ap06_sg_biology - AP® Biology 2006 Scoring Guidelines The...

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Unformatted text preview: AP® Biology 2006 Scoring Guidelines The College Board: Connecting Students to College Success The College Board is a not-for-profit membership association whose mission is to connect students to college success and opportunity. Founded in 1900, the association is composed of more than 5,000 schools, colleges, universities, and other educational organizations. Each year, the College Board serves seven million students and their parents, 23,000 high schools, and 3,500 colleges through major programs and services in college admissions, guidance, assessment, financial aid, enrollment, and teaching and learning. Among its best-known programs are the SAT®, the PSAT/NMSQT®, and the Advanced Placement Program® (AP®). The College Board is committed to the principles of excellence and equity, and that commitment is embodied in all of its programs, services, activities, and concerns. © 2006 The College Board. All rights reserved. College Board, AP Central, APCD, Advanced Placement Program, AP, AP Vertical Teams, Pre-AP, SAT, and the acorn logo are registered trademarks of the College Board. Admitted Class Evaluation Service, CollegeEd, connect to college success, MyRoad, SAT Professional Development, SAT Readiness Program, and Setting the Cornerstones are trademarks owned by the College Board. PSAT/NMSQT is a registered trademark of the College Board and National Merit Scholarship Corporation. All other products and services may be trademarks of their respective owners. Permission to use copyrighted College Board materials may be requested online at: www.collegeboard.com/inquiry/cbpermit.html. Visit the College Board on the Web: www.collegeboard.com. AP Central is the official online home for the AP Program: apcentral.collegeboard.com. AP® BIOLOGY 2006 SCORING GUIDELINES Question 1 A major distinction between prokaryotes and eukaryotes is the presence of membrane-bound organelles in eukaryotes. (a) Describe the structure and function of TWO eukaryotic membrane-bound organelles other than the nucleus. (4 points maximum) NOTE: One point is awarded for each bulleted item. Structure—1 point per box, Organelle Maximum—2 points • Indicate two membranes with either: - infolding of the inner membrane Mitochondria - cristae, or matrix Chloroplasts Endoplasmic Reticulum (ER) • Indicate two membranes with either: - flattened sacs (thylakoids). - flattened stacks (grana). - stroma. • interconnected membranes, vesicles or sacs • rough ER has attached ribosomes and/or smooth ER without ribosomes • series of flattened sacs Golgi apparatus • vesicle (bag, sac) with enzymes Lysosome Peroxisome (glyoxysomes) • vesicle (bag, sac) with enzymes • vesicle (bag, sac) Vacuoles Contractile vacuole Vesicles Leucoplast Chromoplast • vesicle (bag, sac) • sac (bag, sac) • Indicate two membranes with starch • Indicate two membranes with pigments Function—1 point per box, Maximum—2 points • cellular or aerobic respiration (Krebs, ETS) • production of ATP • release of chemical energy • photosynthesis or description of photosynthesis • production of 3-Carbon molecules (sugars, PGAL, glucose). • synthesis of lipids (e.g., steroids) and/or proteins • detoxification of poisons, alcohol • transport • calcium signaling/storage If rough and smooth ER are the two named organelles • synthesis of proteins • modification of molecules • packaging molecules • processing molecules • vesicles (sacs) and their contents can be targeted for various locations in the cell and to its exterior • digestion or breakdown of molecules waste materials and food with digestive enzymes (e.g., nucleases). • cell lysis • recycling organelles • breakdown or detoxify free radicals or peroxides • water balance • turgidity • storage water, ions, nutrients, or waste • expulsion of water from cell • transporting materials to/from ER, Golgi, or cell membrane • storing starch • storing pigments © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). 2 AP® BIOLOGY 2006 SCORING GUIDELINES Question 1 (continued) (b) Prokaryotic and eukaryotic cells have some non-membrane-bound components in common. Describe the function of TWO of the following and discuss how each differs in prokaryotes and eukaryotes. • DNA • Cell wall • Ribosomes (4 points maximum) Component DNA Cell wall Ribosome Function—1 point • contains, stores, or transmits genetic information • codes for proteins or traits • • • • protects supports maintains turgidity maintains shape/ allows adherence • make protein • site of translation Difference between Prokaryotes and Eukaryotes—1 point vs. usually many molecules • single molecule vs. linear molecule • circular molecule vs. 1,000 times the average • on avg. smaller number number of prokaryote bp of base pairs (bp) vs. within nucleus • in cell’s cytoplasm vs. histone proteins • few/no proteins* vs. introns • no introns * *archaebacteria are an exception vs. Cellulose and/or Chitin • Peptidoglycans (murein, amino acid, and sugar polymer) • • • • • smaller free in cytoplasm simultaneous transcription/translation contain different proteins, or RNAs different antibiotic sensitivity vs. larger vs. free and attached vs. non-simultaneous (c) Explain the endosymbiotic theory of the origin of eukaryotic cells and discuss an example of evidence supporting this theory. (2 points) Explain (1 point): Prokaryotic cell was engulfed by another cell and formed a (symbiotic) relationship. Evidence (1 point): • Mitochondria and/or chloroplast contains own DNA. • Mitochondria and/or chloroplast contains own ribosomes. • Mitochondria and/or chloroplast contain double membrane. • Mitochondria and/or chloroplast divides by binary fission. • Mitochondria and/or chloroplast have a similar size to prokaryotic cells. © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). 3 AP® BIOLOGY 2006 SCORING GUIDELINES Question 2 According to fossil records and recent published observations, two species of leaf-eating beetles (species A and B) have existed on an isolated island in the Pacific Ocean for over 100,000 years. In 1964 a third species of leaf-eating beetle (species C) was accidentally introduced on the island. The population size of each species has been regularly monitored as shown in the graph above. (a) Propose an explanation for the pattern of population density observed in species C. [3 points] 1. Description of curve [1 point]: Type of growth is exponential growth (logarithmic or J-shaped curve acceptable). 2. Explanation must describe the growth using an understanding of [1 point each, 2 points maximum]: Lack of limiting factors Low competition Abundant food Low predation Ideal environmental conditions (habitat, temperature, moisture, etc.) Access to mates (b) Describe the effect that the introduction of beetle species C has had on the population density of species A and species B. Propose an explanation for the patterns of population density observed in species A and in species B. [4 points] 1. Describe effect [1 point]: Species C has had little or no effect on species A; however, as species C increases, B decreases. Both lines must be addressed for the point. 2. Explanation for species A or dashed line [1 point]: No or little competition (No niche overlap). 3. Explanation for species B or solid line [1 point]: Competition or Niche overlap. 4. Identification of the niche “Competitive Exclusion Principle” [1 point]: by name or description. (c) Predict the population density of species C in 2014. Provide a biological explanation for your prediction. [2 points] 1. Prediction [1 point]: The population will increase, decrease, or stabilize (level off). 2. Explanation [1 point]: Tie a correct explanation to the prediction. Increase—tie to abundant resources and freedom from competition. Decrease—tie to exhaustion of a key resource or density-dependent cause. Stabilize or level off—tie to carrying capacity or a limiting resource. (d) Explain why invasive species are often successful in colonizing new habitats. [2 points—from either or both areas below] 1. They have lost a controlling population factor from their original habitat: predator, pathogen, or parasite. 2. They have a novel evolutionary advantage brought to the island from their original habitat: an aspect that provides an advantage—a chemical defense, flight advantage, novel enzyme, etc. © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). 4 AP® BIOLOGY 2006 SCORING GUIDELINES Question 3 The movement of water through vascular plants is important to their survival. (a) Explain the mechanism of water movement through vascular plants during transpiration. Include a discussion of how the anatomy of vascular plants and the properties of water contribute to this process. (7 points maximum) * Each dash = 1 point Mechanism (in correct context) • • Movement of water - water evaporates or leaves the plant - transpiration pull OR cohesionadhesion tension theory - continuous column of water - capillarity - root pressure - ψ (water potential differences) - osmosis/diffusion/tonicity Energy driving transpiration - environmentally powered (sun, wind, humidity) - passive on part of plant Anatomy (related to how anatomy contributes to transpiration) - Stomata/guard cells - Spongy mesophyll - Xylem, tubes, tracheids, vessel elements - Any specific root structure (root hairs, Casparian strip) Water Properties (related to how property contributes to transpiration) - Polarity/hydrogen bonding - Cohesion - Adhesion/capillarity - High heat of vaporization (H2O vapor exiting leaf) * Each dash = 1 point (b) Explain how gas exchange affects transpiration. (2 points maximum) • Stomata - Open stomata increased transpiration OR - Closed stomata decreased transpiration • Gas identification - CO2 in and O2 and/or H2O out of the plant (gas exchange must be in correct direction) • Consequence of gas exchange - tradeoff of more gas exchange (for more photosynthesis) resulting in more transpiration (and possible dehydration, wilting, flaccidity) • Environmental factors such as: - humidity - air movement - evaporative cooling - wind stress - intense light/heat (factor must be tied to effect on transpiration) © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). 5 AP® BIOLOGY 2006 SCORING GUIDELINES Question 3 (continued) * Each dash = 1 point (c) Describe TWO adaptations that affect the rate of transpiration in desert plants. (2 points maximum) • Reduced surface area - small leaves - loss of leaves/other parts • Leaf modifications - thick cuticle (not just “waxy”) - thicker epidermis - reflective surfaces - epidermal hairs “trap” water vapor - leaf wilting/curling - leaf orientation • Stem modifications - thick cuticle (not just “waxy”) - thicker epidermis - have stomata • Stomata - concentrated on lower/shady surface - in pits, furrows, depressions - fewer stomata • Metabolism - stomata open at night (CAM plants) - stomata closed when arid/not open as long (C4 plants) (no points for photorespiration) - hydraulic lift • Water storage/uptake - in fleshy stems - roots (large, shallow system for maximum water capture; deep taproots, etc.) • Dormancy © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). 6 AP® BIOLOGY 2006 SCORING GUIDELINES Question 4 The evolution of circulatory systems allowed larger and more-complex animals to arise. (a) Describe the respiratory and digestive systems’ specialized structures that facilitate the movement of oxygen and glucose into the circulatory system of mammals. (4 points maximum) Oxygen Uptake (2 points maximum) • Alveoli/air sacs Glucose Uptake (2 points maximum) • Villi/microvilli/plicae Description of structures • Grape-like clusters • Large surface area in lungs or alveoli • Thin-walled • Moist lungs or alveoli • Proximity to capillaries Description of Structures • Single cell layer • Increased surface area • Associated with capillaries • Villi are finger-like projections • Plicae are folds (of submucosa) • Microvilli are hair-like projections (of cells) • Enzymes related to carbohydrate digestion hydrolyze polymers to monomers (amylase, maltase, sucrase, lactase). (b) Explain how oxygen and glucose are transported within the circulatory system of mammals. (4 points maximum) • • • • • Oxygen Transport (3 points maximum) RBC or Hemoglobin (oxyhemoglobin) attachment to oxygen Description of structure of RBC (biconcave, no nucleus or mitochondria) as related to oxygen transport OR Description of hemoglobin, e.g., iron, quaternary structure, number of O2 molecules bound Cooperative binding (increased affinity as each molecule binds) Small percent dissolved in plasma 4-chambered heart allows separation of oxy/deoxy blood Glucose Transport (1 point maximum) • Dissolved in blood or carried in plasma (NOT merely “carried in blood”) • Explanation of small percent attached to Hb or other proteins, e.g., glycoproteins (c) Explain the transfer of oxygen and glucose from the blood and into the active cells of mammals. (4 points maximum) Oxygen Transfer (2 points maximum) • (Simple) diffusion/down a concentration gradient • Bohr effect described (↓pH, ↑CO2 causes dissociation) • Pathway—hemoglobin, plasma, leaky capillary, interstitial fluid, cell membrane • Description of membrane permeability, e.g., phospholipid bilayer and small molecules, polarity • Binding to myoglobin increases movement into muscle Glucose Transfer (2 points maximum) • Facilitated diffusion/definition (to say diffusion alone is not enough) • Down a concentration gradient • Membrane transporter required for polar/large molecules, polarity • Arterial pressure in capillaries • Pathway as described for oxygen, plus transporter • Insulin increases glucose uptake by cells • Exchange occurs in the capillaries*** *** Can only award this point once, either for glucose OR oxygen © 2006 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). 7 ...
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This note was uploaded on 11/23/2009 for the course BIOLOGY 1101 taught by Professor Keith during the Winter '05 term at The University of Oklahoma.

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