Plants

What is a Plant? Multicellular eukaryotes that have cell walls made of cellulose They develop from multicellular embryos and carry out photosynthesis using the green pigment chlorophyll

What Plants Need to Survive Sunlight: Plants use energy from sunlight to carry out photosynthesis Water and Minerals: All cells require a constant supply of water. Minerals are needed for plant growth. Minerals move into plants through active transport

What Plants Need to Survive Gas Exchange: Plants require oxygen to support cellular respiration as well as carbon dioxide to carry out photosynthesis Stomata

What Plants Need to Survive Movement of Water and Nutrients: Most plants have specialized tissues that carry water and nutrients throughout the plant. Simpler types of plants carry out these functions by diffusion

Xylem and Phloem Xylem: vascular tissue that carries water upward from the roots to the rest of the plant (moves water) Phloem: vascular tissue responsible for the transport of nutrients (glucose) produced by photosynthesis (moves food)

Seed Project: Major Grade! Control group: seeds in water Optional experimental groups: coke, sprite, baking soda, vinegar, seeds in fridge 5 seeds for each group You will work in partners.

4 Groups of Plants

Bryophytes Ferns Gymnosperms Angiosperms

Bryophytes Nonvascular plants (lack vascular tissues: xylem and phloem) Life cycles depend on water for reproduction Features: –Low-growing plants –Found in moist, shaded areas Examples: mosses, liverworts, and hornworts

Ferns Have vascular tissue (xylem and phloem) Have true roots, stems and leaves Ferns produce spores on the underside of their fronds in tiny containers called sporangia Gametes require water for fertilization Frond

Gymnosperms & Angiosperms Both produce seeds Both contain vascular tissue (xylem and phloem) A seed is an embryo of a plant that is encased in a protective covering and surrounded by a food supply.

Gymnosperms Seed plants that bear its seeds in cones Do NOT require water for fertilization Contain Vascular Tissues (Xylem and Phloem) Examples: pines, spruces, cycads, and ginkgoes

Angiosperms Produces flowers for reproduction Do NOT require water for fertilization Contain Vascular Tissues (Xylem and Phloem) Flowers contain ovaries, which surround and protect the seeds Fruits are ripened ovaries

Angiosperms continued… Angiosperms are a diverse group Two classes within angiosperms include: monocots and dicots –monocots and dicots are named for the number of seed leaves, or cotyledons, in the plant embryo

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Plant Adaptations

What are adaptations? Special features that allow a plant to live in a particular place or habitat

Root Adaptations Plants have different root types depending on their environment Taproot System: enlarged, somewhat straight to tapering plant root that grows vertically downward Fibrous Root System: Thin, moderately branching roots growing from the stem

Stem Adaptations Tendrils: used to help the plant climb Rhizome: used for storage

Leaf Adaptations Spine: Used for defense and protection against water loss Carnivorous: modified to form insect trap to capture nitrogen

Leaf Adaptations cont. Plant leafs come in different shapes and sizes. What advantage would a large leaf plant have over a small leaf plant?

Tropism Tropism – growth or movement in response to a stimulus –Phototropism: A plant growing towards the light

Tropisms Gravitropism: Plants will grow in response to gravity. Stem and leaves grow up while roots grow towards the ground Thigmotropism: movement in response to touch

Roots, Stems & Leaves Three principal organs of seed plants

Roots Contains tiny hair like structures known as root hairs Absorbs water and dissolved nutrients Anchor plants in the ground Hold plants upright against forces such as wind and rain

Stems Support system for the plant body Transport system –Lift water from roots up to the leaves and carry the products of photosynthesis from the leaves back down –A defense system that protects the plant against predators and disease

Leaves Plant’s main photosynthetic systems Produces food for plant (glucose) Broad, flat surfaces increase the amount of sunlight plants absorb Waxy cuticle on surface of leaves protects against water loss Contain stomata

Leaves Cont. Contain stomata which allow for gas exchange Take in carbon dioxide; release oxygen When open they allow water loss from the plant

Flowering Plant Life Cycles Annuals: complete a life cycle within one growing season Biennials: complete a life cycle in two years Perennials: flowering plants that live for more than two years

Structure of Flowers

Petals and Sepals Sepals – outermost circle of flower parts that encloses a bud before it opens Petals – brightly colored structure just inside the sepals that attracts insects for pollination

Male Stamen – Male part of the flower; made up of an anther and a filament Filament – a long thin structure that supports an anther Anther – flower structure in which pollen grains are produced

Female Carpel – innermost part of the flower that produces female gametes Stigma – sticky portion at the top of the style where pollen grains frequently land Style – narrow stalk of the carpel in a flower Ovary – contains one or more ovules