Plant Structure and Function

• Plants' uniqueness lies in their structure, reproduction strategies, and survival adaptations.

Plant Structure

• Nonvascular plants (bryophytes) lack specialized tissues for water and nutrient transport.
• Vascular plants possess xylem and phloem for transport.
• Liverworts, mosses, and hornworts differ in habitat and reproductive structures as nonvascular plants.
• The shoot system (stems, leaves, flowers) is responsible for photosynthesis, reproduction, and support.
• The root system (roots) anchors the plant, absorbing water and minerals.
• Dermal tissue provides protection via the cuticle and stomata.
• Vascular tissue transports water (xylem) and nutrients (phloem).
• Vascular plants tissues include: Parenchyma, collenchyma, and sclerenchyma (Storage and support).
• Seedless vascular plants include ferns.
• Seed-producing vascular plants include gymnosperms and angiosperms.
• Gymnosperms bear cones, while angiosperms have flowers/fruits.
• Flower parts include sepals, petals, pistil (stigma, style, ovary), stamen (anther, filament), ovule, and fruit.
• Monocots feature one cotyledon, parallel veins, scattered vascular bundles, and fibrous roots.
• Dicots possess two cotyledons, net-like veins, ringed vascular bundles, and taproots
• Key plant structure vocabulary: Thallus, Rhizoids, Stomata, Cuticle, Xylem, Phloem, Sepal, Petal, Pistil, Ovule, Fruit, Stigma, Style, Stamen, Anther, Pollen, Pollen grains are key plant structure components

Reproduction

• Plant life cycle alternates between a haploid gametophyte and a diploid sporophyte.
• Mitosis facilitates growth and asexual reproduction, yielding identical cells.
• Meiosis produces genetically diverse gametes/spores.
• Nonvascular and seedless vascular plants rely on spores and require water for fertilization.
• Nonvascular plants feature a dominant gametophyte stage.
• Seedless vascular plants have a dominant sporophyte stage.
• Gymnosperms reproduce via cones, using wind pollination and have exposed seeds.
• Angiosperms featuring flowers and diverse pollination methods resulting in enclosed seeds in fruits.
• Seeds protect the embryo, store nutrients, and aid in dispersal.
• Pollination strategies include wind, insects, and animal pollination.
• Methods of seed dispersal include by wind, water, and animals.
• Key plant reproduction vocabulary: Sporophyte, Gametophyte, Gametes, Haploid, Diploid, Zygote, Embryo, Sporangia, Spores, Pollination, and Seed dispersal.

Adaptations

• Plant evolution proceeded from aquatic ancestors to nonvascular plants, then to seedless vascular plants, gymnosperms, and finally angiosperms.
• The cuticle adaptation prevents water loss.
• Stomata facilitates gas exchange in plants
• Roots and vascular tissue facilitate water and nutrient transport.
• Seeds and pollen reproduction without water.
• Plants detect and respond to light, gravity, and touch via signal transduction pathways.
• Auxins enable cell elongation and phototropism.
• Gibberellins trigger seed germination.
• Cytokinins promote cell division.
• Ethylene induces fruit ripening.
• Abscisic acid inhibits growth and aids the drought response.
• Desert plants exhibit succulence, have deep roots, and use CAM photosynthesis.
• Aquatic plants posses Aerenchyma, and floating leaves.
• Climbing plants feature tendrils and thigmotropism.
• Key plant adaptation vocabulary: Mycorrhizae, Aerenchyma, Pneumatophores, Succulence, Phototropism, Gravitropism, and Thigmotropism.

Explore plant structure, from nonvascular bryophytes to vascular plants with xylem and phloem. Understand the roles of shoot and root systems, dermal and vascular tissues, and the distinctions between gymnosperms and angiosperms, including flower parts.