BIOL 1108 1st Edition Exam 2 Study Guide VI Evolution of plants plant structure and growth Learning Objectives 1 Draw and label all the parts of a charophyte algae The very top leaf like structures are the blades The stem like structure is the stipe The root like system is the holdfast 2 Explain why charophyte algae are relevant when we study plant evolution They are relevant because they are the closest relative to land plants and they are the initial plant that went through evolution to become land plants 3 List the four main groups of land plants Non vascular seedless vascular gemnosperms and angiosperms 4 Give a time estimate when the four groups evolved 475mya non vascular first land plants 420 mya vascular plants 305mya gymnosperms 130mya angiosperms 5 Compare and contrast the environments in which these 4 groups are mainly found Nonvascular plants had to be in humid moist environments Most species are tropical but some can be arctic Vascular plants can survive in many types of environments if there is ample amount of nutrients Their cell walls are strengthened by lignin which form the tracheids in the xylem that allows for water transport Gemnosperms and Angiosperms need temperate tropical environments 6 Explain the problems that each environment poses on it s inhabitants In hot dry environments the inhabitants will have difficulty retaining body water or absorbing any more In tropical environments the increased shading can pose a problem for short plants 8 Read from the cladogram which plant groups are the closest relatives Charophytes are closest to Embryophytes and Gymnosperms are closest with Angiosperms 9 List the structures associated with the four groups of land plants and place them on the cladogram Bryophytes mosses liverworts have cell walls made of cellulose and have turgor Pterophytes whiskferns ferns horsetails have true vascular tissue xylon tissue made of lignin and tracheids Gemnosperms and Angiosperms have true secondary growth which has more lignin and more support Gemnosperms have seeds but Angiosperms have coated seeds flowers and fruits 10 Define the following Plant organ A structural unit of a particular system that has a specific function There are vegetative roots stems and leaves and reproductive flower seed or fruit in angiosperms and cone in Gemnosperms Primary cell wall Thin flexible and extensible layer formed while the cell is growing Secondary cell wall A thick layer on the inside of the primary cell wall formed after the cell is fully grown and is not found in all cell types It can contain lignin which strengthens and water proofs the wall Primary growth The lengthening of stems and roots vertical growth Secondary growth The thickening of stems and roots horizontal growth which results in the cell division in cambia or lateral meristems Doesn t occur until gemnosperms Apical meristems Lead to primary growth by its cell division Lateral Meristems Cell division here leads to secondary growth Vascular cambium is a lateral meristem which can produce the secondary xylem inside and ploem outside Cork cambium is the lateral meristem responsible for lateral growth of the epidermis and replaces the epidermis of roots and stems Primary phloem and xylem Laid out by apical meristems and produced by procambium phloem are vascular tissues responsible for sugar solution transport xylem are vascular tissues for water and mineral nutrient transport Secondary phloem and xylem Produced by vascular cambium and have the same function as primary Bark The outermost layer of woody stems and roots or all tissues outside the vascular cambium includes the innermost area of the periderm which replaces the epidermis and acts as a protective covering 11 List all the plant organs and explain their structure and function Leaves carry out photosynthesis in vascular plants and release oxygen through a stomata Stems are the structural support in vascular plants that also transport fluids store nutrients and produce new living tissue through the meristems Roots are the non leaf and non node bearing part of the plant body that absorb water and inorg anic nutrients they also anchor the plant body to the ground for support and help store food and nutrients they partake in asexual reproduction vegetative reproduction 12 List the plant tissue types and explain their structure and function Dermal tissue protects and prevents water loss Found in the epidermis or periderm Ground tissue responsible for photosynthesis food storage regeneration support and protection made of parenchyma collenchyma and sclerenchyma Vascular tissue transports water minerals and food and is found in the phloem and xylem 13 List the plant cell types and explain their structure and function Parenchyma Form the cell membrane and primary cell wall and are responsible for metabolic activity and storage they are generally alive at maturity Collenchyma Form the cell membrane and primary cell wall but has unevenly thickened areas provides flexible support Schlerenchyma Form primary cell walls cell membrane and secondary cell walls between the membrane and primary cell wall They are lignified and dead at maturity 14 Compare and contrast primary growth to secondary growth Primary growth is responsible for the lengthening of roots and stems by apical meristems and secondary growth is the growth in diameter of stems and roots by lateral meristems 15 Explain the relevance of primary and secondary cell walls for support Primary cell walls are made of cellulose and are thin and flexible They are water and gas permeable and allow for flexible support while still allowing for growth The secondary cell walls are thickened and strengthened by lignin for better structural support 16 Explain the function of the waxy cuticle and indicate its evolution on the plant cladogram The waxy cuticle on leaves allows for them to avoid excessive water loss while still permitting some exchange of CO2 and O2 for photosynthesis through the stomatas They evolved when the first land plants were nonvascular plants that grew photosynthetic shoots above the shallow fresh water where they lived 17 Indicate on a cladogram where key traits are evolved True roots vascular tissue and tracheids evolved after bryophytes Leaves vessels seeds and pollen evolved after seedless vascular plants Flowers evolved after gymnosperms 18 Compare and contrast structure and function between four groups of land plants Bryophytes are non vascular plants with no roots