Transcript PLANTS
PLANTS • PLANTS ARE ADAPTED TO LIVING ON LAND • MOST MOSSES AND FERNS LIVE IN MOIST ENVIRONMENTS • SEEDS AND POLLEN ARE REPRODUCTIVE ADAPTATIONS • MANY PLANTS REPRODUCE WITH FLOWERS AND FRUIT. PLANTS ARE ADAPTED TO LIVING ON LAND • Plants are a diverse group of organisms. • Plants share common characteristics • Plant parts have special functions – Roots: anchor plant in ground, absorb water & nutrients from soil (transported to leaves via stems) – Stems & Leaves: make up shoot system; leaves use materials from roots & CO2 from air to make sugars/carbohydrates (& O2); stems then deliver these energy-rich compounds back to rest of plant • Plants grow throughout their lifetimes. PLANTS ARE DIVERSE • Plants are nearly everywhere; they come in all sizes, & shapes. • Plants are found in all types of environments, from icy arctic to steamy tropics Share Common Characteristics • Plants are multi-cellular organisms • A plant cell has a nucleus and is surrounded by a cell wall. • Plants are producers. They capture Energy from the Sun. • Plant life cycles are divided into 2 stages, or generations. Special Functions • In most plants, materials move through a vascular system in the stems, made of long, tubelike cells. • Xylem tissue are big tubes taking water & nutrients up to leaves. Phloem tissue are smaller &take sugars/carbs down from leaves. Special Functions • Plants make sugars via photosynthesis, which takes place in green chloroplasts full of chlorophyll(absorbs sunlight, mostly in upper leaf); vascular tissue in center of leaf brings in WATER & NUTRIENTS and carries away SUGAR/CARBS; • Tiny openings at bottom of leaf (STOMATA) lets in CO2 gas & stores it as oxygen is released. (this is known as gas exchange) • 6CO2 + 6H20 + sunlight C6H1206 + 6O2 • Stomata also let water evaporate out of the leaf(this is called transpiration); both sunlight & wind cause water to transpire/evaporate. SPECIAL FUNCTIONS • Surface of leaf & stem has waxy protective layer (cuticle), keeping water from evaporating. • When air is dry, stomata can close. • Spines of cactus are modified leaves (regular leaves would loose too much water); photosynthesis occurs in the fleshy green stem, which also stores water & carbon dioxide gas. • • • • • Plants Grow throughout Life Plants continue to grow till die (cells at tips of roots & stems divide quicker) Leaves only grow on stems from growth tissue. Stems have vascular system(to transport materials between leaf & root) which gives support through stiff fibers and gives plant its shape. Can also store sugars made by photosynthesis (broccoli). Soft stem plants have stems & leaves that die in bad weather but roots survive (store sugar) to regrow stems & leaves back in good weather. Woody Stem plants have stems that don’t die each year but grow longer & thicker; form special xylem called “wood”; growing tissue near outer surface (so older wood in middle of tree).