Biology Content Knowledge Exam
Part 2: Free Response
Directions: In essay form, write your response to all parts of each question.
Three questions, total time allowed is 75 minutes.
1) Membranes are important structural features of cells.
(a) Describe how membrane structure is related to the transport of materials across a membrane.
(b) Describe the role of membranes in the synthesis of ATP in either respiration or photosynthesis.
2) An organism is heterozygous at two genetic loci on different chromosomes. | | | | | | --|B --|b | | | | --|A --|a | | a) Explain how these alleles are transmitted by the process of mitosis to daughter cells. b) Explain how these alleles are distributed by the process of meiosis to gametes. c) Explain how the behavior of these two pairs of homologous chromosomes during meiosis provides the physical basis for Mendel's two laws of inheritance. Labeled diagrams that are explained in your answer may be useful.
3) Living organisms play an important role in the recycling of many elements within an ecosystem. Discuss how various types of organisms and their biochemical reactions contribute to the recycling of either carbon or nitrogen in an ecosystem. Include in your answer one way in which human activity has an impact on the nutrient cycle you have chosen.
SCED 6416 Biology Content Exam Assessment Standard
Part 2 Item 1: MEMBRANE QUESTION
Membranes are important structural features of cells.
(a) Describe how membrane structure is related to the transport of materials across a membrane. (b) Describe the role of membranes in the synthesis of ATP in either respiration or photosynthesis.
Membranes serve diverse functions in eukaryotic and prokaryotic cells. One important role is to regulate the movement of materials into and out of cells. The phospholipid bilayer structure (fluid mosaic model) with specific membrane proteins accounts for the selective permeability of the membrane and passive and active transport mechanisms. In addition, membranes in prokaryotes and in the mitochondria and chloroplasts of eukaryotes facilitate the synthesis of ATP through chemiosmosis. PART A. (6 Maximum) Membrane Structure (3 Internal Maximum) __ Phospholipid structure - hydrophilic, hydrophobic, amphipathic __ Phospholipid bilayer / fluid mosaic description __ Proteins embedded in the membrane __ Sterols embedded in the membrane __ Well-labeled diagram may replace one of the above Membrane Transport (3 Internal Maximum) __ Use of the term "selectively permeable" or a good definition of selective permeability or an explanation of the role of phospholipids or proteins including nuclear pore proteins in determining selective permeability __ Description of the effect of size, charge, polarity, lipid solubility on membrane permeability Mechanisms + description related to structure: __ Passive transport: diffusion / osmosis + reference to membrane gradient __ Ion channel: transport as a mechanism for a change in permeability __ Facilitated diffusion: description (symport, antiport, uniport) __ Active transport: description __ Exocytosis, endocytosis, phagocytosis, pinocytosis: description (1 pt additional) A good example of one of the above mechanisms PART B.
Membrane Role in Production of ATP in Photosynthesis or Respiration (6 pt Max)
Chemiosmosis: __ Involved molecules are embedded in the membrane __ Electron carriers are sequentially organized __ The energy