2 Review Question Which mode of nutrition do the green plants carry out? A. Autotrophic nutritionB. Heterotrophic nutrition
3 Sorry! You’re wrong!Heterotrophic nutrition is the mode of nutrition in which organisms have to depend on other organisms or dead organic matters as their food sources. Green plants, however, can make organic food by themselves using simple inorganic substances.
4 Very Good! Photosynthesis Autotrophic nutrition is the mode of nutrition in which organisms can make organic food by themselves using simple inorganic substances.The process by which the green plants obtain nutrients is called :Photosynthesis
5 Nature of photosynthesis Occurs in ChloroplastNecessary factors :Carbon dioxideWaterSunlightChlorophyll
7 Destarching – removing starch Reason:To show that any starch found after the experiment is produced during the period of investigationMethod:By placing the plant in dark for for 2 days
8 To test a leaf for the presence of Starch Investigation 8.1To test a leaf for the presence of Starch
9 Why is the leaf first boiled in water ? boiling waterturn off Bunsen burnerboiling alcoholhot wateriodinewhite tileWhy is the leaf first boiled in water ?Ans: Because the process can soften the leaf, break down the cuticle and kill the leaf.
10 Why is the leaf then boiled in alcohol ? boiling waterturn off Bunsen burnerboiling alcoholhot wateriodinewhite tileWhy is the leaf then boiled in alcohol ?Ans: To decolourize the leaf (to remove chlorophyll).
11 Ans: Because alcohol catches fire easily. boiling waterturn off Bunsen burnerboiling alcoholhot wateriodinewhite tileWhy is it important to turn off the Bunsen burner when you are heating the alcohol ?Ans: Because alcohol catches fire easily.
12 Why is the leaf put in hot water after being boiled in alcohol ? boiling waterturn off Bunsen burnerboiling alcoholhot wateriodinewhite tileWhy is the leaf put in hot water after being boiled in alcohol ?Ans: To soften the leaf.(The leaf becomes brittle after boiling in alcohol.)
13 What colour change can be observed if starch is present ? boiling waterturn off Bunsen burnerboiling alcoholhot wateriodinewhite tileWhat colour change can be observed if starch is present ?Ans: The leaf becomes blue-black when iodine solution is added.
14 To show that Chlorophyll is necessary for Photosynthesis Investigation 8.3To show that Chlorophyll is necessary for Photosynthesis
15 Ans: Only the green part. purple partWhich part of the leaf turns blue-black when treated with iodine solution ?Ans: Only the green part.
16 Is chlorophyll necessary for photosynthesis ? green partpurple partIs chlorophyll necessary for photosynthesis ?Ans: Yes.
17 What is the control in this experiment ? green partpurple partWhat is the control in this experiment ?Ans: The green part of the leaf acts as the control.
18 To show that Carbon Dioxide is necessary for Photosynthesis Investigation 8.4To show that Carbon Dioxide is necessary for Photosynthesis
19 Why is potassium hydroxide solution put in one of the flasks ? sunlightBAwaterpotassium hydroxide solutionWhy is potassium hydroxide solution put in one of the flasks ?Ans: To absorb all the carbon dioxide in flask B.
20 sunlightBAwaterpotassium hydroxide solutionWhat happens to each leaf after testing the presence of starch at the end of the experiment ?Ans: The leaf in flask A changes to blue-black while the leaf in flask B stains brown.
21 Ans: Carbon dioxide is necessary for photosynthesis. sunlightBAwaterpotassium hydroxide solutionWhat do your results suggest about the relationship between carbon dioxide and photosynthesis ?Ans: Carbon dioxide is necessary for photosynthesis.
22 Summary of Photosynthesis sunlight6 CO2 + 6 H20C6H12O6 + 6 O2chlorophyllCarbon Dioxide + waterGlucose + oxygen(reactants)(products)By photosynthesis, green plants convert solar energy into chemical energy stored in glucose
26 Mechanism of photosynthesis A series of enzyme-controlled reactionsInvolved in 2 stages:Light-dependent stage (Light reaction)Light-independent stage (Dark reaction)
27 Light reaction (Light-dependent stage) Light is requiredChlorophyll in chloroplast traps Light energyLight energy absorbed by chlorophyll splits water molecules into hydrogen and oxygen(photolysis)
28 Oxygen is formed as a by-product & released as a gas through stoma to outside Hydrogen enters light-independent stage
29 Dark reaction (Light-independent stage) Light is not required; can take place either in light or darknessHydrogen produced in light reaction combines with CO2 to form carbohydratesWater is formed as a by-product
30 Summary of Photosynthesis 6 CO2 + 6 H20C6H12O6 + 6 O2LightWaterCarbon DioxideHLight ReactionDark ReactionGlucose(C6H12O6)Oxygen
32 carbon dioxide and water photosynthesiscarbohydrates (e.g. glucose)release energy by respiration
33 carbon dioxide and water photosynthesiscarbohydrates (e.g. glucose)convert into other products for growth
34 carbon dioxide and water photosynthesiscarbohydrates (e.g. glucose)fatty acidsglycerolcombine to form lipids for use or as a food store
35 join together to become protein molecules carbon dioxide and waterphotosynthesismineral salts from soil(e.g. NO3-, SO42-)carbohydrates (e.g. glucose)amino acidsjoin together to become protein molecules
36 carbon dioxide and water photosynthesis carbohydrates (e.g. glucose)convert into starch / lipid for storageGlucose is not a good storage molecule becauseGlucose is a soluble substanceit can diffuse out & lostit affects water potential
37 carbon dioxide and water photosynthesiscarbohydrates (e.g. glucose)change into sucrose and is transported to other parts through phloem
53 palisade mesophyll (layer) columnar cells closely packed togetherabsorb light more efficientlycontains many chloroplasts
54 spongy mesophyll (layer) irregular cells loosely packed together to leave numerous large air spacesallow rapid diffusion of gases throughout the leafsome (fewer than palisade mesophyll) chloroplasts for photosynthesisspongy mesophyll (layer)
55 same as upper epidermis except the cuticle is thinner lower epidermis
56 opening which allows gases to pass through it to go into or out of the leaf stoma (stomata)
64 The leaf is broad & flattened The leaf is thindecrease diffusion distance for gases & lightThe leaf is broad & flattenedincrease surface area to absorb more sunlight
65 Cuticle in upper epidermis is transparent Allows most light to pass into photosynthetic mesophyll tissues
66 Palisade mesophyll cells are closely packed and contain many chloroplasts To carry out photosynthesis more efficiently
67 Spongy mesophyll cells are loosely packed with numerous large air spaces To allow rapid diffusion of gases throughout the leaf
68 Numerous stomata on lower epidermis To allow rapid gaseous exchange with the atmosphere
69 Extensive vein systemAllow sufficient water to reach the cells in the leafTo carry food away to other parts of the plant
70 Mineral requirements in plants In order to synthesize amino acids, nitrate ions which must be taken into the plant from the soil through the rootOther minerals are also necessary to maintain the life of the plant (N, Mg, P, K, S, etc)
71 The importance of nitrogen For synthesis of proteins, chlorophyll, etcTaken in form of nitrate ionsDeficiency symptoms:Little growth ( - no protein made)Yellowing of leaves ( - no chlorophyll made)
72 The importance of magnesium Essential component of chlorophyllDeficiency symptoms:Yellowing of leaves (no chlorophyll made)Poor growth (no food manufactured because of lack of chlorophyll)
73 Use of fertilizers in agriculture Continuous harvesting crops removes valuable mineral salts from soilFertilizers are added to replace such lossTwo kinds of fertilizers:Natural fertilizersChemical fertilizers
74 Natural fertilizers From manure (animal waste) Organic compounds in it are decomposed by the bacteria in soil to form mineral salts
75 Chemical fertilizersMainly nitrogenous and phosphorous compounds manufactured artificially
76 Comparison between natural and chemical fertilizers Natural fertilizersChemical fertilizersContain humus which can improve soil textureNo humus so cannot improve soil textureLess soluble in water so less likely to be washed awayVery soluble in water so more likely to be washed away
77 Comparison between natural and chemical fertilizers Natural fertilizersChemical fertilizersMuch cheaperVery expensiveLess soluble in water so more difficult to be absorbedVery soluble in water so easier to be absorbedTime is needed for the decomposition to complete before nutrients are available to plantsMore readily to be used by the plants