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NQF Level: 2 US No: 116057 Assessment Guide Primary Agriculture Plant Structure and function Assessor: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Workplace / Company: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Commodity: . . . . . . . . . . . . . . . . . . . Date: . . . . . . . . . . . . . . . . . . The availability of this product is due to the financial support of the National Department of Agriculture and the AgriSETA. Understand the structure and functions of a plant Primary Agriculture NQF Level 2 2 Unit Standard No: 116057 Before we start… T his assessment guide contains all necessary activities and instructions that will enable the assessor and learner to gather evidence of the learner’s competence as required by the unit standard. This guide was designed to be used by a trained and accredited assessor whom is registered to assess this specific unit standard as per the requirements of the AgriSETA ETQA. Prior to the delivery of the program the facilitator and assessor must familiarise themselves with content of this guide, as well as the content of the relevant Learner Workbook. Please Note: This Unit Standard 116057 Assessment Guide must be read in conjunction with the generic Assessor Guide as prescribed and published by the AgriSETA. The assessor, facilitator and learner must plan the assessment process together, in order to offer the learner the maximum support, and the opportunity to reflect competence. The policies and procedures that are required during the application of this assessment are available on the website of the AgriSETA and should be strictly adhered to. The assessor must familiarise him/herself with this document before proceeding. This guide provides step-by-step instructions for the assessment process of: Title: US No: Understand the structure and functions of a plant. 116057 NQF Level: 2 Credits: 5 This unit standard is one of the building blocks in the qualification listed below. Please mark the qualification you are currently assessing, because that will be determined by the context of application: Title ID Number NQF Level Credits National Certificate in Animal Production 48976 2 120 National Certificate in Mixed Farming Systems 48977 2 120 National Certificate in Plant Production 48975 2 120 Please mark the learning program you are enrolled in: Are you enrolled in a: Y Learnership? Skills Program? Short Course? Version: 01 N Mark Note to Assessor: If you are assessing this module as part of a full qualification or learnership, please ensure that you have familiarized yourself with the content of the qualification. Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 1.1 AC 1 NQF Level 2 Unit Standard No: 116057 3 Instructions to learner: Explore and discuss … Learner Guide: Page 7 Facilitator Guide: Page 12 Take a scale from an onion bulb and use a pair of tweezers to tare off a piece of the epidermis tissue. Mount it in a drop of water and study it under a microscope. Write down your observations and discuss it with the rest of the class Model Answer(s): This is only to show the student that there are structures/cells in the plant which cannot be seen with the naked eye, but which play key roles in the growth and normal function of the plant. The student therefore only have to show the ability to work with a microscope and observe the cells in the onion membrane. We can see plant organs with the naked (unaided) eye and we therefore talk about the external structure of the plant. All these organs are made up of cells that we cannot see with the naked eye and need a microscope to see these cells. We therefore talk about the internal structure or the anatomy of the plant. Cells of the same kind and/or function form tissues like the epidermis, cortex and vascular tissue. Each tissue has a specific function in the plant organ. My Notes … . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 1.2 SO 1 AC 1-5 NQF Level 2 Unit Standard No: 116057 4 Instructions to learner: Explore… Learner Guide: Page 9 Facilitator Guide: Page 12 Soak some bean seed and some maize seed in water for 24 hours. Remove the seed coat and try to find the other parts shown in the diagram. Seed coat (box) Cotyledon Plumule Axis Radicle Endosperm (Food) Model Answer(s): Realizing that a seed already contains all the structures which a full grown plant will have later on. Importance of keeping seed intact to protect this potential plant. My Notes … . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 2.1 SO 2 AC 1-4 NQF Level 2 Unit Standard No: 116057 5 Instructions to learner: Go outside and explore … Learner Guide: Page 14 Facilitator Guide: Page 13 Collect 10 weed plants from the garden and describe the root system of each. Model Answer(s): Basic knowledge on how the roots look like, the different types of roots and why it is important also to know what is happening below soil level with the plant. My Notes … . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 3.1 SO 3 AC 1-3 NQF Level 2 Unit Standard No: 116057 6 Instructions to learner: Explore and research … Learner Guide: Page 18 Facilitator Guide: Page 14 Cut a shoot with leaves from a weed plant, put the cut end in a natural stain solution and leave it for 24 hours. Make a longitudinal section of the stem and try to explain what you see. Model Answer(s): Basic knowledge on how the stem look like (outside and inside), the different types of tissue in the stem and the importance/role of each in the functioning of the plant. My Notes … ............................................................................. ............................................................................. ............................................................................. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. ............................................................................. ............................................................................. ............................................................................. ............................................................................ ............................................................................. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 4. 1 SO 4 AC 1-5 NQF Level 2 Unit Standard No: 116057 7 Instructions to learner: Research and discuss … Learner Guide : Page 25 Facilitator Guide: Page 15 Write an illustrated essay on the different leaf types and their function as well as some responses of leaves to the environment. Model Answer(s): Basic knowledge on how the leaf look like (outside and inside), the different types of tissue in the leaf and the importance/role of each in the functioning of the plant. My Notes … . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 5.1 SO 5 AC 1-4 NQF Level 2 Unit Standard No: 116057 8 Instructions to learner: Explore and discuss Learner Guide: Page 30 Facilitator Guide: Page 16 Pick any crop, make the following observations and describe and explain your observations: • • • • • Bud stage of the flowers Description of flowers Pollination, stage of flowers when pollinated and pollination agent Fruit set and stages of fruit development Seed development Model Answer(s): Basic knowledge on how the flower looks like (outside and inside). The different structures within a flower and what role it plays in pollination and fertilization. Students will also see from where fruits and seeds develop. My Notes … ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... ................................................................................... Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 6.1 SO 6 AC 1-4 NQF Level 2 Unit Standard No: 116057 9 Instructions to learner: Explore and discuss… Learner Guide: Page 34 Facilitator Guide: Page 17 Collect a variety of fruits dissect the fruits, describe their structure and try to relate the structure of the parts to specific functions. Model Answer(s): Students will learn that not all fruits are the same. Some are dry while others are fleshy etc. They will also learn that fruit has a specific shape, smell, taste etc. to facilitate spreading of the seeds. My Notes … . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . ............................................................................. ............................................................................. ............................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 Assessment Feedback Form Comments / Remarks Feedback to learner on assessment Feedback from learner to assessor: Learner’s Signature: Assessor’s signature: Version: 01 Date: Date: Version Date: July 2006 10 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 11 S u mma t i v e T e s t a n d At t i t u de & A t t r i b u t e E v a l u a t i on B efore the knowledge test is undertaken, the learner must be reminded of what is expected from him / her in terms of summative and reflexive competence. Read and explain to the learner, the Preparation for Your Final Assessment section in the learner workbook. Learners and assessor should sign off this section to acknowledge that this step was completed. Please set up a knowledge test from the questions given as a guideline to learners and supply each learner with a test sheet. Supply each report with the following heading: Unit Standard: 116057 NQF Level: 2 Learner Name: Questions 1. Could you see the cells and other cell components of the onion scale epidermis without a microscope? If not, what is the reason for not seeing? Model Answers Basic understanding of the size of things and the use of microscopes to be able to see things which cannot be seen with the naked eye. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture ♦ ♦ ♦ • • 2. Identify the important parts of a seed and explain the function of each. • • NQF Level 2 Unit Standard No: 116057 12 Seed coat – the seed coat derives from the integuments of the ovule and covers and protects the seed while in a resting phase (storage). Endosperm – The endosperm derives from the fertilised central cell of the embryo sac and contains the energy (food) for the embryo. In the immature stage, therefore, all seeds contain endosperm. In some seeds the endosperm is absorbed by the cotyledons of the developing embryo, so that the cotyledons become swollen and no endosperm remains in the mature seed. Such seeds are called ex-endospermous. The mature seed therefore contains endosperm that is absorbed only during germination to supply the germinating embryo with the required energy. Embryo – the embryo consists of four parts: Radicle – It is the root apical meristem of the embryo that gives rise to the primary root. Plumule – It is the apical meristem (growing point) of the young embryo that gives rise to the stem and leaves of the new plant. Cotyledon(s) – One in monocotyledonous seeds and two in dicotyledonous seeds, is (are) the first leaf (leaves) of the embryo produced by the plumule and do(es) contain axillary buds like any other leaf. They act as haustoria (absorbing) nutrients from the endosperm. In endospermous seeds (seeds containing endosperm), the cotyledons become active during germination and absorb the nutrients from the endosperm as they are required by the embryo. In exendospermous seeds, (seeds without endosperm), the endosperm is absorbed by the cotyledons before the seed matures and the nutrients are, therefore stored inside the swollen cotyledons. Axis – the part of the embryo connecting the plumule and the radicle. In seeds with epigeal germination (cotyledons appear above the ground), the axis elongates to push the cotyledons above ground and that part of the axis below the cotyledons is then called the hypocotyls. In seeds with hypogeal germination, the axis does not elongate during germination and the cotyledons therefore remain underground. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 3. Identify the different parts of a maize seed. Is this a monocotyledonous or dicotyledonous seed? NQF Level 2 Unit Standard No: 116057 13 Different monocotyledonous seedlings showing the cotyledon (c) imbedded in the endosperm, some elongated to push the plumule into the soil, and (sp) the first leaf covered by a sheath. 1 – Palm (Phoenix), 2 – longitudinal section of 1 to show the sheath and plumule at the base, 3 – Maize, 4 – section of 3, 5 – Wheat. Monocotyledonous seeds contain only one cotyledon and the plumule is situated on the side of the embryo axis. In monocotyledonous plants the leaf base is a sheath covering a part of the stem above the node. In the seedling the first leaf above the cotyledon is usually reduced to the sheath only. 4. Identify the different parts of a bean seed. Is this a monocotyledonous or dicotyledonous seed? Different dicotyledonous seedlings showing the cotyledons (c) and the first leave produced by the plumule between the cotyledons. 1Lupin, 2 - Vetch, 3 - Plantago, 4 – Escholzia, 5 – Geranium, 6 – Eranthis. In dicotyledonous seeds there are two cotyledons and the plumule is situated between the two cotyledons. 5. Explain the function of plant roots. The function of roots are a) for anchoring the plant to the substrate (soil) and b) for the absorption of water and nutrients dissolved in the soil water. The absorption function is carries out by the young epidermis cells, of which some may grow out to form root hairs. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 14 The different root systems: • The tap root system – the tap root derives from the radicle and produces lateral roots of different orders (First order, second order etc.. In dicotyledonous plants the tap root can usually has the same life span as the plant A tap root system can therefore develop only from seedlings. • Adventitious root system - in monocotyledonous plants the tap root functions during the seedling stage, but may thereafter stop growing and adventitious roots develop from the base of the stem, forming an adventitious root system. In grasses and some other plants the adventitious roots are fibrous. They are thin and hair-like and usually contain more fibres than other roots. The whole root system is then called a fibrous root system The feeding roots of many other plants, however, can also be hair-like and fibrous even if they form part of a taproot system. And are often called hair roots. 6. Do all plant species have the same type of root system? If not, give examples of the different types of root system. 7. Have you ever eaten a plant root? If yes, from which plant and what type of root was it? Basic application of embedded knowledge. Exp. Carrot – tap root. How is it possible for water, taken up by the roots, to end up in the leaf? Explain. Almost all the water the plant takes up from the soil enters through the youngest part of the root where the root hairs develop a few millimetres behind the root tip. Absorption takes place directly through the epidermis and root hairs that provide an enormous area of absorption. The walls of the root cells are made up of cellulose fibrils (threads). The open spaces between the fibrils are filled with water which means that water can move through the cell walls from one cell to the other and this movement is called apoplastic movement of water. Water can therefore move from the soil water into the cell walls of the root hairs, through the cell walls of the cortex up to the endodermis where the water is blocked by the casparian strips in the endodermis. The water is then forced through the cytoplasm of the endodermis cells, the pericycle and then into the xylem vessels that takes the water through the root and stem into the leaves. Water can also be absorbed by the root hairs through the process of osmoses (water molecules moving from an area of high concentration – in the soil water - to an area of low concentration – inside the root hair). The water then moves from the root hairs symplastically through the cytoplasm of the root tissues to the endodermis. 8. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 9. How does gravity affect the growth of roots and stems? ♦ Do all plant species have the same type of stem? If not, describe the different stem types and name one plant species having such a stem. ♦ ♦ ♦ ♦ ♦ 11. 12. Unit Standard No: 116057 15 Gravity is a force that pulls everything towards the earth and – tropism is a turning into the direction from where a stimulus comes. The growth of most roots is positively gravitropic which means that they grow towards the direction of the pull of the earth. This phenomenon can be illustrated by planting maize seeds with the sharp end (radicle) of the seed pointing upwards. During germination the root will turn around and grow downwards. Stems on the other hand tend to grow negatively gravitropic, meaning that they grow away from the stimulus coming from the pull of the earth. ♦ 10. NQF Level 2 Herbaceous stems – stems of most monocotyledonous plants with no secondary growth. Or stems of most annual dicotyledonous plants with very limited secondary thickening growth. Woody stems – stems of dicotyledonous plants and gymnosperms with the extensive secondary thickening growth. A source for commercial wood. Stems of vines– long, slender stems that con not support themselves and use other plants or structures to support them like that of runner beans. Tuber – a fleshy, terminal end of an underground stem that can be used for propagation like that of the potato. Some can also be used as food. Rhizome – a swollen underground with distinct nodes and internodes, often with sympodial growth like in Iris and kikuju grass. Can be used for propagation. Corm – a swollen stem base like that of Gladiolus. Can be used for propagation. Bulb – a reduced stem with succulent leaf bases covering the growing point like that of onion. Can be used as food and for propagation. Describe the function of the stem in giving the plant structure. Stems form the framework of the plant, exposing the leaves to the maximum available sunlight. A good example is vines that are often found in forests. They do not spend extra energy to develop strong stems, but rather use other supports to grow out of the forest canopy as quickly as possible to expose their leaves to the sun. Explain the movement of nutrients and carbohydrates in the stem. Stems contain vascular tissue like the vessels and tracheids of the xylem that transport water and inorganic solutes (dissolved minerals) from the roots to other plant organs like leaves, flower and fruit. The sieve tubes and sieve cells of the phloem are transporting organic products from the leaves to other plant organs like stem growing points, flowers, fruit, seed and roots where it is utilised for energy or stored as reserve food. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 Lamina 13. 16 Pinnae Make use of a simple line drawing to show the different parts of a simple and compounded leaf. Petiole Simple leaf 14. Are all leaves of all plant species the same? What functions do the different leaves have? Compound leaf All leaves originate from a stem apical meristem or apical dome as small protuberances called leaf primordia, but during their further development and maturation leaves can take on different forms, shapes and sizes depending on the specific function they have to perform. “Ordinary” or “typical” photosynthetic leaves have green, flattened laminas (leaf blade) and their main function is photosynthesise. These leaves can be simple with an undivided lamina or compound with a subdivided lamina ♦ Bracts – Bracts or scales are leaves that matured in their primordial (baby) form and are mostly colourless or brown. Their main function is to protect buds like flower buds in the young inflorescence, apical buds and axillary buds. ♦ Tendrils - parts of the leaf in some vines are transformed into thin tendrils that curl around support structures to help the plant in its climbing habit like in the sweet pea (Lathyrus odoratus) and Bignonia. ♦ Succulent leaves – the leaves of some plants are adapted to store water like the leaves of aloes or they can store food like bulb scales and cotyledons of the bean seed. Cotyledons have an additional function by acting as haustoria, extracting nutrients from the endosperm. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 17 For the manufacturing of food (carbohydrates), the leaf needs: • • • • Chlorophyll - found in the chloroplasts of the palisade (Pal) and spongy parenchyma cells (SP) of the leaf. Sunlight – leaves to be exposed to light – the light passes through the colourless upper epidermis (UE) and is absorbed by the chlorophyll. Water – supplied by the xylem elements in the vascular bundle (VB). Carbon dioxide (CO2) – passing through the stomata (St) from the atmosphere into the open spaces between the cells inside the leaf. The process: ♦ 15. How do plants get carbohydrates? What important role does sunlight play in this process? ♦ Step 1 dependant on light) Energy from the sunlight is converted to chemical energy by the chlorophyll. • The energy is used to split water into hydrogen (H2) and oxygen (O2). The released oxygen leaves the leaf through the stomata into the atmosphere. • • Step 2- not dependant on light, but influenced by temperature) In another process, which is temperature sensitive, the hydrogen is bound to the carbon dioxide to form a carbohydrate The formula 6CO2 + 12H2O light C6H12O6 + 6O2 + 6H2O The carbohydrates (sugar) is then ‘loaded’ into the phloem in the vascular bundle and transported to the different parts of the plant. Chloroplasts can only develop from proplastids (young plastids) present in dividing cells. Each chloroplast is surrounded by a double membrane The internal structure of the chloroplast is rather complex and can only become fully developed if the cell is exposed to sufficient light. In flowering plants the chloroplasts are usually disk-shaped and measure 4 to 6 micrometers in diameter (1micrometer (µm) = 0.001 mm). The ground substance of the chloroplast inside the double membrane is called the stroma and the stroma is traversed by an elaborate system of membranes in the form of flattened sacs called thylakoids, packed in stacks like coins, called grana (singular granum). The grana are interconnected by a similar double membrane system as the thylakoids. The chlorophyll is contained in the thylakoids of the grana and in the absence of light the grana becomes disorganised and the chlorophyll breaks up Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 16. Can plant leaves react to environmental conditions/stress conditions? If yes, explain how. NQF Level 2 Unit Standard No: 116057 18 ♦ Etiolation – in the absence of light or greatly reduced light, leaves become yellow due to the breaking down if the chlorophyll and the thylakoids in the chloroplasts and we say the leaves are etiolated. The green colour will however return if the plants are returned to light conditions. ♦ Leaves sensitive to touch – The pinnae of Mimosa pudica leaves will close when they are touched. Leaves of the insectivorous Venus Fly Trap contain sensitive hairs and when these hairs are touched by an insect, the two halves of the leaf close quickly to catch the insect Leaf tendrils of plants like the sweet pea will turn around a support as they make contact. ♦ Flowering response – Some plants are sensitive to the number of dark hours in the daily 24-hour cycle. Some plant, called short day plants like chrysanthemum, will flower as soon as the nights become longer than the critical 16 hours. When planted outside, they usually flower in autumn. Long day plants on the other hand, will flower if the nights become shorter than16 hours. Day neural plants are not sensitive to day length. ♦ Heat– Stomata on leaves usually close when the maximum temperature rises above a certain value, meaning that photosynthesis will also stop. Stigma Style 17. Make a simple line drawing to show the different parts of a flower. Recepticle Pedicel Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 19 Pedicel – an elongated internode attaching the flower to the stem Recepticle - a set of very closely spaced nodes bearing the whorls of modified leaves (flower parts). Calyx – the first whorl of flower leaves (sepals)protecting the other 18. After identifying the different parts of a flower, give the function(s) of these parts. leaf whorls during the development of the flower up to the bud stage. Corolla – the second whorl of modified leaves, (petals)usually brightly coloured to attract pollinators to visit the flower. Stamens - one or two whorls of highly modified leaves forming the stamens consisting of the filament (petiole) and the anther (lamina) producing the pollen. Pistil – composed of one or more separate or fused carpels (leaves). The terminal parts of the leaves form the stigma that receives the pollen during pollination. The extended central parts of the leaves form the style while the basal parts of the leaves form the ovary carrying the ovules. In most flowers the carpel leaves are sessile (with no petiole), but in some flowers like those f the Capparidaceae, the petioles form the gynophores. The one or more whorls of anthers of the same flower is referred to as the androecium which forms the male part of the flower producing the pollen (the term gynophore above, therefore means the carrier (-phore) of the gynoecium. One or more carples of the same flower is referred to as the gynoecium, forming the female part of the flower and contain the ovules. After pollination and fertilisation, the stigma and style withers and die while the ovary gives rise to the fruit. The fertilised ovules inside the fruit give rise to the seeds. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture 19. Explain the role of the female parts of the flower in fruit and seed production. NQF Level 2 Unit Standard No: 116057 20 As mentioned above, the pistil, consisting of the stigma. style and ovary, is the female par of the flower. The function of the stigma is to receive the pollen during pollination. If recognised by the stigma, the pollen grain wil germinate and produce a pollen tube that grows down the style in the direction of the ovary The pollen tube carries the two sperm cells derived from the generative cell in the pollen grain. On reaching the ovary, the pollen tube grows to an ovule, enters the ovule through the micropyle, penetrates the embryo sac and sheds the two sperm cells inside the embryo sac from there one will fertilise the egg cell (the nuclei of the two cells fuse) and the other one fuses with the two nuclei of the central cell of the embryo sac (Double fertilisation) The fertilised egg then develops into an embryo (the baby) of the seed, the fertilised central cell produce the endosperm (food) and the integuments of the ovule forms the seed coat (the box). The whole ovule, therefore gives rise to the seed. The developing seed produces hormones that stimulate the ovary wall to develop into the wall of the fruit (pericarp). The whole ovary therefore develops into the fruit, provided the ovules develop into seeds. There are however exceptions where the fruit will develop without fertilisation and seed formation as in the case of the banana and pineapple. This process is called parthenocarpy and the fruits are called pathenocarpic fruit. Pathenocarpic fruit (seedless fruit) can also be artificially produced by spraying flowers with hormones like auxin (seedless tomatoes) of gibberllic acid (seedless grapes). Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 21 Mature fruit are classified in different categories based on the structure of the fruit wall. Different parts of the flower can, however, also take part in determining the fruit structure. 6.1 20. There are different types of fruits available. Say what type of fruit the following are and explain why you think it is that specific type of fruit. Peach, pumpkin, tomato, soybean, strawberry, fig. Simple fruit –fruit developing from a single ovary from a single flower. Single, fleshy fruit – the pericarp is soft and fleshy. • Drupe or stone fruit. – like peach and mango. The pericarp can be divided into exocarp,(the peel of the peach and mango) mesocarp (the soft edible part) and the endocarp, ( hard, stone-like or leather-like layer surrounding the seed). • Berry – also a fleshy fruit, but the mesocarp and endocarp are both fleshy and not distinguishable from each other as in the grape berry, tomatoes, papayas, avocado, coffee, blueberries, gooseberries, and many others. • Pepo – the fruit of the cucurbit family like pumpkins, cucumber and watermaelon are actually also berries, but the carpels are imbedded in the concave receptacle (hypogynous or inferior ovary) that takes part in the formation of the fruit wall. • Pome – like the pepo the fruit also derives from an inferior ovary with the receptacle taking part in the formation of the fleshy fruit wall, but it also has a firm, partly woody endocarp surrounding the seeds. Single dry fruit - in dry fruits the pericarp in the mature fruit is a dry, leathery or papery structure and the three layers are not distinguishable. • Nut – an indehiscent (not opening) fruit consisting of a single carpel as in the nuts falling from oak trees. • Achene –an indehiscent fruit consisting of two carpels as in the sunflower fruit (mostly called a seed). • Capsule –a single, dry dehiscent fruit, usually consisting of more the one carpel and as the classification indicates, the mature fruit dehisces (opens by itself) and the seeds are distributed as in the case of the Strelitzia fruit depicted in the figure above. Capsules are also found in Datura and fruit of orchids. • Pod or legume – a dehiscent fruit, but consists on one carpel only as in the case of a pea pod, a bean, soybean most of the acacias. 6.2 Aggregate fruit –Derive from a single flower but is made up of a number of separate ovaries on the same receptacle like the fruit of the strawberry consisting of an aggregation of small drupelets. 6.3 Multiple fruit – A collection of fruit on a common inflorescence axis as in the syconium of the fig where a great number of achenes deriving from minute flowers are collected in a concave , fleshy inflorescence axis. In the malberry (Morus) and the pineapple,(Ananas) a collection of fleshy fruit and flower parts are collected on a common axis. Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture NQF Level 2 Unit Standard No: 116057 22 Assessment Feedback Form Comments / Remarks Feedback to learner on assessment and / or overall recommendations and action plan for competence: Feedback from learner to assessor: Assessment Judgement You have been found: Actions to follow: Competent Assessor report to ETQA Not yet competent in this unit standard Learner results and attendance certification issued Learner’s Signature: Date: Assessor’s Signature: Date: Moderator’s Signature: Date: Version: 01 Version Date: July 2006 Understand the structure and functions of a plant Primary Agriculture Version: 01 NQF Level 2 Version Date: July 2006 Unit Standard No: 116057 23