Weitzner 1 General Biology for Non Science Majors 8 27 14 Plants are amazing Plants are the longest living organisms and they are the largest organisms on Earth Plants produce chemicals that people use in their every day lives Plants provide the food we eat and the air we breathe CO2 and H2O get transferred into sugars and oxygen Oxygen is a byproduct of photosynthesis Rwanda example ethnic genocide in 1994 1996 The conflict was fueled by the need of recourses that were in the land Rwanda is now one of the most densely populated countries in the world There is 2 3 acres per person Food production is very important A major objective of plant science is to increase food production to compensate the massive population growth Per capita food production has increased over the last 50 years Plant growth is limited by drought Water is extremely important Also depends on the availability and cost of fertilizer One characteristic is the mode of nutrition They use photosynthesis and are green because of it Second characteristic is the structure of plants Their cellular structure is different and helps them lock into place to capture sunlight for photosynthesis They have cell walls Third characteristic is the reproductive system Plants spore flower or seed Fungi are not plants because of their DNA sequences Carl Linnaeus was a doctor and naturalist He laid the foundation for current biological classification systems in the 18th century He classified plants based on their reproductive characteristics Before Linnaeus things were named and classified by the way they looked other Linnaeus used a two name system Species are a group of organisms that can reproduce with each Kingdom phylum class order family genus and species The kingdoms are plants animals fungi bacteria and protists Organisms are classified based on their evolutionary relatedness The distance on the graph is proportional to the relatedness of organisms Weitzner 2 Life begins with bacteria 3 5 bya plants begin photosynthesis 3 bya bacteria separate from other plants 2 bya 450 mya plants invade land Before that green algae flooded in water 400 mya transportation tissues begin to develop Fossil fuels are the remains of plants from millions of years ago 375 mya leaves evolve and photosynthesis begins more efficient 350 mya seeds and pollen make reproduction easy 150 mya flowering plants emerge and take over in a short amount of time 8 29 14 The cellular structure of a plant is different from that of animals Energy is important to all life World energy use is rising Most of the energy we use is from fossil fuels It raises the Earth s temperature due to CO2 emissions Biomass is a form of renewable energy it s the process of using plant based fuels to make a CO2 neutral energy source Algae source their energy in oil instead of sugars which makes them easier to burn Using renewable energy sources reduces CO2 emissions but some sources are better than others Corn alcohol 85 emissions and Algae biodiesel 180 emissions The ultimate source of energy for life on earth is the sun All organisms are composed of cells the cell is the basic unit of life and all cells arise from preexisting cells Cells divide to make more cells Scientific theory a well confirmed broad explanation of a natural phenomenon based on knowledge that has been repeatedly confirmed through observation and experimentation Scientific hypothesis a prosed explanation for a natural phenomenon that can be verified by experimentation Cells are just too small for human eyes to see All cells have a membrane that restricts what goes in and out of the cell The center of the cell is the nucleus that is surrounded by cytoplasm Plant cells have a few more characteristics that animal cells don t have Plant cells have cell walls and chloroplast which is how they use photosynthesis The cell wall provides support and holds neighboring cells together There is no chloroplast in root cells but there is an Weitzner 3 abundant amount of it in leaf cells This is why most leaves are green CO2 H2O light yields sugar and energy and oxygen is a byproduct This is the process of photosynthesis To preform photosynthesis the plant needs to have a large amount of water The surface of a plant cell has to be wet Xylem is the process of moving water from the roots of a plant to the leaves Phloem is the process of moving sugar from the leaves back to the roots for nourishment Water loss due to transpiration causes wilting and reduces growth and can cause the plant to die The cells of a plant lose their rigidness which causes them to wilt Guard cells in the leaf surface create pores called stomates They limit the amount of water that exits the plant With a lot of water the pores open When there isn t much water the pores close so that the plant can stay alive Plant cell walls are composed of long chains of sugars particularly cellulose Wood is 60 cellulose Carbon cycle the carbon in the atmosphere is constantly being recycled Respiration is the opposite of photosynthesis Sugars oxygen yield CO2 H2O energy Corn is used for many things 41 6 animal feed 0 2 seed corn 7 6 industrial products 1 alcohol 1 5 food products 32 8 gasohol and 14 5 exported The government mandates that oil must be mixed with ethanol and almost 100 of ethanol comes from corn As a result the price of corn has increased because there was a higher demand for it 9 3 14 Plants have roots that dig into the ground from the root the shoot sticks out of the ground on the shoot the stem grows on the stem petiole grows out of the stem and leaves grow from that the shoot tip is the place of development lateral buds are dormant shoot tips The tips of the plants have active cells that help them grow in size and length Weitzner 4 If you cut the tip off of the plant the lateral buds will start growing in place of the shoot tip Plants can be multiplied by making cuttings of branches and rooting them in water They will keep growing and start new rooting Plants have vascular tissue that is made up of bundles of xylem and phloem It s the way the plant transports nutrients to several parts of the plant Most plants that live more than one year grow in width as well as in length A ring of cells forms right below the bark of the tree this is why they grow outward Cell divisions in the body of the stem and root increase thickness Plants don t have many organs Flowers are for reproduction When flowering start the shoot tip makes a flower instead of the leaves and
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