photosynthesis

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is being absorbed by plants for the process of Deforestation can have negative effects on our ecosystems. What are the negative effects of deforestation? nitrogen respiration Tick two boxes. Animals and birds migrate because there is less food More habitats are destroyed There is less acid rain There is more biodiversity The global temperature decreases Page 3 (2) (2) (2) M2. (b) (c) (a) water oxygen in this order only accept correct chemical symbols allow H₂O/OH₂ allow light (in / through) / need light do not accept attracts light ignore heat / moisture / carbon dioxide ignore so the plants can be seen accept the converse, ie the black plastic bag would not let light in (1) for photosynthesis / make sugar / glucose so there would be no photosynthesis (1) do not allow make food unqualified Increase (in leaves / new leaves) ignore growth unqualified (then) level off or number of (new) leaves (then) stays the same numerical statement eg max at 3 tablets / 5 (new) leaves should refer to one of the first two marking points for every extra tablet get 1 extra leaf = 2 marks for every extra tablet get 1 extra leaf then it levels off = 3 marks Page 3 1 1 1 1 1 1 1 M3. (a) xylem and phloem (b) (i) (ii) either order allow words ringed in box allow mis-spelling if unambiguous movement / spreading out of particles / molecules / ions / atoms ignore names of substances / 'gases' from high to low concentration accept down concentration gradient ignore 'along'/'across' gradient ignore 'with' gradient oxygen / water (vapour) allow 0₂/02 ignore 0¹/0 allow H₂O/H2O ignore H²O Page 4 1 1 1 1 [7] [4] Q2. (e) Scientists try to reduce the negative effects of human activity on our ecosystems. One way is to protect rare habitats. Give one other way of reducing the negative effects of human activity on our ecosystems. (b) (a) Complete the word equation for photosynthesis. Use words from the box. chlorophyll carbon dioxide + minerals ● ● oxygen ● Plants may grow faster if they have more carbon dioxide. Indigestion tablets dissolve in water to form a solution. This solution slowly gives off carbon dioxide. glucose water A student set up an investigation to see what concentration of carbon dioxide is best for increasing the growth of geranium plants. The student: + Page 4 put a geranium plant in a clear plastic bag put a dish containing water and one tablet in the bag sealed the top of the bag. (1) otal 8 marks) (2) M4. (a) protein (b) (i) (more) magnesium gives more growth / more leaves / more duckweed if converse must be clear that less magnesium gives less growth (ii) A gave highest number of leaves / plants or more than others it equals 'A' use of numbers must compare A with at least one other (c) (i) or A gave most growth / most duckweed or more than others allow faster/ fastest/better / best growth allow more growth with nitrate / less growth without nitrate do not allow 'no' growth without nitrate mark (c) as a whole sensible method: e.g. mass / weighing ignore dry or fresh allow other sensible method involving measuring eg length of roots ignore 'size' of roots or measure roots unqualified (ii) corresponding explanation: ignore accuracy e.g. includes roots /includes whole plantorleaves vary in sizeor(length / mass / surface area given in c(i)) is a continuous variable Page 5 1 1 1 1 [5] (c) Clear plastic bag -Dish containing water and one tablet The student: set up 5 more experiments each with water and a different number of tablets left all the plants in a well-lit place for four weeks. The student used a clear plastic bag, not a black plastic bag. Explain why. After four weeks, the student counted the number of new leaves on each plant. The graph shows his results. Page 5 (2) Number of new leaves after four weeks 6 4 2 0 2 3 Number of tablets dissolved in water Describe the effect of increasing the number of tablets dissolved in water on the number of new leaves that grew in four weeks. Q3. The diagram shows a section through a plant leaf. Page 6 5 (3) (Total 7 marks) M5.(a) oxygen (b) (i) light (c) (ii) chlorophyll (iii) decrease allow 0₂/02 do not accept O² or O any three from: ● • ● for respiration / energy do not accept use energy for photosynthesis to make cellulose / starch accept named carbohydrate other than glucose to make lipid / fat / oil accept fatty acid / glycerol to make protein accept named protein / amino acid /named amino acid to build big molecules from small molecules / metabolism if no other marks awarded for making molecules allow 1 mark for growth / repair / new cells Page 6 1 1 1 1 3 [7] (a) epidermis (b) FOOOOOOOO Use words from the box to name two tissues in the leaf that transport substances around the plant. (ii) mesophyll phloem B and Gases diffuse between the leaf and the surrounding air. (i) What is diffusion? Page 7 xylem Name one gas that will diffuse from point A to point B on the diagram on a sunny day. (1) (2) M6. (a) (i) (c) (ii) C and D (b) (i) A any one from: (ii) D no mark if more than one box is ticked respiration do not allow if other cell parts are given in a list (have) cell wall(s) (have) vacuole(s) apply list principle apply list principle apply list principle Page 7 1 1 1 1 1 [5] M7.(a) chlorophyll is needed for photosynthesis (b) light is needed for photosynthesis increases levels off / reaches a maximum / remains constant / stays the same / plateaus do not allow stops/stationary/peaks allow stops increasing goes up to / reaches a maximum / levels off at (a rate of) 200 (arbitrary units) or levels off at 225 - 240 (light units) (c) (i) ignore references to other numerical values higher light intensity does not increase rate of photosynthesis accept the graph stays level (above this value) allow stops increasing allow the rate of photosynthesis stays the same (above this value) (ii) any two from: carbon dioxide (concentration) temperature / heat (amount of) chlorophyll / chloroplasts allow water allow ions/nutrients ignore ref to surfac area of the af Page 8 1 1 1 1 1 1 2 [8] Q4.Duckweed is a plant. Duckweed grows in ponds. The leaves of duckweed float on the surface of the water and its roots hang down in the water. The drawing shows a duckweed plant. (a) Leaves Roots Duckweed roots absorb nitrate ions from the water. The nitrate ions help the duckweed to grow. Draw a ring around the correct answer to complete the sentence. Duckweed needs nitrate ions to make Mineral ion carbohydrate fat. protein. (b) Some students grew duckweed plants in three different solutions of mineral ions, A, B and C, and in distilled water (D). 5mm Table 1 shows the concentrations of mineral ions in each of A, B, C and D at the start of the investigation. Table 1 (1) (Total 4 marks) Concentration of mineral ions Page 8 (1) M8.(a) (i) (ii) against the force of gravity (b) (i) in the direction of the force of gravity (ii) diagram completed to show stem bending / leaning towards the window the bend / lean can be at / from any point above pot level ignore any leaves more light (for leaves) ignore heat more photosynthesis / biomass / glucose ref to 'more' needed once only, eg 'more light for photosynthesis' = 2 marks if no other marks given allow 1 mark for 'to get light for photosynthesis' Page 9 1 1 1 1 1 [5] Nitrate in mg per dm at the start of the investigation A Phosphate Magnesium 200 (i) 1000 (ii) 300 B 4 0 84 Number of leaves at start Number of leaves after 28 days C 4 0 24 The students counted the number of duckweed leaves in A, B, C and D at the start of the investigation and after 28 days. Table 2 shows their results. Table 2 A 4 D 50 0 0 0 B 4 Page 9 27 C 4 14 D 4 6 Using Table 1 and Table 2, describe the effect of magnesium ions on the growth of duckweed. Solution A contained the highest concentration of nitrate ions. One student said, 'The results show that nitrate ions are needed for the growth of duckweed.' What evidence in Table 2 supports what the student said? (1) (1) M9.(a) (i) (b) (c) LHS = water (ii) light / sunlight accept H₂O do not accept H³O/H2O RHS = oxygen accept O₂ do not accept O/0²/02 (i) 20 (iii) chloroplasts (i) (ii) ignore solar/sun / sunshine do not allow thermal / heat (ii) any one from: allow chlorophyll light (intensity) temperature. To increase the rate of growth of the tomato plants Because it would cost more money than using 0.08% Because it would not increase the rate of photosynthesis of the tomato plants any further Page 10 1 1 1 1 1 1 1 1 [9] Q5.(a) (c) The students measured the growth of the duckweed by counting the number of leaves. (i) Suggest a better method of measuring the growth of the duckweed. (ii) Suggest why your method is better than the students' method. Complete the word equation for photosynthesis. carbon dioxide + water energy glucose + (b) Draw a ring around the correct answer to complete each sentence. (i) The energy needed for photosynthesis comes from (ii) Energy is absorbed by a green pigment called Page 10 light. osmosis. respiration. chloride. chloroplast. (1) (1) (Total 5 marks) (1) (1) (c) (iii) If the temperature is decreased the rate of photosynthesis will 2 3 Q6. The diagrams show four types of cell, A, B, C and D. Two of the cells are plant cells and two are animal cells. Give three ways in which plants use the glucose made in photosynthesis. 1 Tail A chlorophyll. CREEEEE Page 11 decrease. B increase. stay the same. at (1) Cytoplasm (1) (3) (Total 7 marks) Root hair C (a) (i) Which two of the cells are plant cells? Tick (✓) one box. A and B A and D C and D (ii) Give one reason for your answer. 0 O (b) (i) Which cell, A, B, C or D, is adapted for swimming? O 000 Chloroplast (ii) Which cell, A, B, C or D, can produce glucose by photosynthesis? Page 12 (1) (1) (1) (c) Q7.(a) Cells A, B, C and D all use oxygen. For what process do cells use oxygen? Draw a ring around one answer. osmosis . ● photosynthesis A student carried out the following investigation using a plant with variegated leaves. A variegated leaf has green and white stripes. The student: left the plant in the dark for 3 days to remove the starch fixed two pieces of card to a leaf on the plant left the plant in the light for 2 days removed the leaf from the plant tested the leaf for starch. Figure 1 shows how the two pieces of card were attached to the leaf. Leaf without card Figure 1 respiration Leaf with card Page 13 (1) (1) (Total 5 marks) (b) Figure 2 shows the same leaf after 2 days in the light. The leaf has been tested for starch. Figure 2 Position where card had been Give two conclusions from this investigation. Tick (✓) two boxes. Chlorophyll is needed for photosynthesis. Carbon dioxide is needed for photosynthesis. Light is needed for photosynthesis. Key Water is needed for photosynthesis. Page 14 Card No starch present Starch present ☐☐☐ Key White parts of leaf Green parts of leaf Scientists investigated the effect of light intensity on the rate of photosynthesis. Figure 3 shows the scientists' results. (2) 250 (i) 200 (ii) 150 Rate of photosynthesis in arbitrary units 100- 50 0 Figure 3 Describe the effect of increasing light intensity on the rate of photosynthesis. You should include numbers from Figure 3 in your description. 50 100 150 200 250 300 350 Light intensity in arbitrary units (c) At a light intensity of 250 arbitrary units, light is not a limiting factor of photosynthesis. What is the evidence for this in Figure 3? Give two factors that could be limiting the rate of photosynthesis at a light intensity of 250 arbitrary units. Page 15 (3) (1) Q8.A student investigated growth in plants. The student: . planted a seed in damp soil in a plant pot put the plant pot in a dark cupboard. The image below shows the result after 5 days. 2 (a) Soil surface (ii) Damp soil Plant pot (i) After the 5 days, the root had grown Draw a ring around the correct answer to complete each sentence. After the 5 days, the shoot had grown Shoot Seed Page 16 Root (2) (Total 8 marks) away from water. in the direction of the force of gravity. towards light. against the force of gravity. (1) (b) After the plant had grown, the student put the plant pot by a window with lots of light. The illustration below shows this. (i) (ii) away from light. towards water. Window Page 17 <Light Complete the diagram below to show the appearance of the student's plant after 20 days by the window. Window Light Explain the advantage to the plant of growing in the way that you have drawn in part (b)(i). (1) (1) Q9.Photosynthesis uses carbon dioxide to make glucose. (a) (i) Complete the equation for photosynthesis. (b) (ii) carbon dioxide + (i) What type of energy does a plant use in photosynthesis? (iii) Which part of a plant cell absorbs the energy needed for photosynthesis? Rate of photosynthesis in arbitrary units The graph shows the effect of the concentration of carbon dioxide on the rate of photosynthesis in tomato plants at 20 °C. 25 20- 15- energy 10- glucose + 5- (2) (Total 5 marks) 0.00 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 Percentage concentration of carbon dioxide in the air Page 18 What is the maximum rate of photosynthesis of the tomato plants shown in the graph? (2) (1) (1) (c) (ii) At point X, carbon dioxide is not a limiting factor of photosynthesis. Suggest one factor that is limiting the rate of photosynthesis at point X. A farmer plans to grow tomatoes in a large greenhouse. The concentration of carbon dioxide in the atmosphere is 0.04%. The farmer adds carbon dioxide to the greenhouse so that its concentration is 0.08%. (i) Why does the farmer use 0.08% carbon dioxide? Tick (✓) one box. arbitrary units To increase the rate of growth of the tomato plants To increase the rate of respiration of the tomato plants To increase water uptake by the tomato plants (ii) Why does the farmer not use a concentration of carbon dioxide higher than 0.08%? Tick (✓) two boxes. Because it would cost more money than using 0.08% Because it would decrease the temperature of the greenhouse Page 19 (1) (1) (1) Because it would not increase the rate of photosynthesis of the tomato plants any further Because it would increase water loss from the tomato plants Page 20 (2) (Total 9 marks)