Gen bio unit 3 part 1

Plant Biology Photosynthesis (Chapter 8) Plant Organization and Function (Chapter 9) Plant Reproduction and Responses (Chapter 10) Ecology Nature of Ecosystems (Chapter 34) The Biosphere (Chapter 35) Environmental Concerns (Chapter 36)

Photosynthesis converts solar energy into chemical energy. Organisms that carry on photosynthesis are called autotrophs. Heterotrophs are organisms that feed on other organisms.

Autotrophs and heterotrophs use organic molecules produced by photosynthesis THUS THE MAJORITY OF LIFEFORMS ARE DEPENDENT ON PHOTOSYNTHESIS.

Photosynthetic Reaction Solar energy + 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Glucose and oxygen are the products of photosynthesis The oxygen given off comes from water CO 2 gains hydrogen atoms and becomes a carbohydrate

Photosynthesis consists of two sets of reactions Photo refers to capturing light Synthesis refers to producing a carbohydrate The two sets of reactions are called the: Light Reactions - thylakoids Calvin Cycle Reactions - stroma

Electromagnetic Spectrum Visible light is used to drive photosynthesis

Visible Light The photosynthetic pigments in chlorophylls a and b and the carotenoids can absorb specific portions of visible light Chlorophyll a and b absorb violet, indigo, blue and red light Carotenoids absorb violet-blue-green range

Light Reactions Photosynthesis takes place in chloroplasts. Light reactions consist of two alternate electron pathways: Noncyclic electron pathway Cyclic electron pathway Both pathways transform solar energy to chemical energy Both pathways produce ATP The noncyclic pathway also produces NADPH

Noncyclic Electron Pathway A photosystem consists of a pigment complex and electron acceptor molecules within the thylakoid membrane. The pigment complex can be described as a “antenna” for gathering solar energy.

Noncyclic Electron Pathway The noncyclic electron pathway uses two photosystems (PS I and PS II) PS II captures light energy Energized electrons (taken from water) leave PSII and pass down an electron transport chain to PSI This forms ATP PS I captures light energy and ejects an electron that is transferred to NADP+ NADP+ combines with H+, forming NADPH.

The Cyclic Electron Pathway Uses only photosystem I (PS-I) Begins when PS I complex absorbs solar energy Electrons escape from the reaction center and travel down electron transport chain Released energy is stored in the form of a H+ gradient, which causes ATP production Electrons return to PS-I (cyclic) Pathway only results in ATP production

The Calvin Cycle Series of reactions that use CO2 from the atmosphere to produce carbohydrate Includes Carbon dioxide fixation Carbon dioxide reduction RuBP regeneration

Fixation of Carbon Dioxide CO2 is attached to 5-carbon RuBP molecule This results in a 6-carbon molecule that splits into two 3-carbon molecules (3PG) Reaction accelerated by RuBP Carboxylase

Reduction of Carbon Dioxide Each 3PG molecules undergoes reduction to G3P in two steps Energy and electrons needed for this reaction are supplied by ATP and NADPH.

Regeneration of RuBP RuBP used in CO2 fixation must be replaced Every three turns of Calvin Cycle, Five G3P (a 3-carbon molecule) used To remake three RuBP (a 5-carbon molecule) 5 X 3 = 3 X 5

Importance of the Calvin Cycle G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules The hydrocarbon skeleton of G3P can form: Fatty acids and glycerol to make plant oil Glucose phosphate (simple sugar) Fructose (which with glucose = sucrose) Starch and cellulose Amino acids

C3 Pathway When a three-carbon molecule is detected immediately upon CO2 fixation, this is called C3 photosynthesis. RuBP can also bind with oxygen. This can be a wasteful reaction because it uses oxygen and releases carbon dioxide, decreasing the overall efficiency of the enzyme.

C4 Pathway C4 photosynthesis bypasses this problem. CO2 is initially fixed into a four-carbon molecule. The four-carbon molecules is later broken down into a three-carbon molecule and CO2 CO2 enters the Calvin cycle

C4 Pathway C4 plants tend to be found in hot, dry climates. In these climates, stomata tend to close to conserve water. Oxygen then builds-up in the leaves. In C3 plants, the O2 would compete with CO2 for binding to RuBP.

CAM Pathway CAM plants partition carbon fixation by time During the night CAM plants fix CO2 forming C4 molecules, The C4 molecules are stored in large vacuoles During daylight C4 molecules release CO2 to Calvin cycle

Plant organ – a structure that contains different tissues and performs one or more specific functions Vegetative Organs Roots Stems Leaves Reproductive Structures Flowers Seeds Fruits

Flowering plants divided into 2 groups based on number of cotyledons (seed leaves) Monocots – one cotyledon Grasses, lilies, orchids, palm trees, etc. Eudicots – two cotyledons Larger group dandelions, oak trees, etc.

Roots Generally, the root system is at least equivalent in size and extent to the shoot system Anchors plant in soil Absorbs water and minerals Produces hormones Root hairs: Projections from epidermal root hair cells Greatly increase absorptive capacity of root

Root Apical Meristem Protected by the root cap Three Regions Zone of Cell Division Contains primary meristems Provides cells to zone of elongation as cells divide (mitosis) Zone of Elongation Cells lengthen and become specialized Zone of Maturation Contains fully differentiated (mature) cells

Tissue of a Eudicot Root Epidermis Outer layer of the root Cortex Loosly packed cells that permit water and minerals to move through Cell contain starch granules to serve as food storage Endodermis Single layer of cells that form boundary between cortex and vascular cylindar Casparian Strip – prevents water and minerals from moving to adjacent cells Vascular Tissue Xylem (water and minerals) and phloem (photosynthetic products) Pericycle – development of branch roots

Monocot Roots Ground tissue of root’s pith is surrounded by vascular ring Have the same growth zones as eudicot roots, but do not undergo secondary growth

Root Diversity Primary root (taproot) - Fleshy, long single root, that grows straight down Stores food Fibrous root system - Slender roots and lateral branches Anchors plant to the soil

Root Diversity Root Specializations Adventitious roots - Roots develop from organs of the shoot system Prop roots

Root Diversity Root Specializations Haustoria: Root like projections that grow into host plant Make contact with vascular tissue and extract water and nutrients Mycorrhizas: Associations between roots and fungi Assist in water and mineral extraction Root Nodules - Contain nitrogen-fixing bacteria

Woody twigs provide a good example for studying stem organization. Terminal Buds – bud that develops at the apex of a shoot Bud Scale – modified leaves that protect shoot tip Leaf Scars / Bundle Scars – mark location of leaves that have dropped Axillary Buds – bud located in the axil of a leaf; give rise to branches or flowers Lenticle – permits gas exchange

Stems The main axis of a plant that elongates and produces leaves Nodes occur where leaves are attached to the stem Internode is region between nodes Stems have vascular tissue that transports water and minerals In some plants, stems carry on photosynthesis, or store water and nutrients.

Herbaceous Stems Mature nonwoody stems exhibit only primary growth Outermost tissue covered with waxy cuticle Stems have distinctive vascular bundles Herbaceous eudicots - Vascular bundles arranged in distinct ring Monocots - Vascular bundles scattered throughout stem

Woody Stems Woody plants have both primary and secondary tissues Primary tissues formed each year from primary meristems Secondary tissues develop during first and subsequent years from lateral meristems; increases girth of trunks, stems, branches, and roots Woody Stems Woody stems have no vascular tissue, and instead have three distinct regions Bark Wood Pith

Bark Bark of a tree contains cork, cork cambium, and phloem Cork cambium produces tissue that disrupts the epidermis and replaces it with cork cells. Cork cells provide waterproofing Lenticels are pockets of loosely arranged cork cells that allow gas exchange Phloem transports organic nutrients

Wood Wood is secondary xylem that builds up year after year Vascular cambium dormant during winter Annual ring is made up of spring wood and summer wood In older trees, inner annual rings no longer function in water transport Annual rings can provide a growth record.

Stem Diversity Stolons: Above-ground horizontal stems Produce new plants when nodes touch the ground Rhizomes: Underground horizontal stems Contribute to asexual reproduction Variations: Tubers - Enlarged portions functioning in food storage Corms - Underground stems that produce new plants during the next season

Leaves Major part of the plant that carries on photosynthesis Deciduous plants are those that lose their leaves every year. Evergreens retain their leaves for two to seven years. Foliage leaves are usually broad and thin Blade - Wide portion of foliage leaf Petiole - Stalk attaches blade to stem Leaf Axil - Axillary bud originates

Leaves are the organs of photosynthesis Photosynthesis occurs within the chloroplasts in the mesophyll tissue of the leaves Epidermal cells are covered with waxy cuticle to protect the leaf

Leaves are the organs of photosynthesis Trichomes (leaf hairs) are protective structures Veins – contain xylem (water and mineral transport) and phloem (organic solutes) Stoma – opening in the epidermis for gas exchange

Identify the following on the diagram Trichomes Cuticle Epidermis Mesophyll Vascular tissue Xylem Phloem Stoma

Identify the following leaf arrangements

Spines – catus spines are modified leaves that protect the fleshy stem Tendrils - allow attachment to a physical support Bulbs - Leaves that store food Some leaves are designed to protect buds, and in some cases leaves capture insects.

Tension created by evaporation (transpiration) at the leaves pulls water along the length of the xylem from the root hairs to the leaves

Water moves into root cells by osmosis; minerals by diffusion and active transport Transpiration-evaporation from the leaves creates a “sucking” force that pulls water upward through the xylem Adhesion-water molecules interact with the walls of the xylem vessels to reinforce strength of column Cohesion-water molecules are attracted to each other and form a continuous column within xylem from leaves to roots Tension-created by transpiration; reaches from the leaves to the roots as long as column is continuous

Role of Phloem Transports products of photosynthesis from the leaves to the site of storage Pressure-flow Model of Phloem Transport Sugar is actively transported into sieve tunes at a source Water follows by osmosis A positive pressure causes phloem contents to flow from the source to a sink Sugar is actively transported out of sieve tubes, and cells use it for cellular respiration; water exits by osmosis Some water returns to the xylem, where it mixes with more water absorbed from the soil Xylem transports water to the mesophyll of the leaf Most of the water is transpired, but some is used for photosynthesis, some reneters the phloem by osmosis

Plants have two stages in their life cycle. A diploid stage alternates with a haploid stage. The diploid plant is called the sporophyte. The haploid plant is called the gametophyte. Flowers are the reproductive structures of angiosperms. Flowers produce two kinds of spores. Microspores develop into the male gametophyte. The male gametophyte produces sperm. Megaspores develop into the female gametophyte. The female gametophyte produces an egg.

Upon fertilization, a zygote is formed. The zygote develops into an embryo. A seed contains the embryo and stored food. When a seed germinates, a new sporophyte emerges.

Parts of a Flower Sepals - leaf-like structures that protect the developing bud Petals - attract pollinators Stamens - male portion of the flower Anther - produces pollen grains Filament - a slender stalk that supports the anther Carpel - female portion of the flower Stigma - an enlarged stick knob Style - a slender stalk Ovary - encloses one or more ovules Flowers that have sepals, petals, stamens and carpels are called complete flowers. Flowers that do not are called incomplete.

Life Cycle of Flowering Plants During fertilization, one sperm nucleus unites with the egg nucleus, producing a zygote. The other sperm unites with the polar nuclei, forming a 3n endosperm cell.

Development of the Eudicot Embryo The endosperm cell divides to produce endosperm tissue. The zygote divides into two cells. One cell will become the embryo. Embryonic cells near the suspensor become the root, and those at the opposite end form the shoot The other cell will give rise to the suspensor. The suspensor anchors the embryo and transfers nutrients to it.

Development of the Eudicot Embryo The embryo changes from a ball of cells to a heart-shape Cotyledons (seed leaves) appear The embryo next becomes torpedo-shaped, and the root tip and shoot tip become visible The epicotyl portion of embryo contributes to shoot development The hypocotyl portion contributes to stem development The radicle contributes to root development

Eudicots (two cotyledons) Cotyledons store nutrients that the embryo uses Monocots (one cotyledon) Cotyledon absorbs food molecules from the endosperm and passes them to the embryo

Fruit Types Fruits are derived from an ovary Fruits protect and help disperse offspring The ovary wall thickens to become the pericarp (may have three layers; exocarp, mesocarp, endocarp)

Fruit Types Simple fruits are derived from a simple ovary or from a compound ovary (several fused carpels). Dry fruits – ex. Legumes, cereal grains, etc. Fleshy fruits – Peaches and cherries – mesocarp fleshy; endocarp hard Tomatoes – pericarp fleshy Accessory fruits – bulk of fruit is from the receptacle instead of the ovary (ex. apple)

Fruit Types Compound fruits develop from several individual ovaries. Aggregate fruits Many separate carpels of the same flower (straberry, raspberries) Multiple fruits – many different carpels from separate flowers (pineapple)

Monocot Seed Structure and Germination Cotyledon does not have a storage function Plumule and radicle are protected by sheaths Plumule and radicle burst through the sheaths when germination occurs Young shoot is straight, not hooked

Eudicot Seed Structure and Germination Cotyledons shrivel and degrade Epicotyl produces immature leaves and is called a plumule Young shoot is hook-shaped as it emerges through the soil

Germination of Seeds Some types of seeds remain dormant until conditions are favorable for growth. Temperature Moisture Regulatory Factors (stimulatory and inhibitory) Mechanical Action (examples: water or fire) Dispersal of Seeds Seeds may have hooks or spines that attach to fur or clothing Seeds may pass through the digestive tract of animals Seeds may be gathered and buried by animals Seeds may be carried by wind or water

Hormones are small organic molecules that serve as chemical signals between cells and tissues. Groups of Plant Hormones Auxins Gibberellins Cytokinins Abscisic Acid Ethylene Plant hormones bind to a specific protein in the plasma membrane. This brings about a physiological response.

Auxins Auxins affect many aspects of plant growth and development. Auxins: Promote apical dominance Increase the development of adventitious roots Promote the growth of fruits Are involved with phototropism and gravitropism.

Gibberellins Gibberellins are growth-promoting hormones that promote elongation.

Cytokinins Promote cell division Prevent senescence (aging) Initiate growth The ratios of auxins to cytokinins play a role regarding the differentiation of plant tissues.

Abscisic Acid Produced by green portions of plant Closes stomata and maintains seed and bud dormancy Considered a plant “stress” hormone A decrease in abscisic acid and an increase in gibberellins breaks dormancy

Ethylene: Is a gas that moves freely through the air Is involved with abscission (leaf drop) Promotes the ripening of fruit

Plant Responses Are Influenced By: Light Day length Gravity Touch Plant Tropisms: Phototropism: Growth in response to light Gravitropism: Growth in response to gravity Thigmotropism: Growth in response to touch

Gen bio unit 3 part 1

More Related Content

What's hot (20)

Viewers also liked (10)

Similar to Gen bio unit 3 part 1 (20)

Recently uploaded (20)

Gen bio unit 3 part 1