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HighFour Biology Category C: Grades 9 – 10 Round 3 Monday, November 9, 2015 The use of calculator is not required. Answer#1: endemic species Explanation: Endemic species are those exclusively found in a defined geographic location and nowhere else. Defining factors of endemism include the uniqueness of meteorology, soils, and presence of certain predators or prey. Answer #2: Endosymbiont Theory Explanation: The Endosymbiont Theory states that the mitochondrion and chloroplast may have first existed as endosymbionts, or cells living in another cells. Over evolution, the host cell and the endosymbionts may have merged together to form a single organism, forming the mitochondrion-containing animal cells and the chloroplast-containing plant cells we know now. Answer #3: convergent evolution Explanation: Despite the distinction in the lineages of the two mammals in the example, convergent evolution has allowed them to share features as a result of similar adaptations in similar environments. Answer #4: uniform / uniform dispersion Explanation: A uniform pattern of dispersion results from an evenly-spaced localization of individuals in a population. This pattern could arise from antagonistic social interactions between animals, or from the secretion of chemicals that inhibit the growth of nearby plants that can compete with resources. Answer#5: pneumatophores Explanation: Pneumatophores, also called air roots, are present in mangroves and bald cypresses. The projection of these roots above the water provides the additional oxygen necessary for the growth of the trees. This structure originated from the need to sustain the plant despite the lack of oxygen in muds or wetland environments. HighFour Biology Category C: Grades 9 – 10 Round 3 Monday, November 9, 2015 The use of calculator is not required. Answer #6: Foraminifera Explanation: Members of the Foraminifera, also called forams, are amoeboid protists which produce an external shell called “test”. Most have calcareous tests made from calcium carbonate, while some possess agglutinated sediments as their tests. Answer #7: Gram stain / Gram staining Explanation: Gram stain / Gram staining was developed by Hans Christian Gram. Bacteria with more peptidoglycan (Gram-positive) trap crystal violet in their cytoplasm when washed by alcohol, masking the red safranin dye. On the other hand, bacteria with thinner layer of peptidoglycan (Gram-negative) permit the dissolution of the crystal violet with the alcohol, resulting to their pink or red appearance. Answer #8: radial symmetry Explanation: The body of the sea anemone exhibits radial symmetry. The use of radial symmetry allows the sessile sea anemone to meet the environment equally well from all sides. Other animals with radial symmetry are starfishes and jellyfishes. Answer #9: adductor muscle Explanation: The adductor muscle is the main muscular system in bivalves. The contraction and the relaxation of the adductor muscle allow the bivalves to control the protection of the animal's soft body. Answer#10: estuary / estuaries Explanation: An estuary is an aquatic biome where freshwater from rivers and streams mixes with saltwater from the ocean. Nutrients carried by the rivers make estuaries one of the most productive biomes. HighFour Biology Category C: Grades 9 – 10 Round 3 Monday, November 9, 2015 The use of calculator is not required. Answer#11: demography Explanation: Demography is a science that deals with the study of the vital statistics, such as births, deaths, diseases, and marriages, of populations. Demography is not exclusively limited to humans, and may be applied to plants and other animals. Answer #12: niche / ecological niche Explanation: The ecological niche of a species describes the factors which allow it to fit into an ecosystem. For example, the niche of a tropical bird includes the size of branches it perches on, the types of insects it feeds on, and the range of temperature it can tolerate. Answer #13: dominant species Explanation: The dominant species in a community or an ecosystem is the most abundant species by biomass. They are distinct from keystone species, in that they exert control in a community through numerical presence, instead of their ecological roles. Answer #14: hydrogen peroxide Explanation: Oxidation or the addition of oxygen onto fatty acids is accompanied by the production of hydrogen peroxide (H2O2). Since hydrogen peroxide is harmful to cells, peroxisomes also contain the enzyme catalase which breaks down hydrogen peroxide. Answer #15: hypertonic solution Explanation: A solution that is hypertonic to the cell has a greater concentration of solutes in its exterior than its interior. The movement of water from the inside of the red blood cells to the outside is governed by osmosis, which is the spontaneous net movement of water molecules from a region of lower solute concentration to a region of higher solute concentration through a semi-permeable membrane. HighFour Biology Category C: Grades 9 – 10 Round 3 Monday, November 9, 2015 The use of calculator is not required. Answer #16: haustoria Explanation: The haustoria are specialized hyphae which can penetrate the cell wall of plants. An example of fungus that employs haustoria is the mychorrhizal fungi which form mutually beneficial relationships with plant roots. Answer #17: phylogenetic tree / phylogeny / evolutionary tree Explanation: The examination of phylogenetic trees can provide information on the evolutionary history of a group of organisms. The ancestors and the closest relatives of any group of animals could be also identified with this type of diagram. Answer #18: protist / Phytophthora Explanation: Between the endophyte and the protist, the protist Phytophthora is responsible for the elevated levels of leaf mortality. Whether or not the endophyte was present did not affect the mortality of the seedlings. Mortality was also only observed in the presence of the protist. Answer #19: carbon dioxide Explanation: The process of converting inorganic carbon in the form of carbon dioxide to organic compounds by living organisms is called carbon fixation. Autotrophs, which include the lithoautotrophs and the photoautotrophs, subsist on fixing carbon dioxide as their carbon source. Answer #20: centrifuge Explanation: Cell fractionation is the separation of the major components, organelles, or subcellular structures of cells. The primary instrument used in cell fractionation is the centrifuge, which employs high-speed rotation to separate materials suspended in a liquid medium.