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HighFour Biology Category C: Grades 9 β 10 Round 2 Tuesday, October 13, 2015 The use of calculator is not required. Answer #1: Explanation: vestigial/rudimentary organs Vestigial/rudimentary organs are structures that have lost some or all of their ancestral functions. Examples of which are the hind limb and pelvic girdle bones of whales and snakes, and the coccygeal tail vertebrae and vermiform appendix of humans. Answer #2: Explanation: Louis Pasteur Louis Pasteur first discovered the use of heat in food preservation, a process called pasteurization, when the heating of beer and wine resulted to the prevention of spoilage. Pasteurization is different from sterilization, in that the former is only capable of killing a fraction of the microorganisms present with only marginal changes in the property of the food. Answer #3: Explanation: micelle One of the stable configurations of phospholipids is a micelle. A micelle could be formed from the aggregation of hydrophobic groups in the center and the exposure of the hydrophilic groups outside of a phospholipid sphere. Answer #4: Explanation: zygote A zygote is formed when a sperm fertilizes an egg. Having all the necessary genetic information for early development, the zygote eventually becomes a multicellular structure with increased complexity. HighFour Biology Category C: Grades 9 β 10 Round 2 Tuesday, October 13, 2015 The use of calculator is not required. Answer #5: Explanation: extinct species According to the International Union for Conservation of Nature (IUCN), a species is said to be extinct when an individual belong to the said taxon can no longer be found in wild or captivity. Answer #6: Explanation: nitrogen fixation Nitrogen fixation is the initial step of the nitrogen cycle. It is carried out by nitrogen-fixing organisms, such as the aerobic Azotobacter, the anaerobic Desulfovibrio, and the Rhizobium found in association with root nodules of legumes. Answer #7: Explanation: competition A competition is more typically defined as the interaction between individuals vying for a common resource. Competition can also be described as the direct or indirect interaction of individuals which results to the lowering of the fitness of one due to another. Answer #8: Explanation: 0-10 hours The number of a population at a time is different from the change in the number of the population during a period. Although the population was at the peak between 50-60 hours, the population growth was at its most drastic between 0-10 hours, having exhibited a population change of 400 (400 [at the 10-hr mark] minus 0 [at the 0-hr mark]). HighFour Biology Category C: Grades 9 β 10 Round 2 Tuesday, October 13, 2015 The use of calculator is not required. Answer #9: Explanation: pyramid of numbers / number pyramid The pyramid of numbers is distinct from the pyramids of energy and biomass, in that it depicts the number of organisms in an ecosystem, with increasing trophic levels beginning from the bottom. The appearance of the pyramid of numbers varies from ecosystem to ecosystem. Answer #10: Explanation: 0.6% The percentage of energy transferred from the sunlight to the green plants can be calculated by dividing the energy harnessed by the green plants by the energy contained in sunlight: 24 000 ππππ ππβ2 × 100 = 0.6% 4 000 000 ππππ ππβ2 Answer #11: Explanation: Dmitri Ivanovsky Dmitri Ivanovsky first noted the existence of viruses (in particular, the tobacco mosaic virus) when he mashed up tobacco mosaic disease-infected leaves and the resulting fluid was passed through ceramic filters supposedly able to strain the tiniest of bacteria. The filtered fluid was still able to infect healthy tobacco plants with the disease, indicating the presence of a novel infectious agent. Answer #12: Explanation: septate / septate hypha A septate hypha is divided into compartments, such as that shown in the image. The dividing walls within the hypha are called the septa. HighFour Biology Category C: Grades 9 β 10 Round 2 Tuesday, October 13, 2015 The use of calculator is not required. Answer #13: Explanation: ostia/ostium Each pore along the body of sponges through which water flows in for feeding is called the ostia (plural: ostium). Filtered water is expelled from sponges through the osculum. Answer #14: Explanation: Eukarya / Eukaryota Organisms under the Kingdom Plantae are all multicellular eukaryotes. All eukaryotes belong to the domain Eukarya / Eukaryota. Answer #15: Explanation: orange cosmos plant (Cosmos sulphureus) A pioneer species is the first species to colonize and occupy a place where there are no previous living organisms. In this scenario, the pioneer species of a portion of the forest is the orange cosmos plant (Cosmos sulphureus). Answer #16: Explanation: taiga / boreal forest The taiga / boreal forest biome is situated between 50 to 70 degrees latitude north. The primary flora populating this biome are coniferous trees because of the terrestrial, sub-artic, and humid environment. HighFour Biology Category C: Grades 9 β 10 Round 2 Tuesday, October 13, 2015 The use of calculator is not required. Answer #17: Explanation: Chilopoda Aves (birds), Chondrichthyes (cartilaginous fishes), and Reptilia (reptiles) are all classes under the phylum Chordata. All of them possess a notochord and a nerve cord. On the other hand, Chilopoda (centipedes) belongs to the phylum Arthropoda. Answer #18: Explanation: binomial nomenclature The binomial nomenclature system is a formal system of assigning an unambiguous name, which consists of a genus and a specific epithet, for each species. For example, the onion has a scientific name of Allium cepa. The first part of the name (Allium) corresponds to the genus, whereas the second name (cepa) represents the specific epithet. Answer #19: Explanation: crista / cristae The arrow is pointing to the crista, which is a fold in the inner membrane of the mitochondria. The cristae give the characteristic wrinkled shape of the cross-section of the inner membrane of the mitochondria when viewed under the microscope. Answer #20: Explanation: cytoskeleton The cytoskeleton is a crucial component in the maintaining the shape and rigidity of cells. It is constituted of several components, namely actin, microtubules, and intermediate filamentsβeach of which has unique functions to the health of cells.