hair cell to the xylem in the root. [1]
(c) Explain why the root hair cell has a large number of mitochondria. [2]
20. A student wanted to test a leaf for starch. The steps are listed below, but they are in the wrong order.
- Place the leaf in a boiling tube of ethanol.
- Dip the leaf in boiling water for 1 minute.
- Place the leaf on a white tile and add iodine solution.
- Place the boiling tube of ethanol in a hot water bath.
- Wash the leaf in cold water.
(a) Arrange the steps in the correct order. Write the numbers in the correct sequence. [1]
Correct order: ______, ______, ______, ______, ______
(b) Explain why the leaf is placed in ethanol. [2]
(c) State the expected observation if starch is present. [1]
(d) Explain why a plant produces starch. [1]
END OF QUIZ
Check your answers carefully before submitting.
Answers
Secondary 3 Biology Quiz - Plant Biology — Answer Key
Total Marks: 40
Section A: Multiple Choice (5 marks)
1. B — Carbon dioxide + Water → Glucose + Oxygen (in the presence of light and chlorophyll) [1]
2. B — The plant produced less glucose than normal. [1] Explanation: Without CO₂, the light-independent reactions cannot proceed, so glucose synthesis is reduced.
3. B — X (palisade mesophyll layer) [1] Explanation: The palisade mesophyll contains the highest density of chloroplasts for maximum light absorption.
4. B — 2.0 mm per minute [1] Calculation: 60 mm ÷ 30 min = 2.0 mm/min
5. C — To reduce water loss by avoiding direct sunlight [1] Explanation: More stomata on the lower surface reduces exposure to direct sunlight and wind, minimising transpiration while still allowing gas exchange.
Section B: Structured Questions (25 marks)
6. (a) Cell A: Guard cell [1]; Cell B: Palisade mesophyll cell [1] [Total: 2 marks]
(b) Any one of: [1 mark]
- Controls opening and closing of stomata
- Allows gas exchange (CO₂ in, O₂ out)
- Regulates water loss through transpiration
(c) [2 marks — 1 for adaptation, 1 for explanation]
- Adaptation: Contains many chloroplasts / chloroplasts arranged near the top of the cell
- Explanation: Maximises light absorption for photosynthesis / chloroplasts positioned to capture maximum light energy
- OR: Adaptation: Columnar/elongated shape and tightly packed arrangement
- Explanation: Allows more cells to be packed vertically, increasing light interception per unit area
7. (a) Distance of lamp from the plant / Light intensity [1]
(b) Any two of: [2 marks — 1 each]
- Temperature of water
- Carbon dioxide concentration
- Type/species of aquatic plant
- Size/amount of aquatic plant
- Duration of counting (time interval)
- Same lamp/bulb used
(c) As the distance of the lamp increases, the number of bubbles per minute decreases. [1] Accept: There is an inverse relationship between lamp distance and bubble count / rate of photosynthesis decreases with increasing distance.
(d) [2 marks — 1 for link to light intensity, 1 for link to photosynthesis]
- As the lamp moves further away, light intensity decreases
- Less light energy is available for the light-dependent reactions of photosynthesis
- Therefore, less oxygen is produced (fewer bubbles observed)
(e) Any one of: [1 mark]
- Bubbles may vary in size / not all bubbles are the same volume
- Some oxygen may dissolve in the water instead of forming bubbles
- Difficult to count accurately at high rates / human counting error
- Bubbles may stick to the plant or sides of the beaker
8. (a) Osmosis [1]
(b) [2 marks — 1 for water potential, 1 for direction of movement]
- The cell sap in the root hair cell has a lower water potential (more concentrated) than the soil water
- Water moves from a region of higher water potential (soil) to a region of lower water potential (root hair cell) across a partially permeable membrane
(c) Active transport [1]
(d) [1 mark]
- Active transport moves substances against the concentration gradient (from lower to higher concentration), which requires energy from respiration/ATP
9. (a) Tissue P: Xylem [1]; Tissue Q: Phloem [1] [Total: 2 marks]
(b) [1 mark]
- Transports water and dissolved mineral ions from roots to leaves/stems
(c) [2 marks — 1 for adaptation, 1 for explanation]
- Adaptation: Xylem vessels are hollow/dead cells with no cytoplasm / no end walls (forming continuous tubes)
- Explanation: Allows uninterrupted/unobstructed flow of water through the vessel
- OR: Adaptation: Xylem walls are thickened/lignified
- Explanation: Provides structural support to prevent collapse under tension/negative pressure
(d) Translocation [1]
10. (a) Xylem [1]
(b) [3 marks — 1 for transpiration, 1 for transpiration pull, 1 for cohesion/continuous column]
- Water evaporates from the mesophyll cells in the leaves and diffuses out through the stomata (transpiration)
- This loss of water creates a water potential gradient that pulls water up from the xylem in the leaf veins
- The transpiration pull creates tension/suction that draws water up the continuous column of water in the xylem vessels
- Water molecules cohere (stick together) due to hydrogen bonding, maintaining an unbroken column from roots to leaves
- This cohesion-tension mechanism allows water to move up tall trees against gravity
Accept any three valid points. Award marks for clear explanation of the transpiration-cohesion-tension mechanism.
Section C: Data-Based Question (10 marks)
11. (a) [2 marks — 1 for trend, 1 for detail]
- As carbon dioxide concentration increases from 0% to 0.3%, the rate of photosynthesis increases
- The increase is steep/rapid initially (0% to 0.2%) and then begins to slow/level off (0.2% to 0.3%)
- OR: There is a positive correlation between CO₂ concentration and rate of photosynthesis up to 0.3%
(b) [2 marks — 1 for CO₂ role, 1 for link to photosynthesis]
- Carbon dioxide is a raw material/substrate for photosynthesis
- It is used in the light-independent reactions (Calvin cycle) to produce glucose
- As CO₂ concentration increases, more CO₂ is available for fixation, so the rate of photosynthesis increases
- At low CO₂ concentrations, CO₂ is the limiting factor
(c) [1 mark]
- The rate of photosynthesis remains constant / plateaus / levels off / does not increase further
(d) [2 marks — 1 for limiting factor concept, 1 for specific factor]
- At CO₂ concentrations above 0.4%, carbon dioxide is no longer the limiting factor
- Some other factor, such as light intensity or temperature, becomes the limiting factor
- The enzymes involved in photosynthesis are working at their maximum rate / all active sites are occupied
- The light-dependent reactions cannot produce ATP and NADPH fast enough to keep up with the available CO₂
(e) [3 marks — 1 for each valid suggestion with explanation; max 3 marks]
- Suggestion 1: Increase light intensity (e.g., use additional lighting/lamps)
- Explanation: Light provides energy for the light-dependent reactions; more light energy → more ATP and NADPH produced → faster light-independent reactions → higher rate of photosynthesis
- Suggestion 2: Increase/optimise temperature (e.g., use greenhouse heaters)
- Explanation: Higher temperature increases kinetic energy of molecules, leading to more frequent enzyme-substrate collisions; enzymes involved in photosynthesis work faster at optimal temperature → higher rate of photosynthesis
- Suggestion 3: Ensure adequate water supply
- Explanation: Water is a raw material for photosynthesis (provides electrons/hydrogen for light-dependent reactions); water stress causes stomatal closure, reducing CO₂ uptake
- Suggestion 4: Use plants with higher chlorophyll content / ensure adequate mineral nutrition (e.g., magnesium for chlorophyll)
- Explanation: More chlorophyll → more light energy absorbed → higher rate of light-dependent reactions
Accept any two valid suggestions with correct biological explanations. Award 1 mark per suggestion-explanation pair (max 2 pairs = 2 marks) OR 1 mark for one suggestion with detailed explanation and 2 marks for two suggestions with explanations.
12. (a) Palisade mesophyll layer [1]
(b) Any one of: [1 mark]
- Allows diffusion of carbon dioxide to photosynthesising cells
- Allows diffusion of oxygen away from photosynthesising cells
- Provides a large surface area for gas exchange
(c) [2 marks — 1 for reason, 1 for explanation]
- Tightly packed to maximise the number of cells exposed to sunlight
- This arrangement allows maximum light absorption for photosynthesis
- OR: Tightly packed to minimise air spaces, ensuring that most light is intercepted by chloroplast-containing cells
(d) Structure: Stoma / Stomata [1] Function: Allows gas exchange (carbon dioxide in, oxygen out) / Allows transpiration (water vapour out) [1]
13. (a) As temperature increases from 10°C to 30°C, the rate of transpiration increases. [1]
(b) [2 marks — 1 for evaporation, 1 for diffusion/kinetic energy]
- Higher temperature increases the rate of evaporation of water from the mesophyll cells
- Higher temperature increases the kinetic energy of water molecules, so they diffuse out of the stomata faster
- OR: Higher temperature reduces the relative humidity of the air, increasing the water vapour concentration gradient between the leaf and the atmosphere
(c) [2 marks — 1 for stomatal closure, 1 for reason]
- At high temperatures (40°C and 50°C), the stomata close to reduce water loss
- This reduces the rate of transpiration because water vapour cannot escape from the leaf
- OR: High temperatures may denature enzymes/proteins in the guard cells, preventing them from functioning properly
14. (a) To reset the air bubble / to push the air bubble back to the start of the capillary tube [1]
(b) [2 marks — 1 for preventing air entry, 1 for maintaining continuous water column]
- Cutting under water prevents air from entering the xylem vessels
- This ensures that the water column in the xylem remains continuous, allowing water uptake to continue
(c) 45 mm ÷ 15 min = 3.0 mm per minute [1]
15. (a) Guard cells [1]
(b) [2 marks — 1 for water entry, 1 for shape change]
- During the day, guard cells photosynthesise and produce glucose/sucrose, lowering their water potential
- Water enters the guard cells by osmosis, causing them to swell/become turgid
- The uneven thickening of the guard cell walls causes them to curve/bend, opening the stoma
(c) Any one of: [1 mark]
- Reduces water loss through transpiration when photosynthesis is not occurring
- Conserves water for the plant
Section D: Extended Questions (10 marks)
16. (a) [2 marks — 1 for chlorophyll absorption, 1 for energy]
- Chlorophyll absorbs red light most effectively / red light is strongly absorbed by chlorophyll
- This light energy is used in the light-dependent reactions to produce ATP and NADPH, driving a high rate of photosynthesis
(b) [2 marks — 1 for reflection/transmission, 1 for link to photosynthesis]
- Green light is reflected/transmitted by chlorophyll, not absorbed
- Therefore, very little light energy is available for the light-dependent reactions, resulting in a low rate of photosynthesis
(c) [1 mark]
- Chlorophyll also absorbs blue light effectively / blue light has high energy, which can drive photosynthesis efficiently
17. (a) Tissue E: Xylem [1]; Tissue F: Phloem [1] [Total: 2 marks]
(b) Any one of: [1 mark]
- Xylem cells are dead/hollow; phloem cells are living
- Xylem cells have lignified walls; phloem cells do not have lignified walls
- Xylem cells have no end walls; phloem cells have sieve plates with pores
(c) [2 marks — 1 for adaptation, 1 for explanation]
- Adaptation: Xylem vessels are hollow/dead with no cytoplasm or end walls, forming continuous tubes
- Explanation: This allows uninterrupted flow of water and dissolved mineral ions from roots to leaves
- OR: Adaptation: Xylem walls are thickened with lignin
- Explanation: Provides structural support to prevent collapse under the tension created by transpiration pull
18. (a) [2 marks — 1 for lack of oxygen, 1 for effect on roots]
- Waterlogged soil lacks oxygen / has very low oxygen concentration
- Root hair cells cannot carry out aerobic respiration to produce energy (ATP)
- Without energy, active transport of mineral ions stops, reducing the water potential gradient
- Water uptake by osmosis is reduced, so the plant wilts despite the abundance of water
(b) Any one of: [1 mark]
- Improve drainage of the soil
- Add organic matter to improve soil structure
- Install drainage pipes/tiles
19. (a) [2 marks — 1 for adaptation, 1 for explanation]
- Adaptation: Long, narrow extension/projection (root hair)
- Explanation: Increases surface area to volume ratio for faster/more efficient absorption of water and mineral ions
- OR: Adaptation: Thin cell wall
- Explanation: Reduces the distance for diffusion/osmosis, speeding up absorption
(b) Osmosis [1]
(c) [2 marks — 1 for energy requirement, 1 for link to active transport]
- Root hair cells absorb mineral ions by active transport, which requires energy (ATP)
- Mitochondria are the sites of aerobic respiration, where ATP is produced
- A large number of mitochondria provides sufficient energy for active transport of mineral ions against the concentration gradient
20. (a) Correct order: 2, 1, 4, 5, 3 [1 mark for fully correct sequence]
(b) [2 marks — 1 for chlorophyll removal, 1 for decolourisation]
- Ethanol dissolves/removes chlorophyll from the leaf
- This decolourises the leaf so that the colour change with iodine solution can be clearly observed
(c) The leaf turns blue-black / dark blue [1]
(d) [1 mark]
- Starch is a storage form of glucose/carbohydrates produced during photosynthesis
- It is stored for later use when photosynthesis is not occurring (e.g., at night)
END OF ANSWER KEY