General Characteristics: • Eukaryotes • Multicellular; organized into tissues, organs and systems • Cell walls present (cellulose) • Autotrophs; contain chloroplasts • Reproduce sexually
General Characteristics What Plants need: • Sunlight to carry out photosynthesis • Water and minerals • Gas exchange (oxygen for respiration; carbon dioxide for photosynthesis) • Movement of water and nutrients
Origin: • Probably descendants of green algae (Protist) • Algae always live in water, which supports nutrient transport & absorption, stable environment, gamete transfer & development, and structural support.
Origin: • Life on land requires many adaptations • protection from drying out • gas exchange with surrounding air • transport for water & nutrients through multicellular body • support to grow upright on land
Adaptations & Specialized Structures: • Cuticle – a waxy layer from the outer epidermis of the plant surface that prevents water loss to the external environment (osmosis) • Stomata – small openings on the leaf surface to allow gas exchange • Guard Cells – surround the stomata to control the opening and closing of the pore
Adaptations & Specialized Structures: • Vascular Tissues – tubes that allow transport of water and nutrients to different parts of the plant; form vascular bundles throughout the plant * Xylem – transport water and minerals up from the roots throughout the plant * Phloem – transport food (sugars) from the leaves and stems, where it is made, to other parts for use or storage
Adaptations & Specialized Structures: * Cambium – produces new xylem & phloem
Adaptations & Specialized Structures: • Cell Walls – rigid structure provide structural support for growth on land. • Roots – specialized tissues (usually underground) that absorb water & minerals, anchor the plant for upward growth, and store food as starch • * Root hairs – extensions that increase absorption
Adaptations & Specialized Structures: • Stems – tissues that support the above-ground parts of the plant and allow movement of materials between leaves and roots. Also store food.
Adaptations & Specialized Structures: • Flower – assist in pollination process by attracting birds and insects with color or scent. Contain the male and female reproductive organs. • * Sepal – protects the young bud • * Petal – attracts pollinators, serve as a landing pad • * Stamen – male reproductive organ - Anther – produces male gametes (pollen) - Filament – supports the anther
Adaptations & Specialized Structures: • Pistil – female reproductive organ • Ovary – swollen base of the pistil where ovules (eggs) are produced • Style – neck of the pistil, allows for sperm transfer to ovary • Stigma – sticky or rough surface at the tip of the style • Seed – a plant embryo with a food supply enclosed in a tough, protective coat; allows for success through harsh conditions
Life Cycle of Plants Alternation of generations: • haploid gametophyte (gamete producing plant) • diploid sporophyte (spore producing plant) Plants can reproduce asexually with leaves, stems and roots. • regeneration • vegetative propagation (stolons, rhizomes, tubers and bulbs)
Classification within the Kingdom: Nonvascular Plants – lack the specialized tissues to transport water * individuals are very small; only a few cells thick to allow diffusion of nutrients and water * grow in clumps or “carpets” in very moist environments *depend on water for reproduction * examples – moss, hornworts and liverworts (Phyla: bryophytes)
Classification within the Kingdom: Vascular Plants – have tube-like tissues to transport water and nutrients * requires development of different tissues (roots, stem, leaves) for success on land * allows for upright growth & development into complex organisms * simple examples – club moss, horsetails & ferns - require growth in moist environments for sperm dispersal, produce spores
Classification within the Kingdom: Gymnosperms – non-flowering vascular plants * leaves are in the form of needles or scales * seeds are not enclosed in fruit * many produce cones to protect seeds (conifers) * do not produce flowers * sperm is protected in a hard coat called pollen and are dispersed by wind * very hard cell walls allow for tall growth (woody tissue)
Classification within the Kingdom: Angiosperms – flowering vascular plants * seeds are enclosed in fruit, a ripened ovary * leaves are flat * have woody and non-woody stems * divided into 2 groups based on the number of cotyledons (leaf-like parts of the plant embryo in the seed)
Classification within the Kingdom: Monocots – one cotyledon on seed * flower parts in multiples of 3 * vascular bundles scattered throughout the stem * parallel veins in narrow leaves * fibrous roots * examples – grasses, corn, rice, oats, wheat, tulips Dicots – two cotyledons on seed * flower parts in multiples of 4 or 5 * vascular bundles form a ring in the stem * branching, netlike veins in broad leaves * tap roots * examples – oak & maple trees, garden flowers, beans, fruit trees, broccoli, carrots
Tropisms • Occur when plants respond to external stimuli • Cause a change in plant growth • Can be negative (away from stimuli) or positive (toward stimuli)
Plant Hormones • Auxin - Stimulates cell elongation; involved in phototropism, gravitropism, stimulates fruit development. Too much can prevent growth. • Abscisic Acid – slows or stops growth and cell division in plants. • Gibberellin - Stimulates shoot elongation, stimulates flowering in biennials. • Ethylene - Stimulates fruit ripening
Assignment: • Sketch the general life cycle of plants (p 664) • Sketch and label the structure of a flower. • How do plants obtain energy? • What are the plant tropisms? Give examples. • Draw the cladogram on page 613 • What would be the derived characters in this cladogram? • From which organisms did plants evolve? Which kingdom does that ancestor belong to?
Define the following terms • Thigmotropism • Gravitropism • Photoperiodism • Germination • Regeneration • Vegetative reproduction • Tropism • Cotyledon • Monocot • Phototropism • Plant • Cuticle • Stomata • Vascular system • Pollen grain • Seed • Pollination • Gymnosperm • Angiosperm • Cone • Flower • Fruit • Dicot • Xylem • Phloem • Root hair • Fibrous root • Tap root • Guard cell • Alternation of generations • Sporophyte • Gametophyte • Ovary