Baby Bio Study Guide Plants and People Section Introduction Key Characteristics of plants o Green because they contain chlorophyll o Photosynthesis Plant nutrition o Can t move because of their cell wall o Different mode of reproduction they produce flowers fruits seeds and spores Classification of organisms o Kingdom o Phylum o Class o Order o Family o Genus o Species Now based on organisms evolutionary and genetic relatedness not just their physical features 5 kingdoms bacteria animals fungi protists plants The first organisms bacteria appeared about 3 5 billion years ago Start Some bacteria evolved photosynthesis which led to oxygen in the atmosphere that previously had none More complex multicellular organisms then appeared about 1 5 billion of life years ago About 1 billion years ago plants fungi and animals appeared The Special Features of Plant Cells Flowering plants Angiosperms o The most diverse abundant and important plant group Most cells are 1 40 mm in diameter o The cell membrane controls the movement of substances in and out of the cell o DNA is located in the nucleus or control center o Most activity takes place in the cytoplasm o Plant cells unlike other cells have chloroplasts for photosynthesis They trap light energy to create a chemical reaction in which carbon dioxide from the atmosphere is combined with water to make sugars Oxygen is a byproduct of photosynthesis Plants use the sugars to power their growth and metabolism The reverse of photosynthesis is respiration o Animals take the sugars they consume from plants and combine them with oxygen to release energy Carbon dioxide and water are byproducts of respiration So photosynthesis and respiration create the carbon cycle in which carbon from the atmosphere passes to plants then passes to animals then passes back to the atmosphere the movement of water from the roots to the leaves then to the Transpiration atmosphere o To restrict water loss plants have a waxy layer on their leaves surfaces that allows carbon dioxide uptake and water release only through special pores called stomates Stomates have guard cells that swell when the soil has lots of water to open the stomates and allow carbon dioxide in and water out Guard cells shrink when soil is dry to reduce water loss but this also stops carbon dioxide uptake which stops photosynthesis The main component of a cell is cellulose which is composed of sugar chains that form stiff rods o This is how plant cells have cell walls Cell walls prevent the plants from moving and are useful to humans for tools Gives us wood paper cloth and rope How Plants are Put Together The very top of a plant is where the shoot tip is located o New cells form at the shoot tip and plant growth takes place The above ground portion of a plant is the shoot The below ground portion is the root o Some plant roots have lateral roots branching out that have root tips at the end Cell division and root growth occur at the root tip Growth at the shoot and root tips makes plants growth longer not wider o Cell division causes growth in width When a plant flowers the shoot tips stop making leaves and make flowers instead o Most flowers are hermaphroditic they have both male and female parts o Pollen o The center of the flower contains the pistil which has the stigma at the end and an grains form in the anthers and contain sperm ovary at the base The ovary contains ovules which each contain an egg Pollination and Seed Dispersal o Reproduction involves 2 parts Pollination Fertilization the transfer of pollen to the stigma the fusion of the sperm and egg to form the next generation of plants Ovule Ovary develops into the seed which contains the plant embryo develops in to the fruit Self pollination Genetic variability permits adaptation to changing environments leads to genetic uniformity Wind pollination and insect pollination carry pollen from one flower to another Animal pollinated flowers provide an attractant to help the animal find the flower and a reward usually pollen and sweet nectar at the base of the petals Bees are attracted to blue and yellow colors and sweet odors They also need a place to land when they pollinate because they can t hover so bee pollinated plants have a broad open surface or large petals Colorful specs guide the bee to the nectar and pollen attached to the bee as it drinks Then the bee takes that pollen to the next flower it visits Butterfly pollinated flowers are similar to bee pollinated flowers and they are generalists meaning they visit many different flowers Hummingbirds are specialists They only pollinate plants with odorless red flowers that produce lots of nectar Bats and nocturnal moths pollinate plants whose flowers open at night are white dull colored and have heavy musty or fruity odors Flies pollinate flowers that are reddish brown and smell like rotting meat When animals eat fruits from plants they digest the seeds and then poop them out which disperses them and allows them to germinate and further aid in the development of the next generation of plants Some plants explode their seeds out some plants seeds cling to animals and disperse that way and some disperse through water The Algae and the Evolution of Land Plants The base of the food chain in the ocean is phytoplankton microscopic unicellular organisms o They photosynthesis and provide food for the other animals o 30 of the oxygen in the atmosphere comes from the phytoplankton s 2 groups diatoms and dinoflagellates The ancestor of all land plants is green algae o Green algae began growing in streams 450 million years ago o 400 million years ago plants had evolved that had xylem and phloem roots leaves and stomates with guard cells Ferns They have internal fertilization where the sperm has to swim to the eggs After fertilization the embryo remains attached to the parent plant and grows into a fern plant while destroying its parent 2 separate generations in their reproductive cycle a spore forming generation and gamete forming generation o This method is called alternation of generations and is shared by all land plants The remains of ferns from 400 300 billion years ago built up faster than they could decay and eventually got buried and compressed into today s coal deposits The other 2 fossil fuels oil and natural gas originate from plankton remains accumulated in deep deposits on the ocean floor being pulled into earth s crust Under intense heat and pressure the long dead plankton turned into gas and
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