Selection 2 points maximum sickle cell condition

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Unformatted text preview: . • Changing glutamate (glutamic acid) to valine (in β-globin). Selection (2 points maximum) • Sickle cell condition protects against or resists malaria. • Changed hemoglobin leads to oxygen-deprivation minimizing malarial infection. • Heterozygotes maintain a reproductive advantage/success. NOTE: Stating that sickle cell confers immunity to malaria does not earn a point. © 2008 The College Board. All rights reserved. Visit the College Board on the Web: www.collegeboard.com. AP® BIOLOGY 2008 SCORING GUIDELINES Question 2 2. Consumers in aquatic ecosystems depend on producers for nutrition. (a) Explain the difference between gross and net primary productivity. (2 points) • • Definition of gross primary productivity (1 point) o Total energy converted/transformed by photosynthesis o Total organic molecules produced or carbon fixed Definition of net primary productivity (1 point) o The biomass or total energy converted minus the amount used by the producers for cell respiration o The amount of energy or organic molecules left for the next trophic level o The energy that is available to organisms that eat primary producers o Gross primary productivity minus respiration (b) Describe a method to determine net and gross primary productivity in a freshwater pond over a 24-hour period. (1 point for each bullet; 4 points maximum) Measurement described • Dissolved oxygen production or increase in biomass, or carbon dioxide uptake Instrument/technique used to collect the data • Winkler or C14 or oxygen probe Methodology/design described • Initial/baseline comparison • Light and dark bottle comparison Data analysis • Light minus initial = net productivity • Initial minus dark = respiration • Light minus...
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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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