Introducing plants

Criteria for Kingdom Plantae Cell type: Eukaryotes. Cell number: Multicellular. Cell structure: Cell wall made of cellulose. Mode of nutrition: Autotrophic. Carry out photosynthesis using the green pigments chlorophyll a and b. Some are parasitic or saprobes.

Plant Life Cycle All plants have a life cycle with alternation of generations, in which the haploid gametophyte phase alternates with the diploid sporophyte phase.

Plant Life Cycle Alternation of Generations! Haploid (N) Gametophyte plant (N) Produces either sperm or eggs. (gametes = reproductive cells) Diploid (2N) The sperm and egg join to create the Sporophyte plant (2N), which is diploid. Egg and sperm join to create spores by meiosis.

Plant Survival Sunlight needed to carry out photosynthesis. Minerals and water are needed to make new plant parts. Gas exchange (through photosynthesis and cellular respiration) must occur without losing excessive amounts of water. Movement of water and nutrients is required for plant energy production and growth.

Evolutionary Cladogram of Plants (Angiosperms) (Gymnosperms) (Bryophytes)

Overview of the Plant Kingdom The majority of plant life is ______________.

Bryophytes

Bryophytes (ex. mosses, liverworts, hornworts) Life cycles depend on water for reproduction. Abundant in moist environments (bogs, near streams, in rain forests) because there is no vascular tissue. Sphagnum moss alive is used in gardening, and when compacted (peat) it’s used for fuel. (Angiosperms)

Typical Moss Plant Capsule Sporophyte Stalk Leaflike Structure Stemlike Rhizoid Sporophyte Gametophyte Typical Moss Plant

Life Cycle of a Moss

Ferns: Seedless Vascular Plants

What developed between plant divisions 1 and 2? Vascular Tissue developed! Vascular tissue: specialized tissue to transport water and nutrients throughout the plant.

Phylum Pterophyta: Ferns Ex. horsetails, club mosses, ferns. Leaves are called fronds. Undergound stems called rhizomes . Found in moist, shaded forest areas. Sori – clusters of sporangia (spores on the underside of fronds).

Vascular Tissue Tracheids are specialized cells that can move fluids through the plant body, even against the force of gravity. Xylem (moves water upward). Phloem (moves nutrients and carbohydrates throughout the plant).

Typical Fern Plant

Life Cycle of a Fern

Gymnosperms: Seed Plants

Gymnosperms: Cone Bearers Means “naked seed”. Includes conifers (pines & spruces) and palms (cycads & ginkgoes). Adapted seed to allow reproduction without water; able survive in dry and extreme temperatures.

Reproduction Free from Water Second evolutionary development of plants = seeds. Adaptations that allows seed plants to reproduce without water include: Flowers and cones. Transfer of sperm by pollination. Protection of embryos in seeds. Necessary to meet the challenges of surviving on land.

Diagram of a Pine Seed Embryo Endosperm Seed Coat Growing part of seed containing: Endosperm Tissue that provides nutrition for the developing seed. Seed Coat Protective outer covering of the seed. Embryo Endosperm Seed Coat

Reproduction Germination: early growth stage of a plant embryo. Dormancy: period of time during which a plant embryo is alive but not growing. Features that allow seeds to reproduce without water: Reproduction in cones. Movement of gametes by pollination. Protection of embryo in a seed.

Pollination Transfer of pollen from the male reproductive structure to the female reproductive structure.

Adaptations Needles Winged Seeds

Angiosperms: Flowering Plants

Anthophyta: Angiosperms Dominate plant life. Flowers are the reproductive organs of plants. has ovaries (fruit) to protect the seeds. Attracts animals which help with pollination.

Diversity of Angiosperms Can be classified into: Stems: herbaceous vs. woody. Lifespans: annuals, biennials, perennials. monocotyledon vs. dicotyledon.

Monocots vs. Dicots

Lifespans Annuals Complete life cycle in one year. Biennials Life cycle takes 2 years Year one: germinate and grow roots, maybe leaves. Year two: grow new stems, leaves, and flowers. Perennials Live through many years May die back in winter, but re-grow in the spring (asparagus, peonies, many grasses). Most have woody stems (palms, trees, honeysuckle).

Examples of Monocotyledons (Liliopsida) Grasses which include grains such as corn and wheat. Lilies. Orchids. Palms.

Examples of Dicotylendons (Magnoliopsida) Roses Mallows Tomatoes Oaks Daisies                             

Plant Parts Transport Energy Production Reproduction Roots, stems, leaves. Energy Production Leaves. Reproduction Flowers.

Roots (Transport) Taproot: primary root grows down from the stem with secondary roots forming. ex. carrot, potato, radish Fibrous: small lateral roots that spread out just below surface of the soil. ex. weeds

4 Root Functions Absorbs water & nutrients from the soil. Transports water & nutrients to stem. Anchors plant to maintain stability. Stores food and water.

Structure of Roots Outermost layer of cells Site of absorption Within cortex; contains cells for transport of water, nutrients, & minerals) Site of absorption Tissue that stores starch Protection of root tip

Stems (Transport) Woody Herbaceous Thick cell walls that support the plant. Trees, shrubs, and vines. Herbaceous Stems are smooth, supported by hydrostatic pressure (turgor). Dandilions, zinnias, petunias.

Stems

3 Functions of Stems Transports water & nutrients from roots to leaves. Supports/produces leaves, branches, fruits/flowers. Stores food.

Transport in Plants Capillary action: the tendency of water to rise in a thin tube. The result of the water molecules’ ability to stick to one another (cohesion)and to the walls of the tube (adhesion). Contributes to the movement of water up the cells of the xylem tissue.

Leaves (Transport & Energy Production) Photosynthesis Process that plants use to produce their food. 6CO2 + 6H2O C6H12O6 + 6O2 Transpiration Loss of water and exchange of carbon dioxide.

Structure of Leaves Cuticle Mesophyll Waxy outer surface; retains moisture. Mesophyll Middle layer of leaf where photosynthesis occurs. Palisade layer (upper). Spongy layer (underside).

Structure of Leaves (cont’d) Epidermis “Skin” of leaf - responsible for gas exchange. Upper and lower. Stomata Outside layer of leaf opening in epidermis where gas and water exchange (controlled by guard cells).

Gas Exchange in Leaves Turgor pressure (water pressure) Stomata close automatically when supplies of water from roots start to dry up. Guard cells trigger when water is scarce causing stomata to become flaccid and pores close.

Leaf Vein Types Parallel Pinnate Palmate

Structure of Flowers

Typical Flower Structure Petals Highly colored part of the flower, may contain perfume and/or nectar glands. Sepals Small green structures on the base of a flower that protect the flower bud. Image found at: http://biology.clc.uc.edu

Flowers (Reproduction)

Male Plant Organ Stamen contains: Anther: produces pollen. Filament: upholds anther.

Female Plant Organ Pistil (carpels) contains: Stigma: sticky for pollen to attach. Style: sperm travel to ovary. Ovary (fruit): stores ovules (eggs).

Seed Dispersal Flower Pollination Wind Water Animal Flower Pollination Animals Wind Factors that affect seed germination: Temperature Moisture

Plant Response Plant hormones – chemical substances that control a plant’s patterns of growth & development. Target cell – cell that has a receptor for a particular hormone.

Tropisms (Response) Tropism – response of a plant to an environmental stimulus. Gravitotropism: response of a plant to the force of gravity. Phototropism: tendency of a plant to grow towards light. Thigmotropism: response of plants to touch. Auxin – substance produced in the tip of the seedling that stimulates cell elongation.

Photoperiodism: the timing of seasonal activities such as flowering and growth. Herbicides: auxinlike compounds in high concentrations that are toxic to plants therefore inhibiting growth. Chemical defenses: many plants defend themselves against insect attack by manufacturing compounds that have powerful effects on animals, ex. poison oak.