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Biological Sciences
BIO_SC 1200
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Unit 5 Plant Diversity What tool do we have for identifying unknown plants in the field? We have a tool called a dichotomous key It is a series of questions with yes or no answers Each answer either leads to the solution or another question We discussed 5 major categories of plants. Our discussion of these categories moved from "first evolved" to "most recently evolved." For each category, know what new characteristic(s) it had that previous plants did not. Moss (Bryophytes) ---> Vascular tissue, sporophyte dominant, leaves ---> Ferns (Pterophytes) ---> seeds, cones ---Gymnosperms (Pinophytes or Coniferophytes) ---> flowers, fruit ---> Angiosperms (Anthrophytes) For each category also know: Characteristics (Leaves? Roots? Dominant stage? Etc.) Example of members of this category Human uses. Algae Characteristics Single or multicellular Span three kingdoms Prokaryotic or eukaryotic Dominant life stage can be sporophyte, gametophyte, or neither Many are photosynthetic Example of members of this category Seaweed Algae in algae blooms Human uses Seaweed - high in protein, potassium, and iodine Omega03 gist oils are made by algae and eaten by fish As gelling agent for foods, lotions, toothpaste, and paints A tool in the lab (gels and growth media) Mosses (Bryophytes) Characteristics No roots No vascular tissue No seeds No flowers Gametophyte dominant Small, leaf-like structures Need water to reproduce Examples of members of this category Sphagnum moss Peat Human uses Burned for energy--peat is dying sphagnum moss As wound treatment before antibiotics As decoration in horticulture Ferns (Pterophytes) Characteristics Have vascular tissue Sporophyte dominant Have root-like structures No seeds No flowers No fruits Need water to reproduce Leaves called fronds Examples of members of this category Tree ferns Water ferns Human uses Most of our oil comes from decomposed ferns Decorative plants Air filters Building supplies (tree ferns) Gymnosperms (Pinophytes or Coniferophytes) Characteristics Have roots Produce seeds Have cones No flowers Don�t need water to reproduce Needle-like leaves Cuticle on leaves Vascular Sporophyte dominant Most do not lose their leaves Examples of members of this category Pines - needles for leaves, hard and woody stems Ginko - deciduous, dioecious, extracts are used to enhance memory (not safe, not effective) Cycads - woody plants, similar to ferns (have cones), generally tropical Human uses Building materials Decorative uses Angiosperms (Anthrophytes) Characteristics Flowering Vascular Sporophyte dominant Make seed protected by fruits Have leaves Leaves usually covered by cuticle Have roots Monocots or dicots Examples of members of this category Hydrophytes - flowering water plants, modified leaves with no cuticle, stomata open and numerous Wood species - "hardwoods" (more durable than softwoods) Cacti - na�ve to the Americas, large and porous taproot, have spines instead of leaves, extra think cuticle Human uses Food Spices � � Energy, Plant Metabolism, Photosynthesis, and Respiration Why is wood so heavy? What provides that weight? Carbon makes up a majority of the mass in plants Plants that cannot do photosynthesis do not take in carbon and will subsequently lose weight after respiration Where does the energy we use to run our bodies come from? All of the energy we have on earth has come from the sun. Plants use light energy and carbon to make glucose. Humans eat plants (and the glucose) and use it to make ATP, which powers our bodies Is energy created of destroyed? Yes. JK, no Energy is only changed from one form to another What is our (or a plant's) metabolism? Metabolism is all of the reactions inside a living organism The two major metabolic processes are photosynthesis and respiration We looked at two sets of metabolic reactions: Photosynthesis and Respiration. What are the primary requirements for photosynthesis? Light, carbon dioxide, water What are the primary products of photosynthesis? Oxygen, glucose Why is photosynthesis beneficial? Plants are able to make their own food Makes oxygen for respiration Makes glucose for respiration What are the primary requirements or cellular respiration? Glucose, oxygen Why is cellular respiration beneficial? Respiration converts sugars into ATP Does respiration = breathing? Why or why not? No, respiration is not the same as breathing because it does not require oxygen. However, respiration usually does use oxygen that comes from breathing Does all respiration require oxygen? No, anaerobic respiration does not require oxygen, but it is less efficient than aerobic respiration � � Global Warming/Climate Change What is Global Warming/Climate Change? Global Warming/Climate Change is an increase in the average heat energy on Earth, as measured by temperature What are some measured symptoms that Global Climate Change is occurring? Increased air and water temperature Melting of polar ice caps Rising shore line Change in wind pattern Compare and contrast the slow and fast carbon cycles. How do the contribute to Global Climate Change? Fast carbon cycle - Exchange of carbon between biotic factors Photosynthesis in plants and respiration in all living organisms Plant are being killed and cannot convert as much carbon dioxide to oxygen Slow carbon cycle - Exchange of carbon between abiotic factors (in general) Decayed plant material in crust Volcanic eruptions release carbon into atmosphere Humans use carbon from earth for energy Humans have caused a large increase in the carbon concentration in the troposphere What are the hypothesized causes of Global Climate Change? Mankind's activities have increased greenhouse gasses through: Increased carbon dioxide emissions Decreased carbon dioxide use (deforestation) Increased greenhouse gasses trap heat Natural fluctuation Normal increase in carbon dioxide levels Past 1950, carbon dioxide level is higher than it has ever been Increased solar input The sun is releasing more energy Only the layer with greenhouse gasses are heating, the others (past this layer) are cooling Are the possible causes mutually exclusive of each other (is only one "right")? The most accepted theory is that mankind is affecting global climate change It could be a combination of several causes What are the concerns or possible outcomes if Global Climate Change continues? Change in weather Change in local climates on land and in the ocean Rising ocean level Change in producers (like plants)--including agriculture Change in habitat species Change in disease distribution What are some things we can do individually to decrease the amount of energy we use on a daily basis? Fluorescent or LED light bulbs Drive more efficient cars Move the thermostat up two degrees in the summer and down two degrees in the winter Use low-flow shower heads Turn off your computer monitor at night Wrap your water heater Recycle Plant a tree--or a whole garden What good is reducing our "Carbon Footprint" with respect to Global Climate Change? The average American produces 15,000 pounds of carbon dioxide each year from energy use (not cellular respiration) � Unit 6 Plant Physiology: Hormones What is plant physiology? Plant physiology is the study of plants that investigates the growth and hormones of plants. What is the relationship between hormones and gene expression? Hormones control gene expression and genes control hormones. We discussed 6 plant hormones. What are they? Auxin Cytokinin Abscisic acid (ABA) Gibberellin Brassinosteroids Ethylene Which plant hormone is the primary growth regulator? Auxin What is phototropism? Gravitropism? Thigmotropism? Phototropism is the tendency of plants to grow towards light. Gravitropism is the tendency of roots to grow downward and shoots to grow upward. Thigmotropism is the tendency of plants to grow toward or away from touch. How does auxin cause roots to bend down (with gravity), but stems to bend up (against gravity)? When a plant is not facing the correct direction, the hormone auxin accumulates on the side that is closest to the grown due to gravity. In stems, these high concentrations of auxin cause those cells on the downward side of the plant to expand. This causes the bottom of the plant to grow more than the top, and the plant grows up. These high concentrations cause roots to stop growing. Auxin is in high levels on the bottom side of the roots, so the top side will grow more. When the top side grows but not the bottom, the root will bend downward. What other functions does auxin have besides moving plants? Controls other hormones Plant growth regulator Helps loosen cell walls, causing cells to grow Slows fruit ripening Blocks early fruit drop Helps pollen tubes grow Can be used as a herbicide (2, 4-D) What 5 functions did we discuss for cytokinin? Promotes cell division Promotes seed germination Slows senescence of leaves and fruit Helps auxin with cell differentiation Signals chloroplast synthesis What is differentiation? Differentiation is when cells are given specific functions within an organism. What 2 functions did we discuss for ABA? Inhibits shoot growth and promotes root growth Signals closing of stomata (water conservation) What 4 functions did we discuss for ethylene? Lead abscission Fruit ripening Releases dormancy in seeds Stimulates flower opening What 2 functions did we discuss for gibberellin? Stem elongation Stimulates flowering What 2 functions did we discuss for brassinosteroids? Works with auxin to promote cell growth Protects plants during chilling or drought stress How can money be made by manipulating these hormones? Auxin can be used to promote growth and has a herbicide. Cytokinin can be used to speed up germination and keep fruit on plants longer. ABA can be used to help plant resist drought. Ethylene can be used to ripen fruits at a specific time. Gibberellin can be used to make plants grow taller or shorter. Brassinosteroids can be used to protect plant form droughts or cold conditions. Plant Physiology: Photobiology What is a pigment? Pigments (also known as photoreceptors) are molecules that are found in plants. They absorb specific wavelengths of light and reflects others, giving plants color. If a pigment absorbs red and reflects blue, what color will it be? Blue What two pigment types are involved in photosynthesis? Chlorophyll and phytochromes What wavelength(s) do(es) phytochromes absorb? Red and far red What is the difference between the Pr and Pfr forms of a phytochrome? Pr absorbs red light and becomes Pfr. Pfr absorbs far red light and becomes Pr. What color of light do phototropins absorb? Cryptochromes? Phototropins and cryptochromes both absorb blue light. Which pigment is the one that perceives which direction light is coming from? Phototropins Which pigments absorb damaging UV light? What other two things did we discuss that this pigment does? Anthocyanins absorb damaging UV light, as well as attract pollinators and defend against pests. For each of the following processes, understand 1) which pigment perceives the light and sends the signals and 2) what the reaction th
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