1.
Which graph shows the effect of temperature on the rate of photosynthesis?
Correct Answer
D. D
Explanation
Photosynthesis is controlled by enzymes. High temperature will denature the enzymes. So the graph is the same as that of the enzyme.
2.
In which conditions will a plant photosynthesise fastest?
Correct Answer
B. B
Explanation
Increase in rate of carbon dioxide concentration and optimum temperature
3.
The graph shows the amount of oxygen produced by a green plant during a 24-hour period. Which letter represents midnight?
Correct Answer
D. D
Explanation
A - early morning, 3pm, no sunlight, no photosynthesis, B-C , day time and evening, photosynthesis takes place. D - midnight, the level of oxygen declines.
4.
The diagram shows one type of plant cell. What type of cell is it?
Correct Answer
B. mesophyll cell of a leaf
Explanation
epidermal cell, root hair cell, xylem - no chloroplast, mesophyll cell - chloroplasts for photosynthesis
5.
Four regions of a green leaf are listed.
1. air space
2. spongy mesophyll cell
3. stoma
4. xylem vessel
In which order does a molecule of water, transported from the stem, pass through these regions into the air surrounding the leaf?
Correct Answer
C. C
Explanation
Water is transported by xylem vessels to the leaf xylem. Water enters the spongy mesophyll cells by osmosis. Water forms a layer outside the walls of mesophyll cells. Water evaporates into water vapour into the intercellular air spaces. Water vapour diffuses out of the stomata by transpiration.
6.
The diagram shows a transverse section from the middle of a root of a dicotyledonous plant. In which tissue are sugars and amino acids transported?
Correct Answer
B. B
Explanation
Xylem is found in the centre of the root forming a star shape. The large cells thickened with lignin are the xylem cells which transport water and mineral ions from roots to stems to leaves. Phloem are much smaller found mostly at B. A - xylem, C and D - root cortical cells
7.
During translocation in plants, what substance is moved from which organ to which organ?
Correct Answer
B. B
Explanation
Phloem - transports sucrose and amino acids (food) from leaves to roots by TRANSLOCATION
8.
The diagram shows a section of a stem. Which tissue transports sugars and amino acids from the leaves to other parts of the plant?
Correct Answer
B. B
Explanation
A is the cortex cell, B is the phloem - transports sugars and amino acids. C is the xylem near to the centre. D is the pith.
9.
When a complete ring of bark is removed from the trunk of a tree, it will eventually die because this action cuts off the supply of
Correct Answer
B. Nutrients to the roots.
Explanation
Bark - phloem tissues, no sucrose and amino acids transported by phloem from leaves to roots.
10.
When a leafy shoot is placed in a solution of dye, which part becomes most heavily stained?
Correct Answer
D. Xylem vessels in the stem
Explanation
xylem transports water and minerals from roots to the leaves.
11.
The diagrams show transverse sections from the root and the stem of a plant. Which tissues carry amino acids in solution?
Correct Answer
A. Root (1) and stem (3)
Explanation
xylem vessels are mostly found in the centre of the root and stem sections.
12.
A young plant may wilt when dug up and re-planted in another place. What causes this?
Correct Answer
D. The surface area of the root is reduced.
Explanation
When the plant is dug up, some of the roots are damaged or torn away. Hence, less roots results in less surface area for water uptake by osmosis
13.
Four tubes, A, B, C and D are left in sunlight for one hour. The bicarbonate indicator solution in each tube is red at the start of the experiment.
Bicarbonate indicator solution stays red if there is no change in carbon dioxide concentration. The indicator goes yellow if carbon dioxide concentration increases and purple if the carbon dioxide concentration decreases.
In which tube does the colour change to purple?
Correct Answer
B. B
Explanation
Bicarbonate indicator solution will change to yellow when it is acidic - presence of CO2.
If less CO2 and more O2 due to photosynthesis, the indicator changes to purple - less CO2.
B - photosynthesis takes place, so more O2 than CO2, purple.
Respiration - breaks down glucose to release energy and CO2, the indicator turns yellow.
14.
Where and how does carbon dioxide enter a plant?
Correct Answer
D. D
Explanation
Carbon dioxide enters the leaves through stomata by a diffusion process. The gas diffuses into the intercellular air spaces and then dissolves in the water layer outside the mesophyll cells.
15.
_________________ traps light energy and converts it into chemical energy for the formation of glucose.
Correct Answer
Chlorophyll
chemical
Explanation
Chlorophyll traps light energy not chloroplast which is just an organelle containing chlorophyll.
16.
The cell wall of xylem vessels is made of ___________ to provide support to the plant. It also helps to prevent bending of stem caused by wind.
Correct Answer
lignin
support
bending
Explanation
The cell wall of xylem vessels is made of lignin, which provides support to the plant. Lignin is a complex polymer that gives rigidity and strength to the cell walls, allowing them to withstand the pressure exerted by water and provide structural support to the plant. Additionally, lignin helps to prevent the bending of the stem caused by wind, as it adds stiffness and resistance to deformation.
17.
The graph shows how the rate of photosynthesis in a plant varies with light intensity at two different carbon dioxide concentrations. The temperature is kept constant at 20 °C. Which factor is limiting the rate of photosynthesis at point X?
Correct Answer
C. Light intensity and carbon dioxide concentration
Explanation
Limiting factor - factor required in minimum amount. As light intensity increases, the rate of photosynthesis does not continue to increase. Other factors will help to increase the rate of photosynthesis
18.
The diagram shows a photosynthesis investigation. The plant has leaves that are green in the middle and white round the edges. Which leaf areas lack only one factor needed for photosynthesis?
Correct Answer(s)
A. P and Q
C. Q and S
Explanation
R - green with chlorophyll, sunligh, water and CO2. all factors present. Q - all except chlorophyll - 1 factor missing P - no chlorophyll and CO2 - 2 factors missing S - no CO2 - 1 factor missing