1a. General: Give examples of advantages of there being a wide variety of plants. Greater number of characteristics for breeding. Bigger choice for use as raw materials, foods and medicines. Provide different sources of food for animals. Maintains gas balance. Improves our environment. 1b. Credit: Explain possible consequences to man and other animals of a reduction in the variety of species. Loss of potential resources. Loss of habitats. Loss of potential breeding characteristics. Loss of food supplies for animals. 2a. General: Describe 3 specialised uses for plants. Plants can be used as: i. raw materials ii. foods iii. medicines 2b. Credit: Describe a production or refining process e.g. malting barley, rapeseed, raspberries, timber. Describe timber production as: i. tree seedlings raised in nursery ii. planted out at 2-4 years iii. first trees harvested at 15 years iv. felled at 40-50 years v. timber used in a variety of ways as stated in 2a. 2c. Credit: Describe 2 potential uses of new plants or plant products e.g. new medicines, new food sources. Sugar cane crops can be converted into sugar cane alcohol and used in warmer countries, such as Brazil, as a fuel source for cars. Development of new medicines, particularly new antibiotics and anticancer drugs. World of Plants Summary Booklet page 1
3. General: Describe the functions of three main parts of the seed of a dicotyledon, i.e. seed coat, embryo, food store. The seed coat is a protective layer. The embryo plant is made up of a young root and young shoot. The food store provides the embryo plant with food. 4a. General: Describe the effect of temperature and the availability of water and oxygen on germination. Germination is the stages involved in the development of a new plant from the embryo plant in a seed. Before germination can take place a seed must have water, oxygen and a warm temperature. Water is needed for the seed to swell up and allow the embryo to grow. Oxygen is needed to produce energy for germination. A warm temperature is needed for good germination. 4b. Credit: Describe the changes in percentage germination that occur over a range of temperatures. The percentage of seeds germinating at very low temperatures (0-5 C) or at very high temperatures (above 45 C) is very low or zero. Seeds normally have a high percentage germination over a range of temperatures with highest germination taking place at a temperature known as the optimum. 5a. General: Describe the functions of the parts of flowers, i.e. sepal, petal, stamen, anther, stigma, ovary, nectary. The function of the parts of the flower are: i. Sepal = protects the flower when it is a bud. ii. Petal = attracts insects to the flower. iii. Stamen = male part of the flower. World of Plants Summary Booklet page 2
petals iv. Anther = Produces pollen grains. v. Stigma = Catches pollen grains. vi. Ovary = Contains the ovules (egg cells). ovary vii. Nectary = Makes a sepals sugary liquid called nectar. nectary anther stigma 5b. General: Describe methods of pollination. Pollination is the transfer of pollen grains from the anther to the stigma. Self-pollination is the transfer of pollen to the stigma in the same flower or another flower on the same plant. Cross-pollination is the transfer of pollen to the stigma of another plant of the same species. 5c. General: Describe fertilisation and fruit formation. Fertilisation occurs after pollination, and is when the male gamete in the pollen tube joins with the female gamete in the ovule. Following fertilisation, fruits are formed from the ovary of the flower, which surrounds the seeds. After fertilisation the ovary swells to form the fruit and the ovules inside become the seeds. In a fleshy fruit the main part of the fruit is soft and juicy e.g. tomato, plum. In a dry fruit the main part of the fruit is hard and dry e.g. dandelion, sycamore. 5d. Credit: Explain the structure of wind- and insect-pollinated flowers in relation to sexual reproduction. The structure of insect pollinated flowers in relation to sexual reproduction is: i. have brightly coloured petals to attract insects. ii. have a smell to attract insects. iii. usually produce nectar to attract insects. World of Plants Summary Booklet page 3
iv. have sticky/spiky pollen grains to stick to insects. v. have sticky stigmas inside the flowers so that insects have to brush past it and transfer pollen. vi. stamens are inside the flowers surrounded by petals so that insects will brush past them and pick up pollen. The structure of wind pollinated flowers in relation to sexual reproduction is: i. have small flowers with green or dull coloured petals as they do not need to attract insects. ii. have no smell as they do not need to attract insects. iii. does not produce nectar as they do not need to attract insects. iv. produces large amounts of very light pollen grains so that it can be blown by the wind. v. have feathery stigmas, which hang outside the flower so that pollen in the air can be trapped on them. vi. Have large stamens, which hang outside the flower to catch the wind, which will blow the pollen away. 5e. Credit: Describe the growth of the pollen tube and fusion of gametes. During fertilisation a pollen tube carrying the male gamete (sex cell) grows out of the pollen grain and down the style to the ovary. Fertilisation is the fusion of the male gamete in the pollen tube with the female gamete in the ovule. 6. Credit: Describe one example of each of the following different dispersal mechanisms: wind, animal-internal, animal-external. The three methods by which seeds can be dispersed are: i. wind ii. animal-internal iii. animal-external Wind dispersed have extensions which act as parachutes or wings for carrying the seed/fruit away by the wind e.g. dandelion, sycamore. Wind dispersed can also have fruits which when shaken by the wind, act like a pepper pot. Animal-internal = cherry, tomato juicy fruit to appeal to animals, with seeds that have indigestible coatings to survive digestive juices of the animal. Animal-external = Burdock has hooks to attach to the coats of passing animals. World of Plants Summary Booklet page 4
Some plants may have self or explosive dispersed seeds. These build up pressure inside the fruit, which will disperse seeds when they shoot out of the fruit at high pressure. 7a. General: Describe ways of propagating flowering plants artificially by cuttings and grafting. Flowering plants can be propagated by: i. taking a stem cutting by removing a small piece of stem with some leaves still attached and placing it in a rooting medium. ii. grafting by taking a portion of a plant and joining it to a plant with an established root system. iii. layering by bending the stem to touch the ground so that it will produce roots while still attached to the parent plant. 7b. Credit: Explain the advantages to man of artificial propagation in flowering plants. Quick method of reproduction. Can produce required varieties easily. Grafting produces fruit of known variety and quality. Bud grafting can be used to produce large numbers of plants on a single stock. 7c. Credit: Describe what is meant by the term clone. A clone is a group of cells all originating from the same single parent cell and are therefore identical to each other and the parent. 8a. General: Describe asexual reproduction by runners and tubers. A runner is a side shoot, which grows out from the parent plant. Buds form at points along this runner and eventually root and grow into new plants e.g. spider plants, strawberries. A tuber is an underground food store, which stores food over the winter and provides the new plant with food until it can make its own. New World of Plants Summary Booklet page 5
food made by the plant is sent to make new tubers e.g. potatoes, carrots. 8b. Credit: Describe the advantages of both sexual and asexual reproduction in plants. Sexual reproduction i. gives rise to variation, which may be an advantage if conditions change. ii. allows dispersal of seeds to new areas. Asexual reproduction i. early, quick growth possible because there is no fusion of gametes involved. ii. offspring share parental characteristics allowing beneficial characteristics to be passed on. iii. offspring dispersed in a clump so reducing competition from other species. iv. vulnerable stages of germination and pollination are not present. World of Plants Summary Booklet page 6
9a. General: Explain the need for transport systems in a plant. Water is required for photosynthesis. Food manufactured in the leaves is needed for growth and energy by the plant. 9b. General: Describe the pathways of movement of water and food in xylem and phloem. Water and minerals are carried from the roots to the leaves in tubes called xylem vessels. Food is carried from the leaves to those parts of the plant that need it for growth or energy or to areas where it is stored, in tubes called phloem. 9c. Credit: Describe the structure of phloem and xylem and identify other functions of the transport system. Xylem and phloem are usually found close together in groups called vascular bundles. In the stem the vascular bundles are round the outside. In a root the vascular bundles are in the centre. Vascular bundles also help to give the stem support. Xylem cells are dead. The walls of xylem have rings or spirals of a tough substance called lignin. Phloem cells are alive. Phloem contains two types of cell: 1) sieve tubes and 2) companion cells. The end walls of sieve tubes have pores. 10a. General: State that plants take in carbon dioxide from the air through stomata, which can open and close. Stomata are tiny pores on the surface of a leaf. Carbon dioxide enters the leaf through the stomata. During the day stomata are open. During the night stomata are closed. World of Plants Summary Booklet page 7
10b. Credit: Describe the external features and internal structure (epidermis, mesophylls, veins) of a leaf in relation to its function in gas exchange. A leaf has a large surface area to allow the maximum amount of light to enter the leaf. A leaf has a large surface area to expose it to as much air as possible. A leaf is thin to allow the carbon dioxide to pass quickly to the cells, which carry out photosynthesis, and allow oxygen to leave the cells as quickly as possible. A leaf is thin to allow sunlight to penetrate to all cells. The outer layer of cells on a leaf is called the epidermis. The epidermis is transparent to allow light through. The epidermis contains stomata, which allow gases in and out. The top layer of cells in a leaf is called the palisade mesophyll layer. The layer of cells below the palisade layer is called the spongy mesophyll. The spongy mesophyll cells are loosely packed with large air spaces to allow carbon dioxide and oxygen to get to and from cells quickly. Leaf veins are made up of xylem and phloem within a short distance of every mesophyll cell to carry food away from and water to leaf cells. 11a. General: State that water vapour is lost through stomata. The tiny pores (stomata) on the surface of a leaf allow water to be lost from the leaf. 12a. General: State that green plants make their own food which may be stored as starch. Green plants are able to make their own food. Green plants make food in the form of sugar. The sugar made by the plant is either used straight away or converted to starch and stored. World of Plants Summary Booklet page 8
12b. Credit: Describe the fate of carbon dioxide as structural and storage carbohydrates in plants and as energy stores. Sugar made by plants from carbon dioxide and water can be: i. stored as starch until needed ii. used as supply energy iii. used as building material e.g. cellulose in plant cell walls 13a. General: State that green plants convert light energy to chemical energy using chlorophyll. The process by which green plants make their own food is known as photosynthesis. Photosynthesis is a process which converts light energy into chemical energy. Photosynthesis takes place in the leaves of green plants. 13b. General: Describe the process of photosynthesis in terms of raw materials and products. Photosynthesis combines carbon dioxide and water to produce glucose (sugar) and oxygen. Chlorophyll found in the chloroplasts of plant cells is essential for photosynthesis. Chlorophyll traps the light energy from the sun. The light energy from the sun is used to combine carbon dioxide and water. 13c. Credit: Explain what is meant by a limiting factor and describe the main limiting factors in the process of photosynthesis. A limiting factor is a factor that if in short supply can cut down or limit the rate of photosynthesis. The main limiting factors in photosynthesis are carbon dioxide, light, temperature and water. World of Plants Summary Booklet page 9