Chemical World Practical Quiz

Chemical World Notes

• 15 stations are set up around the room for practical exercises.
• Each station will have a practical setup previously done in class. For example: iron rusting in a bottle of HCl.
• There is a 1.5 hour rotation time.
• Students need to answer 2 short questions at each station describing what happened in the practical.
• Part A is worth 30 marks and involves explaining the reactions.
• Part B is 10 marks and relates to chemical world skills and content.
• Part C is 10 marks and relates to the Living World.
• There's a question on graphs in either Part B or Part C.
• Students are not expected to memorize chemical equations like combustion.
• Students need to know how to write simple balanced chemical equations (2 lines).
• No ATSI environment damage.
• Ionic compounds are formed when metal or non-metal loses or gains electrons (e.g. salt).
• Natural disasters can change ecosystems and effect producers.
• No specific labelling of brain parts is required, but understanding the functions of neurons is necessary.
• Neurotransmitters such as dopamine release neurosignals.
• A periodic table is provided.

Molecular Bonding

• Anions are negatively charged atoms that have gained electrons.
• Cations are positively charged atoms that have lost electrons.
• Ionic bonding occurs when oppositely charged ions are attracted to each other.
• Salt (NaCl) is an example of an ionic compound where sodium (Na) loses an electron and chlorine (Cl) gains one.
• This is to achieve full outer shells. After the reaction, sodium becomes a cation and chlorine becomes an anion, forming an ionic bond.
• Covalent bonds form when atoms share electrons.
• Covalent bonds only happen between two non-metals (example: H2O or CO2).

Physical & Chemical Changes

• A physical change alters the state of a substance without changing its chemical composition. Example: water boiling.
• A chemical change transforms a substance into a new substance with a different chemical composition.
• Example of chemical changes: Combustion (fuel and oxygen react to form heat and new products such as CO2 and H2O). Observations include presence of oxygen in reactants, products having water and carbon dioxide, change in temperature
• Corrosion (metals react with oxygen and water to form metal oxides). Requirements include oxygen in the air, and water.

The Living World Notes

• An ecosystem is a community of organisms with its non-living environment (e.g., forests, grasslands).
• Abiotic factors are non-living factors like sunlight, temperature, precipitation, and salinity, which can affect the ecosystem and the types of organisms present.
• For example, forest ecosystems have abiotic factors like light, temperature, wind, and water influencing factors such as photosynthesis, plant growth, seed dispersal, and pollination, among other biota.
• Biogeochemical cycles (e.g., nitrogen, carbon) involve the continuous circulation of elements through various components of the Earth's spheres, demonstrating interactions between living and non-living elements.

Nitrogen Cycle

• Nitrogen-fixing microbes convert atmospheric nitrogen into ammonia.
• Nitrifying bacteria further transform ammonia into nitrites and then nitrates.
• Plants absorb nitrates as essential nutrients.
• Animals consume plants.
• Decomposers break down dead matter, returning nitrogen to the soil in the form of ammonia.
• Denitrifying bacteria return nitrogen to the atmosphere in the form of nitrogen gas.

Carbon Cycle (Land)

• Carbon enters the atmosphere as CO2 through industrial processes (e.g., fossil fuel burning) and respiration (animals and plants).
• Plants remove CO2 from the atmosphere during photosynthesis and use it for energy.
• Animals consume plants, absorbing carbon.
• Decomposition releases carbon back into the atmosphere.

Carbon Cycle (Water)

• Carbon in the form of CO2 is absorbed by water.
• Marine animals use carbon to form shells.
• When organisms die, their shells form limestone deposits.
• Limestone releases carbon back into the atmosphere as CO2 when exposed to air.

Energy Flow

• Biotic factors are living organisms.
• Biomass pyramids show energy flow in ecosystems via producers (autotrophs) and heterotrophic consumers.
• Ten percent of energy is transferred to the next trophic level, while the remainder is lost as heat.

Ecological Relationships

• Mutualism: both organisms benefit.
• Commensalism: one benefits; the other isn't affected.
• Symbiosis: both organisms are interdependent, meaning neither can easily survive alone.
• Competition: both are negatively affected as they compete for resources.
• Predator-Prey: the predator consumes the prey.
• Parasitism: one benefits while the other is harmed.

Natural Disasters and Human Impacts

• Droughts decrease water availability, increasing competition among organisms.
• Floods, earthquakes impact population sizes by killing individuals or decreasing resources.
• Human competition for resources in habitats can lead to significant changes in animal migration and plant removal.
• Pollution can introduce harmful chemicals causing mutations or ecosystem collapse.

Sensory Organs and Nervous System

• Sensory organs receive external and internal stimuli.
• Sensory neurons transmit signal to the CNS and the CNS transmits impulses to motor neurons.
• Motor neurons carry signals to effectors, like muscles, which respond to the signals.
• Reflex arcs are involuntary responses where the spinal cord directly triggers a response to a stimulus. Reflexes happen very quickly without the brain's intervention.
• The brain is composed of billions of specialized neurons that transmit electrical and chemical signals.
• Neurons are the fundamental units of the nervous system, consisting of a cell body, dendrites (receive signals), axon (transmits signals), and terminal buttons (pass signals to other neurons).
• Myelin is a fatty covering around the axon that speeds up signal transmission.
• The nervous system includes: the central nervous system (CNS), containing the brain and spinal cord, and the peripheral nervous system (PNS), encompassing nerves throughout the body communicating with CNS. The PNS is divided into: Somatic Nervous System (voluntary movements) and Autonomic Nervous System (involuntary functions), with sympathetic (alert) and parasympathetic (relaxation) divisions.

Endocrine System

• Hormones are chemical messengers secreted by glands throughout the body.
• Hormones trigger responses in specific parts of the body.
• Various glands such as the pineal, hypothalamus, pituitary, parathyroid, thyroid, thymus, adrenal, pancreas, kidneys, testes, and ovaries produce vital hormones that control many bodily functions, including metabolism, water balance, reproduction, stress response, and blood sugar regulation.
• Examples of specific hormones and their functions, such as cortisol (stress), adrenaline (fight-or-flight), insulin (blood sugar regulation).

Homeostasis

• Homeostasis is maintaining stable internal conditions within the body.
• Key factors involve regulation of blood pH, glucose levels, temperature, and other vital nutrients, all regulated through the release of various hormones.
• Vasodilation (widening blood vessels) and vasoconstriction (narrowing blood vessels) control body temperature, allowing heat to be lost or retained as needed.

Models

• Scientific theories may be too complex for simple understanding.
• Models can simplify theories to make them easier to grasp.
• Models are useful tools to represent complex concepts and to communicate scientific ideas effectively.
• Models have strengths and limitations: models cannot include all the details of complex scientific concepts or theories, models are approximations of real-world phenomena.