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World of Plants 1- Give examples of advantages of having a wide variety of plants 2- Describe three specialist uses of plants (i.e. raw plant material needs to be processed before use) and give two examples for each. 3- (C) Explain possible consequences to humans and other animals of a reduction in the variety of plant species 4- (C) Describe a production or refining process e.g. malting barley, paper making, biofuel. (answer provided for malting barley) 5- (C) Describe two potential uses of plants or plant products ( e.g. new medicines, new food sources) World of Plants 1- Describe the functions of the three main parts of a seed. 1- Introducing plants - provides a wide range of edible products - provides a wide range of medicinal substances - medicine: e.g. morphine from poppies, digitalin from fox gloves. - clothing: e.g. cotton and linen - paper from wood - Loss of potential new medicines - Loss of potential crop species - Loss of genetic storehouse to improve crops by genetic engineering The barley is left to germinate for a few days. During this process called malting, the sugar maltose is produced from grain‟s starch. Yeast uses maltose to produce alcohol in a process called alcoholic fermentation (= anaerobic respiration) New medicines: new antibiotics New food sources: new species resistant to pests/ drought 2- Growing plants 1- seed coat: protects embryo 2- embryo: develops into a new plant 3- food store: food (starch) available to provide energy for embryo growth until food can be obtain by photosynthesis. 2- Describe the effect the following factors on germination: - temperature - water - oxygen - temperature: too low → germination prevented because enzymes cannot work efficiently enough. Too high enzymes will be denatured - water: needed for cell processes and for making new cells - oxygen: needed to release energy from food store Low temperature → enzymes work inefficiently or not at all Optimum temperature enzymes work most efficiently High temperature → enzyme work inneficiently or may be denatured (i.e. irreversibly damaged) 3- (C) Describe the changes in percentage germination that occur over a range of temperatures. 4- Identify and describe the function of the parts of a flower 1- Flower stalk: supports flower so they stand out. 2- Sepal: protects flower bud from insects and cold. 3- Petal: attract pollinators + protection of sexual organs 4- Stamen: male sex organ of plant 4a: filament: supports anther 4b: anther: produce male gamete (sex cell) called pollen 5- Carpel: female sex organ of plant 5a: ovary: produces ovule containing female gamete 5b: stigma: sticky platform on which pollen is deposited. 6- Nectary: produce nectar (sugary liquid to attract pollinator) What is meant by pollination? What is self-pollination? What is cross-pollination? 5- Describe methods of pollination 1/Insect 2/Wind 6- (C) Explain the structure of insect and wind-pollinated flowers in relation to sexual reproduction. 1- Petals 2- Stigma 3- Anthers 4- Pollen 5- Nectaries 7- Describe fertilisation. 8- (C) Describe the growth of the pollen tube and the fusion of gametes. When a pollen grain is transferred from an anther to a stigma Pollen of a flower is transferred to the stigma of the same flower Pollen of a flower is transferred to the stigma of a different flower 1/Insect enters flower to find nectar, brushes against anthers and pollen stick to its body. Insect flies into other flower and brushes its body covered in pollen against stigma → pollination. 2/ Pollen grain are carried away by wind to the stigma Insect Pollinated Wind Pollinated Large, brightly coloured, Small, green, not scented scented → no need to → attract pollinator attract insect Small and sticky Large, feathery, hanging 2 → insect brushes onto them → large surface area exposed to wind 3 Small and firmly held Large, loosely attached → insect brushes onto them → pollen can be shaken off easily 4 Small quantities produced Large quantities produced Spiky → attaches to insect smooth and light → easily carried by the wind 5 Present Absent 1 The fusion of the two nuclei, the male gamete from the pollen grain and the female gamete contained in the ovule. After landing on the stigma, the pollen grain germinates, i.e. it grows a pollen tube which eventually reaches the ovule. The male gamete travels down the pollen tube to fuse with the female gamete. 9- Describe fruit formation. 10- (C) Describe an example of each of the following different seed dispersal mechanisms. 1/ Wind 2/ Animal internal 3/ Animal external 4/ Self-explosive 11a- Describe ways of propagating flowering plants artificially by cutting 11b- Describe ways of propagating flowering plants artificially by grafting 12 (C)-Explain the advantages to humans of artificial propagation 13- State what is meant by asexual reproduction 14- Describe asexual reproduction by runners; Give an example. 15- Describe asexual reproduction by tubers; Give an example. After fertilisation, the ovule develops into a seed which contains the embryo plant. The outer part of the ovule becomes the seed coat. The ovary wall may become fleshy (e.g. apple) or hard (e.g. hazelnut), i.e. a fruit. 1/ Wind: e.g. dandelion, sycamore → light seeds with wing-like extensions or parachutes → blown by wind away from mother plant 2/ Animal internal: e.g. tomato, apple → seed carried away from parent plant in digestive system of animal → excreted with faeces (fertiliser). 3/ Animal external: e.g. sticky willy → dry hooked fruits stick to animal fur → carried away from parent plant 4/ Self-explosive: e.g. gorse when fruits dry they explode sending the seeds away from the mother plant - stem cut just below leaf/leaf bud - Hormone powder dusted onto basis of stem - stem placed in damp compost - new roots and shoots develop after a few weeks - notch cut made into receiving branch called stock - part of branch of donor plant is cut to fit notch. - desirable characteristics conserved - fast - grafts: best features of two plants can be combined The generation of offspring from only one parent which does not involve gametes (i.e. sex cells). - horizontal shoot grows over ground - young plant develops at the end of shoot - young plant obtains nutrients and water from mother plant until able to grow independently. e.g. Strawberry - underground stems swell up during growing season and stores food (e.g. starch in potatoes). - plant dies in autumn, underground swollen stem remains. - following spring, shoots and roots are growing from underground stem → new plants are produced e.g. potatoes 16a-(C) Advantages and disadvantages of sexual reproduction 16b-(C) Advantages and disadvantages of asexual reproduction Advantages Disadvantages more likely to adapt to environmental change and resist disease. - seeds dipersed away Less competition for resources (e.g. light, water) some characteristics may be lost in offspring - variety of offspring: Advantages - no variety of offspring: Good characteristics are kept through generations - grows next to parent : Environment suitable for growth - no need for pollination World of Plants 1- Explain the need for a transport system in plants. 2- Describe the role of the xylem 3- Describe the role of the phloem 4- Identify xylem and phloem from the diagrams: - variety of offspring: - seeds dipersed away May land in unsuitable environment - requires pollination: chancy process Disadvantages -no variety of offspring: May not be able to adapt to changes in environment and resist disease. - grows next to parent : May compete with. parent 3- Making food - to transport water and minerals from roots to leaves - to transport food (i.e. sugar) from leaves to parts of the plant which do not make food Transport water and soluble minerals after they enter root hairs to all parts of the plant up to leaves. Transports food from food-producing cells to other parts of the plants where it is needed (root, shoots and fruits) - 1: xylem (at the centre of the root and stem‟s vascular bundle; on the upper side of the leaf‟s vein) - 2: phloem (to the outside of the vascular bundle in the root and stem; on the lower side of the leaf‟s vein) 5- (C) Describe the structure of the xylem and identify other functions of the transport system. - Xylem cells are dead cells forming tubes. - Ligning bands are strengthening the tubes, give structural support to the plant. Eventually, old and unused xylem tubes become wood. 1- cell wall 2- ring of lignin 3- pit ( allow water and minerals to reach neighbouring cells 4- direction of the flow (from roots to leaves) 5- xylem tube 6- (C) Describe the structure and function of cells in the phloem. Identify the different parts from a diagram. - Phloem is made of two types of living cells: - sieve tubes: cells arranged as a tube with perforated cell wall in between (sieve plate). Strands of cytoplasm transport sugar from cells to cells. - companion cells: have nucleus and cytoplasm, they control neighbouring sieve tubes. 12345- 6- Explain how carbon dioxide is transported from the air to photosynthesising cells inside leaves. 8- State where these „holes „are located. Explain what the meaning of “clone” sieve tube sieve plate strands of cytoplasm companion cell direction of flow, from photosynthesising cells in leaves to cells that cannot produce their own food. Through holes called stomata (Sing. Stoma). When the stoma opens: carbon dioxide goes in and oxygen and water vapour go out by diffusion. Stomata are found mostly on the lower surface of leaves. An organism which is genetically identical to the organism from which it has been produced. 9- State what is lost through these Water vapour is lost when the stomata are open. At „holes‟ night, when there is no light for photosynthesis, stomata close to prevent water loss. 10- (C) Describe the external features and internal structures of a leaf in relation to its function in gas exchange. 11- State where plants get their food from and how they store it. 12- State what energy change takes place during photosynthesis 13- State which (green) chemical substance is needed for photosynthesis. 14- Describe the process of photosynthesis in terms of raw materials and products. 15- (C) Describe the fate of carbohydrates made during photosynthesis. 16- (C) Explain what is meant by a limiting factor and describe the main limiting factors in the process of photosynthesis. 1- Waxy cuticle: prevents water loss 2- Upper epidermis: protection 3- Palisade mesophyll: where most photosynthesis takes place. 4- Spongy mesophyll: where some photosynthesis takes place. Cells are not compactly packed and have a large surface area exposed to air. This allows the diffusion of carbon dioxide into cells. 5- Air spaces: allow free movement of gases inside the leaf. 6- Lower epidermis: protection 7- Guard cells: specialist cells which open or close the stoma 8- Stoma: allows gas exchange with the atmosphere (carbon dioxide goes in; oxygen and water vapour go out) 9- Phloem 10- Xylem 11- Veins: carries water and minerals to photosynthesising cells, takes away sugar from photosynthesising cells to other parts of the plants. Plants make their own food from CO2 + H20 using light energy. They store it as starch. Light energy is converted into chemical energy. Chlorophyll in chloroplasts. Raw materials: carbon dioxide and water Products: oxygen and sugar (glucose) - used directly for energy (i.e. during respiration) - stored as starch= storage carbohydrate (i.e. food reserve) - made in cellulose= structural carbohydrate to build new cell wall. An environmental factor, that, when in short supply, prevents photosynthesis happening at its optimum rate. Main limiting factors are: carbon dioxide, temperature and light intensity.