BIO 311D 2nd Edition Exam 2 Study Guide Lectures 11 20 Lecture 11 Learning objectives 2 1 Review the general features of plant cells and the functions of the following chloroplasts mitochondria central vacuole cell wall What are plasmodesmata Chloroplasts convert solar energy to chemical energyphotosynthesis Mitochondria generate the majority of the cell s energy Central vacuole stores water and ions a structural component Cell wall cell structure prevents the cell membrane from bursting Plasmodesmata microscopic channels which traverse the cell walls of plant cells and some algal cells enabling transport and communication between them 2 2 What modern group of the kingdom Protista is closest to the ancestors of the Plant Kingdom Therefore in making a cladogram phylogeny of Plants what is the best group to use as outgroup Green algae compare cell walls etc 2 3 Name three major challenges faced by ancestral plants as they successfully colonized land Lack of water UV radiation too hot Predators Changes in weather 2 4 What adaptations plant derived traits did plants eventually evolve for greater success on land Apical meristems localized regions of cell division at the tips of shoots and roots Alternation of generations result in both haploid and diploid stages that exist as multicellular bodies two multicellular body forms alternate Multicellular embryo that is dependent on the parent plant parent provides nutrients to the embryo develop from zygotes that are retained within tissues of the female parent Sporangia that produce walled spores makes the walls of spores very tough and resistant to harsh conditions protect the developing spores until they are ready to be released into the air Gametangia that produce gametes produce gametes within multicellular organs called gamentangia 2 5 Tell a characteristic feature e g a new trait in the group of each of the following divisions of the Plant Kingdom ferns gymnosperms angiosperms Ferns living seedless vascular plants Gymnosperms a vascular plant that produces seeds those are not protected by fruit but are hidden in a woody cone They do not have flowers but most retain their leaves year round Angiosperms vascular plants that produce flowers and fruit with one or more seeds Lecture 12 2 6 The three main vegetative non reproductive organs of plants are leaves stems and roots Tell the main general functions of each and be able to pick out these structures in different plants including vegetable foods Leaves photosynthesis Stems support and transport Roots anchor and absorb 2 7 Give some examples of evolutionarily modified stems roots leaves e g cactus spine and tell what specialized functions they serve that allow that particular type of plant to be adapted for a certain habitat or way of life Modified Shoots These are examples of shoots including both the stem and leaves that have become secondarily modified Bulbs These shoots are an adaptation for interrupted life for existence in environments with a dormant season due to annual rainfall variations or to life in the temperate climates Thorns The thorns of Hawthorne are modified dwarf shoots Tendrils Tendrils of grape are modified flowering shoots Modified Stems Rhizomes While typically competition results in vertical stems there are environments where horizontal stems are adaptive These are termed rhizomes Tubers Like bulbs these are adaptations for interrupted life Irish potatoes are tubers It is clear that they are stems when you realize that the eyes are axillary buds Corms Like tubers and bulbs these are adaptations for interrupted life Often mistakenly called bulbs a corm is a solid underground stem vertically oriented where typically only one bud germinates at the end of dormancy Stolons These are like rhizomes in that they are oriented horizontally However they are adapted to generate new plants that are clones of the original Succulent photosynthetic Stems In extremely dry environments often the leaf becomes reduced and nonphotosynthetic and the stem becomes the primary photosynthetic organ of the plant A barrel shape provides a low surface to volume ratio which reduces water loss Cladophyll If a plant becomes genetically boxed in like the plants in the preceding link and the environment becomes more mesic the same set of factors that caused the generic leaf to become thin and flat will work to make barrel shaped succulent stems thin and flat too Modified Leaves Succulence In a dry environment leaves may either become reduced like in cacti or else become succulent Succulent leaves not only retain lots of moisture but also have a lower surface to volume ratio Stipular Spines Stipules can become modified into spines for defense Stipular Spines Modified for Mutualistic Ants In bullhorn acacia evolution has preceded one more step In this plant the stipular spines are hollow and house mutualistic ants The leaves are further modified to provide yellow structures on the margins of the leaves which only function to feed the ants The perioles bear glands that excrete nectar for the ants too Spines for Defense The non photosynthetic leaves of cacti have become modified for defense Tendrils In peas the terminal leaflet of the leaf has become modified into a tendril for climbing Leaves modified for Reproduction Typically leaves are determinately growth The grow function and then die without sustaining new growth But Kalanchoe has leaves that have become modified to generate new plants Modified Roots Storage Like bulbs and tubers this is an adaptation for interrupted life Further unlike stems and shoots the primitive habit of roots is subterranean where it is best to secure energy and propagative resources Climbing Some vines will form adventitious roots that assist the plant in clinging to a substrate Poison ivy has this habit Lecture 13 2 8 What is meristem Where could meristem be found in this figure Where are apical meristem lateral meristem vascular cambium in trees This is a tissue formed by a group of cells mitosis Meristem cells aren t specialized but when they divide some of the new cells specialize into tissues Areas of growth that lengthen the tips of roots and stems are called apical meristems Lateral meristems found all along woody roots and stems increase the thickness of these plant parts 3 Plant Tissue Types Ground tissue Dermal tissue Vascular tissue Structural features Various shapes and cell wall thicknesses thin external layer Elongate shape porous cell walls Major