Bio Lecture exam notes

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Biological Sciences
Ivana Stehlik

BIOLOGY LECTURE NOTES 1/10/2012 Lecture 01 EVALUATION: LAB Module 1 6% Module 2 6% Module 3 6% Assign. 4% Term test 30% Final (Cumulative) 40% Module 1: Plant form & Function - Bacteria fossils were found to have dated back to 3650 MYA - Green algae were discovered to be the first group of plants - The angiosperms are the largest branch of plants o The bryophytes are second largest, ferns, lycophytes, and then gymnosperms BRYOPHYTES - Bryophytes require moist environments (ex. mosses) in order to do photosynthesis - Liverworts are flattened plants that develop reproductive structures  start off as males and then slowly develop into females - The cycle of the haploid and diploid generation varies between different species/groups of plants (cycle is present in all plants, just different lengths of the cycle) - Mosses  antheridium (M), archegonium (F) - The spermatozoid swims over and requires a thin film of water o Senses the female archegonium - The zygote develops in the archegonium and grows out of the archegonium o After it grows, it creates haploid spores in the capsule which it releases afterwards - Spore grows into protonema which develops into the gametophyte o Some become male and some become female (50/50) - Protonema + gametophyte undergo photosynthesis for food o Sporophyte cannot make its own food  take food from gametophyte generation (parasitic) - The spermatozoid is water-dependent and short-distance dispersal - The spores are wind-dependent and long-distance dispersal - The gametophytic generation (haploid) is much longer than the sporophytic generation (diploid)  diploid is only once a year in bryophytes - NOT ADAPTED FOR TERRESTRIAL LIFE: o Take-up/lose water quickly (no cuticle) o Don’t transport water/nutrients efficiently (no vascular system) - Result: loss of water quickly, usually live in moist habitats - However it can survive in total desiccation o Can come back when water returns - No active transport, only passive permeation o Therefore bryophytes are typically small 1/12/2012 Lecture 02 FERNS - Appeared after glycophytes - Overall group of ferns are “true ferns” o Different shapes and sizes (can be tiny aquatic ferns to tree-like ferns) - Sorus are on fern leaves, spores come out when sorus is ready to break open - Prothallium (heart-shaped) produces spores o Antheridia (M), arcagonium (F) - Both generations are photosynthetic - Spores are wind-dependent, long-distance dispersal - Gametophyte are self-propelled, short-distance o Longer sporophytic generation than gametophytic generation (opposite of bryophytes) - Prothallium has NO cuticle  loses water quickly and dies o Bottleneck stage for ferns (must be in moist conditions) - Partially decayed material became fossilized peat o Peat was compressed into coal - Peat contains fossilized ferns and other plants GYMNOSPERMS - Came after ferns - Redwood are the biggest & largest gymnosperms - Bristlecone pines are oldest trees in Ontario - Different groups: gingko, ephedra, welwitschia (2 leaves), gnetum (flat leaves) - “coni-fers” = “cone bearers”  reproduce through F & M cones - “gymno-sperms” = “naked seeds”  seeds aren’t protected - Wood was invented from gymnosperms because they were sturdy ANGIOSPERMS - Developed a little after gymnosperms o Best known due to flowers - Flower (diploid) but pollen is haploid - Same as gymnosperms but with flower instead of cones - Centre of flower is usually ovary with haploid cells; stigma opening o Anther are the male reproductive structures (made of two side pockets) - Pollen can be transferred by wind or by animals o Fertilization creates fruits - Angiosperms have “covered seeds”  encased by fruits or shells, unlike gymnosperms - Different flowers mimic different things to attract pollinators (ex. bees, beetles, butterflies, etc.) - In bryophytes, gametophyte feeds sporophyte - Ferns & lypophytes  both photosynthetic - Angiosperms & gymnosperms  sporophytes feed gametophyte - Dependence on water decrease as you go up the tree 1/13/2012 Lecture 03 Plant form and Function - Different plants have different modifications to a stem - Leaves in plants have other functions other than photosynthesis (ex. venus fly trap traps insects with their leaves - Different plants have different root lengths as well (ex. some vegetables store nutritions in their roots for us to eat) o Some roots provide housing for other organisms (ex. some fungi grows on roots) - There are two different types of cells: undifferentiated and differentiated cells UNDIFFERENTIATED CELLS - Plants have Indeterminate growth: growth that keeps going and doesn’t stop o Humans have determinate growth: growth that stops after a certain time - Stem cells (meristematic) can give rise to any other cells  ex. can turn into skin cells, liver cells, etc. o The tree keeps creating meristematic cells that help the tree keep growing because the cells can all develop different functions and cell types - Each adult male has 959 cells (C. elegans) predetermined amount of cell divisions o Plants don’t have a concrete amount of cells that are predetermined - Plants grows from primary apical meristems shoot grows from shoot aprical meristems (SAM), root grows from root apical meristems (RAM) - Plants protect their SAM and RAM by producing leaf primordial  it protects the apical meristems from the environment from bending in (refer to slide 15) - Root meristematic tissue is not protected to push through soil and ground, so the RAM is set back by a few layer of cells (not at the very tip), there is a root cap which covers and protects the tissue o Cells grow and push forward, root cap cells peel off when the root pushes through the ground DIFFERENTIATED CELLS - Simple tissue: made of ONE cell type; complex tissue: made of TWO or more cell types - Parenchyma cells are alive, thin-walled, and least specialized, and often block-shaped  most common type of cell o They are mostly used as space fillers, photosynthesis, and for storage (refer to slide 22  used for space filler) - Chlorenchyma are the parenchyma cells that have chloroplast  mostly does photosynthesis in a leaf - They are used for storage of water and nutrients (contains a lot of starch) ex. in potatoes and apples - Collenchyma cells are alive, elongated, thickened in corners o Function: supports young stems, roots, and petioles (supports leaves or flowers) or around vascular bundles - Sclerenchyma cells are dead at maturity  cell interior almost completely filled, cell walls thicken with cellulose and usually made of lignin, used for strength o Two main types: sclereids and fibers - Sclereids: short cells and branched, also used for hard seed coats and shells of nuts - Fibers: are usually in bundles and “dead”  we grow the plant and extract the fiber to make ropes or cloths o Also used for cotton to make clothes, hemp is used for accessories, and flax is used for ropes/cloths - Epidermis is made of cuticle (protection), stoma(H O2& air exchange), glands (protection), and hairs (protection, H2O & nutrient uptake) o its found on non-woody plants, one cell layer thick and is alive - the thicker the cuticle, the less pleasant it is for insects to eat the leaf  thickness increases water permeability and resistance to bacteria and pests 1/17/2012 Lecture 04 Plant cells and Plant Tissues (Continued) EPIDERMIS - root tip protected by root cap  root meristems pushes the root through the soil o behind the root cap is an area where the root hair grows (very tiny/microscopic) - even big trees have root hairs at the tips of their roots  they might have big root sizes but the zone where roots take up nutrients and water is very small - root hair is very short-lived - epidermal glands are heads filled with liquids that are located on the plants  individual cells grow a gland or an epidermal cell might grow a gland o glands also produce chemicals that people use for smoking - glands are important on female flowers - plants have glands for protection AND attraction: o protection  protects against herbivores using toxins in the glands - the stinging nettle has “hairs” made of silica  very brittle so when you touch the stingers, it breaks and the chemical soaks under the skin - the surface of some flower petals are “bumpy” which breaks the effect of the light and attracts different insects - some plants protect themselves from loss of water by growing epidermis into star-shape platelets  reduces exposure to sun - the Lotus leaves use the upper surface of their leaves to exchange carbon dioxide  has a “bumpy” surface which makes a slippery surface so that water runs off the leaf - epidermis of the pitcher plant: the roots are on top of a tree (not in the soil) so it doesn’t have access to minerals (especially nitrogen) o each one of the “pitcher” is a modified leaf and they are filled with water which is mixed with digestive enzymes produced by the plant  when plants fall in, they are digested - epidermis cells OUTSIDE the pitcher plant are star-shaped so that insects crawl up; when it reaches the top, the cells are smooth so the insect falls in and inside the pitcher, the cells are smooth so the insects can’t climb out PERIDERM - used for protection & exchange  “bark” - made from cork cambium (source of new periderm)  cork cells = secondary meristems o cork cells are dead at maturity, walls of lignin (anti-microbial) and suberin (wax-like) XYLEM & PHLOEM - xylem: used for transport of water, support, and storage - made of tracheids and vessels (transport/support  dead at maturity), parenchyma (storage) and fibers (support) - tracheids are strongly tapered cells which overlap at tapering ends with tiny pores (pits) - vessel members are more sophisticated/evolved  water doesn’t just move through the pits, but through larger openings (water transport is faster and more efficient) o but vessel members also have pits so water can move sideways through adjacent pits to other cells o vessels have thick lignified cell walls - tracheids are in conifers/gymnosperms; vessels AND tracheids AND fiber are in angiosperms (hardwood) o wood of conifers is softer than angiosperms - phloem: responsible for transporting minerals  sieve tube members (transport) and companion cells (“support” with transporting) o companion cells are like the brain of the transport - sieve tube members are separated by sieve plates  sieve tube members are empty cells; but are alive o sieve tube members lack nucleus, so companion cells are responsible for controlling the metabolic actions - vascular bundle: made of xylem & phloem cells  has more xylem than phloem in non-woody plants and supported by collenchymas - when counting tree rings, it is mostly xylem  only a little bit of phloem and a little bit of periderm GROUND TISSUE - mostly used for support & storage  anything that’s not vascular bundle (xylem & phloem) or dermal tissue (epidermis & periderm) - made of parenchyma, collenchymas and sclerenchyma  used for photosynthesis, storage of nutrients, and to fill space o sclerenchyma is the most “expensive” to make - located between dermal and vascular tissue 1/19/2012 Lecture 05 From Seed to Tree SEED GERMINATION (SEED DISPERSAL) - seed dispersal  most seeds are deposited close to mother plant o creates parent-offspring competition for space, also creates inbreeding - so seeds have to be “removed” from home done by other animals or abiotic factors (ex. wind) - wind dispersal (anemochory) : dandelions or other lightweight plants (ex. winged maples) o there are also microscopic seeds - water dispersal (hydrochory): jewelweed  usually seed pods with seeds inside, the walls are under pressure, so when they are touched, the seed pods open up o pod wall explodes and seeds fly away - another one is Herb Robert, the seeds get catapulted away when the sun dries off the plant - ant dispersal (myrmecochory): o done by elaisosomes (fleshy structure attached to seeds which are rich in lipids and proteins) o ants only carry seeds in order to get nutrients from the elaiosome (don’t want the seed) o ex. white trillium, bloodroot, trout lily - external hitchhiking (epizoochory): usually have hooks which hook onto fur/hair - internal hitchhiking (endozoochory): usually berries; eaten by animals and comes out as their poop - gravity dispersal (barochory): usually acorns or nuts that squirrels eat - water dispersal is usually the furthest distance, then internal, wind, gravity SEED ANATOMY - contains plant embryo with protective seed coat, also has food for embryo to germinate with, and embryonic shoot, root, and cotyledons o cotyledons can also be food for the animals - endosperm: food storage inside seed for the embryo o developed through double fertilization: (only happens in angiosperms) one pollen nucleus (1n) fertilizes central cell (2n) inside ovule which creates endosperm (3n) - the nucleus in the central cell replicate, so many nuclei are developed in one cell  they all share the same cytoplasm o 2 sperm cells fertilize different nuclei in the cell - Food from endosperms get absorbed by seeds in early seed development into cotyledons - Some seeds remain dormant to survive harsh conditions o Dormant seeds: dry, very low metabolism FROM PRIMARY TO SECONDARY PLANT BODY - Annual & biennial life cycles  starts off as seedling, then have leaves to maximize photosynthesis and the next spring, energy creates leaves (ex. carrot, radish, turnip) 1/20/2012 Lecture 06 From Seed to Tree SHOOT AND ROOT PRIMARY GROWTH - Herbs are non-woody (primary growth) - Primary meristems: shoot apical meristem (SAM) and the root apical meristems (RAM) - Secondary meristems: vascular cambium (VC) and ground meristems - in shoot apical meristems, cells multiply and elongate o produces procambium which eventually becomes the vascular cambium in the region of differentiation/maturation o protoderm becomes epidermis - primary phloem and primary xylem is separated by the VC - primary growth in roots is similar and different than the shoots  root cap, RAM, and procambium/protoderm/ground meristems o xylem is in centre and phloem on outside  different from shoot because xylem fills up the space in the root (star-shaped) - roots have two additional tissue: endoderm and pericycle - main function of the double ring is selective of nutrients/minerals being taken up by roots into the plant (not required in shoots) - there is a maximum height for primary growth  ex. max height of a sunflower SHOOT SECONDARY GROWTH - secondary growth is needed to grow horizontally  increase of girth o requires secondary meristems: VC, and cork cambium which give rise to secondary tissue - trees and shrubs have circular, continuous phloem & xylem  the circular vascular cambium continues to produce 2 year phloem & 2 year xylem - increase layers of xylem and outer portion of stem breaks but cork cambium fills the cracks - in spring, the size of the xylem cells are much larger than the size of the xylem tissues in fall/winter - pith = first year, wood = xylem, bark = phloem & cork cambium - primary growth is responsible for elongation  always primary growth if a plant continues to grow; secondary growth is used to help the plant stay sturdy and to grow girth  cambium produces more than just primary phloem & primary xylem APICAL DOMINANCE AND GROWTH FORMS - why are there different growth forms? Ex. trees that grow more vertically and trees that grow more horizontally - has to due with SAM and other places where tree grows  SAM produces auxin which is usually highest away from RAM  SAM exerts apical dominance through production of auxin to suppress buds to not grow into twigs o only when auxin concentration is low enough, then buds start growing into twigs - so different growth depends on amount of auxin concentration - SAM can decide to grow OR it can form a flower  when it forms a flower, that is the end of the SAM, so it doesn’t suppress the side buds and the side buds grow o Also external factors such as bugs, droughts, etc. which affect the buds BODY PLANS OF MAJOR ANGIOSPERM GROUPS - Angiosperms are most closely related to gymnosperms; species of angiosperms are much larger than species of gymnosperms o Four main groups: basal angiosperms, magnoliids, monocots, and eudicots MONOCOTS EUDICOTS - Parallel leaf veins - Net pattern leaf veins - Fibrous roots (roots are the same size) - Tap root (one dominant root ex. radish with secondary roots) - Flower petals come in groups of 3 - Flower petals come in groups of 4-5 - Vascular bundles are scattered - Vascular bundles are arranged in ring shape - Xylem to centre, phloem, and collenchymas - Xylem to centre, phloem, and collenchymas to both sides to one side - WOOD ONLY PRODUCED IN EUDICOTS !!! - WOOD ONLY PRODUCED IN EUDICOTS !!! 1/24/2012 Lecture 07 From tree to seed: aka sex in plants - general flower structure: has four whorls: sepals, petals, stamen, carpel - sepal: protects the inner flower organs before the bud of the flower opens (usually green) - petals: in most plants, it is colourful to attract pollinators - stamen: pollen producing sacs; anther has 2 pollen sacs - stigma: female reproductive organ; usually sticky landing platform for pollen - style: connects the stigma to the ovary - ovary/ovule: contains one to multiple ovules  ovule contains egg cell - how does a shoot meristems grow into flowers? - Goethe believed that flowers were modified versions of leaves - Research has shown that to be true - 3 groups of genes are need to make flower organs: ABC model of flower development o A = sepals o A + B = petals o B + C = stamen o C = carpel - The rose was modified so that instead of making anthers, it made more petals - Dioecious: when a plant is JUST male or JUST female (like humans) - Monoecious: when there is a plant with male and female part - Inbreeding depression: when two plants that are not o Mating between cousin plants have lower germination success in plants  works better with outbreeding - Monoecious and hermaphroditic species (94%) are under risk of selfing  have to develop mechanisms to avoid that o Temporal separation (dichogamy): sexual phases separated in time o Spatial separation (herkogamy): separation of sexual organs within flowers o Self incompability - Dichogamy: some plants have the female/male reproductive organ work/open first and then the next one during the next day o Male phase stays closed while female is opened - However, insects often visit more than one flower  creates geitonogamous selfing (asynchrony) 1/26/2012 Lecture 08 SELF-INCOMPATIBILITY - When pollen lands on stigma, plant can tell whether or not its pollen from the same plant - If there is an outcross pollen, the pollen tube begins to grow - There are cells in the style that help prevent pollen tube from the same pollen from growing (stops the growth)  present in apple andpears - There are many ways to prevent incompatible mating SEX SLAVES OF THE PLANT KINGDOM - Non-directed (non-living/abiotic ex. wind) and directed (living/biotic ex. insects) depositing of the pollen - Invention of flowers created a diversity of plants - As the amount of species of angiosperms increased, amount of insects increased too - Each plant has to produce at least 2 seeds  prepared through mechanics to bring F & M gametes together o Specialization of floral architecture optimized pollen uptake (attracts many more insects to the plants) - Sometimes there are things that stimulate senses (ex. sight/smell); or food (pollinators do it based on the reward) - 10% of plants are wind-pollinated; most likely to happen at: o Higher altitude/latitude (stronger wind) o Dry environments (difficult for gametes to travel) o Open vegetation o Island flowers (easier to pollinate) - Wind pollination plants: (refer to slide for examples) - Biotic pollination; requires reward (pollen, nectar) o Sometimes a specific plant serves a specific pollinator: co-evolution - Bees see yellow, blue, UV (not red) o Also have nectar guide which leads them to nectar & pollen - Some flowers cheat; don’t provide food (reduces costs of reproduction) - Orchids: smells like female wasp; mimics it so that males go on the flower and receives pollen - Some flowers smell bad to mimic meat for flies - Flowers that attract butterflies have red/orange flowers o Also have long, narrow nectar tubes just for butterflies - Hummingbirds see a variety of colour, but they need more liquid/watery nectar 1/27/2012 Lecture 09 Transport in Plants - Water transports through the xylem, sugar transports through the phloem WATER TRANSPORT THROUGH XYLEN - Three hypotheses: capillary action, root osmotic push, transpiration - Capillary action: 2 O moves up a small tube through cohesion to tube walls and adhesion between the H O2molecules o Not possible because the maximum height it can go up to is 1m - Osmosis: (osmotic pressure) the H 2 diffuses through the semi-permeable membrane (ex. cell wall) from a low concentration to a higher concentration of salt/minerals o The sal
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