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Emily Luetschwager Science 7, Hr 7 Long Term Project Research Plant Biology: Plant biology is the study of the life of plants. Plants are living things. They have all the six traits of life: they have cells, they grow and develop, they have DNA, they sense and respond to change, they reproduce, and they use energy. Plants start from seeds. Each seed contains a tiny plant waiting to germinate. In the early life of a plant, the small seedling relies on the food stored within itself to get energy. Once the plant develops, it gets its energy through the process of photosynthesis. Photosynthesis is the process by which plants make food from light, water, nutrients, and carbon dioxide. Also during photosynthesis, plants release oxygen to the air. When the plant is first starting to grow, it pushes its roots down into the soil, that way the plant can easily access water and minerals. In addition while the roots are getting pushed down, the stem and the new leaves are getting pushed up to the light. The germination stage ends as soon as the plant pushes through the surface of the ground. Plants are producers, which means that they make their own food. Plants need several different things to make food, those things are: chlorophyll, light, carbon dioxide, water, nutrients and minerals. Chlorophyll is a green pigment found in the cells of plants. Chlorophyll colors the leaves green and produces the food through the process of photosynthesis. Light, carbon dioxide, water, nutrients and minerals are important because those are the things that the plant gets its energy to make food from. Plants must go through pollination in order to reproduce. Pollination starts in the flower of a plant. The male part of the flower is called the stamen. The stamen produces the sticky powder we know as pollen. The flower of a plant also contains a female part called the pistil. The top of the pistil is the stigma which is often sticky. Seed will eventually be made at the bottom of the pistil in the ovary. In order for the plant to be pollinated pollen has to be transferred from the Emily Luetschwager Science 7, Hr 7 Long Term Project Research stamen to the stigma. There are two different types of pollination, self-pollination and crosspollination. Self-pollination is when pollen from a plant’s stamen is transferred to its own stigma. Cross-pollination is when pollen from a plant’s stamen is transferred to another plant of the same species’ stigma. This type of pollination often produces stronger plants. Pollen gets transferred from one plant to another either by animals or by the wind. Pollen is transferred by animals by pollen getting stuck on the animal while feeding. Then the animal goes to another flower and the pollen comes off there. Pollen can be moved by the wind as well. Some plants have longer stamens and pistils that way the wind can easily move the pollen. Once a flower is pollinated it travels down the pistil and enters the ovary. The male cells (also known as pollen), fertilizes the eggs, which then develop into seeds. The seeds become a part of a pod after the petals wilt and fall away. One last part about plant biology is that plants do many things to help humans and other animals out too. Plants give us food, oxygen, and shelter. Without plants nothing would be able to live on Earth. Genetics: Genetics is a branch of biology that studies heredity and inherited characteristics. Heredity is the passing on of traits from one organism to another. Heredity traits are determined by specific genes located in a cell. Within DNA, there are many different genes that exist for different purposes. There are genes for hair color, for height, for weight, etc. There are some variations of a gene that relate to the same trait. These variations are called alleles. Every organism carries two genes for each trait. One gene is from the father’s sperm and one from the mother’s egg. One of these genes is more dominant than the other. The other allele is called a recessive allele, and is masked by the dominate allele. Emily Luetschwager Science 7, Hr 7 Long Term Project Research R.C. Punnett, the British Biologist, developed a method to show the concept of dominate and recessive alleles. This method is called the Punnett Square. In the Punnett Square picture graph, dominate alleles are show by a capital letter, and recessive alleles are shown by the same letter in lowercase. So for example, if the mother has a dominate allele, T, and a recessive allele, t, and the father has to recessive alleles, t, there are two different combinations of height that the offspring could be. The offspring could be a Tt, a tall hybrid, or a tt, which is short. So, there is a 50% chance of the child being tall or being short. There is a difference between being a tall hybrid and a pure tall. If the symbols line up to being TT, that means you are a pure tall. If the symbols combine to be Tt, you would be a tall hybrid. If the symbols end up tt, you are short. You can make a Punnett Square with two or more traits as well. These types of Punnett Squares are an example of the Law of Independent Assortment. The Law of Independent Assortment means that one trait doesn’t affect another. An example would be that having blonde hair doesn’t mean you a have good eyesight, so the traits are independent of one another. Sometimes, there aren’t recessive and dominant alleles. These alleles are called co-dominant alleles. An example of co-dominant alleles would be skin color. If one parent is fair-skinned and the other is darkskinned, the offspring would be a mix of the two. When an individual organism reproduces, the cells segregate through a process of meiosis. Meiosis is similar to mitosis, but meiosis involves the sex/reproduction cells, sperm and egg. Reproduction cells have 23 chromosomes. This is called a haploid, which means “one set”. Now, when the cells combine they form a diploid, which means “two sets”. In the first stages of meiosis the chromosomes are copied and they divide normally, just like in mitosis. The next step is different from mitosis though, the chromosomes will start to cross-over. When the chromosomes are crossing-over, some of the paired up chromosomes will switch genetics data. Emily Luetschwager Science 7, Hr 7 Long Term Project Research This is how the Punnett Square is involved. The Punnett Square simply shows the switching of the genetic data, so that both parents’ genes will be present in the offspring. Instantly after the cells divide, they will divide again without copying the chromosomes, creating four reproduction cells, each with 23 chromosomes. That is how genes are transferred from one organism to another. Plant Genetics: Plant genetics is the study of heredity in plants, and how various plants pass on traits. Plant cells have chloroplasts in them instead of mitochondria. These chloroplasts have their own DNA, which will be passed on to the next generation. The male or female reproduction cells have their own alleles which decide the traits of the plant. For example, a pea plant would have an allele for flower color, either purple or white. You can figure out what color the flower would be by using a Punnett Square. If both parents have purple flowers, the offspring would have a purple flower. If one parent has a white flower and one ahs a purple flower, the offspring would have a 50/50 chance of either having a purple or a white flower. So, it all depends on what the dominant and recessive alleles are to decide the different traits of the plant. According to the principle of individual assortment, different pairs of alleles are passed to offspring independently of each other. This means that the color of the flower of a pea plant won’t affect the color of the pea seeds. This basic principle was discovered by Gregor Mendel. Mendel studied how plants reproduced and how traits were passed on from one generation to the next. Mendel started his experiments with pea plants because they can self-fertilize and they grow very quickly. Mendel focused on 7 characteristics of the pea to study: texture, color of the peas, color of the outer coat of the peas, shape of full-grown pea pod, color of unripe pea-pod, Emily Luetschwager Science 7, Hr 7 Long Term Project Research position of the flowers on the stem, and length of the stem. After two years of breeding the plants to make sure they are pure-breeders, Mendel started to cross-breed the plants. He would cross the plants with very different characteristics, for example: tall and short, yellow and purple, etc. He then realized that most of the offspring from the tall and short plants were tall, only 1 compared to every 3 plants was short. He noticed that many plants had similar ratios like this. He experimented for 8 years figuring out heredity in plants. He finally completed his studies in 1863, and in 1865 he presented his idea to the Nation History Society in Brunn. Mendel then published his results in their journal, Transactions of the Brunn National History Society. Without Mendel’s work, we wouldn’t have found out the basic information about heredity in plants. Plant Breeding: Plant breeding is the science of changing genetics in plants. It is usually done to get the characteristics of plants to what you want them to be. Plant breeding has been practiced for thousands of years, by many different types of people as well. Gardeners, farmers, and professional breeders will all use plant breeding. Modern plant breeders use techniques of molecular biology to select and insert the traits into the plant. This method is known as Molecular Breeding or Genetic Modification. In genetic modification, the scientists will either add a specific gene or take out a gene using RNAi. In order to genetically modify a plant, the scientist must design a genetic construct, which is like a blue-print telling then what genes they are going to take out and what genes they are going to add. To accomplish this task, a promoter must drive a termination sequence to stop the old gene and to add the new genes to the plant. Once the plants are transformed, they will grow on antibiotics, because otherwise they will die. Most of the modern day plant breeders will Emily Luetschwager Science 7, Hr 7 Long Term Project Research put a resistance to insect pests into the plant, nor a gene that could make a variety of the plant to grow in a different season. Some other motives that scientists wish to accomplish from plant breeding are: cold tolerance, improvement of quality, changing maturity duration, dormancy (failure to fully develop a seed), and disease resistance. There are some concerns with plant breeding though. Some scientists say that when you insert certain genes into the plant, other genes may be ignored or forgotten about, which could lower their nutritional value. Otherwise, plant breeding is a way that scientists have developed to make a better crop and grow crops faster without getting eaten by insects. Identification of Alternate Dwarfing System in Wheat: The process of the alternate dwarfing system in wheat is also known as the Green Revolution. The Green Revolution was after the 1960s, referring to the enormous increases in grain yields. This all happened because of the introduction of new varieties of wheat and rice, which were discovered by Norman Borlaug. Borlaug introduced dwarfing genes to wheat. These genes gave wheat a shorter, stronger stem that helped the plant survive in the wind and rain. This method was soon recognized and large commercial wheat farmers started to use this gene. The wheat plant is protected by herbicides that way it doesn’t have to fight with weeds for the sun. The genes that are associated with the dwarfing system in wheat are known as Reduced Height (Rht) genes. These genes are either dominant or semi-dominant; assuring that the plant will have a shorter and stronger stem. Two genes that are used in numerous commercial wheat varieties are Rht-B1b and Rht-D1b.These two genes affect the growth of the plant making it shorter. There is also a very severe dwarfing gene for wheat known as Rht-B1c. This gene will make the wheat smaller than what the two genes used in commercial farming would. Overall, the method of the Emily Luetschwager Science 7, Hr 7 Long Term Project Research alternate dwarfing system of wheat helps the wheat withstand the natural elements of wind and rain, which helps increase the wheat production, therefore, feeding more families. The Genes Involved in the Reproduction of Soybean: Soybean reproduces through eight stages. During the first stage the soybean begins to start flowering. The plant will usually have at least one flower. The plant will then go into the full flowering stage where there will be an open flower on one of the two uppermost nodes. After the soybean gets the full flower, a pod will begin to form on one of the four highest nodes. These beginning pods are 3/16th of an inch long. The pod will then fully grow and become 3/4th of an inch long. After the pod is at its full length, a seed will start to develop inside of it. The next stage is the full green seed, which fills the pod capacity. The plant will then begin its maturity when one of the normal pods on the main stem has reached the mature pod color. Lastly, the plant will be fully mature when 95% of the pods have reached the full mature color. One of the genes that controls the flowering process in soybean is the gigantea gene. The gigantea specifically controls the flowering time in the soybean plant. This gene is one of the most important genes in the process of reproduction of the soybean plant. Without this gene, a soybean plant wouldn’t flower at the proper time and would develop healthy beans, which would affect many people worldwide. In summary, the gigantea gene is very important when it comes to the reproduction of the soybean. Highlighted Color Key: Important Vocabulary words with definitions (12). Important Scientists