PLANT STRUCTURE AND FUNCTION PLANT STRUCTURE AND FUNCTION Copyright © 2009 Pearson Education, Inc.

Evolution and types of plants Since the earth was once covered in water, plants had to make three adaptations to survive on land The ability to prevent water loss The ability to reproduce in the absence of water The ability to absorb and transport nutrients Plants can be placed under two groups Vascular- having true roots, leaves, and stems Ex. ferns, conifers, flowering plants Nonvascular- not having true roots, leaves, and stems Ex. mosses, liverworts, hornworts

Vascular Plants can be divided into two groups Seedless Plants Seed Plants Made up of ferns and plants closely associated with ferns Two types of seed plants Gymnosperms- which includes pine trees, produce seeds that are not encased in fruit Angiosperms- aka flowering plants, produce seeds within a protective fruit

The two main groups of angiosperms are the monocots and the dicots Monocots One cotyledon Parallel leaf venation Scattered vascular bundles Flower parts in 3s or multiples of 3 Fibrous roots Student Misconceptions and Concerns 1. Students often fail to see the specific applications of fundamental principles of biology. For example, many structural adaptations increase the surface-to-volume ratio in plants and animals. The divisions within the human lung, as well as microvilli, leaves, and root hairs, are examples. Increased surface areas are typically found where something is exchanged: gases exchanged at respiratory surfaces, nutrients absorbed by microvilli, light absorbed by leaves, and water and minerals absorbed by root hairs. If this chapter is one of the final topics addressed in your course, illustrating these broad principles with examples from a variety of subjects can serve as a unifying review. Teaching Tips 1. Figure 31.2 provides a visually simple but important comparison of monocots and eudicots. By referring to this figure in class, students will be able to absorb more details during lecture that they can then review at their leisure. 2. Consider bringing living examples of monocots and eudicots to class or taking a short trip outside during a related lab to quickly compare examples.

The two main groups of angiosperms are the monocots and the eudicots Dicots- aka eudicots Two cotyledons Branched leaf venation Ring of vascular bundles Flower parts in 4s or 5s (or multiples) Taproot system Student Misconceptions and Concerns 1. Students often fail to see the specific applications of fundamental principles of biology. For example, many structural adaptations increase the surface-to-volume ratio in plants and animals. The divisions within the human lung, as well as microvilli, leaves, and root hairs, are examples. Increased surface areas are typically found where something is exchanged: gases exchanged at respiratory surfaces, nutrients absorbed by microvilli, light absorbed by leaves, and water and minerals absorbed by root hairs. If this chapter is one of the final topics addressed in your course, illustrating these broad principles with examples from a variety of subjects can serve as a unifying review. Teaching Tips 1. Figure 31.2 provides a visually simple but important comparison of monocots and eudicots. By referring to this figure in class, students will be able to absorb more details during lecture that they can then review at their leisure. 2. Consider bringing living examples of monocots and eudicots to class or taking a short trip outside during a related lab to quickly compare examples.

A typical plant body contains three basic organs: roots, stems, and leaves Plants absorb water and minerals from soil through roots Plants absorb the sun’s energy and carbon dioxide from the air through shoots (stems and leaves) Plant roots depend on shoots for carbohydrates produced via photosynthesis Plant shoots depend on roots for water and minerals Teaching Tips 1. Challenge your students to suggest circumstances when apical growth is more adaptive for a plant, and other situations in which branching would be more favorable. Copyright © 2009 Pearson Education, Inc.

A typical plant body contains three basic organs: roots, stems, and leaves Plant roots Anchor plant Absorb water and nutrients Store food Plant shoots Stems, leaves, and reproductive structures Stems provide support Leaves carry out photosynthesis Teaching Tips 1. Challenge your students to suggest circumstances when apical growth is more adaptive for a plant, and other situations in which branching would be more favorable. Copyright © 2009 Pearson Education, Inc.

Terminal bud Blade Leaf Flower Petiole Axillary bud Stem Shoot system Node Internode Root hair Root hairs Figure 31.3 The body plan of a flowering plant (a eudicot). Taproot Root system Epidermal cell

Many plants have modified roots, stems, and leaves Modifications of plant parts are adaptations for various functions Food or water storage Asexual reproduction Protection Climbing Photosynthesis Teaching Tips 1. The modifications of the three plant organs described in Module 31.4 reveal the remodeling nature of evolution. As Francois Jacob noted, evolution works more like a tinkerer than an engineer. The common ancestry of eudicots is revealed by the diverse modifications of three basic plant organs derived from the shared ancestors. Your students’ appreciation of the enormous evidence in support of evolution will grow if you note such examples frequently throughout your course. Copyright © 2009 Pearson Education, Inc.

Many plants have modified roots, stems, and leaves Root modifications Food storage Examples include carrots & potatoes Teaching Tips 1. The modifications of the three plant organs described in Module 31.4 reveal the remodeling nature of evolution. As Francois Jacob noted, evolution works more like a tinkerer than an engineer. The common ancestry of eudicots is revealed by the diverse modifications of three basic plant organs derived from the shared ancestors. Your students’ appreciation of the enormous evidence in support of evolution will grow if you note such examples frequently throughout your course.

Many plants have modified roots, stems, and leaves Stem modifications Runners (allow for asexual reproduction) Teaching Tips 1. The modifications of the three plant organs described in Module 31.4 reveal the remodeling nature of evolution. As Francois Jacob noted, evolution works more like a tinkerer than an engineer. The common ancestry of eudicots is revealed by the diverse modifications of three basic plant organs derived from the shared ancestors. Your students’ appreciation of the enormous evidence in support of evolution will grow if you note such examples frequently throughout your course.

Many plants have modified roots, stems, and leaves Leaf modifications Climbing tendril Example: pea plants Protection Thorns or spines Example: Cactus spine Teaching Tips 1. The modifications of the three plant organs described in Module 31.4 reveal the remodeling nature of evolution. As Francois Jacob noted, evolution works more like a tinkerer than an engineer. The common ancestry of eudicots is revealed by the diverse modifications of three basic plant organs derived from the shared ancestors. Your students’ appreciation of the enormous evidence in support of evolution will grow if you note such examples frequently throughout your course.

Plant cells and tissues are diverse in structure and function Plants cells have three structures that distinguish them from animals cells Chloroplasts used in photosynthesis A large, fluid-filled vacuole A cell wall composed of cellulose Student Misconceptions and Concerns 1. Students may not understand turgor, although they encounter it in their lives. The shape of a water balloon is different from the shape of an uninflated balloon due to internal fluid pressure (turgor). A plant in need of water may have drooping leaves, a consequence of decreased turgor. Teaching Tips 1. Cellulose is the most abundant organic compound on Earth. Students often find this fact worth remembering. 2. Students will remember the function of phloem more easily if you remind them that both phloem and food start with an “F” sound. For the BioFlix Animation Tour of a Plant Cell, go to Animation and Video Files.

PLANT GROWTH Copyright © 2009 Pearson Education, Inc.

Primary growth Plants are categorized based on how long they live Plants are categorized based on how long they live Annuals complete their life cycle in one year Biennials complete their life cycle in two years Perennials live for many years Student Misconceptions and Concerns 1. Students often expect determinate growth in plants, because it is characteristic of humans. However, most plant species show indeterminate growth and are capable of growing as long as they can live. Teaching Tips 1. Lobsters are one of the few animals that show indeterminate growth. Copyright © 2009 Pearson Education, Inc.

Primary growth allows roots to push downward through the soil and shoots to grow upward Terminal bud Axillary buds Figure 31.7A Locations of apical meristems, which are responsible for primary growth. Arrows = direction of growth Root tips

Secondary growth increases the girth of woody plants Year 1 Early Spring Year 2 Late Summer Year 1 Late Summer Figure 31.8A Secondary growth of a woody eudicot stem.

Secondary growth increases the girth of woody plants Cork cambium produces the outer bark Student Misconceptions and Concerns 1. Students typically expect that as a tree grows taller, the trunk will “stretch” upward along its entire length. This expectation arises naturally from the experience of our own growth as humans. However, as a tree grows, the entire trunk does not increase in size. Instead, growth occurs at the upper ends and through expansion of the trunk. Therefore, initials carved into the trunk of a tree will remain at that height as long as the tree is upright and healthy. Teaching Tips 1. Students may not realize that the cork used to seal a wine bottle is the same cork that is discussed in Module 31.8. 2. Students may not appreciate the many important functions of tree bark. Carving into bark, or peeling it away from a trunk, exposes the inner tissues to pathogens. In many ways, the functions of human skin and bark are similar. Copyright © 2009 Pearson Education, Inc.

Secondary growth increases the girth of woody plants Wood annual rings show when new growth starts each year. Sapwood (transport)- functional, lighter-colored wood near the outside of the trunk Heartwood (storage)- the darker wood at the center of the trunk Student Misconceptions and Concerns 1. Students typically expect that as a tree grows taller, the trunk will “stretch” upward along its entire length. This expectation arises naturally from the experience of our own growth as humans. However, as a tree grows, the entire trunk does not increase in size. Instead, growth occurs at the upper ends and through expansion of the trunk. Therefore, initials carved into the trunk of a tree will remain at that height as long as the tree is upright and healthy. Teaching Tips 1. Students may not realize that the cork used to seal a wine bottle is the same cork that is discussed in Module 31.8. 2. Students may not appreciate the many important functions of tree bark. Carving into bark, or peeling it away from a trunk, exposes the inner tissues to pathogens. In many ways, the functions of human skin and bark are similar.

Secondary growth increases the girth of woody plants Xylem- transports water Phloem- transports food Student Misconceptions and Concerns 1. Students typically expect that as a tree grows taller, the trunk will “stretch” upward along its entire length. This expectation arises naturally from the experience of our own growth as humans. However, as a tree grows, the entire trunk does not increase in size. Instead, growth occurs at the upper ends and through expansion of the trunk. Therefore, initials carved into the trunk of a tree will remain at that height as long as the tree is upright and healthy. Teaching Tips 1. Students may not realize that the cork used to seal a wine bottle is the same cork that is discussed in Module 31.8. 2. Students may not appreciate the many important functions of tree bark. Carving into bark, or peeling it away from a trunk, exposes the inner tissues to pathogens. In many ways, the functions of human skin and bark are similar.