1. Introduction to Plant Life Interest Grabber Plants Make the World Go Round Life as we know it today could not exist without plants. Plants provide us with many essential items other than food. 1.With your partner, list five items you use daily that are byproducts of plants. 2.With your partner, list three items that plants must get from animals—either directly or indirectly. 3.Using your answers to questions 1 and 2, construct a diagram that illustrates the interdependence of plants and animals. Go to Section:

2. Introduction to Plant Life Section Outline Introduction to Plants A.What Is a Plant? B.The Plant Life Cycle C.What Plants Need to Survive 1.Sunlight 2.Water and Minerals 3.Gas Exchange 4.Movement of Water and Nutrients D.Early Plants 1.Origins in the Water 2.The First Plants E.Overview of the Plant Kingdom Section 22-1 Go to Section:

3. Introduction to Plant Life What is a plant? Dominant group of organisms on land (based on biomass) Characteristics: Size ranges from 2mm to 100 m tall. Most are photosynthetic Some are parasitic

4. Introduction to Plant Life Haploid Diploid MEIOSIS Spores (N) Sporophyte Plant (2N) Gametophyte Plant (N) FERTILIZATION Sperm (N) Eggs (N) Section 22-1 Generalized Plant Life Cycle Go to Section:

5. Introduction to Plant Life KEY CONCEPT Plant life began in the water and became adapted to land.

6. Introduction to Plant Life Land plants evolved from green algae. Plants and green algae have many common traits. – both are photosynthetic eukaryotes – both have the same types of chlorophyll – both use starch as a storage product – both have cell walls with cellulose

7. Introduction to Plant Life Genetic analysis points to the common ancestor of all plants. – extinct green algae species in class Charophyceae – modern charophyceans common in lakes and ponds

8. Introduction to Plant Life

9. Important plant characteristics likely originated in charophyceans. –multicellular body allowing for specialization of cells and tissues –cell division that allows for chemical communication between cells –reproduction involving sperm swimming to egg

10. Introduction to Plant Life –Ancestral charophyceans lived in areas of shallow water. True plants evolved through natural selection. –Those that could survive longer dry periods were favored. –First true plants probably grew at edges of water. –True plants have embryos that develop while attached to female parent.

11. Introduction to Plant Life True plants evolved through natural selection.

12. Introduction to Plant Life Plants have adaptations for life on land Copyright © 2009 Pearson Education, Inc. Land plants are a clade, defined by a set of derived characters –Alternation of haploid and diploid generations –Walled spores produced in sporangia –Male and female gametangia –Multicellular, dependent sporophyte embryos

13. Introduction to Plant Life Copyright © 2009 Pearson Education, Inc. Life on land offered new opportunities –Unlimited sunlight –Abundant CO 2 –Initially, few pathogens or herbivores

14. Introduction to Plant Life Copyright © 2009 Pearson Education, Inc. Challenges of terrestrial life –Maintaining moisture within cells –Obtaining resources from soil and air –Supporting body in air –Reproducing and dispersing offspring without water

15. Introduction to Plant Life Challenges of living on land have selected for certain plant adaptations. A cuticle allows plants to retain moisture. –waxy, waterproof layer – holds moisture in

16. Introduction to Plant Life Stomata are tiny holes in the cuticle. stoma –can open and close –allow air to move in and out

17. Introduction to Plant Life A vascular system allows resources to move to different parts of the plant. sugars water and mineral nutrients –collection of specialized tissues –brings water and mineral nutrients up from roots –disperses sugars from the leaves –allows plants to grow higher off the ground

18. Introduction to Plant Life Copyright © 2009 Pearson Education, Inc. Plant diversity reflects the evolutionary history of the plant kingdom Four key adaptations for life on land distinguish the main lineages of the plant kingdom –Dependent embryos (characteristic of all plants) –Lignified vascular tissues –Seeds –Flowers

19. Introduction to Plant Life Lignin allows plants to grow upright. –hardens cell walls of some vascular tissues –provides stiffness to stems plant cells lignin

20. Introduction to Plant Life Pollen grains allow for reproduction without free-standing water. –pollen grains contain a cell that divides to form sperm –pollen can be carried by wind or animals to female structures

21. Introduction to Plant Life Copyright © 2009 Pearson Education, Inc. In all plants, the zygote develops into an embryo while attached to and nourished by the parent plant Plants are embryophytes, with multicellular, dependent embryos

22. Introduction to Plant Life A seed is a storage device for a plant embryo. –seed coats protect embryos from drying wind and sunlight –embryo develops when environment is favorable

23. Introduction to Plant Life Plants evolve with other organisms in their environment. Plants and other organisms can share a mutualistic relationship. –a mutualism is an interaction in which two species benefit –plant roots and certain fungi and bacteria –flowering plants and their animal pollinators

24. Introduction to Plant Life Plants have adaptations that prevent animals from eating them. –defensive chemicals –spines and thorns

25. Introduction to Plant Life Spores Flagellated sperm Stem Leaf Seed Pollen Leaf Fern Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization requires moisture Roots Stem Roots Pine tree Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization does not require moisture Moss Stomata only on sporophytes; primitive roots anchor plants, no lignin; no vascular tissue; fertilization requires moisture Spores Flagellated sperm Leaf Stem Roots Flagellated sperm Vascular tissue Key Holdfast (anchors alga) Alga Water supports alga. Whole alga performs photo- synthesis; absorbs water, CO 2, and minerals from water.

26. Introduction to Plant Life Flagellated sperm Stem Leaf Fern Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization requires moisture Roots Moss Stomata only on sporophytes; primitive roots anchor plants, no lignin; no vascular tissue; fertilization requires moisture Spores Flagellated sperm Leaf Stem Roots Flagellated sperm Vascular tissue Key Holdfast (anchors alga) Alga Water supports alga. Whole alga performs photo- synthesis; absorbs water, CO 2, and minerals from water. Spores

27. Introduction to Plant Life Leaf Seed Pollen Stem Roots Pine tree Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization does not require moisture Vascular tissue Key

28. Introduction to Plant Life Cone-bearing plants 760 species Ferns and their relatives 11,000 species Mosses and their relatives 15,600 species Flowering plants 235,000 species Section 22-1 Figure 22-7 The Diversity of Plants Go to Section: