Chapter 5 Structure & Function of the Cell



Plant Evolution & Classification

I. What is a plant? Kingdom Plantae includes over 350,000 species of Eukaryotic, multicellular, land dwelling, photosynthesizing organisms.

A. What do plants have in common? Chloroplasts (contain chlorophyll-pigment that traps light energy), undergo photosynthesis (CO2 + H2O C6H12O6 + O2), & a cell wall.

II. Plant Classification: Nonvascular plants and Vascular plants.

A. Nonvascular plants-The earliest, most primitive of plants. There are 23,000 species. *Definition-plants that do not contain vascular tissue (stems) (tube-like cells that carry water from the roots to the leaves and food from the leaves to the roots), no true roots or leaves.

1. Common characteristics: grow close to water and very short.

2. Examples: Mosses and liverworts- small nonvascular plants that contain a primitive stem and leaves, but no roots.

a. Often found fixed to the ground or a tree trunk near water.

b. Used as food for small animals (worms/snails, etc.)

3. Sphagnum moss- Found in bogs (acidic watery environments). Due to acid environment, can preserve organisms. After millions of years, sphagnum moss becomes peat, which forms into coal.

4. Moss reproduction- Alternation of generations: One generation uses sexual reproduction, and the next generation uses asexual reproduction, etc. (refer to handout).

B. Vascular plants- Plants that contain vascular tissue (tubes that carry water from the roots throughout the plant and carry food from the leaves down to the roots.

1. Characteristics: Size is not an issue due to its vascular tissue, they do not have to be located near water, and they can live in a variety of environments.

2. Major organs

a. Roots- anchor plants to the ground and take in water and minerals from the soil.

b. Stem-composed of xylem and phloem. Xylem- is a tube that carries water and minerals from the roots to the leaves, and phloem carries food from the leaves to the roots. Stem also holds up the leaves to the sunlight.

c. Leaves- food production occurs here. Where most of the chloroplasts are located.

3. Examples of vascular plants from most primitive to most advanced (evolutionary terms)

a. Seedless vascular plants- reproduce via spores (alternation of generation). Usually found in most areas. Fern is an example. They have been around form 300 million years. Leaves grow from an underground stem in which the spores are found underneath the leaves. Primitive root system.

b. Seeded plants: 2 types- Gymnosperms and the angiosperms. Reproduce by forming seeds- plant embryo (baby) plus a food source. (Sexual reproduction)

1. Gymnosperms (conifers)- plants that produce naked seeds in cones. These plants leaves usually stay green all year round thus called evergreens. Have been around for millions of years. Ex: pine, spruce, fir, redwood, ect. They can grow in all types of environments and contain very hard wood. (3/4 of lumber in the world).

2. Angiosperms (flowering plants)-majority of plants (275,000 species). They contain protected seeds, flowers and often fruits (protects the seed and is used in seed dispersal via animals, insects, wind, etc. (Grass, Maple trees, roses, ect.)

a. Classification: Monocot or Dicots (majority of flowering plants. Cotyledon-seed leaves.

| |# Of Cotyledons |Type of Venation |# Of Petals |

|Monocot |1 |Parallel |In 3’s |

|Dicot |2 |Net Venation |4’s or 5’s |

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