Biology: Exam 1 Study Guide
Biology: Exam 1 Study Guide Biology 1120-001
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This 7 page Study Guide was uploaded by Anzlee on Saturday February 13, 2016. The Study Guide belongs to Biology 1120-001 at Middle Tennessee State University taught by Andrew Brower in Spring 2016. Since its upload, it has received 252 views. For similar materials see Biology in Biology at Middle Tennessee State University.
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Date Created: 02/13/16
Biology: Exam 1 Study Guide • The sun is the power of life on earth (photosynthesis) • Plants provide: o food by beginning the food chains (producer) o fuel by either being burned directly or through fossil fuels o building materials (cotton, wood, etc.) o medicines (aspirin-bark of elm tree, etc.) o ecosystem services (habitat, prevent erosion, produce oxygen) Plant Lineage and Important Adaptations: Non-Flowering Plants Green Algae- Chlorophyta • may be unicellular or colonial and multicellular species • mostly aquatic, produce a lot of oxygen • can live in harsh conditions, even inside rocks • have been classified as protists, but are very closely related to terrestrial plants (share chloroplast with both chlorophylls a and b, starch as a storage of sugar, and cellulose cell walls) • became abundant around 700 million years ago, because oxygen levels increased and diversification of heterotrophic food chains • help us understand the evolution of multicellularity • *note- blue-green algae is not the same as green algae Land Plants • very abundant, and many adaptations to prevent water loss • most plants are protected from desiccation by a waxy cuticle and stomata, which prevent too much evaporation of water and take in the correct amount of carbon dioxide • example of evolution: increased photosynthetic area • defining characteristic- protection of embryos; some produce seeds; • all have haploid and diploid phases; most have vascular tissue • xylem- water transport; phloem- food transport Plant Life Cycles Haplodiplontic: • Sporophyte- diploid generation • Gametophyte- haploid generation • Basics of life cycle: diploid produced spores through meioisis; spores divide by mitosis producing a haploid gametophyte; gametes are produced through mitosis (then two gametes fuse together again to form a 2n diploid zygote) Bryophytes • non vascular plants: liverworts (hepiticophta), mosses (bryophyta), and hornworts (anthocerophyta) • examples of important use: peat- (composed of moss) source of energy; drives global warming by drying out and releasing carbon dioxide • dioecious- two separate sexes are included in the life cycle • moss and liverwort life cycles- gametophyte is longer than sporophyte stage, sperm swim to egg then fertilization occurs (water must be present) • moss life cycle- sporophyte actually grows out of the gametophyte Vascular Plants • xylem and phloem • evolution has allowed these to grow taller to gain access to the sun (lignin is part of the structure) Ferns • Lycophyta and Pterophyta • club mosses, no roots, seeds, or flowers o whisk ferns-simplest morphology, 6 species, evenly spaced stems o horsetail- 15 species, sporophytes at the top • life cycle: does not pollinate itself, but instead mixes genes for diversity and maximized offspring; monoecious; sporophyte stage is more dominant than the gametophyte stage; a structure called the thalus grows out of the archegonia (female part) of the gametophyte stage Seed Plants Gymnosperms • cycadophyta (cone bearing, dioecious), ginkophyta (gender different via tree; very old unchanged species with loose leaves), coniferophyta (cone bearing; dioecious) • protection, dispersal, dormant phase; increase embryo survival by waiting for favorable environmental conditions • life cycle: sporophyte phase dominates life cycle; female cones contain megasporocytes while male cones contain microsporocytes Flowering plants Angiosperms • characterized from flowers and fruits; ovule enclosed within diploid tissue • very diverse group of plants • evolution of land plants; success of angiosperms may be because of pollination and seed dispersal interactions with animals; ex. colors • seed plants are heterosporous: microsporangia- sperm; macrosporangia- egg; seeds have a dormant stage, and allow for more efficient dispersal and the spread of genetics • pollen- sperm no longer needs water for dispersal; wind, birds, insects, etc. • embryo- seeds package them with a food supply and protect them from desiccation (nutritive tissue and protective coat) • life cycle: anther- meiosis takes place to produce male pollen grain with three nuclei (1 is tube, 2 is fertilization); ovule/megaspore- female (ovary grows into fruit while the ovule grows into seed); pollen lands and produces pollen tube, then double fertilization takes place • structure of flowers: • Examples of Types of Angiosperms: o amborella- most basal lineage o star anise o nymphaeales- water lilies o magnoliales- magnolias, avacados, nutmeg, etc. o monocots- monophyletic group; seed with single cotyledon, no true wood, flower parts usually in multiples of three, parallel venation; ex- bananas, asparagus o dicots- 2 cotyledons; parts in multiples of 4 or 5; branches venation; ex- beans o eudicots- many species, ex. cacti, pitcher plants, cacao pods • Growth and Structure o growth is often indeterminate; initiated from meristems (many cells divide here rapidly and allow the plant to continue growth) o Primary vs. Secondary Growth: § primary growth is when the plant grows into the soil and up into the air through apical meristems § secondary growth is when the plant grows wider and thicker through lateral meristems o variation in shoot (above ground):root (below ground) ratio- dependent on nutrient levels in soil o parenchyma cells function in photosynthesis and gas exchange o collenchyma cells are sturdier and act as a support o sclerenchyma- support, transport, protection (secondary cell wall- lignin) o epidermal- outermost, secretes waxy cuticle o guard cells- open/close to limit water loss, o trichomes- hair like projections for defense and water loss o Types of Tissues: § ground tissue § vascular tissue- xylem: sclerenchyma cells dead at maturity; vessel elements and tracheids; phloem- sieve tube elements and companion cells § dermal tissue: root hairs- increase surface area for absorption of minerals and water, • Plant Transport • Water transport through the xylem is passive (direction: up) o 80-90% of herbaceous plants are made of water; 50% of woody plants o Must maintain turgor pressure (stomata opens and closes to maintain this) o Water potential- tendency of water to move from high to low pressure; solute + pressure potential = water potential (solutions have negative solute potentials and water has zero solute potentials) o Most water is absorbed by root hairs and travels to xylem, through: § transmembrane route (straight through water channels) § apoplastic route (between pores/cell walls) § symplastic route (through plasmodesmata) o Does water get pushed or pulled? Pulled through transpiration!! • Sugar/nutrient transport through the phloem is active (bidirectional) o Phloem- moves products of synthesis o Cells include: sieve-tube cells that act as doors; companion cells provide support o Essential Macronutrients: § Nitrogen § Potassium § Calcium § Phosphorous § Magnesium § Sulfur o Examples of micronutrients: chlorine, manganese, iron, zinc, boron Types of Plants Based on Consumption • Parasitic plants- tap into vascular tissue of the host to receive nutrients • Carnivorous plants- receive nitrogen directly from other organisms, ex. pitcher plants • Epiphytes- commensal with fellow plants, meaning both plants benefit Sensory System in Plants • can sense: light, gravity, touch, parasites, etc. • respond by: change in growth, cellular activity, and genetic expressions (response to stimuli: tropism) • Light: o Phototropism/photomorphogenesis o plants respond particularly to blue light (not to green light) o the stomata responds as well as the growth pattern o auxin is the hormone responsible for this tropism (cells at the tip of the plant senses and sends a signal to create the response) o can sense shade because there are different wavelengths (full sunlight has an equal ratio of far red light to red light while shade has more far red light which acts as an inhibitor and can trigger photomorphogenesis); plants can sense when there are plants crowding them, so they will produce thin long stems to elongate o etiolation- white stems grow to elongate instead of produce chlorophyll; once in sunlight, chlorophyll will be produced • Gravity o Gravitropism o shoots grow up, roots grow down o auxin on the lower side of the stem has a higher concentration to allow the plants to grow up against gravity; meristematic cells in root cap sense gravity • Touch o Thigmotrophism o directional growth; not rapid; example- response to wind would allow them to not grow as tall and have a thicker stem o nutation- slowly swing around so they can find something to wrap around o plants move rapidly through: charges created from action potentials of water/nutrients passing through membranes; turgor pressure • Other tropisms: electrotropism (electricity), chemotropism (chemicals), thermotropism (temperature), etc. • Sensing Time/Day and Night o flower opening and closing o leaf folding/unfolding o scent production Dormancy • have the ability to cease growth and become dormant to survive • protection from freezing, drought, and heat shock • allow better chance of seed survival as well to spread genes Chemical Signals in Plants • plant hormones are involved in internal signaling processes • 7 categories: o auxin- mediates phototrophic response (promotes bending and elongation), increases plasticity of cells, mediates gravitopic response which allows roots to grow downwards (inhibits cell elongation) o gibberellins- responsible for elongation of stems, hasten seed germination o abscisic acid- induces dormancy, suppresses bud growth, opens and closes stomata (opposite of gibberellins) o cytokinins- help cell division and differentiation; most in root apical meristem; pathogens/bacteria can cause this to be overproduces which leads to large growths on the plants called a “crown gall” o brassinosteroids- broad spectrum of effects; triggered by environment o ethylene- helps fruit development/ripening and leaf and flower senescence; can be manipulated to delay ripening Plants are Affected Negatively by: • Herbivores • Nematodes • Fungal Spores • Pathogenic fungi • Bacteria and viruses • Mites • Insects (ex. wood, leaf, fruit boring insects) Plants Fight Back • Allelopathy- plant vs. plant: slow growth or block seed germination • Forms of offense: thorns, spines, sap, latex, chemical toxins • Antagonistic coevolution: evolution of chemical and physical deterrents • Systemin- hormone produced by damaged cells, which then binds to undamaged cells which then produce jasmonic acid • Jasmonic acid acts as a defense and ‘distress call’ • Pathogen-Specific Response: o Hypertensive response- response to invader: rapid death around site o Systematic acquired response- prepares for future attacks (allows it to respond quicker in the future)
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