Exam Review II - sample question and answer-1

Exam Review II - sample question and answer-1 - 1. The...

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Unformatted text preview: 1. The function of peptidoglycan in a bacterium is to • • a. kill its host b. make the cell membrane c. cause cell division d. form the cell wall e. sense light • • (next slide ** = correct answer) Answer and justification Answer 1. The function of peptidoglycan in a bacterium is to • • a. kill its host (not a toxic molecule) b. make the cell membrane (sugars and amino acids) c. cause cell division (not a cyclin, cdk) d. **form the cell wall e. sense light (not a photoreceptor) • Gram-Positive Cell Wall Wall Walls very thick Consist mainly of peptidoglycan Gram positive (stain with crystal violet) Penicillin sensitive (interfers with – glyan synthesis) Gram-Negative Gram-Negative Cell Wall Cell Walls have thin peptidoglycan layer and outer membrane (like plasma membrane) Gram negative (stain washes out with alcohol) Many are Penicillin resistant Prokaryotic Cell Prokaryotic Gram negative bacteria Capsule surrounding cell wall - pathogenic bacteria e.g. Strep pneumoniae NB: FA is a straight chain hydrocarbon with a carboxylic (COOC) grouping at the end (makes an ester linkage to glycerol) Archaea have hydrocarbons with a carbonyl linkage (COC) grouping making an ether linkage to glycerol • Extra A: which of the following is descriptive of an F-plasmid: • • • • • A. During conjugation a sex pili transfers the plasmid from the donor cell to the recipient cell B: it contains genes for antibiotic resistance C: it is usually transferred between bacteria by transduction D: it is a good example of a composite transposon E: it makes bacteria resistant to phage • • Answer and justification Extra A: which of the following is descriptive of an Fplasmid: • A. **During conjugation a sex pili transfers the plasmid from the donor cell to the recipient cell • B: it contains genes for antibiotic resistance (Rplasmid) • C: it is usually transferred between bacteria by transduction (usually refers to a virus or viral vector and the transfer of DNA in bacteria) • D: it is a good example of a composite transposon (movement of DNA sequence from one position on the same or to another chromosomal DNA) • E: it makes bacteria resistant to phage (DNA insertion of an anti-phage sequence into bacterial genome) Conjugation Conjugation Two cells of different mating types exchange genetic material This F factor (also called F plasmid) contains 20 genes – important in conjugation: Encodes enzymes necessary to transfer DNA and produce the sex pili 2. Green algae share which of the following features with land plants? • • • • a. chlorophyll c b. phycobilins c. peptidoglycans d. chlorophyll b e. nitrogen fixation • Answer and Justification Answer 2. Green algae share which of the following features with land plants? • • • a. chlorophyll c (in dinoflagellates, heterokonts e.g.diatoms and kelp) b. Phycobilins (pigments in cyanobacteria and red algae) c. Peptidoglycans (in bacterial cell walls) d. **chlorophyll b e. nitrogen fixation (in rhizobia) • • Please note the clarification on the chlorophyll content of red and green algae in the slide following: In some publications; red algae only contain chlorophyll a, but other studies have now elucidated a role for chlorophyll c, and minute quantities of chlorophyll b Chlorophyll d has also been recently found in marine red algae • • Red and Green Algae Red • Red and Green Algae: • • • Chloroplasts with double membranes containing chlorophyll (a) (b) (c) (d) plus carotenoids Chlorophylls a and b in green algae Chlorophylls a and c (and minute quantities of b) as well as d in red algae • Now included with land plants Reproduction involves both asexual and Reproduction involves both asexual and sexual reproduction – varied in green algae: • • • Isogamous – two flagellate gametes identical in size Anisogamous – two flagellate gametes of different sizes Oogamous – nonmotile egg and flagellate male gamete • No evidence of flagellate cells in red algae 3. Most of the nuclei in a mushroom fruiting body are • • a. dikaryotic, n + n b. diploid, 2n c. haploid, n d. triploid, 3n e. tetraploid, 4n • Answer and Justification Answer • 3. Most of the nuclei in a mushroom fruiting body (basidiocarp) are • a. **dikaryotic, n + n b. diploid, 2n (karyogamy doesn’t occur in the fruiting body of any fungi) c. haploid, n (mating hyphae prior to plasmogamy and germinating spores– therefore not in fruiting body) d. triploid, 3n (more a reference to endosperm; three sets of chromosomes in one cell – no three nuclei stage in mushrooms) e. tetraploid, 4n (or four sets of chromosomes; four nuclei in basidium in haploid stage) Life Cycle of a Basidiomycete Basidiomycete e.g. mushroom Basidiomycete Fruiting Bodies Basidiomycete Basidia lines gills of Jack O’ lantern Stink horn – smell attracts flies; helps disperse basidiospores And don’t forget the edible mushroom! Bracket fungus; grow on live and dead trees – shelllike fruiting body Fungal Life Cycles Fungal Plasmogamy Dikaryogamy Karyogamy ** dikaryogamy starts in the basidiomycetes and the ascomycetes Germination of a Mold Spore Germination Coenocytic thallus • • • • 4. You are given an unknown organism to identify. Its cells are haploid and green, but the organism is a flat structure that lacks any leaf-like or stem-like organs. Rhizoids grow from the lower surface. Archegonia and antheridia are present. In one archegonium an embryo has begun to form with roots and leaves. The organism is most likely a a. moss gametophyte b. fern gametophyte c. moss sporophyte d. fern sporophyte e. pine gametophyte Answer and Justification Answer • • • 4. You are given an unknown organism to identify. Its cells are haploid (gametophyte, photosynthetic) and green, but the organism is a flat structure (prothallus) that lacks any leaf-like or stem-like organs. Rhizoids (nutrition by osmosis and diffusion; anchors) grow from the lower surface. Archegonia and antheridia are present. In one archegonium an embryo has begun to form with roots and leaves (sporophyte (2n) and vascular). The organism is most likely a a. moss gametophyte (not flat; no rhizoids – no shoots and leaves in sporophyte) b. **fern gametophyte c. moss sporophyte (not haploid) d. fern sporophyte (not haploid) e. pine gametophyte (gametophyte - pine cones!) • Fern Life Cycle Fern Gametophyte lacks vascular tissue; has tiny rhizoids Sporophyte - vascular Moss Life Cycle Moss Phylum Bryophyta Antheridia and Archegonium can be on same gametophyte nonvascular Sporophyte remains attached to the gametophyte generation Liverwort Life Cycle Liverwort Phylum Hepatophyta Body form is a flat, lobed thallus – no leaves, stems or roots nonvascular Sporophyte remains attached to gametophyte, and nutritionally dependent Pine Life Cycle Pine Male gametophyte = inside pollen grain Female gametophyte = inside the ovule • Extra B: The haploid gametophyte stage is dominant in the life cycle of which of the following: • • • • • A: a pine tree B: a fern C: a dandelion D: a green moss E: all of above Answer and Justification Answer • Extra B: The haploid gametophyte stage is dominant in the life cycle of which of the following: • • • • • A: a pine tree (sporophyte dominant) B: a fern (sporophyte dominant) C: a dandelion (flowering plant!) D: **a green moss E: all of above (nope!!) • Extra C: A heterosporous plant is one that: • • • • A. produces a gametophyte that bears both antheridia and archegonia B. produces microspores and megaspores, which give rise to male and female gametophytes C. produces spores all year long instead of just one season D. produces two kinds of spores, one asexually by mitosis and the other sexually by meiosis Answer and Justification Answer • Extra C: A heterosporous plant is one that: • • • • A. produces a gametophyte that bears both antheridia and archegonia (homosporous) B. **produces microspores and megaspores, which give rise to male and female gametophytes (the only one that fits) C. produces spores all year long instead of just one season D. produces two kinds of spores, one asexually by mitosis and the other sexually by meiosis Life Cycle Comparison Life Seedless (ex some club mosses and ferns) Seeded (all) 5. Which structure is found in the mature seed of a monocot, but not a dicot? • • a. seed coat b. embryo c. endosperm d. cotyledon(s) e. all of the above would be absent from a mature dicot seed • Answer and Justification Answer 5. Which structure is found in the mature seed of a monocot, but not a dicot? • • • a. seed coat (surrounds both monocot and dicot seeds) b. Embryo (present in all viable seeds) c. **Endosperm (reduced/absent in eudicots) d. cotyledon(s) [in both mono (1) and dicots (2)] e. all of the above would be absent from a mature dicot seed (oops! – not a seed) Mature Eudicot Seed Mature • Contains • • a young plant embryo nutritive tissue for use during germination: endosperm depleted ; now stored in cotyledons (seed leaves; nutrient tissue for germination) • Tough, protective seed coat surrounds seed Embryonic Development Embryonic Seed Structure Seed Contains embryonic plant and food Surrounded by seed coat (originally integuments – outer layer of ovule) Seed enclosed in fruit Contains: Radicle – embryonic shoot Cotelydon – seed leaf • Single in monocots • Two in eudicots Hypocotyl – connects radicle to cotyledon Plumule –shoot apex Revision - Monocots Revision - Monocots (Class Monocotyledones) • Class includes: palms, grasses, orchids etc • • • • Most have floral parts in threes Leaf venation is parallel (unbranched) Fibrous root system Secondary growth is absent, but can contain sclerenchyma tissue – hard and wood-like Vascular bundles – Seeds each contain: • One cotyledon or embryonic seed leaf • Endosperm or nutritive tissue in maturing seed phloem, xylem • • Scattered vascular bundles Revision - Eudicots Revision - Eudicots (Class Eudicotyledones) • Class includes oaks, roses, cacti etc • Leaf venation is netted (megaphyll) • Gymnosperms and woody eudicots have secondary growth • Usually have floral parts in fours or fives, or multiples thereof procambium phloem • Seeds each contain 2 cotyledons: • endosperm is reduced; nutrition in cotyledons at germination xylem pith • • 6. The ovule develops into the a. endosperm b. seed coat c. embryo d. Aleurone (a granular protein) e. seed Answer and Justification Answer 6. The ovule develops into the: a. Endosperm (no this is from the fusing of the polar nuclei in egg with sperm nuclei = triploid nucleus) b. seed coat (no - integuments surrounding the ovule) c. Embryo (no- egg in the ovule) d. Aleurone (a granular protein) obviously not! e. **seed (yes, ovule contains the embryo and endosperm and develops Double Fertilization Double Ovary Ovule – develops into seed Male and Female Gametophytes Gametophytes Female gametophyte or embryo sac develops within the ovule The immature male gametophyte or pollen grains, develop within pollen sacs in the anthers. Each male gametophyte or pollen grain becomes mature when its generative cell divides mitotically to produce two sperm cells Relationships Relationships • Ovules: potential to develop into seeds Ovaries: potential to develop into fruits Fruits: mature, ripened ovaries Seeds: enclosed within fruits • • • • Extra D: Which of the following is common to all phyla of seedless plants? • • • • • A. alternation of generations B: dominance of the gametophyte generation C: pollen cones D: xylem and phloem E: double fertilization Answer and Justification Answer • Extra D: Which of the following is common to all phyla of seedless plants? • A. **alternation of generations • B: dominance of the gametophyte generation (ferns etc sporophyte dominant) • C: pollen cones (seeded gymnosperms) • D: xylem and phloem (bryophytes are nonvascular) • E: double fertilization (gnetophytes and angiosperms are seeded) Plant Evolution Plant Earliest plants Earliest were seedless were Bryophytes: no specialized vascular system – rely on diffusion and osmosis Typically small Don’t form seeds – reproduce by haploid spores Double fertilization • 7. Name the living cell with unevenly thickened primary walls, whose only function is support. a. tracheid b. fiber c. sieve tube element d. parenchyma e. collenchyma • 7. Name the living cell with unevenly thickened primary walls, whose only function is support. a. Tracheid (non-living, secondary walls, vascular) b. Fiber (elongated, tapering, dead at maturity with thick secondary walls) c. sieve tube element (living but vascular) d. Parenchyma (storage, photosynthesis thin primary walls) e. **collenchyma Ground Tissue Cell Types Ground Tissue Cell Types a. Parenchymal cells: living, actively metabolizing with thin primary cell walls b. Collenchyma cells: living, elastic support with primary cell walls, unevenly thickened at corners c. Sclerenchyma cells: Fibers often dead at maturity (no nuclei or cytoplasm) with thick secondary walls; lumens Sclereid cells may be living or dead: common in wood, inner bark, leaf veins in flowering plants 3 Plant Tissue Systems Plant All tissue systems are continuous throughout the plant: e.g vascular system in the leaf is continuous with the vascular system in the stem, which is continuous with the vascular system in the root Cell Walls have Common Cell Walls have Common Biochemistry • Cellulose: polysaccharide of β1-4 linked glucose • 40-60% dry weight primary cell walls • Forms as microfibrils (thin fiber bundles) • Held together with hemicellulose (β 1-4 links plus xylose) - more soluble than cellulose • Pectin: cementing polysaccharide • Polymer of α- galacturonic acid (glucose derivative) Lignin: strengthening protein • 35% of secondary cell walls • Vascular Conducting Cells a. Tracheid cell: Dead at maturity; lacks secondary wall at pits Conducts water and nutrient minerals through pits; support b. Vessel elements: b. Dead at maturity; end walls Dead at maturity; end walls have perforations; lack secondary walls at pits Run the length of plant from roots to leaves and other shoot parts More efficient in conduction of water and nutrient minerals; provide support Vascular Conducting cells: c. Sieve tube element: living but gradually looses nucleus and other organelles at maturity; end walls are sieve plates with pores for conduction d. Phloem tissue showing interactions between sieve tube elements, and companion cells through plasmodesmata Apical Meristems Apical • Growth involves 3 processes: • • • cell division (new cells) cell elongation (cytoplasm grows, vacuole increases in size) cell differentiation (into various cell types) • Primary Growth: increase in stem and root length in all plants Lateral Meristems Lateral Secondary growth: responsible for increase in stem or root Secondary growth: responsible for increase in stem or root girth in woody eudicots Vascular Cambium: Meristematic cells are located between wood and bark Division adds more cells to wood (secondary xylem) and inner bark (secondary phloem) Cork Cambium: Located in outer bark (periderm) Cells divide and form cork cells toward outside and one or more underlying layers of cork parenchyma - storage ...
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