Test Guide Unit 5 Organismal Biology

Unit 5: Organismal Biology Plants Plant Classification ❖ Bryophytes ➢ No vascular tissue and are very small ➢ Live in wet environments ➢ Examples: mosses, liverworts, hornworts ❖ Tracheophytes ➢ Have vessels (xylem and phloem) ➢ Can be seedless (ferns; use spores to reproduce) or have seeds ➢ Ones that have seeds are divided into gymnosperms and angiosperms ➢ Gymnosperms - have cones ➢ Angiosperms - flowering plants Traits that Allowed Transition from Sea to Land ❖ Cell walls for support (made of cellulose) ❖ Stomates to let gases in ❖ Roots + root hairs to increase nutrient absorption from soil ❖ Waxy cuticle to prevent dehydration Root Layers ❖ Zone of cell division - has meristem cells that divide constantly + make new cells ❖ Zone of elongation - cells elongate + push root cap down ❖ Zone of differentiation - cells here are specialized + create 3 tissue systems (xylem/phloem, ground tissue, epidermis) Root Structure ❖ Epidermis - covers root surface + specialized for absorption ❖ Cortex - has parenchyma cells which have lots of plastids to store starch + other things ❖ Stele - also called vascular cylinder; xylem and phloem, which transport water and nutrients ❖ Endoderm - decides what minerals can enter the vascular cylinder + plant body From Simple Studies: https://simplestudies.edublogs.org & @simplestudiesinc on Instagram Types of Roots ❖ Taproot - one large root that branches into smaller lateral roots; usually in dicots ❖ Fibrous root system - common in monocots; holds plant in place ❖ Adventitious roots - roots above ground such as: ➢ Aerial roots - in mangroves (stick out of water) or ivy to let it attach to buildings ➢ Prop roots - support plant (ex. corn) Stem Structure ❖ In monocots, vascular bundles (xylem on inside, meristem tissue in middle, phloem on outside) are scattered in the stem ❖ In dicots, vascular bundles are organized into a ring around stem edge Leaf Parts ❖ Epidermis - for protection ❖ Waxy cuticle - prevents loss of water ❖ Guard cells - controls opening/closing of stomata ❖ Palisade mesophyll - photosynthesis ❖ Spongy mesophyll - photosynthesis + diffusion of gases in/out of cells ❖ Veins - transport water/nutrients from soil to leaves + carry sugar from leaves to rest of plant Stomates ❖ Responsible for taking in gases (oxygen or carbon dioxide) and giving off water vapor; controlled by guard cells ➢ Must be closed at times to avoid water loss ➢ Guard cells control them through osmosis Plant Reproduction ❖ Asexual - vegetative propagation (ex. Graftings, bulbs, etc.) ❖ Sexual - flower is the sexual organ ➢ Flower parts: ■ Petals - bright colors to attract pollinators ■ Sepals - encloses and protects flower before it opens, are green ■ Pistils/carpels - produces female gametophytes (has ovary, stigma, and style) ● Ovary - contains ovule where meiosis produces ova (female gametophytes) ● Style - long and thin stalk ● Stigma - sticky top part of style where pollen can land ■ Stamen - male flower part (made of anther + filament) ● Anther - pollen (sperm) is produced here ● Filament - threadlike; supports anther ➢ After plant is pollinated + fertilized, ovule becomes the seed and ovary becomes the fruit Seed ❖ Made of ➢ Seed coat ➢ cotyledon/endosperm (food for embryo) ➢ Embryo ❖ Embryo consists of: ➢ Hypocotyl - becomes lower part of stem + roots ➢ Epicotyl - becomes upper part of stem ➢ Radicle - first organ to erupt from a germinating seed ❖ Monocot seed does not split in half, dicot seed does Alternation of Generations ❖ Sexual life cycle where haploid (gametophyte) and diploid (sporophyte) generations alternate ❖ Gametophyte produces gametes by mitosis and these combine to make diploid zygotes ➢ These zygotes develop into sporophytes which produce haploid spores ➢ Haploid spores then produce new gametophyte Plant Hormones ❖ Auxins - cause tropisms (growth toward/away from a stimulus like light) ❖ Cytokinins - stimulate cytokinesis + cell division ❖ Gibberellins - promote elongation of the leaves + stem ❖ Ethylene gas - promotes ripening of fruit ❖ Abscisic acid (ABA) - stops growth + makes seeds dormant