Agricultural Sciences Grade 11 P1 2020 Memo (Eng)

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 11 NOVEMBER 2020 AGRICULTURAL SCIENCES P1 MARKING GUIDELINE EXEMPLAR MARKS: 150 This marking guideline consists of 9 pages.

Downloaded from hlayiso.com 2 AGRICULTURAL SCIENCES P1 (EC/NOVEMBER 2020) SECTION A QUESTION 1 1.1 1.1.1 C 99 1.1.2 D 99 1.1.3 C 99 1.1.4 A 99 1.1.5 C 99 1.1.6 D 99 1.1.7 A 99 1.1.8 B 99 1.1.9 D 99 1.1.10 B 99 (10 x 2) (20) 1.2 1.2.1 B only 99 1.2.2 A only 99 1.2.3 None 99 1.2.4 B only 99 1.2.5 Both A and B 99 (5 x 2) (10) 1.3 1.3.1 Halogen 99 1.3.2 Lewis structure 99 1.3.3 Loam 99 1.3.4 Nitrogen 99 1.3.5 Colloid 99 (5 x 2) (10) 1.4 1.4.1 Cation 9 1.4.2 Hygroscopic 9 1.4.3 Acid 9 1.4.4 Mycorrhiza 9 1.4.5 Illuviation 9 (5 x 1) (5) TOTAL SECTION A: 45 Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/NOVEMBER 2020) AGRICULTURAL SCIENCES P1 3 SECTION B QUESTION 2: BASIC AGRICULTURAL CHEMISTRY 2.1 Compounds 2.1.1 Classification of compounds A – Organic 9 B – Inorganic 9 (2) 2.1.2 Reason A – Presence of carbon atom 9 B – Absence of carbon atom 9 (2) 2.1.3 Name of compounds with the same molecular formula but different structure Isomers 9 (1) 2.1.4 Chemical formula of a compound represented by structure A x C4H10 99 OR x CH3 (CH2)2 CH3 99 (2) 2.1.5 Identification of the letter (a) C 9 (b) B 9 (2) 2.2 Matter/elements/compounds/mixtures 2.2.1 Identification of substances A – Compound 9 B – Homogeneous mixture 9 C – Heterogeneous mixture 9 (3) 2.2.2 Difference between an element and a compound Element is a substance that cannot be broken down by chemical means 9 Compound is a substance formed when two or more elements are chemically combined 9 (2) 2.2.3 Distinguishing between homogeneous and heterogeneous mixtures Homogeneous – mixture in which the dissolved solute cannot be separated from the solvent by physical means 9 Heterogeneous – mixture in which the components can be separated by physical means 9 (2) Copyright reserved Please turn over

Downloaded from hlayiso.com 4 AGRICULTURAL SCIENCES P1 (EC/NOVEMBER 2020) 2.3 Fatty acids 2.3.1 Identification of the fatty acid A – Unsaturated fatty acid 9 B – Saturated fatty acid 9 (2) 2.3.2 Indication of the letter representing the fatty acid (a) Originating from plants – A9 (b) Solid at room temperature – B 9 (c) Has a high melting point – B 9 (d) Liquid at room temperature – A 9 (4) 2.3.3 TWO importance of fats in living organisms x Provide a source of stored energy 9 x Source of insulation and temperature control 9 x Vital part of membrane structure 9 x Play a role in the flow of energy in and out of living cells 9 x Assist in signal transduction 9 (Any 2) (2) 2.4 pH values 2.4.1 Indicating the pH of substances Baking powder – Alkaline 9 Orange juice – Acidic 9 Milk – Neutral 9 Battery acid – Strongly acidic 9 (4) 2.4.2 Indicating the substance with a high concentration of (a) Hydroxide ion – Baking powder 9 (b) Hydrogen ion – Battery acid 9 (2) 2.5 Monosaccharide 2.5.1 Names of the structures A – Fructose 9 B – Glucose 9 (2) 2.5.2 Indication of the compound formed from fructose and glucose Sucrose 9 (1) 2.5.3 TWO elements that are basic composition of carbohydrates x Carbon 9 x Hydrogen 9 x Oxygen 9 (Any 2) (2) [35] Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/NOVEMBER 2020) AGRICULTURAL SCIENCES P1 5 QUESTION 3: SOIL SCIENCE 3.1 Soil texture 3.1.1 Indication of the sample (a) Sample B 9 (b) Sample A 9 (c) Sample B 9 (d) Sample A 9 (4) 3.1.2 Commenting on the pore space of soil sample B by referring to bulk density Soil sample B has a high bulk density / 3,2 g/cm3 9and therefore lower pore space 9 (2) 3.2 Soil structure 3.2.1 Identification of the structure A – Platy 9 B – Prism-like/columnar/prismatic 9 C – Crumb/spheroid 9 (3) 3.2.2 Indicating the letter representing the structure (a) A 9 (b) C 9 (2) 3.2.3 TWO malpractices leading to the destruction of structure x Flood irrigation 9 x Cultivation of soil when it is too dry or wet 9 x Ploughing and other tilling methods 9 x Overgrazing / burning / removal of plant material 9 x Movement of animals and equipment over wet soil 9 x Irrigation leading to salt accumulation 9 (Any 2) (2) 3.3 Soil moisture 3.3.1 Naming the term A – Saturation point 9 B – Field water capacity 9 (2) 3.3.2 Reason A – Soil is completely filled with water 9 B – Amount of water held in soil after saturation and drainage 9 (2) 3.3.3 Plant response grown in soils in Container C and D (a) B – Plants will grow optimally 9 (b) C – Plants will wither/die 9 (2) 3.3.4 Differentiation between temporal and permanent wilting points Temporal wilting – The point when plants appear wilted only during the hottest part of the day and recover 9 Permanent wilting – Plants do not recover from wilting 9 (2) Copyright reserved Please turn over

Downloaded from hlayiso.com 6 AGRICULTURAL SCIENCES P1 (EC/NOVEMBER 2020) 3.4 Soil colour 3.4.1 Differentiation between homogeneous and non-homogeneous soil colour Homogeneous – Single dominant colour in soil 9 Non-homogeneous – Mixture of soil colours 9 (2) 3.4.2 TWO factors determining the colour of soil x Presence of water 9 x Gleying conditions 9 x Organic material 9 x Presence of oxides 9 x Presence of carbonates 9 (Any 2) (2) 3.5 Soil gas 3.5.1 Indication of the gas deficient in experiment 1 Oxygen 9 (1) 3.5.2 Role the gas could have played if not deficient Influenced seed germination 9 (1) 3.5.3 Gas high in soil as a result of activities in experiment 2 Carbon dioxide 9 (1) 3.5.4 Reason for the high amount of carbon dioxide Released during respiration 9 of plant roots and soil micro – organisms 9 (2) 3.6 Soil temperature 3.6.1 Indication of the letter (a) A 9 (b) C 9 (c) A 9 (3) 3.6.2 TWO methods to manipulate soil temperature x Irrigation 9 x Mulching 9 x Clear plastic covers 9 x Shading 9 (Any 2) (2) [35] Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/NOVEMBER 2020) AGRICULTURAL SCIENCES P1 7 QUESTION 4: Soil science 4.1 Soil horizons 4.1.1 Sketching the soil profile A B 99 C R (2) 4.1.2 Indication of the horizon (a) E 9 (b) G 9 (2) 4.1.3 TWO diagnostic horizons of A horizon x Humic 9 x Vertic 9 x Melanic 9 x Orthic 9 (Any 2) (2) 4.2 Soil classification 4.2.1 THREE reasons for classification of soil x Optimal utilisation of country’s natural resources 9 x Scientific planning of farm 9 x Determining the crop production potential of the soil 9 x Improved soil science communication 9 x Development of new regions 9 x Valuation of soils 9 (Any 3) (3) 4.2.2 System used in South Africa to classify soil Binomial system 9 (1) Copyright reserved Please turn over

Downloaded from hlayiso.com 8 AGRICULTURAL SCIENCES P1 (EC/NOVEMBER 2020) 4.3 Soil pH 4.3.1 Line graph Effect of soil pH on availability of Molybdenum Availability of Molybdenum (g) 16 14 12 10 8 6 4 2 0 2 4 6 8 10 12 Soil pH Criteria/rubric/marking guideline x Correct heading 9 x X-axis : Correctly calibrated and labelled (Soil pH) 9 x Y-axis : Correctly calibrated and labelled (Availability of molybdenum) 9 x Line graph 9 x Accuracy 9 x Correct unit (g) 9 (6) 4.3.2 Deduction of the influence of acidity and alkalinity on the availability of molybdenum In acid soil/low pH molybdenum is not available 9 In alkaline soil / high pH molybdenum is more available 9 (2) 4.3.3 Measures to solve problems of: (a) Decreased availability of molybdenum in soils with a pH of between 2 and 4 Application of basic fertilisers such as lime/CaCO3 9 (1) (b) Toxic quantities of molybdenum in soil with pH of 14 Application of gypsum/CaSO4 9 (1) 4.4 Soil colloid 4.4.1 Deduction of the process A – Cation adsorption 9 B – Cation exchange 9 (2) 4.4.2 Reason for cation exchange Potassium cation from the soil solution exchanges with the hydrogen adsorbed in the colloid 9 (1) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/NOVEMBER 2020) AGRICULTURAL SCIENCES P1 9 4.4.3 Indication of the hydrogen cation having an effect on plants Hydrogen in the soil solution 9 (1) 4.4.4 TWO types of colloids Organic colloid9 Inorganic colloid 9 (2) 4.4.5 Differentiation between sodic and saline soils with regard to dominant salts Sodic soil – Sodium carbonates 9 Saline soil – Chlorides and sulphates of sodium, calcium and magnesium 9 (2) 4.5 Soil organisms 4.5.1 Classification of the worms into groups of soil organisms Macro-organisms 9 (1) 4.5.2 TWO conditions for the survival of worms x Organic nutrients 9 x Mineral nutrients (nitrogen/phosphorus/potassium) 9 x Soil moisture close to field water capacity 9 x Soil air for respiration9 x Optimum temperature (temperature between 25 °C and 30 °C 9 x Optimum soil pH 9 (Any 2) (2) 4.5.3 Explanation of how worms will assist farmers x Break down plant and animal remains 9 to liberate plant nutrients 9 x Improve soil structure 9 for increased water retention capacity 9 x Worm casts is rich in organic matter 9 which improves soil fertility 9 x Maintain CO2 concentration 9 which is used by plants during photosynthesis 9 (Any 1) (2) 4.6 Nutrient cycle Nutrient cycle increasing nutrient content in plants (a) Protein content – Nitrogen cycle 9 (1) (b) Carbohydrate content – Carbon cycle 9 (1) [35] TOTAL SECTION B: 105 GRAND TOTAL: 150 Copyright reserved Please turn over