Plant Evolution and Adaptations PDF

SECTION 21.1 PLANT EVOLUTION AND ADAPTATIONS OBJECTIVES  Compare the characteristics of plants and green algae.  Identify and evaluate adaptations of plants to land environments.  Assess the importance of vascular tissue to plant life on land.  List the divisions of the plant kingdo...

SECTION 21.1 PLANT EVOLUTION AND ADAPTATIONS OBJECTIVES  Compare the characteristics of plants and green algae.  Identify and evaluate adaptations of plants to land environments.  Assess the importance of vascular tissue to plant life on land.  List the divisions of the plant kingdom.  Explain alternation of generation of plants. PLANT EVOLUTION  Plants are vital to our survival.  Biologists describe plants as multicellular eukaryotes with tissues and organs that have specialized structures and functions.  Plants have photosynthetic tissues and organs that anchor them to soil or to an object. PLANT EVOLUTION  Multicellular land plants and green algae share a common ancestor since they have the following common characteristics: - Cell wall composed of cellulose. - Cell division including cell plate. - Same type of chlorophyll. - Similar genes for rRNA. - Food stored as starch. - Same type of enzymes in cellular vesicles. PLANT ADAPTATIONS TO LAND ENVIRONMENTS  Plants that inhabited land developed adaptations that helped them survive limited water resources as well as other environmental factors.  Adaptations such as: - cuticle. - stomata. - vascular tissues. - seeds. - reproductive strategies. PLANT ADAPTATIONS TO LAND ENVIRONMENTS  1- Cuticle - An adaptation found on most aboveground plant parts called cuticle which is a fatty or waxy coating on the outer surface of plant cells. - Fats and waxes are lipids that are insoluble in water. - Cuticle helps prevent water evaporation from plant tissues. - Cuticle acts as a barrier to invading microorganisms. PLANT ADAPTATIONS TO LAND ENVIRONMENTS PLANT ADAPTATIONS TO LAND ENVIRONMENTS  2- Stomata - Most plants carry on photosynthesis which requires gas exchange between the plant and the environment. - Cuticle might prevent gas exchange between the plant and the environment. - Stomata (singular: stoma) are openings in the outer cell layer of leaves and some stems that enable gas exchange even with the presence of cuticle. PLANT ADAPTATIONS TO LAND ENVIRONMENTS PLANT ADAPTATIONS TO LAND ENVIRONMENTS  3- Vascular tissues - Another plant adaptation is vascular tissues. - They are specialized transport tissues that enable faster movement of substances than by osmosis or diffusion. - They also provide structure and support. - Plants vascular: with vascular tissues. - nonvascular: no vascular tissues. PLANT ADAPTATIONS TO LAND ENVIRONMENTS Click to edit Master text Click to edit Master text Vascular plants Nonvascular plants styles styles PLANT ADAPTATIONS TO LAND ENVIRONMENTS  4- reproductive strategies - Some land plants reproduce by spores that have waterproof protective coverings. - Spores are haploid (n) cells capable of producing an organism without reproduction. Note: plants that produce by spores, need water so the sperm can swim to an egg. PLANT ADAPTATIONS TO LAND ENVIRONMENTS  5- Seeds - Is a plant structure that contains: - embryo - nutrients for the embryo - protective coat. - These features enable seeds to survive harsh environmental conditions and then sprout when favorable conditions exist. PLANT ADAPTATIONS TO LAND ENVIRONMENTS ALTERNATION OF GENERATIONS  All plants have a life cycle known as alternation of generations.  In alternation of generations, a haploid gametophyte (n) produces gametes ( eggs and sperms). Gametes unite and give rise to a. diploid sporophyte ( 2n).  Through meiosis, the sporophyte produces haploid spores, which develop into gametophytes. ALTERNATION OF GENERATION  Depending on the plant’s type, one generation is dominant over the other.  The dominant generation is usually larger and accounts for more time in plant’s life cycle. In vascular plants: - Sporophyte is dominant (large, more noticeable) - Gametophyte is recessive (small, microscopic) In nonvascular plants: - Sporophyte is recessive - Gametophyte is dominant ALTERNATION OF GENERATION ALTERNATION OF GENERATION PLANT CLASSIFICATION PLANT CLASSIFICATION