Topic 9: Plant pictorial history

My plant started growing in the 5th week. I measured the height of my daisy from the top of the soil to the top of the leaf, It showed as 0.4cm. And it had two leaves, as I showed at the topic 1.

At the half of 5th week, It growed faster than usual. Three leaves, 0.6cm height.

At the 6th week. It did not grow as fast as the 5th week, but still growing. Four leaves, 0.8cm.

At the 7nd week,  it did not grow a new leaf, but one of the leaves grow longer.  Just a little bit different.

At the last week of this term. I noticed that my plant seems like stop growing. The soil looked so dry. And there were lots of bugs in the cup, the leaves turned  a little bit yellow. So I changed a place to put my plant. Hope it will grow better.

Finally, my daisy ends up like that:

After this project, I will bring my plant home. I hope it will be a pretty daisy. Come on, please don't ever stop growing! I feel the growth of my plant is exactly the same as my growth as a student of biology. Even though sometimes we stuck when we are learning biology, but we should still keep going and find out the reason that why we failed. Just the same as caring a plant, if you don't try to figure out the reason and avoid it, the plant will die, the same as you will learn nothing from biology.

Topic 8: example of a signal transduction pathway found within a plant

      Ethylene serves as a gaseous hormone in plants, and is perhaps most widely known for its role in the ripening of such fruit as tomatoes, bananas, and apples. The ethylene signal transduction pathway is probably the best understood hormone signaling pathway, whose elucidation of this pathway has been greatly aided by the isolation of mutants that are either blocked in ethylene response or display a constitutive ethylene response in the absence of the gas. In the absence of ethylene, the ethylene receptors constitutively activate CTR, a Raf protein kinase, and the ensuing signaling cascade culminating in the repression of the positively acting EIN2 protein. Binding of ethylene to the receptors disrupts the interaction between the receptors and CTR and somehow inactivates the latter, as well as the ensuing MAP kinase cascade. This relieves the repression of the EIN 2 protein leading to ethylene response gene activation. Production of the ETR1 protein in bacteria has facilitated its biochemical characterization. In vitro studies demonstrated that the hydrophobic Nterminal domain of ETR1 is responsible for ethylene binding, whilst the C terminus contains a domain with histidine kinase activity which is dependent on Mn2. The precise mechanism by which the signal is relayed from the ethylene receptor to CTR is, however, not known. Like all other MAP kinases, full-length CTR1 may not be active because of an auto-inhibitory effect involving the N-terminal domain.

     Four plants hormones:

1.  Auxin, stimulates stem elongation; promotes the formation of lateral and adventitious roots; regulates development of fruit; enhances apical dominance; functions in phototropism and gravitropism; promotes vascular differentiation; retards leaf abscission.
2. Cytokinins, regulates cell division in shoots and roots; modify apical dominance and promote lateral bud growth; promote movement of nutrients into sink tissues; stimulate seed germination; delay leaf senescence.
3. Gibberellins, stimulate stem elongation, pollen development, pollen tube growth, fruit growth, and seed development and germination; regulate sex determination and the transition from juvenile to adult phases.
4.  Strigolactones, promote seed germination, control of apical dominance, and the attraction of mycorrhizal fungi to the root.

Topic 7: Difference between crop domestication through selective breeding and genetically modified agricultural crops

    Farmers have used selective breeding for ages to increase the robustness and output of their crops and to produce and encourage other desirable traits. But there are some pretty huge differences between the techniques they’ve traditionally used and the high-tech ones being implemented today on mega farms that produce GM corn, cotton, soy, and canola. If traditional selective breeding is like two people with two different sets of genes being paired up by a matchmaker who thinks they’ll have pretty, healthy kids together, then modern high-tech GM breeding is like Victor Frankenstein slicing ‘superior’ body parts out of fifteen different corpses and using them to sew together his powerful, yet frighteningly unpredictable, monster. The most critical difference between natural and GM breeding is that natural breeding crosses only organisms that are already closely related—two varieties of corn, for example—whereas, in contrast, GM breeding slaps together genes from up to 15 wildly different sources.

      To make a GM plant, scientists need to isolate DNA from different organisms—bacteria, viruses, plants, and sometimes animals. They then recombine these genes biochemically in the lab to make a "gene construct," which can consist of DNA from five to fifteen different sources. This gene construct is cloned in bacteria to make lots of copies, which are then isolated. Next, the copies are shot into embryonic plant tissue, or moved into plant tissue via a particular bacterium that acts as a vector. After getting the construct copies into the embryonic plant tissue, whole plants are regenerated. Only a few plants out of many hundreds will turn out to grow normally and exhibit the desired trait—such as herbicide resistance.

     And it’s not just cotton, corn, soy, and canola that are being genetically modified anymore—GM alfalfa and GM sugar beets are on the way.  Many food safety activists are, like Holdrege and Mendelson, concerned about the effects these six major GM crops will have on ecosystems, on agricultural production, and on our bodies. All that aggressive lab work, they argue, has the potential to bring consequences we can’t anticipate. Genetic modification has certainly upped agricultural output, which is a plus when food prices are high and many parts of the world are experiencing or are at risk for famine.

     In my opinion, Through the mass genetic modification of nature via GMO crops, animals, biopesticides, and the mutated insects that are created as a result, mega biotechnology corporations are threatening the overall genetic integrity of the environment as well as all of humankind. As the production and consumption of GMO crops continue to soar, it is becoming increasingly apparent that consumers worldwide are unknowingly participating as ‘test subjects’ in a massive experiment on the long-term effects of GMO crops and ingredients. In fact, nearly 93% of US soybeans are genetically modified in order to resist powerful weed-killers that were found to be killing the actual soybeans as well as the weeds. So it turns out that the weedkiller was actually strong enough to kill the soybeans, yet it is considered safe for consumption. After the genetic alteration, these powerful weed-killers now simply drench the genetically modified soybeans.

Topic6：The reproductive structures of angiosperms and their life cycle

     There are two reproductive structures in angiosperm, namely the stamen or the androecium, the male part which produce the pollen and the female part which is called gynoecium or the pistil. The stamens consists of anther which housed the pollen grain, connected by filament, a tube-like structure which connected the anther to the flower structure. The pistil are made up of ovules enclosed in the ovary, the style and the stigma. The ovary is connected to the stigma by a tube-like structure called style. Stigma is the site where the pollen will be lending during pollination. The Pollen will germinate, and the male gametes will be transported into the ovary to fertilize the ovules to form the zygote and eventually will grow into embryo and upon germination the embryo will grow into new plants.

     The adult, or sporophyte, phase is the main phase of an angiosperm's life cycle . As with gymnosperms, angiosperms are heterosporous. Therefore, they generate microspores, which will produce pollen grains as the male gametophytes, and megaspores, which will form an ovule that contains female gametophytes. Inside the anthers' microsporangia, male gametophytes divide by meiosis to generate haploid microspores, which, in turn, undergo mitosis and give rise to pollen grains. Each pollen grain contains two cells: one generative cell that will divide into two sperm and a second cell that will become the pollen tube cell.

Diagram of  angiosperms' life cycle

     For the pollination process, Pollination is when pollen grains from the anther, the male portion of a flower, are transferred to the female part of the flower, known as the stigma. In order for pollination to be successful, the pollen grains transferred must be from a flower of the same species. After the pollen grains land on the stigma, it creates a pollen tube through the length of the style or stalk connecting the stigma and ovary. Once the pollen tube is complete, the pollen grain will send sperm cells from the grain down to the ovary. When the sperm cells reach the ovary and the egg cells, fertilization will occur, which will result in the formation of the seed. The seed will then be released from the parent plant and will be able to grow into a plant and continue the reproductive cycle using the method of pollinatio. Although All Flowering Plants Rely On Pollination For Reproduction, There Is Variation In How Plants Pollinate. There Are Two Types Of Pollination Called Self-Pollination And Cross-Pollination. Self-Pollination is The More Basic Type Of Pollination Because It Only Involves One Flower. This Type Of Pollination Occurs When Pollen Grains From The Anther Fall Directly Onto The Stigma Of The Same Flower. Although This Type Of Pollination Is Simple And Quick, It Does Result In A Reduction In Genetic Diversity Because The Sperm And Egg Cells Of The Same Flower Share Genetic Information. Cross-pollination is a more complex type of pollination that involves the transfer of pollen from the anther of one flower to the stigma of a different flower. This type of pollination results in an increase in genetic diversity because the different flowers are sharing and mixing their genetic information to create unique offspring.

     Coevolution is the interactive evolution of two or more species that results in a mutualistic or antagonistic relationship. When two or more different species evolve in a way that affects one another’s evolution, coevolution is taking place. This interactive type of evolution is characterized by the fact that the participant life-forms are acting as a strong selective pressure upon one another over a period of time. The coevolution of plants and animals, whether animals are considered strictly in their plant-eating role or also as pollinators, is abundantly represented in every terrestrial ecosystem throughout the world where flora has established itself. Coevolved relationships include an immense number of relationships between plants and animals, and even between plants and other plants. One of the most obvious and complex coevolutionary relationships are the mutualisms that have evolved between plants bearing fleshy fruits and vertebrate animals, which serve to disperse the seeds in these fruits. Another example are bees and flowers. 

Topic5：How do plants move water and other nutrients througout the organism

       Plants have roots that stick down into the earth. The roots pull water, which has nutrients dissolved in it, up from the ground, providing fuel. A few special forces cause the water to move up the stem of the plant through the specialized tissue called the xylem.

Water moves through the plant by one of these mechanisms:

·                     Osmosis: Osmosis uses the difference in concentrations of nutrients between the soil and the root to move water (and nutrients) into the plant. More minerals and nutrients are in the center of the root, which is an area called the stele or vascular cylinder (higher concentration), than are in the outside of the root (lower concentration).

·                    The water and nutrients keep moving toward the center of the root to the xylem, which is a tube that then sends the water and nutrients up the root and into the stem. During osmosis, water moves from an area of lower concentration to the area of higher concentration.

·                    Capillary action (adhesion): Once the water and nutrients are inside the xylem, adhesion and cohesion continue to move the water up through the plant. Adhesion occurs when the water molecules cling to the xylem tissue. Adhesion provides the force to pull water up the sides of the tube in the xylem.
              Cohesion-tension: Cohesion occurs when water molecules stick to each other. Cohesion causes the water in the tube of the root and stem to become one long column of fluid and nutrients. As water evaporates from the plant into the atmosphere (called transpiration in plants but respiration in animals), the column of water continues to move up to fill the space left by the water molecules that were “pulled out” of the leaves upon evaporation.

Topic4： Differences between non-Vascular plants and vascular plants

     The difference between vascular and non-vacular plants is that, vascular plants have tubes that carry water up the plant/tree, non-vascular plants dont have those in which case, they need to live near water. Vascular plants are considered the "flowering plant", non-vascular plants have spores and don't need to "mate" with another plant to make a new one, they just need to get their seeds off of them the right way. Vascular plants have a system of cells that transport water through the plant, non-vascular plants do not.

     Alternative forms of photosynthesis are used by specific types of plants, called C4 and CAM plants, to alleviate problems of photorespiration and excess water loss. Photosynthesis is the physiological process whereby plants use the sun’s radiant energy to produce organic molecules. The backbone of all such organic compounds is a skeleton composed of carbon atoms. Plants use carbon dioxide from the atmosphere as their carbon source. The overwhelming majority of plants use a single chemical reaction to attach carbon dioxide from the atmosphere onto an organic compound, a process referred to as carbon fixation. This process takes place inside specialized structures within the cells of green plants known as chloroplasts. The enzyme that catalyzes this fixation is ribulose bisphosphate carboxylase , and the first stable organic product is a three-carbon molecule. This three-carbon compound is involved in the biochemical pathway known as the Calvin cycle. Plants using carbon fixation are referred to as C3 plants because the first product made with carbon dioxide is a three-carbon molecule. Surrounding the bundle sheath is a densely packed layer of mesophyll cells. The densely packed mesophyll cells are in contact with air spaces in the leaf, and because of their dense packing they keep the bundle sheath cells from contact with air. In C4 plants the initial fixation of carbon dioxide from the atmosphere takes place in the densely packed mesophyll cells. After the carbon dioxide is fixed into a four-carbon organic acid, the malate is transferred through tiny tubes from these cells to the specialized bundle sheath cells.  These two modified photosynthetic pathways adequately describe what happens in most terrestrial plants, although there is much variation. For example, there are species that appear in many respects to have photosynthetic characteristics intermediate to C3 and C4 plants. Other plants are capable of switching from exclusively C3 photosynthesis to CAM photosynthesis at different times of the year. Photosynthesis by aquatic plants appears to present even more variation. C3-C4 intermediate plants seem to be relatively common compared to the terrestrial flora, and several species have C4 photosynthesis but lack Kranz anatomy.

Topic3: How plants grow

      The plant will continue to grow upward and outward as its cells multiply. New leaves will appear, as will flowers in many plants. As the plant grows, it will continue to need the proper nutrients from the soil and water as well as sunlight or the right artificial light. Plants in good health will eventually reach their full height and maturity, which is dependent upon their specific variety. Once a plant reaches maturity, it will reproduce. Plants can reproduce as long as they have a male and a female reproductive system. This can happen in plants that are hermaphrodites or with a separate male and female plant that are near each other. Plants also reproduce, or are propagated, in the following ways:

·         Splicing two plants together- such as a Red Delicious apple with a rare apple variety

·         Runners or Stolons- as seen on the strawberry plant

·         Adventitious buds - such as those seen on the trunks of trees that have been cut down

·         Suckers- as seen on Elm trees, tomatoes and roses

·         Bulbs - plants like the onion, garlic and tulips reproduce by forming new bulbs

·         Corms - glads and crocuses reproduce by forming new corms

·         Tubers - similar to bulbs, the dahlia and potato reproduce more tubers

      First, let’s look at primary growth. Primary growth extends the length of a plant both aboveground and belowground. Since humans generally live aboveground, we usually only see the aboveground parts of a plant: the shoot system. The entire shoot system, no matter how large or small, owes its beginnings to a small region of the plant called the shoot apical meristem. An apical meristem is a region of high cell division that contributes to the extension of the plant. The shoot apical meristem is an apical meristem that is in the shoot system, as opposed to the root apical meristem that is, you guessed it, in the roots. It is only through the activity of the shoot apical meristem that the plant grows taller. The shoot apical meristem is found at the tip of the plant stem, so growth extends upward from the top of the stem, not the bottom. Those bottom leaves aren’t going anywhere until they fall off the plant. That means if you carve your name into the trunk of a tree, it will still be there many years later. One more meristem is the intercalary meristem. This is a region of rapid cell division at the base of nodes. This type of meristem is only found in monocots, so don't go looking for it on eudicots. You’ll be looking a long time. These are particularly important to monocots because they allow stems to elongate quickly and also for leaves to regrow quickly if they have been damaged. Just like a human body has all its different parts, a plant body has parts that are the same on every plant, though they may look different in different species.

The parts of a shoot system are the:

·         Stem (nodes + internodes) 

·         nodes are where leaves attach to the stem

·         internodes are the spaces on the stem in between the leaves

·         Leaf (petiole + blade)

·         Branches, which grow out of axillary buds

·         Reproductive parts (the flowers and fruit)

     A leaf is made up of a blade and a petiole. The blade is the flat green part that you usually think of as the leaf, and the petiole is just the little stem that attaches the blade to the main stem. In between the leaf primordia, where new leaves form, and the stem below, are the axillary buds. These will form branches, which will have their own apical meristems on the ends. Axillary buds are often protected by bud scales. A bud scale is a modified leaf that covers the delicate bud until it starts to grow into a shoot. Most of the parts named above are visible as they originate on the shoot apical meristem. The shoot apical meristem is comprised of leaf primordia, which turn into leaves, and the apical dome, where the stem elongates. Under a microscope, the tip of a plant shoot looks like this:

     Now we know how a plant gets taller and its roots get longer. Even a big tree with an enormous trunk starts out as a puny seedling. Popeye eats a lot of spinach to grow big and strong, but what do spinach plants eat? The width of a plant, or its girth, is called secondary growth and it arises from the lateral meristems in stems and roots. As with apical meristems, lateral meristems are regions of high cell division activity. However, the cells they make grow outward rather than upward or downward. Eudicots use lateral meristems to add to their width; monocots, however, do not experience secondary growth. We’ll come back to them later. The lateral meristems that produce secondary growth are called cambiums, which just means a tissue layer that adds to plant growth. The two important ones for secondary growth are the vascular cambium and the cork cambium. The vascular cambium produces more vascular tissue, which provide support for the shoot system in addition to transporting water and nutrients. Because the xylem and phloem that come from the vascular cambium replace the original xylem and phloem, and add to the width of the plant, they are called secondary xylem and secondary phloem. Here is what that looks like:

Topic2: Basic Plant Structures, and Different types of plant cells

        While you are throughout my tour, let's learn some biology facts of plants. The basic plant structures are roots, stems, and leaves. Root is an organ that anchors a vascular plant in the soil, absorbs minerals and water, and often stores carbohydrates. Taproot, lateral roots, and root hairs are in the root system: taproot consists one main vertical root and develops from an embryonic root; root hairs grow by the thousands just behind the tip of each root, it increases the root's surface area. Stem is an organ that raises or separates leaves, exposing them to sunlight, also rise reproductive structures, facilitating dispersal of pollen and fruit. Each stem consists of an alternating system of nodes, the points at which leaves are attached, and internodes, the stem segments between nodes. In the upper angle formed by each leaf and the stem is an axillary bud, a structure that can form a lateral shoot, commonly called a branch. Most of the growth of a young shoot is concentrated near the shoot tip, which consists of an apical bud, or terminal bud, that is composed of developing leaves and a compact series of nodes and internodes. Plant cells differ structurally from the cells of most other organisms in a few key ways. Specifically, they are usually larger than animal cells and are surrounded by a rigid cell wall made from cellulose. They also often have a large central vacuole that takes up most of the cell, and if they carry out photosynthesis, the cells will have chloroplasts. This does not mean that all such cells are the same, and in fact, there are a number of different types of cells found in most plants. Plants basically have three types of tissues, which are made up of different types of cells. Surface tissue forms the protective outer layer covering the plant. Fundamental, or simple tissues, are usually only composed of one type of cell and are normally grouped based on the level of thickness of the cell wall. Vascular tissues are complex tissues that consist of more than one type of cell. There are only two types of vascular tissue: xylem and phloem. The surface tissue, or epidermis, of a plant is often only one cell thick, although it can be much thicker if the plant lives in a very dry environment and protection from water loss is crucial. It is made up of epidermal cells, which often have a very large vacuole. The cell wall that faces the outside of the plant is often thicker than cell wall that faces into the plant. Epidermal cells in the leaves may be specialized as guard cells. These cells control the opening and closing of small holes in the leaves, called stomata. In this way, they regulate the movement of gases into and out of the plant. The function of epidermal cells that line the roots is water absorption from the soil. To increase the surface area, many epidermal cells grow long hair, or filaments, from their surface. There are several types of fundamental tissues, including parenchyma, collenchyma and sclerenchyma. Parenchyma is made up of parenchyma cells and occurs in the roots, leaves and stems of plants. These plant cells are relatively unspecialized and contain large vacuoles and a thin cell wall. Within the leaves and stems, most of the chloroplasts are found in parenchyma cells. They give the cells their green color and allow photosynthesis to take place.

        Here is the diagram of my plant's basic structure:

     

Topic1: Introduce my plant

     Hi, I am Chloe, who is a busy senior and is taking AP Biology class. I am kind of interesting about everything related to biology. My plant for Green Thumb Project is a daisy. Daisy Daisies belong to the daisy family of Compositae, now known as Asteraceae in flowering plants. Daisies are native to north and central Europe. Daisies are simple yet sophisticated and are some of the most beautiful flowers in the floral world. Daisies convey cheer and exuberance in spades. Not surprisingly, daisies are popular both for gifting and growing in gardens. In Biology field, Daisies are in Plantae Kingdom, Anthophyta Phylum, Magnoliopsida Class. Daisies can be grown very easily. Daisies are hard perennials. Daisies are commonly grown from seeds. Daisies can be directly seeded into the flowerbed.

   Well, let's talk about how I get this little daisy for my project. The first day of AP Biology class is kind of fascinating for me. Mr. Spieckemier handed everyone in class a little daisy seed. Actually, this is my first time to plant a daisy in class while we are throughout the term. I never do that before. I planted it in a little blue plastic cup. We put soil and the seed together in the cup. The soil smelled so good. And I can't wait to see how my daisy will grow at the end of the term.  I think the mening of Green Thumb Project is that we can not only learn knowledge about biology in class but also can approach biology by experiencing it from the life. This will be a great and instructive project for us. I hope  I can learn about how to care a plant based on different situation through this project. By the way, I am truly green thumb. After five weeks we planted the daisies, nobody's plant is growing except mine! I had never ever felt so lucky in my life before! Oh, thanks Jesus!

    And now I am the only one who keep my daisy growing. I don't need to buy another new plant for my project and that save me money. Lol, just joking. All right, the lucky star now is starting her tour of plating daisy!