Plants

1. Plants • What are plants and why are they important to study?

2. **Learning Objectives: Plant Kingdom • What are the characteristics – special evolutionary adaptations - of plants? • What are the major structures (vascular, reproductive, tissue) of a plant and what do the structures do? • What are the major types of plants (how are the classes broken down)? • What is the difference between a monocot & dicot? • How does a plant reproduce? • Label a flowering plant and a flower and describe the function of the parts.

3. Plant General Characteristics • Carry out photosynthesis (autotrophs) • Produce cellulose in their cell walls • Non-motile (don’t move around) • Reproduce sexually and asexually • Have specialized tissues and organs Botany: the study of plants

4. Where did Plants come from? • Evolutionary biologists believe plants likely evolved from plant-like Protist green algae ancestors from a watery environment, but this is not relevant and unsubstantiated. • Big Bang timeline: • Likely came into existence first only 500-400 million years ago. • Relative timeline: • Have been around for only about the last 10% of Earth’s history. • Remember, according to the current interpretation of geologic evidence, oxygen was present on Earth before plants because of bacteria.

5. Important Plant Adaptations • 3 Major Adaptations that make living on land possible: • Being able to conserve water • Cuticle: Waxy coating that prevents water loss • Being able to gather nutrients from the surroundings without having to move to it. • Roots: Being able to absorb nutrients through the ground from long distances. • Mycorrhizae: symbiosis with fungus • Being able to reproduce on dry land • Spores and Pollen (male & female reproductive gametes) = dry distribution • Seeds resist drying out, plus other advantages. • Other adaptations of plants that make them unique. • Tissue specialization: Roots, vascular tissue, seeds, cuticle, flowers, cellulose cell walls. • Endosymbiosis of chloroplasts (chloroplasts have their own DNA different from the plant itself) • Masters of utilizing capillary action.

6. What Do Plants Need to Survive?Think Photosynthesis • Sunlight & Carbon Dioxide: • For photosynthesis • Suitable ground supplied with Water and Minerals • For growth and health • Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, and Sulfur. • Exchange gases • Stomata = CO2 in O2 and H2O out. • open/close based on: • Temperature, hydration, light, CO2 • Movement of Water and Nutrients • Vascular Tissue and/or… • Uses Passive Transport as much as possible (osmosis, diffusion) • Not to be cut down (lol)

7. Major Plant Structures • What makes up their cells? • What’s inside their cells? • How their cells are organized? • How they get water and nutrients in? • Diffusion/Osmosis (mosses) or Vascular Tissue. • What makes up their body structures? • What are their reproductive structures?

8. CHLOROPLAST Specializes in photosynthesis CENTRAL VACUOLE Increases cell surface area; stores metabolic wastes CELL WALL Protects, structurally supports cell NUCLEUS nuclear envelope Keeps DNA separated from cytoplasm; makes ribosome subunits; controls access to DNA nucleolus DNA in nucleoplasm CYTOSKELETON microtubules Structurally supports, imparts shape to cell; moves cell and its components microfilaments RIBOSOMES intermediate filaments (not shown) (attached to rough ER and free in cytoplasm) Sites of protein synthesis ROUGH ER MITOCHONDRION Modifies proteins made by ribosomes attached to it Energy powerhouse; produces many ATP by aerobic respiration SMOOTH ER Makes lipids, breaks down carbohydrates and fats, inactivates toxins PLASMODESMA Communication junction between adjoining cells GOLGI BODY Finishes, sorts, ships lipids, enzymes, and membrane and secreted proteins PLASMA MEMBRANE Selectively controls the kinds and amounts of substances moving into and out of cell; helps maintain cytoplasmic volume, composition LYSOSOME-LIKE VESICLE Digests, recycles materials • Cell Type: Eukaryotic = Has nucleus • Body Type: Multi-cellular • Cell Structure: Membrane + Cell walls of the sugar cellulose. • Specialization: + Chloroplasts, Large Central Vacuole, Plasmodesma

9. Kingdom Plantae Adaptations:Specialized Tissues • The most basic plants are mosses. • They are flat, grow like carpet. • Mosses obtain their nutrients by absorption from the surroundings using osmosis and diffusion. • All other plants grow up because they have… • **Vascular tissue (like arteries and veins!) that allows for capillary action. • (UP) Xylem– transports materials up from the roots to leaves and supports the plants as “wood” after the cell dies • (DOWN) Phloem– transports materials down from the leaves to roots and stem • Vascular Cambium – makes more vascular tissue • Parenchyma – used for storage, surrounded by vascular tissue • Meristematic tissue – only tissue that produces new cells by mitosis, found on the leading edges of stems and roots. • Cork Cambium – outer bark of trees

10. Plant Structure: Roots • Rootsanchor plants into the ground, absorb water & minerals from the soil, protect the plant from bad bacteria/fungi, and transport these materials to the stem. • Contain xylem and phloem in the center of the root. • Root pressure – dew is an example of root pressure (forcing excess water out of the plant) • The root cap burrows through the soil and the cells are replenished by the apical meristem. • Meristem = areas of rapidly dividing cells

11. Plant Structure: Stems • Stems can be either woody or herbaceous. • Herbaceous: flexible, like the stems of many flowers. • Woody: Xylem cells become fixed and hardens creating “wood” tissue • Xylem – transports water & minerals up • Phloem – transports sugars & hormones down • Portion of a plant that stores sugar is called a sink. • Capillary Action! • Transpiration – as water evaporates, the energy released pulls water up the stem • Vascular tissues are arranged differently in stems than leaves. • Monocots: scattered in stem • Dicots: circular pattern in stem

12. Plant Structure: Leaves • Leaves are protected from dehydration by a waxy cuticle. • Petiole – vascular tissues extending from stem to leaf (appear as veins) • Mesophyll (middle layers) – contain chlorophyll-rich cells • Guard Cells & Stomata – regulate water loss (Transpiration) and gas exchange through openings on the underside of the leaf • Monocots: parallel veins • Dicots: net veined

13. Plant Asexual Reproduction • Vegetative Reproduction – when plants form new plants from portions of their own roots, stems, or leaves • Like strawberries • Spores – non-seed vascular plants release spores • Like ferns

14. Plant Sexual Reproduction Overview • Pollination – when pollen is deposited on stigma. • Fertilization – when pollen grain reached the ovary and fuses with the egg. • After fertilization, the seed develops food storage regions for the embryo called fruit. • Seeds are eventually dispersed using many different methods. (Wind, Animals, Water, Fruit, etc) • Remember, this is called the Alternation of Generations! • Can remain dormant until temperature and moisture cause the seed to start early growth called germination. • The systematic cultivation of plants by humans is called agriculture.

15. How Plants Reproduce: Flowers & Flowering Pistil or • Flowers are made up of four organs: (called the “Perfect Flower”) • Petals – colorful leaf like structure around the stem. • They attract insects and other pollinators of the flower. • Sepals –leaf-like structure around the flower stem beneath the petals. • They enclose the bud before it opens and protect the flower while it is developing. • Stamens – male part of the flower where at their tip is the anther that rests on the filament and contains pollen. • Carpel– [Also called the Pistil] Female part of the flower, which contains sticky stigma where pollen grains land and travel down the style to the ovary and ovules. Not all sepals are green. Alstroemeria (a lily-like monocot) have sepals the same color as the petals.

16. Fertilization: Seed & Fruit Production • 2 sperm fertilize the female, one the egg (1n), the other the central cell (2n) • The walls of the ovule become the protective seed coat, the central cell becomes the endosperm or food for the embryo, and the ovary wall the fruit. • Because two fertilization events take place at the same time, it is called double fertilization. • Fruits and seeds are modified specifically for the type of dispersal and environment. • Shape of seed can determine type of dispersal (wind, water, animal, etc) • “Fruit” (not always sweet) feeds the seed, attracts disperers (birds, bugs, humans), or aids in dispersal (relocation). • Seeds can stay dormant for long periods of time! Sometimes decades. Maple seed. The fruit isn’t edible but designed with a wing to float away from the tree.

17. Plant Responses: Hormones • Hormones cause a physiological change or response within the plant to either promote growth or development. • Auxins (IAA) – cell elongation. • Gibberellins – increase rate of seed germination and allows the stem to grow taller. • Cytokinins – stimulate proteins for cell division and extends the life of the plant. • Ethylene – ripens fruits and the emergence of seeds from the soil. • Abscisic Acid – helps leaves prevent water loss by hardening certain leaf cells.

18. Plant Responses & Tropisms • Plants don’t have a nervous system, but do respond to their environment as other organisms do. • Photoperiodism affects the timing of flower production. • Duration of light and dark periods in the day • Not all the same: Short-day plants, Long-day plants, day-neutral plants • Tropism – a plant’s response to an external stimulus that comes from a particular direction. • Involve growth, so they are notreversible. • Phototropism (Light) • Gravitropism (Gravity) • Thigmotropism (Touch) • Nastic movement –Does not involve growth, so are reversible. • Example: folding of a venus flytrap.

19. Plant Kingdom Contains **4 Main Groups • Bryophytes = Mosses • Seedless Vascular Plants = Ferns • Gymnosperms = Conifers • Angiosperms = Flowering plants • Broken down into monocots and dicots.

20. Classification of Plants

21. Bryophytes – Non Vascular Plants • Includes: mosses, liverworts, hornworts • First land plants; had to overcome obstacles • avoid drying out (desiccation) – live in moist areas • develop a means of support (roots and stems) • develop new reproductive methods • obtaining nutrition • No vascular tissue, so they are close to the ground to draw up water using the properties of water (adhesion & cohesion)! • Their reproduction also relies on the use of water!

22. Bryophytes Moss: common Liverwort: Marchantia polymorpha Hornworts: Anthocerotophyta Moss: Splanchnum

23. Seedless Vascular Plants • Includes: Ferns, Club mosses, Horsetails • 3 Key Adaptations • Vascular System = xylem/phloem = larger, roots, stems, and leaves. • Larger Sporophyte = better distribution of spores • Drought resistant Spores = thickened spore wall

24. Seedless, Vascular Plants: Ferns Fern Club Moss Horsetails

25. Tracheophytes – Seeding Vascular Plants • Gymnosperms – means “naked seed”, not protected by fruit. Can reproduce through wind or other methods on land! • Class Ginkoopsida – Gingkos; one species exists today, living fossil • Class Cycadopsida – Cycads; found in tropics • Class Pinopsida – cone bearers; 9 families contain over 300 species, evergreens: pines, spruce, hemlocks, firs, etc. What does Vasuclar Tissue mean? Means they have xylem (water) and phloem (sugar) to transport water up from the ground into the rest of the plant!

26. Tracheophytes – Flowering Vascular Plants Angiosperms – flowering plants, produce a form of fruit! (A wall of tissue surrounding a seed.) Give animals a tasty treat encouraging them to distribute plant offspring elsewhere. Can reproduce on land. • Two classes of angiosperms are based upon the number of Cotyledon: tiny seed leaves that store or absorb food for developing embryo. • Class Monocotyledonae = Monocots (1) • Class Dicotyledonae = Dicots (2) • Have Unique life spans. • Those who completely die in one season are called annuals. • Most weeds, grasses, and many flowers. • Those with a 2-stage life cycle (produce flowers 2nd year) are called biannuals. • Most vegetables. • Those who live many years are called perennials. • Established trees, shrubs, some grasses, flowers, fruit trees

27. KNOW