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Plants and Flowers 7th grade science Part ONE Plants There are many strange plants throughout the world Some plants trap animals, some bloom only once every thirty years, and some have flowers that smell like rotting meat! Venus Flytrap, Dionaea muscipula, is a carnivorous plant that catches and digests animal prey—mostly insects and arachnids Corpse Flower smells like rotting meat when it blooms, only opens up once in several years, and only stays in bloom for a few days. You interact with plants every day, when you eat, when you see moss on a tree or plants in a pond. All plants, even the strange ones have things in common. What is a Plant? -Plants belong to the Kingdom plantea, they share several characteristics. Nearly all plants are autotrophs, organisms that produce their own food. All plants are eukaryotes that contain many cells. Plants are autotrophs, a sun powered food-making factory. Sunlight provides the energy for this food making process, photosynthesis. Plants are multicellular, with cells organized into tissues. Plants vary in size from the tiniest moss to the largest redwood tree. Adaptations for Living on Land- Most plants live on land but some live in water. Water plants obtain water and nutrients directly from the water. Water also gives them a place to grow and when these plants reproduce the sperm cells swim through the water to the egg cells. For plants to survive on land, they must have several things……. •a way to get water and nutrients from their environment, to retain or hold onto the water so they don’t dry out, a way to transport materials in their bodies, a way to support their bodies giving them a place to grow. a way to reproduce To live on land plants must have adaptations to survive. They need a way to get water and nutrients from the soil. Retaining Water- One adaption that helps a plant reduce water loss is a waxy layer called a cuticle which covers the leaves of most plants. Transporting Materials.Plants need to transport materials from one part of its body to another. In small plants it is easy for materials to move from one cell to the next. Large plants need a more effective system. These plants have transport tissues called vascular tissues. These tissues are tube like structures inside a plant that water, minerals and food move. Support- A plants food making parts must be exposed to as much sun as possible. Rigid cell walls and vascular tissue strengthen and support the bodies of these plants so they are best exposed to the light. Reproduction- All plants go through sexual reproduction that involves fertilization, the joining of a sperm cell with an egg cell. A zygote is the fertilized egg. For some plants the sperm cell swims through the water. Other plants have adapted to their environments and use different methods of fertilization. Classifying Plants part 2 Scientists “informally” group plants into two major groups: non-vascular and vascular. Nonvascular Plants - Nonvascular plants lack a well-developed system of tubes for transporting materials. (non = not, vascular = tubes to transport fluids) Growing in damp shady places these plants are low growing and don’t have roots. They absorb what they need directly from their environment. These materials pass through the cell walls into the cells. This is a slow process compared to vascular transport. The cell walls are thin and can not support a tall plant, most of these plants are only a few centimeters tall. Vascular Plants Plants with defined vascular tissues are called vascular plants. Vascular plants are able to transport materials over greater distances efficiently and quickly. The vascular tissues also provide support. These plants can grow very tall. Plant Origins- The oldest plant fossils are about 400 million years old. These plants already had many adaptations such as vascular tissue. Through chemical analysis of different plants, such as the specific make up of chlorophyll, as well as genetic testing, has lead scientists to hypothesize that ancient green algae is the ancestor of today’s modern plants. Some scientists think that green algae should be classified as a plant. Some plants, such as the Gingko tree, and many others have been around since prehistoric times. Complex Life Cycles -Plants have complex lifecycles that include two different stages, the sporophyte stage and the gametophyte stage. In the sporophyte stage (SPOH ruh fite) stage, the plant produces spores. Spores are tiny cells that grow into new organisms. Spores develop into the plants next stage, the gametophyte stage. In the Gametophyte stage (guh MEE tuh fyt) the plant produces sperm cells and egg cells. The sperm cell and egg cell then combine to form a zygote. The zygote develops into sporophyte. The sporophyte produces spores which develop into the gametophyte which produce sperm and egg cells…..the sporophyte looks very different from the gametophyte. Characteristics of Seed Plants part 3 Parvis e glandibus quercus, a Latin proverb translates to "mighty oaks from tiny acorns grow." What is a Seed Plant?- Seed plants outnumber seedless plants by more than ten to one. We eat many seed plants, rice, squash, tomatoes, peas, and squash are all see plants. We even wear cloths made from seed plants like cotton and flax. Many homes are made from see plants, oak, pine, maple trees, and in some country people “thatch” their roofs with thatch which is a grass. We breathe oxygen that is produced mainly by seed plants. Seed plants share two very important characteristics 1. They have vascular tissue 1. They use pollen and seeds to They also have roots, stems (bodies), and leaves. Some have complex life cycles that include the sporophyte and gametophyte stages. The gametophytes are microscopic, the plants are the sporophytes. The vascular tissue helps support the plant as well as transports nutrients. There are two types of vascular tissue. Phloem (FLOH um) vascular tissue transports food from the leaves to the rest of the plant. Water and minerals travel through vascular tissue called xylem, (ZY lum) from the roots to the top of the plant where the stems and leaves are. Pollen and Seeds- Seed plants can live in many environments. They produce pollen, a tiny structure that later becomes sperm cells. Once the sperm cell fertilizes the egg, seeds develop. A seed contains a young plant inside a protective covering; the covering helps young plants from drying out. How Seeds Become New Plants- All seeds are similar. Inside each seed is a partially developed plant. If the seed lands in an environment with favorable conditions it will begin to grow. Seed Structure-A seed has three main parts: Embryo: stores the beginning of roots, stems, and leaves. Uses the food stored in the seed until it can make its own food through photosynthesis. The embryo has one or more seed leaves called cotyledons (kaht uh LEED unz) in some plants food is stored in the cotyledons, in other is it stored outside the embryo. The outer covering is the seed coat. The covering protects the seed like plastic saran wrap protects food. It keeps moisture in allowing the seed to remain inactive for long periods of time until it is in the perfect environment for germination. In many plants fruit Seed Dispersal.- The scattering of seeds is called dispersal. Seeds are dispersed in many ways. 1. Other organisms eat the fruit around the seeds and also consume the seeds. The seed travels through the digestive system and are deposited in new areas. 2. Some seeds have barb like structures and “hitch hike” a ride on an organism to a new spot. 3. Some seeds travel in water, across oceans (like coconuts) 4. Lightweight seeds can be carried in the wind. Some of these seeds have structures to help them travel away from the parent plant. 5. Some plants eject their seeds; the force scatters the seeds in many directions. 6. Being far away from the parent plant so it does not have to compete for light, food and water helps to increase the survival of the new plant. GerminationWhen the conditions are right a seed will germinate. The seed absorbs water from the environment allowing the embryo to absorb food and start to grow. Germination (jur muh NAY shun) occurs when the embryo begins to grow and pushes out of the seed. First the root pushes downward. Next the stem and leaves push upward. Once you see the leaves the plant is called a seedling. Roots - There are 2 major root systems. Fibrous root system is made up of a tangled dense mass of similarly sized roots. When you pull these plants, such as grass, out of the ground they bring a lot of soil up with the root system. A taproot system has one thick main root with smaller roots branching out from the main root. This kind of root system is difficult to pull out of the ground. Carrots have a tap root. T A P F I B O R U S Root Structure- The root cap is a rounded tip at the end of the root that protects the root from injuring itself as it grows. Behind the root cap are cells that divide quickly to form new root cells. Root hairs grow out of the root and enter the soil to absorb water and nutrients and to anchor the plant in the soil. The absorbed material is transferred to the vascular tissue (xylem) where it is transported up into the plant. From the leaves the vascular tissue (phloem) transports the food back to the root tissue to be stored or fuel plant growth. Stems- Stems carry substances between stems and leaves, provide support and hold the leaves up so they are exposed to the sun. Stems can be herbaceous (hur Bay shus) or woody. Herbaceous stems are often soft and contain no wood. Woody stems are hard and rigid. Woody stem has an outer layer of protective bark surrounding a layer of cambium (KAM bee um) which divide to produce vascular tissues. At the center of the wood is the heart, it is darker and has become hard. It does not transport fluids but it does provide support. When you look at a tree stump you can see the each ring, one ring is created each year of the trees life. Count the rings and you can see how old the tree is. Each contains both kinds of vascular tissue as well as other supportive cells. Leaves- Leaves of all shapes and sizes capture the suns energy and carry out photosynthesis. The top and bottom layer of the leaf protect the inside of the leaf. The cells on the inside are surrounded by vascular tissues or veins. The surface of the leaf has stoma. Stoma are pores that allow substances into (CO2) and out of ( O2, H20) the leaf. Stoma translated to mouth but don’t look like a mouth. Pea Leaf Stoma The Leaf and Photosynthesis- The leaf is a perfect structure for carrying out photosynthesis. Chloroplasts are near the upper surface to collect the most sunlight most efficiently. Photosynthesis-Photosynthesis is the process of which plants change sunlight into energy. This energy is their food which contains oxygen and glucose. the conversion of light energy into chemical energy by living organisms. The raw materials are carbon dioxide and water. The energy source is sunlight, and the end-products include glucose and oxygen. 6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O Respiration: During respiration a plant releases energy through chemical reactions. This results in the break down of sugar into oxygen, to carbon dioxide. Respiration is basically the opposite of photosynthesis because it uses energy and photosynthesis stores energy. It uses food instead of producing food. It uses carbon dioxide instead of oxygen and it does not require light. glucose + oxygen + water = water + carbon dioxide + ENERGY C6H12O6 + 6 O2 + 6 H2O → 6 CO2 + 12 H2O Carbon dioxide enters the leaf through the stoma, water travels up from the roots through the xylem to the leaf. The chloroplast absorbs sunlight/energy. The leaf then uses the carbon dioxide and water to produce sugar (usable energy) that travels through the phloem to the rest of the plant, and oxygen, that is released back through the stoma into the air. Controlling Water LossThe leaf has a large surface exposed to the air, to keep moisture from evaporating, transpiration; too quickly the leaf can close the stomata. Pine needles have less area exposed to the elements and a thick waxy coating to help protect them and keep them moist. The Structure of Flowers : The function of all flowers is reproduction. All flowers no matter what they smell like or look like have the same parts. Sepals and petals when a flower is a bud it is covered by leaf like structures called sepals which are often green. Under the sepals are the colorful petals. The shape, size and color will vary between varieties of flowers. Stamen inside the petals are the reproductive parts of the flower. The stamen is male reproductive parts. They produce the pollen and make sure it is released where it can be transferred to the female parts. Pistils found in the center of most flowers, they are the female parts of the flower. Some flowers have one pistil, some have two Pollinators organisms that transfer pollen from the male parts of a flower to the female parts. Birds, bats, insects. Some are attracted by the odor of the flower, some flowers smell sweet but some smell bad. Section TWO Flower Parts Petals are used to attract insects into the flower; they may have guidelines on them and be scented. They are brightly colored, some pollinators are attracted to certain colors, other pollinators are attracted by scent. Anther contain pollen sacs where pollen is produced. The sacs release pollen on to the outside of the anthers that brush against insects on entering the flowers. The pollen once deposited on the insect is transferred to the stigma of another flower or the same flower. The ovule is then able to be fertilized. Stigma Is covered in a sticky substance that the pollen will stick to. Style raises the stigma away from the Ovary to decrease the likelihood of pollen contamination. It varies in length. Ovary protects the ovule and once fertilization has taken place it will become the fruit. Contains one or more ovule. Pistils The female reproductive part of the flower. The parts of the pistils are the sticky stigma, the slender tube called the style, and the hollow structure called the ovary at the base Sepals are small leaf like structures; they protect the flower while the flower is developing from a bud. Anthers contain pollen sacs where pollen is produced. The sacs release pollen on to the outside of the anthers that brush against insects on entering the flowers. The pollen once deposited on the insect is transferred to the stigma of another flower or the same flower. The ovule is then able to be fertilized. Stamen Male reproductive part of the flower. Pollen is produced in the anther held high up on the filament