Download Chapter 22 What is a plant? A multicellular eukaryote that has a cell

Chapter 22
What is a plant? A multicellular eukaryote that has a cell wall made of cellulose, develops from multicellular embryos, and
carries out photosynthesis using the green pigments chlorophyll a and b.
Plant Life Cycle:
Two alternating phases known as alternation of generations. Mitosis and meiosis alternate to produce two types of
reproductive cells- gametes and spores. Diploid phase= Sporophyte Haploid phase= Gametophyte
Plants need 4 things to survive:
-Sunlight
-Water & Minerals
-Gas Exchange
-Movement of Water & Nutrients
Know the Cladogram of evolutionary relationships between plants on page 554.
Bryophytes- life cycles that depend on water for reproduction. No vascular tissue, can only draw up water by osmosis a
few cm above the ground (low growing).
Mosses- No true roots- rhizoids that anchor them and absorb water/minerals. Liverworts & Hornworts
Vascular Plants: have vascular tissue to transport water and nutrients throughout the plant.
Two types of vascular tissue:
-Xylem: carries water upward from the roots to every part of the plant
-Phloem: transports solutions of nutrients and carbohydrates produced by photosynthesis
Ferns are seedless vascular plants in the Phylum Pterophyta. They have roots, leaves, and stems. The diploid sporophyte
is the dominant stage (like in all vascular plants).
Ferns are seedless, and produce haploid spores on the underside of their fronds. Water is required for fertilization within
the gametophyte to occur. Understand the fern life cycle on p. 563.
Seed plants are divided into 2 groups:
-Gymnosperms- “naked” seeds are directly on surface of cones
-Angiosperms- flowering plants- seeds are within a layer of protective tissue
Seed plants do not require water for reproduction, so they can live in drier areas. Adaptations that allow this include:
-Cones & Flowers: These are the seed bearing sporophtye structures on the plant where the gametophyte generation
grows.
-Pollen- The male gametophyte is in a pollen grain. This grain is carried to the female gametophyte by wind, insects, or
small animals. This is called pollination.
-Seeds: A seed is an embryo of a plant, surrounded by a food supply, and encased in a protective covering. It is the early
sporophyte stage and is diploid. Seeds can survive for long periods of time, growing only when conditions are right.
Gymnosperms: Phylum Coniferophyta: Conifers= Pines, spruces, firs, cedars, sequoias, redwoods, junipers, and yews.
Most are evergreens.
Angiosperms: Most diverse group of plants. Phylum Anthophyta. Angiosperms develop flowers to attract pollinators (more
effective than wind). The flowers contain ovaries which develop into a fruit and surround and protect the seed.
Two classes in Phylum Anthophyta, named for the number of seed leaves (cotyledons) in the plant embryo.
-Class Monocotyledonae- Monocots- One cotyledon
-Class Dicotyledonae- Dicots- Two cotyledons
There are three categories of life spans in angiosperms:
-Annual: Germinate, flower, produce seeds, & die in one year.
-Biennial: Generally a two year life cycle- grow the first year, flower, reproduce, & die the 2nd.
-Perennial: Plants that live for many growing seasons. Even if the top part dies off in the winter, the roots remain alive.
Chapter 23
Three organs of vascular plants:
-Roots: Absorb water and dissolved nutrients and anchor plant to the ground.
-Stems: Support system for the plant body, transport system to carry nutrients, defense system to protect against
predators/disease.
-Leaves: Where photosynthesis occurs.
Three main tissue systems:
-Dermal tissue: Outer covering of plant- single layer of epidermal cells. On leaves, can be a waxy coating to protect
against water loss and injury or as trichomes- fuzzy looking projections for protection. In roots, hair cells to increase
surface area.
-Vascular tissue: transport system that moves water and nutrients thru the plant. Two main subsystems- xylem and
phloem.
-Ground tissue: Lies between dermal and vascular tissue. Three kinds of cells:
1. Parenchyma: packed with chloroplasts for photosynthesis.
2. Collenchyma: strong, flexible cell walls for support (celery "strings")
3. Sclerenchyma: thick, rigid cells to make ground tissue tough and strong.
ROOTS: Two main types:
-Taproots: dicots- a large, long, primary root. Carrot.
-Fibrous roots: monocots- very branchy so no one root is larger than the rest. Grasses.
Root structure: Has all 3 types of tissue systems. Root hairs increase surface area for water absorption. Only cells in the
tip of the root divide for growth. The root cap is at the very tip, and pushes the root into the soil.
Root function: Anchors plants and water/nutrient uptake. Plants require a variety of nutrients found in the soil. Known table
on p. 586
STEMS: 3 important functions: produce leaves, branches, & flowers, hold leaves up to sunlight, transport substances
between roots and leaves.
Nodes: where leaves are attaches
Internode: between the nodes
Buds: undeveloped tissue that forms new stems/leaves.
Monocot stems: vascular bundles spread thruout.
Dicot stems: vascular bundles in ring around outside.
Stems exhibit 2 types of growth:
Primary growth- meaning new cells are produced at the tips of roots and shoots. increases length. This area of new
growth occurs in the apical meristem.
Secondary growth- increases width. Occurs in lateral meristematic tissue.
Formation of wood: Wood is layers of xylem. As the plant grows, the xylem at the center is not used for transport and
becomes heartwood. Lighter colored sapwood surrounds this, and is active in transport. Sapwood growth is seasonalwhen it grows fast, cells are large and light in color. When it grows slow, cells are small, thick, and dark colored. This
alternation is what creates tree rings.
LEAVES: Structure is a flat blade attached to the stem by a thin stalk (petiole). Have 3 main functions:
-Photosynthesis: Specialized ground tissue called mesophyll is where it occurs.
-Transpiration: loss of water through the leaves. Leaf must be moist for gasses to be exchanged.
-Gas Exchange: CO2 enters and O2 exits through stomata- pore like openings under the leaf. The stomata do not always
stay open- the plant would lose too much water. They tend to be open during the day when photosynthesis is occurring,
and closed at night. Sometimes if it's really hot and dry during the day, they will remain closed to conserve water.
Two substances are transported in plants: water and nutrients.
-Water Transport- Achieved through a combination of root pressure, capillary action, and transpiration. Capillary action is
the tendency of water to move up through a thin tube. Water is attracted to the walls of the tube through adhesion and to
each other through cohesion. Adhesion is greater in a narrower tube, causing the water to go higher.
-Transpiration- For really tall plants, root pressure and capillary action aren't enough to lift the water to the top. As water is
lost through transpiration, it pulls more water up from the roots. On a hot day, transpiration rates are higher, causing more
water to be drawn in.
-Nutrient Transport: When nutrients are pumped into or removed from the phloem system, the change in concentration
causes a movement of fluid in that same direction. As a result, phloem is able to move nutrients in either direction to meet
the nutritional needs of the plant. The source cell produces sugar, the sink uses or stores it.