* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Plants - GZ @ Science Class Online
Plant use of endophytic fungi in defense wikipedia , lookup
History of botany wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Plant defense against herbivory wikipedia , lookup
Plant breeding wikipedia , lookup
Plant secondary metabolism wikipedia , lookup
Pollination wikipedia , lookup
Plant nutrition wikipedia , lookup
Plant stress measurement wikipedia , lookup
Plant ecology wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Plant physiology wikipedia , lookup
Plant morphology wikipedia , lookup
Photosynthesis wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Flowering plant wikipedia , lookup
Plant reproduction wikipedia , lookup
Sustainable landscaping wikipedia , lookup
Plants Junior Science 1 1a All plants belong to the same kingdom (Plantae). Plants are called autotrophs, which means they make their own food through the process of photosynthesis which also produces sufficient oxygen to the atmosphere to allow all living organisms to respire. Plants have laid down the fossil fuels that provide humans with energy. Every other animal relies on plants either directly or indirectly for nutrition. The Plant Kingdom Plants grow mainly on land but also can be found in the oceans and fresh water. They have been on Earth for millions of years. Plants species currently number about 260,000. 1a The Plant Kingdom – the main Phylum (Groups) Ferns Flowering Plants Ginkos Plant Kingdom Mosses Cycads Conifers Liverworts Horsetails 1b Plants are special because they have leaves and are able to produce their own food by the process of photosynthesis from sunlight using raw materials that they get from the air and soil. Plants can be thought of as ‘food factories’ which provides most living organisms on Earth with a source of energy and nutrients. They produce the energy that is at the start of any food chain and therefore the group of plants are known as Producers. Plants as Producers 1c The structure and functions of parts of the plant The Shoot System Above ground (usually) Lifts the plant above the soil Main functions include: Leaves - photosynthesis Flowers - reproduction Fruit – seed dispersal Stem - food and water transport The Root System Underground (usually) Anchor the plant in the soil Main functions include: Absorb water and nutrients Transport water and nutrients Food Storage 2c Plants take up water through root hairs Extra for experts Water moves into the plant through root hairs. Water being drawn up the plants xylem due to transpiration decreases the pressure inside the root hair cells and this negative pressure pulls water in. 2c Osmosis is the diffusion of water molecules through a partially permeable membrane (extension) Extra for Diffusion means that the net movement of particles (molecules) is from an area of high concentration to low concentration. Oxygen, Carbon Dioxide and water move across the cell membrane by diffusion. experts 2c Osmosis is the diffusion of water molecules through a partially permeable membrane (extension) Extra for experts Osmosis is the diffusion of water only through a partially permeable membrane from where water is in higher concentration to where it is in lower concentration. (or where the solute is in higher concentration) 2d The process of transpiration Extra for experts Transpiration is the process where plants lose water from their leaves. Water enters a plant through root hairs. When stomata, on the underside of leaves, are open to allow CO2 to diffuse in and O2 to diffuse out, water vapour evaporates and diffuses out. 2d The process of transpiration Extra for experts 1. Water enters plant through root hairs by osmosis – high to low concentration of water. 2. Attraction between water particles pulls water up the plant through the xylem. 3. Water evaporates from the leaves through transpiration. GZ Science Resources 2014 2d The process of transpiration Extra for experts 2d The xylem transports water and the phloem transports the products of photosynthesis Extra for experts Transport water around the plant Special features >Cells join into long and tube-like hollow vessels. >Cells have no end walls, so form a 'pipeline' carrying water from leaves to root. >Spirals and rings of lignin surrounding the cells strengthen the walls, to withstand pressure of water. 2d The xylem transports water and the phloem transports the products of Extra for photosynthesis experts The xylem is probably the longest part of the pathway that water takes on its way to the leaves of a plant. It is also the path of least resistance, with about a billion times less resistance than cell to cell transport of water. Xylem cells are called tracheids (cells with narrower diameters) or vessels (cells with wider diameters). Their cell walls contain cellulose and lignin making them extremely rigid. Xylem cells contain no membranes and are considered dead. These cells overlap to create a series of pathways that water can take as it heads to the leaves. There is no single column of xylem cells carrying water. 2d The role that stomata have in the process of transpiration Stomata are normally found only on the under or shaded sides of leaves. Their function is to capture CO2 from the atmosphere by exchanging water for carbon dioxide. The exchange is accomplished by having water directly open to air to facilitate the capture. Extra for experts 2d The role that stomata have in the process of transpiration extension Leaves are the main site of photosynthesis. They make food from carbon dioxide and water in the presence of light. As stomata open in the presence of light, carbon dioxide will diffuse into the leaf and at the same time, water vapour will exit the leaf through the stomata to the surrounding atmosphere through the process of transpiration. Plants will lose water vapour while taking up carbon dioxide through their stomata. If this water loss is uncontrolled, plants can deplete their water reserve. Stomata prevent water loss from the stoma by closing once the leaf has sufficient carbon dioxide. 2d Extra for experts Plant features that control transpiration The structure of a plant influences the rate of transpiration. These features can reduce the rate of water loss from the plant. cuticle boundary A layer of nonmoving air around the leaf surface that decreases water loss. Hair can increase boundary size. A waxy waterproof layer on plant epidermis to prevent water loss. stomata Pores in the plant that can be closed to stop plant transpiration 2e Aquatic environment adaptations boundary stomata >many do not have stomata as they use energy to open and close >Unimportant to increase boundary as mostly surrounded by water and reducing transpiration not an issue > Many have large leaves to maximise light collection because they do not have to reduce their surface area exposed for transpiration >if they have stomata they are on the upper part of the leaf in contact with the air (especially in floating plants) cuticle > Thin cuticle or none at all because water retention not necessary. > Some have thin cuticle to prevent algae growth and allow water to roll off extension 2e Extra for experts Temperate environment adaptations boundary stomata >stomata have active guard cells that are triggered to close by high CO2 in the plant and low water levels in the plant or soil. > Larger leaves are often found on plants in the undergrowth (also because of low light levels to collect more light) and smaller leaves on plants exposed to wind – the less surface area the less boundary to protect. > Some plants will lose there leaves (and reduce boundary) during winter when water is limited. >closing and opening of the stomata uses active transport (ATP) so comes at a cost. cuticle > A cuticle of wax around the plant is present to prevent water loss through the epidermis layer of the leaves and stem. The wax is water repellent but transparent so still allows light to reach the chloroplasts. 2e Desert environment adaptations boundary stomata > Many plants have fine hairs on their epidermis to reduce air movement and increase the size of their boundaries – moist air is also trapped in the hairs > Often their stomata are sunken in pits (crypts) or in channels > Leaves can roll up tightly and reduce surface area available for transpiration > Have very small leaves, reduced them to spines or lost them completely cuticle > Some plants can open their stomata at night (C4 plants) to get CO2 for photosynthesis – a special dark process that doesn’t directly need light. Transpiration is much reduced in this cooler dark environment. > Often very thick, leathery and tough – covering the entire leaf and plant. > the thick cuticle is shiny and reflects light lowering the temperature extension 3a The significance of photosynthesis in making food Most living organisms depend on plants to survive. Plants convert energy from sunlight into food stored as carbohydrates through photosynthesis. Because animals cannot make their own food they must eat plants to gain nutrition. Plants produce oxygen, which is released during photosynthesis, which all organisms need for respiration. 3a The adaptations of leaves for photosynthesis The flat surface of the leaf called the blade helps capture maximum sunlight for photosynthesis. The leaf is attached by a stem-like petiole to the plant which branch out into veins. Inside these are xylem tubes to transport water to the leaf cells, which they require for photosynthesis and to keep the leaf cells turgid or rigid. The veins also contain phloem tubes which are able to transport the sugars (and starch which they are converted into), produced during photosynthesis, away to other parts of the plant for use and storage. 3a The adaptations of leaves for photosynthesis A waxy cuticle on the outside of the leaf provides a waterproof covering while remaining transparent to allow light into the leaf cells for photosynthesis. Openings (usually on the underside of the leaf) called stomata allow carbon dioxide to enter and diffuse into cells as well as allowing oxygen to move in and out. Two guard cells on either side of the stomata open and close the openings. extension Photosynthesis transfers energy from sunlight into energy in chemicals such as glucose and starch. 3b Light enters the leaf and is trapped by chlorophyll contained within the chloroplasts in the cells. Water is transported via xylem to the cell and the carbon dioxide enters through the stomata and diffuses to the cell. These substances react chemically within the chloroplasts, powered by the light and glucose (a sugar) is produced along with oxygen which diffuses out. The sugar leaves the leaf via the phloem. Carbon dioxide + Water +light → Glucose + Oxygen 3d The structure of a leaf enables photosynthesis to occur effectively The cells at the top of the leaf are filled with chlorophyll, which gives leaves the green colour. The chlorophyll allows the leaf to absorb light energy which is required for photosynthesis. The spaces between cells in the spongy mesophyll allow carbon dioxide to diffuse around through the cells. 3d The leaf structure and types of cell inside a leaf Cuticle: Waxy layer water proofing upper leaves. Upper epidermis: Upper layer of cells. No chloroplasts. Protection. Vascular Bundle: Bundle of many vessels (xylem and phloem) for transport. Xylem: Living vascular system carrying water & minerals throughout plant. Phloem: Living vascular system carrying dissolved sugars and organic compounds throughout plant. Palisade Mesophyll: Tightly packed upper layer of chloroplast containing cells. Spongy Mesophyll: Lower layer of cells. Air space: Area for gases to disperse Lower Epidermis: Lower external layer of cells in leaf. Stomata: Opening between guard cells for gas & water exchange. Guard Cells: 2 cells surrounding stomata that control rate of gas & water exchange. 3e Starch test When a plant undergoes photosynthesis it produces glucose which is converted into starch for storage. If we want to investigate what factors are required for photosynthesis we use the starch test to enable us to reach a conclusion. 4a The parts of the flower and the role of the flower in pollination, seed production and dispersal Plants that produce flowers are known as angiosperms. The flowers are the reproductive structures where fertilisation occurs and seeds are produced. 4a The reproductive parts of an insect-pollinated flower Insect-pollinated flowers have visible, often colourful petals that surround the flower's sexual reproduction parts. The petals can "advertise" for specific pollinators through their shape, size, colour and sometimes smell. The flowers are surrounded by sepals, which are small and usually green structures that protect the flower as its developing. The reproductive parts of an insect-pollinated flower and their functioning 4a The female part of the flower is called the pistil. The pollen from a male part of a flower is brought to the stigma by a pollinator. This process is called pollination. The pollen travels down the style into the ovary to join with an egg cell inside the ovules in a process called fertilisation. The male part of a flower is called the stamen. The pollen is produced in the anther which is held up by the filament. The pollen is collected by a pollinator. The pollen contains male gametes which will later fuse with the female gametes in the ovule during fertilisation. The reproductive parts of an insect-pollinated flower and their functioning 4b GZ Science Resources 2014 Insect-pollinated Flowers often contain nectar, a sweet sugar produced by the plant, to attract an insect. As the insect reaches into the flower for the nectar it may be brushed with pollen from the anther. If the insect moves to another flower it may brush the pollen against the stigma and therefore pollinate the flower. Flowers ripen their male and female parts of the flower at different times to prevent self pollination. 4b Summary of pollination in plants 1. The male parts of the flower are the anther and filament 2. The female parts of the flower are the stigma, style and ovary 3. Male gametes are found in Pollen Produced in the Anther 4. Pollen needs to be moved to the female part called the Stigma of the species of plant to reproduce same 5. This process is called Pollination 6. Pollination can be helped by Wind Or Animal 7. An example of wind pollination is grass plants 8. A wind pollinated flower is most likely to look like - small, green, unscented 9. An example of animal pollination is a rose plant pollinated by insects 10.An animal pollinated flower is most likely to look like – colourful, with large petals, perhaps with a scent The differences in structure between insect-and wind-pollinated flowers 4c Insect pollinated flowers are easily seen and often contain scent and nectar to attract the insects. The male parts are adapted so they make contact with the insect as it feeds from the flower. Wind pollinated flowers are often small and green with no scent. Male anthers protrude out from the flower to allow the wind to pick up the pollen and disperse it away from the plant. Male and female parts develop at different times. 4c Examples of insect-pollinated flowers GZ Science Resources 2014 4c Examples of wind-pollinated flowers GZ Science Resources 2014 4d Fertilisation in flowering plants Extra for experts 1. Pollen from either the same plant (self-pollination) or another plant (crosspollination) needs to arrive on the flowers stigma 2. The pollen sends a tube down the style to reach the ovule, and the male gametes (there are two in every pollen grain) enter the ovule to fertilise the egg (female gamete) 3. One male gamete joins with one female gamete to form a zygote and the plant is fertilised. (The fertilised ovule develops into a seed) 4d The differences between pollination and fertilisation in flowering plants Pollination just refers to pollen landing on the female stigma of the plant. This can either be with a pollinator or wind. Fertilisation refers to the sperm cell (that was in the pollen grain) joining with the egg cell to form a single cell (zygote). Pollination does not always lead to fertilisation Extra for experts 5a The formation of seed and fruit from ovule and ovary Once the flower has been fertilised by pollen the ovary grows to form the fruit. The ovules become the seeds. The outer part of the ovule grows into the seed coat. The zygote grows into the young plant – or embryo A fruit may have one or more seeds. The petals, sepals and other parts of the flower start to die and fall off. 5a Seed dispersal Pollen is dispersed (or spread) from plant to plant so the flowers can be pollinated and fertilised seeds produced. Once the Seeds are mature they then also need to be dispersed so they are not competing with the parent plant for space, light, water and nutrients. There are various ways that plants have evolved to disperse their seeds; forming inside fruit that animals will eat and spread, forming structures on the seed so the wind will carry them away, can float away, be forced away or tangle in the coat of an animal to be carried away. 5a Seed dispersal How are seeds dispersed? By animals By the wind Self dispersal 5b The conditions needed for germination of seeds Seeds will remain dormant until they receive water warmth light oxygen Then they will germinate. Other types of seeds may also require >fire to burn seed coat >soaking in water >scratched seed coat >being digested by animals Before they germinate 5b The conditions needed for germination of seeds Extra for experts Testa The seed contains the embryo plant and cotyledons (starch stores) Water enters the seed through the micropyle and activates enzymes. The water also softens the testa to allow it to split. Plumule (embryo shoot) Radicle (embryo root) Micropyle Cotyledon 5b The conditions needed for germination of seeds Extra for experts Plumule starch embryo plant amylase secreted maltose Radicle This is the first part to grow out of the seed as it needs to absorb more water The enzymes break starch down into maltose and then glucose. The glucose is used in respiration to provide energy for growth 5b The conditions needed for germination of seeds Whilst germinating the plant uses food stores in the cotyledon to provide energy for growth germination The seedling can now photosynthesise and make its own food Plant growth and development 5b The conditions needed for germination of seeds Seed loses weight as it uses up starch stores in the cotyledons as the seedling cannot photosynthesise yet Dry mass/g Weight increases as the seedling can photosynthesise and plant grows Dry mass is the mass of solid matter with all water removed Days 5b The conditions needed for germination of seeds Summarise the findings of the experiment shown below: Pyrogallol (absorbs oxygen) Oxygen present Oxygen present No light Oxygen present Oxygen present No oxygen moist 4oC A dry moist moist moist Warm B Warm C Warm D Warm E 5c The structure of a seed The seed consists of the seed coat or the testa which surrounds the cotyledons or the food storage area. The embryo consists of the radicle which is the embryonic root and the hypocotyl which forms the first shoots and leaves of the plant. A small pore in the seed may be seen called the micropyle. This is where the pollen originally entered the ovule.