Download HighFour Biology Round 3 Category C: Grades 9 – 10 Monday

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.