Plant Kingdom: Adaptations and Classifications

• Plants are multicellular eukaryotes containing chloroplasts for photosynthesis.
• Plants are non-motile, fixed in one location, and possess cell walls made of cellulose.
• Plants exhibit responses to their environment, with the earliest plants living in water.

Plant Adaptations to Land

• Protection from drying out for leaves and stems.
• A system of vessels to transport water, nutrients, and wastes.
• Stems and leaves function to hold the plant up and conduct photosynthesis.

Non-vascular Plants

• These plants lack a system of vessels for transporting nutrients, water, or waste.
• They were the earliest land plants
• Reproduction requires a moist surface for gametes to unite.
• Non-vascular plants reproduce via spores, not seeds
• Osmosis and diffusion facilitate nutrient movement between cells, limiting their growth.

Vascular Plants

• Ferns represent the first vascular plants.
• Vascular tissue enables material transport within the plant, promoting taller growth.
• Ferns have true roots for anchorage and absorption.
• Fern leaves are photosynthetic for energy production and gas exchange.
• Ferns reproduce with spores.

Seed Plant Evolution

• Seeds provide a means of sexual reproduction without water for gamete transfer.
• Seeds contain a fully developed embryo, a food supply, and protective coat.
• Gymnosperms produce "naked seeds" like pine cones.
• Angiosperms are flowering plants with seeds protected in fruit, attracting animals for seed dispersal.
• One pollen fertilizes each seed/ovule.
• Pollen also fertilizes the ovary, which becomes the fruit.

Monocots and Dicots

• These are two classes of angiosperms, differentiated by seed leaf number.
• Monocots have one seed leaf, and dicots possess two.
• Angiosperms share plant parts but differ in organization, affecting root, stem, and leaf structures.
• Vascular bundle patterns in roots, stems and leaves are how theses two classes differ.

Vascular Bundles

• Two types of vessels comprise a vascular bundle: xylem and phloem.
• Xylem transports water and minerals from roots to stems, leaves, and flowers.
• Phloem transports sugars between plant cells.

Xylem

• Xylem transports water, forming from dead tracheid cells.
• Water moves into xylem in the roots by osmosis.
• Transpiration is the process where water evaporates from leaves.

Phloem

• Phloem facilitates sugar transport, forming from living sieve tube elements.
• Translocation is the process by which sugar, dissolved in water, moves throughout the plant.

Monocots and Dicots Compared

• Monocots have fibrous, networked roots; dicots have taproots.
• Monocots have one seed leaf; dicots have two seed leaves.
• Monocots have scattered vascular tissue; dicots have vascular tissue in an outer ring.
• Monocots have parallel leaf veins; dicots have a network of leaf veins.
• flower parts of Monocots are in multiples of 3; petals of Dicots are in multiples of 4 or 5.

Root Functions

• Anchoring the plant
• Absorbing water and minerals
• Protecting against soil erosion
• Transporting water to the plant through xylem

Root Zones

• Zone of Maturation: cells differentiate into specialized cell types.
• Zone of Elongation: increasing root depth.
• Meristematic Region: area of rapid mitosis of undifferentiated cells.
• Root Cap: protects the meristematic region.

Absorption in Roots

• Root hairs, extensions of the root epidermis, expand surface area for absorption.
• Water enters roots via osmosis and flows through the xylem.
• Nutrients like nitrates, phosphates, potassium, and magnesium dissolve in water and are absorbed by the roots.

Stems

• Annual stems, found on plants that grow from seed every year, are green.
• Woody stems are typical of perennial plants like shrubs and trees.

Stem Functions

• Holding leaves up to receive light
• Transporting water and minerals in xylem.
• Transporting dissolved sugar in phloem.
• Specialized stems for asexual reproduction or starch storage.
• Stolons (runners): asexual reproduction (e.g., strawberries).
• Rhizomes: underground stem buds for asexual reproduction (e.g., irises).
• Tubers: starch storage (e.g., potatoes).

Leaf Functions

• Trapping light energy for photosynthesis to produce glucose.
• Exchanging gases (CO2 and O2).
• Water loss through transpiration aids water pull from roots.
• Serving as food, shade, habitat, and oxygen source for various organisms.

Leaf Types: Deciduous vs. Needles

• Deciduous leaves are wide for maximizing light capture and flat to increase surface area for gas exchange via diffusion.
• Needles have features that are advantageous:
  • Waxy coating to save water
  • Tough to eat
  • Photosynthesize year-round
  • Low wind resistance, surviving ice and snow

Leaf Structure

• Cuticle: waxy layer protecting from water and gas loss.
• Epidermis: transparent cells for sunlight penetration, providing mechanical strength with stomata and guard cells on the lower epidermis.
• Palisade Cells: contain large numbers of chloroplasts with chlorophyll, the main site of photosynthesis.
• Stomata: gas exchange (CO2 in, O2 out), water vapor release, and regulation of gas exchange according to CO2 needs. Open during the day and closed at night.

Spongy Mesophyll

• Loosely packed cells with air spaces for gas diffusion.
• Water vapor moves into the air spaces and exits through stomata (transpiration).

Vascular Bundles

• Xylem and phloem are found in leaf veins.
• Xylem carries water and minerals to leaf cells.
• Phloem carries glucose from leaf to other plant cells.

Explore plant characteristics, adaptations to land, and the differences between non-vascular and vascular plants. Understand how vascular systems enable plant growth. Learn about early land plants and the role of osmosis and diffusion.