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5B LIFE CYCLES : KEY WORDS AND PHRASES words and phrases associated with life processes e.g. reproduction, life cycle names for parts of a flower e.g. stamen, style, stigma, sepal, petal, ovary, pollen names for processes related to life cycles and associated verbs e.g. reproduction/reproduce, germination/germinate, pollination/pollinate, fertilisation/fertilise, dispersal/disperse descriptions and explanations using a sequence of ideas. adaptation animal anther bacteria camouflage carpels colonise competition control cotyledons decay dispersal distribution ecosystem fertilisation filament food chain germination growth habitat life cycle microorganisms micropyle nectar nutrients organism ovary petals plant plumule pollination populations predator prey radicle root seeds sepals shelter shoot species stamens stem stigma style succulents wind dispersal woody stems xylem 5B LIFE CYCLES : KEY KNOWLEDGE Seeds need light, water and space (to get air and sunshine) in order to grow after they have germinated. Plants grow from seeds that are in the soil even though we cannot see them. Some plants grow from pieces of root or underground stem left in the soil when it is dug. Plants need light to produce food for growth. Green leaves are essential for the plant to carry out this process. Some plants e.g. radish, potato, carrot, have an underground food store called a tuber. New plants can grow from the tuber (as well as from seeds also produced by these plants). Plants take up water from the soil through their roots. It is transported through the stem to other parts of the plant The water is given off from the leaves as water vapour. This water normally goes out into the atmosphere but will condense inside a closed polythene bag covering the leaves. Some plants take up and give off more water than others. A control is used in an experiment to compare experimental data with 'normal' conditions. Some plants, e.g. cacti and succulents are especially adapted to living in dry conditions. Plants take up water from the soil through their roots and pass it up the stem in xylem vessels. They can also take up substances dissolved in water e.g. ink, but not insoluble substances, e.g. chalk. Nutrients dissolved in water can make plants grow and flower more vigorously. These may be naturally present or can be added in solution e.g. Baby Bio. Life processes including growth, nutrition and reproduction are common to plants Most flowers have: sepals, petals, stamens (anthers and filaments) and carpels (stigma, style and ovary). Flowers of the same species have common characteristics i.e. the same number, shape and arrangement of sepals, petals, stamens and carpels. In flowers of different species the size, shape and arrangement of these is different. Seeds need space to grow away from the parent plant. They may be eaten by birds e.g. blackberries; flung away as pods dry, e.g. gorse; blown away by the wind e.g. dandelion; stuck to animal coats, e.g. burdock; buried by animals, e.g. hazelnuts Insects visit flowers in search of nectar. As they reach deep into the flowers, pollen from the stamens is brushed off onto their bodies. The insect moves on to other flowers carrying the pollen to the stigma where the male gamete travels down the pollen tube to the ovary and fertilizes the seeds. Most plants cannot pollinate their own flowers (usually stamens ripen before the seeds are ready to be fertilized). Cross pollination results in strong new plants. When the petals fall, the seeds ripen, they are dispersed from the plants and grow into new plants Trees have flowers and seeds. Seeds can grow into trees. Some trees have two kinds of flower. These can be on the same tree or on different trees of the same kind. Catkin flowers have lots of pollen as they depend on the wind to blow it on to the stigma of flowers on another tree. Grasses are also wind pollinated. Seeds cannot grow (germinate) without water. A bean seed has: - a small hole, the micropyle, which allows water to enter the seed and soften it; - an outer covering, the testa, which protects the seed; - two halves, the cotyledons, which are the food store for the growing plant; - the radicle and plumule, which become the root and shoot of the growing plant. As the plant grows, the food store is used up and the bean shrivels. A number of different species live together in a pond, an ecosystem. They are specially adapted for life (or a stage of their life cycle) in water. All animals need oxygen. This may be obtained from the air or from dissolved oxygen in the water. Different species are found in different areas of the pond, or at different levels. Life processes including movement, growth, nutrition and reproduction are common to animals. Several species of animals live in one habitat. Animals living in a habitat, i.e. under stones or logs, are especially adapted to it. Animals live in a habitat because the conditions there suit them, e.g. temperature, moisture, light and shelter. If animals are moved a short distance from their habitat, many will return. Life processes, including movement, growth, nutrition and reproduction are common to animals. 5B LIFE CYCLES : THINKING SKILLS Information-processing skills These enable children to locate and collect relevant information, to sort, classify, sequence, compare and contrast, and to analyse relationships. 5B LIFE CYCLES : ICT IDEAS Unit 5B Life Cycles 1. Pupils could use CD-ROMs to view newly born animals and gather information about gestation periods. 2. Use a computerised microscope to observe stamen with pollen and pollen grains from a number of sources – (class activity). 3. Connecting an Intel microscope to a computer and data projector would allow the whole class to make close observations of flower structures. It is also possible to scan leaves and flowers for the children to look at. Children could produce a display of a life cycle using a word processor, some children might simply order pictures, most children could add labels and some could make comparisons between different life cycles. Web Sites: www.endangeredearth.com/ www.panda.org/ www.panda.org/kids/ 5B LIFE CYCLES : TESTABLE QUESTIONS 5B Unit Life Cycles 1. How is seed germination affected by size/ soaking/ light/ temperature/ motion? 2. What are the possible factors which affect the rate at which frogspawn develops in the classroom compared to the pond? 3. What do seeds require in order to germinate? 4. How will pollution effect plant growth/seed germination? 5B LIFE CYCLES : BIG IDEA All living things will die; and if the species is to continue, and is to have any future, then it needs to reproduce. Reproduction produces new offspring of their kind - plant or animal. As the old die off, the young take their place. A species that is good at reproduction will survive. Green plants reproduce by flowering. The flowers contain the cells that will combine to produce the seeds and then the new plant. Ideally, cells from two different plants will combine; but if all else fails, a plant can fertilise itself to produce seeds. The flower produces female egg cells in its ovary. The ovary has a sticky stigma on a long style to catch the male pollen cells. The pollen cells are produced in the stamens. These tiny specks are carried to the stigma of another plant by the wind, or on an insect. The insect gets sticky, sugary nectar from one plant and gives it to another plant - like a postal service. When the egg cell is fertilised, it develops into a seed. The ovary may develop too, into a fruit. Because now the challenge is to move the seed - away from its parent plant to somewhere where it will grow. The wind may blow it, or water may carry it; it may stick to a passing animal, or be swallowed by one, only to emerge in the animal's droppings and grow. The new plant will flower in turn. This is all a risky business - and so lots of pollen and seeds are produced to help ensure that new plants will grow. The whole process - from flower to flower - is called the flower's life cycle. 5B LIFE CYCLES : ASSESSMENT GRID 5B Life Cycles Date Level 3 1. name the parts of a flower and sort a series of pictures to demonstrate the life cycle of a plant or human; Level 4 2. name the male and female parts of a flowering plant; 3. explain the phrase 'optimum growing conditions'; 4. describe two methods of pollination and two methods of dispersal; Level 5 1. explain the need for seed dispersal in terms of competition and nutrition; Sc1 Investigating the effects of pollution on plant growth Planning Pupils can: Level 3 Level 4 Level 5 make a supported prediction, e.g. 'I think that the seeds growing in salt water will germinate because plants grow near to the sea'; plan a fair test in which they vary only one thing, e.g. amount of fertiliser/pollutant, type of seed; plan the investigation giving a scientific explanation, e.g. 'I am going to change the amount of fertiliser given to each dish of seeds because I think that if I give some too much it will have no further effect on seed germination'; Obtaining and Presenting Pupils can: measure carefully quantities of water and/or fertiliser, pollutant; Considering and Evaluating Pupils can: identify a simple pattern, e.g. 'all the seeds grown in the warmth germinated'. make a series of observations of the germination of their seeds; link their conclusions to the plants' need for water and warmth in order to germinate. make a series of observations and use averages of the measurements as necessary when encountering odd results; calculate the rate of germination in terms of percentages of the seed samples, or plot a growth curve on a graph, length against time. 5B LIFE CYCLES : DISPLAY Seeds Collections: Seeds and seed cases; fruits: familiar ones and more exotic, e.g. kiwi fruit star fruit, watermelon, etc. - and tomato, marrow, fruit sliced in different ways to expose the seeds; seed cases from flowers e.g. poppy heads, love-in-the-mist honesty (display these with a sample of the seeds); tiny seeds sprinkled onto adhesive tape to aid observation and handling; seed pods - peas and runner beans; conkers and their prickly seed cases along with sweet chestnuts, hazel nuts, beech nuts, coconut etc dried grasses, ears of wheat or barley; from the kitchen: dried beans, rice, nuts and seeds used for flavouring, e.g. fennel cardamom, caraway etc.; advertising posters or free samples from seed merchants ; packs of seeds. Display: Slice open unusual or colourful fruits—observe using hand lenses and draw or paint Make a scarecrow to scare away the birds from seeds you may have planted outside. Make miniature scarecrows and stick them into flowerpots filled with soil. Observational drawings or paintings of seed heads, grasses, dandelions, etc. (White crayon on black, or white wax with a dark wash is particularly effective.) Make a seed picture frame. Arrange seeds in a pattern against a frame on card and attach using good quality glue. When dry, apply a coat of paint which has PVA glue mixed with it. Use it to display artwork or photographs. Design a seed packet, or container, perhaps for sale at a summer fair. 5B LIFE CYCLES : EQUIPMENT 5B collection of pictures of plants with fruit e.g. apple trees, vines, dandelions, beans, horse chestnut, tomatoes hand lenses/microscopes examples of flowers e.g. mallow, buttercup and pictures of flowers collection of fruits and seeds including those dispersed by different mechanisms pictures illustrating the plants from which seeds come rapidly germinating seeds e.g. radish, spring onion thermometers containers in which to germinate seeds soils etc in which to germinate seeds secondary sources e.g. video, CD-Rom, reference books showing newly born animals and giving information about gestation periods 5B LIFE CYCLES: PROGRESSION OF IDEAS Plants The life cycle ensures that new plants are produced. Plants only produce flowers at certain times of the year. Flowers are part of the plants reproductive system. Flowering plants have different parts that have to be combined to produce seeds. In order for this combination to occur pollen has to be transferred from the anther of one flower to the stigma of another. This is called pollination. Pollination can take place in different ways but the two most common methods are by insects or the wind. If pollination is successful a seed will develop Seeds need to be carried away from the parent plant so that the new plants can survive and grow healthily. Seed dispersal is the process by which seeds are carried away from the parent plant. Seed dispersal is carried out in a variety of ways by different plants. All plants of the same species use the same method of seed dispersal. When a seed starts to grow into a plant it is said to have germinated. Water and warmth are required for germination to occur. Humans Humans are alive. Humans move. Humans grow. Humans feed. Adults have babies. Babies grow into children and then into adults. Humans are animals and have processes in common with all other animals’ e.g. they move, feed, grow and reproduce. Humans change gradually as they grow older. Humans start their life as babies and change into children, as they grow their bodies change. Children grow into adolescents because changes occur in their bodies. Adolescents grow into adults because more changes occur in their bodies. Humans need food for energy. Humans need food for growth. 5B LIFE CYCLES : PROGRESSION RELATED TO SCIENCE ENQUIRY Variation and Classification Context Recognise similarities and differences between themselves and others. Learn to group living things using observable similarities and differences. To use observable features to group locally found living things and to use a key for that purpose of identification. Using characteristic features devise a simple key to help identify animals and plants belonging to a common group Concepts There is a wide variety of living things and these can be grouped by observable characteristics. Living things reproduce and some characteristics are inherited from one generation to the next. Inherited characteristics help living organisms to survive by helping them adapt to the environment in which they live. Vocabulary and S.I. Units KS1 Animal, autumn, backbone, bird, coat, conditions, egg, environment, fish, flower, insect, leaf, limbs, mammal, offspring, petal, plant, reproduce, root, seeds, skin, spring, stem, summer, tree, S.I. Units: Length - metre (m), Mass - kilogram (Kg) KS2 Amphibian, carnivore, chromosomes, classification, cycle, extinct, fish, genes, group, inherit invertebrate, key, kingdom, reptile, variety, vertebrate, zone S.I. Units: Length - metre (m), Mass - kilogram (kg) Variation and Classification K N O W L E D G E E N Q U I R Y Level 1 2 3 4 5 6 Know some obvious physical differences between common animals/plants around them. Be aware there is a variety of living things and they are different in appearance and able to describe differences between common animals e.g. cats/ dogs. Know they can group animals/plants by simple observable features like number of legs or skin or shape of leaf. Able to group animals into large common families like dogs showing a notion of share common characteristics e.g. recognise a small and large dog are both dogs. Recognise the obvious features that make an organism best suited to is environment such as birds having wings for flying but these are different in animals from different groups and although similar they are different within a group e.g. insect wings from bird wings or leaf shape. Know animals can be grouped by shared observable characteristics such as skin, number of legs, wings etc., so they classify simple animals into groups like insects, mammals etc. Be able to use a simple key to group organisms into simple groups Use scientific ideas to describe when animals or plants reproduce observable inherited characteristics are passed between parent and offspring during reproduction. Know that organisms are classified according to shared features and devise a simple key. Describe simple differences between two common animals or plants like dog, cat and themselves or a pine tree, oak tree; or a tulip and a daffodil. Describe observed physical differences by talking or record by pictures /simple charts the differences. In observations describe key factors to sort animals and plants into groups. Make comparisons of different common characteristics like shape, size of leaf. Compare length/shape using non- standard measurement and record results in a prepared chart. In a description o shape comment on the tree shape and where found Responding to questions they suggest factors like light or soil type to vary in an investigation on plants and their differences. Simple predictions such as a plant with broad leaves needs more light than a small leaf plant. Make simple measurements of length, width and shape of leaf, enter them in tables and write about the environment the plants grow best in. Explain the changes, differences they see and the simple patterns in the results. Investigate a local environment using simple IT such as sensors for temperature and light and record in simple spread sheets. Use a simple key to identify/ group organisms found in that environment and link them with conditions in the place they were found. Make simple predictions about what will hap- pen if conditions change Record in tables and interpret patterns to draw a simple causal link between habitat and organism. Identify key differences between organisms in an environment and classify them using a key. Predict using science knowledge what variation to expect in two different environments such as a pond and a wooded zone, give a reason for the variation they expect. Measure, record simple repeat differences in conditions. Draw simple charts or maps to show location, density of organisms. Using the evidence explain with science ideas the Know that some differences are inherited by information stored on cellular components called chromosomes. An offspring inherits two components of inherited characteristics on genes one from the male and one front the female. Know a species is an organism with genetically inherited characteristics. Identify key factors affecting the inheritance of a characteristic like hair colour or tongue rolling. Using IT spreadsheets and science ideas make predictions about the offspring. Look for relationships in the data such as eye colour with hair colour. Use the evidence and related scientific ideas to justify the conclusion they have formed to make predictions about offspring. 5B LIFE CYCLES : BACKGROUND SCIENCE A living thing is characterized by the fact that it has the potential for movement, respiration, sensitivity to stimuli, growth, reproduction, excretion and feeding. Young children tend to over-emphasize movement as the sole characteristic of a living organism. A living thing has the ability to carry out all or most of these processes at some stage during its life cycle. For example, a dried pea has no obvious signs of being alive, but if it is put in water and then planted it may quickly demonstrate that it is living. As a dried pea it was 'ticking over' (respiring very slowly) until conditions were suitable for growth to take place. As a plant, the pea demonstrates its ability to carry out all the processes of living things. It is the combination of all these processes that enables us to identify something as living. All living things are made up of discrete microscopic units called cells. These contain the information needed to carry out the vast number of chemical reactions that allow the living thing to remain alive. Effects of the environment Shape, colour, size, and behaviour are some of the characteristics that may be changed as the result of environmental factors. In some cases the effect is only slight, but in others it can be quite dramatic. For example, hydrangea plants generally have pink, white or blue flowers. However, the blue flowers occur only when the plant is growing in an acid soil; in other soils the flowers are either pink or white. The effects of environmental influences on organisms are generally identified by an examination of physical features. However, the consequence of such influences on characteristics such as behaviour and intelligence in humans is by no means clear and the evidence is far from conclusive. Effects of heredity Offspring inherit characteristics from their parents. For sexual reproduction to occur a male and a female parent are needed. The offspring show some of the characteristics of each parent and so cannot be exactly like either of them. In addition, the way in which the various characteristics come together during reproduction involves a high degree of chance. Thus each individual offspring will have the characteristics of their parents combined in different ways, so they will also vary from each other. In some organisms reproduction can also take place asexually. In this process one individual produces an offspring by dividing in two or producing another structure which eventually becomes independent. Plants are produced asexually when a gardener takes cuttings. Offspring resulting from asexual reproduction are almost exactly like their parents. Similarities are retained but there is little or no opportunity for any variation. Thus variation within a species occurs as a result of sexual reproduction. Sudden changes in characteristics From time to time offspring will be produced with a characteristic that is very distinct and unexpected. These sudden changes, called mutations, occur with varying frequency in different species and are the result of changes that have taken place during the formation of the male sex cells (sperm or pollen) and/or the female sex cells (egg or ovum). When the egg and sperm come together at fertilization these new characteristics become part of the offspring. Often these changes are lethal so the offspring do not live, but occasionally the mutation results in a characteristic that is of benefit to the individual. The peppered moth used to be white, but in the nineteenth century a black form appeared which was better able to survive on tree-trunks blackened by smoke in Britain's cities. Plants The life cycle of a flowering plant Many of the plants which add colour to our gardens each year, such as antirrhinums, asters, lobelias and so on, are referred to as annuals because they complete their life cycle in one growing season. Other plants such as Canterbury bells are biennials: that is, they take two years to complete a life cycle, from seed to producing seeds. Perennials are those plants such as roses which flower each year, the same plant surviving from one season to another. Plant reproduction Plants can reproduce both sexually and asexually. In sexual reproduction, a male and a female part from either the same or different plants come together. Pollen is usually then transferred from the stamens, considered to be the 'male' part of the flower, to the stigma, considered to be the 'female' part of the flower, and this results in fertilization of the plant's seeds. It is possible for parts of a plant other than seeds to grow; for example a potato tuber, a willow twig or a carrot top. In these cases reproduction is asexual (vegetative), as it does not involve the male and female part of the plant.