Science Notes T3 PDF

The Chemical World Notes Sorry mark Notes: 15 stations around the rooms Stations will have a setup result of a practical performed previously in class (e.g one station will have iron rusted in a bottle with hcl) 1:30 mins rotation time Answer 2 very short questions on each station usually explaining...

The Chemical World Notes Sorry mark Notes: 15 stations around the rooms Stations will have a setup result of a practical performed previously in class (e.g one station will have iron rusted in a bottle with hcl) 1:30 mins rotation time Answer 2 very short questions on each station usually explaining what reaction is taking place or recognising results of the practical (e.g corrosion) 30 marks total - Part A Part B - Chemical World skills and content based questions -10 marks Part C - Living world - 10 marks Graph question in Part B or C No memorisation of Chemical Equations (e.g combustion) Need to know how to balance chemical equations oi by short like what? 2 lines? No ATSI environment damage Need to know: ionic compound is a metal or non-metal that loses or gains electrons eg salt How natural disasters change ecosystems (e.g producers die) No specific brain parts or labelling Need to know: functions of a neuron such transmitting signals, release neurotransmitters e.g dopamine Periodic Table provided Molecular Bonding Anions & Cations Anions are atoms that have gained some electrons from other atoms during a chemical reaction, making them negatively charged Cations are atoms that have lost some of their electrons, making them positively charged. Ionic Bonding An ionic bond is a bond between atoms to form a molecular bond. This is done through the electrostatic attraction between opposite ions. For example, NaCl ( salt ) is a type of ionic compound where one salt atom is bonded with one chlorine atom. They are attracted to each other as they need to achieve a full outer electron shell by losing or gaining electrons. In this case, a sodium atom has one electron in the outer shell, and a chlorine atom has seven electrons in its outer shell. Therefore the sodium atom wants to use the one electron to achieve a full outer shell and a chlorine atom needs one electron to achieve a full outer shell. After chemical reaction, the sodium becomes an cation and the chlorine becomes an anion which they form an ionic bond with each other. Covalent Bonding A covalent bond is when atoms share electrons to form chemical bonds. The shared electrons are called bonding electrons. Covalent bonds are only formed when the two atoms are both non-metal. ( E.g. H2O or CO2) In this case, the Hydrogen shares its only atom and the oxygen shares one of the electrons ( overall two for both hydrogen atoms). This makes the hydrogen to gain one electron to obtain a full outer shell and the oxygen to also receive a full outer shell as the two hydrogens have provided 2 electrons. Valency Physical & Chemical Changes A physical change refers to the change from one state to another without a change in the chemical composition (e.g liquid water into water vapour by boiling) A chemical change refers to the change of a substance into a new substance with a different chemical composition → the arrangement of atoms has changed Combustion Combustion is a chemical change in which fuel and oxygen react to create energy, most often in the form of heat energy and a new substance/s such as CO2 and H2O Observations: - Reactants contain the presence of oxygen - Products contain water and carbon dioxide - Change in temperature - heat is created Corrosion Corrosion is a chemical change in which metals react with oxygen and water to form metal oxides. Necessary conditions for corrosion: - Presence of oxygen in the air - Presence of water How can corrosion be avoided?  - Barrier Methods: focus on preventing oxygen and water from touching metal→ such as paint, oil and electroplating (the layering of another metal on top of the main metal) - Sacrificial Methods: focuses on adding a more reactive material → the more reactive material will rust, leaving the main metal behind. - Galvanising: coating a metal with zinc → implications: forms a barrier which prevents oxygen and water from reacting + if scratched, zinc continues to rust due to higher reactivity. Precipitation Reactions Precipitation reactions occur when Acids & Bases The Living World Notes Biosphere Biotic & Abiotic Factors An ecosystem is a community of organisms and its environment. Consists of forests, grasslands, deserts and more. Abiotic: are the conditions and factors of the habitat and are non-living. Abiotic factors include sunlight, pH, temperature, precipitation and salinity. How can they affect ecosystems? Forest Ecosystem: Abiotic Factor How it affects the ecosystem Light Affects photosynthesis; influences plant growth and animal distribution Temperatur Determines the metabolic rate of organisms; impacts species survival Wind Influences seed dispersal and pollination Water Essential for plant hydration and nutrient uptake; influences animal population and biodiversity Carbon & Nitrogen Cycles In natural ecosystems, no matter is neither created nor destroyed; chemical element does not increase or decrease Biogeochemical cycles such as nitrogen and carbon cycles refer to the cycles of matter through Earth’s spheres and are an example of how non-living and living elements interact - They are important because they allow essential elements to plant and animals to be available, maintaining the health of ecosystems (right to left) 1. Nitrogen-fixing microbes in the soil turn nitrogen in the atmosphere into a usable form, Ammonia. 2. Nitrifying bacteria convert Ammonia into nitrites and then nitrates (the process of nitrification) 3. Plants absorb the nitrates (essential plant nutrients) in the soil (the process of assimilation) 4. Animals eat the plants 5. Decomposers break down the tissue of dead animals/plants and return nitrogen to the soil. (the process of ammonification) 6. Denitrifying bacteria return nitrogen to the atmosphere via nitrogen gas. (the process of denitrification) (left to right) Carbon Cycle on Land: 1. Carbon enters the atmosphere as CO2 through industrial ways such as burning fossil fuels or through respiration in animals and plants/decomposition of organic material. 2. Plants use photosynthesis to remove carbon from the atmosphere and use it as a source of energy 3. Animals eat the plants, absorbing the carbon 4. Animals and plants die, decomposers feed on the organic material, releasing carbon back into the atmosphere 5. The cycle repeats Carbon Cycle on Water: 1. Carbon in the form of CO2 gets absorbed by water through diffusion 2. Carbon is used by animals to form shells 3. The animal dies and the shells are left behind → marine deposits 4. Eventually, the shells form limestone 5. When limestone gets revealed to air, carbon is released back into the atmosphere as CO2 Energy Flow Biotic: are the organisms of the ecosystem - relating to living things Biomass Pyramids: graphical representation of energy flow in an ecosystem Produces or Autotrophs: organisms which use the sun’s light for food/energy Heterotrophs / Consumers: organisms that require a source of food for energy Biomass: the mass of living organisms in an area 10% of the available energy at each tropic level is passed on to the next level → energy is lost as heat and to do work Therefore, → the total mass of the organisms at the next level decreases Why? 1. Organisms don’t eat every part 2. Organisms do not absorb everything they eat 3. Energy and biomass released as wate products such as urea. Biotic Relationships Ecological relationships: describe the interactions between and among organisms within their environment. Neutral / Beneficial relationships - Mutualism: the relationship between two organisms in which both organisms benefit. Commensalism: the relationship between two organisms where one benefits and the other is unaffected Symbiosis: the relationship between two organisms where both are so interdependent, neither can survive with the other. Detrimental relationships - Competition: the relationship between two organisms where both are negatively affected as they compete for the same resources Predator-Prey: the relationship between a predator and prey; predator eats prey (benefits) and the pray is harmed Parasitism: the relationship between two organisms where one organism lives inside the other, most often, the parasite benefits and host is harmed Natural factors affecting the population: Limiting Resources: as the population increases, the environmental resources will begin to deplete → increasing competition and causing organisms to leave as there are not enough resources Seasonal changes: for example, as the weather gets colder, birds migrate to warmer areas, causing the population to decrease Diseases: the impact of the disease depends on the population's ability to fight it and the cause. It can wipe out a whole population or have little effect. Natural Disasters: Droughts- plants and animals suffer as the availability of water decreases and competition for water increases significantly Floods, earthquakes and other natural disasters affect population sizes, usually reducing them significantly as individuals are killed, or resulting decrease in resources increasing competition. Human factors affecting ecosystems: Competition for resources: removal of habitats causes significant changes to the population; animals migrate or die and plant removal reduces pollination and nesting sites for many animals. Humans increase the demand for resources such as water, affect other species and place plants under extreme stress during droughts. Pollution: the introduction of chemicals into the ecosystem can lead to mutation/death of organisms, resulting in the collapse of the food web. - Introduction of chemicals such as fertiliser runoff can produce algal blooms which remove oxygen from the water, causing surrounding aquatic organisms to die and block sunlight from entering the water → no photosynthesis and replenishing of oxgeyn Greenhouse effect:  - More humans = more fossil fuels for technology, etc → more heat trapped in the atmosphere, causing areas to become hotter, colder or have extreme, less predictable weather Introduced Species - The introduction of new species can compete with existing species that have not adapted to them → leading to a decrease in its population which can have negative / positive impacts Models: Strengths: - Can represent scientific theories that are too complex, small or large to comprehend - Communicate observations and ideas to other people - Can be used to form hypothesis and predictions Limitations: - Cannot include all details of the scientific theory - Are approximations, meaning models do not exactly behave like the things they represent - Accuracy is lost in order to make models simple to understand Body Systems Sensory Organs Sensory organs allow humans to receive information from the outside world. They consist of specialised receptors that catch the stimuli, ( eg, light, sound and taste) and transmit them to appropriate places in the nervous system for interpretation via the sensory neurons. Primary Sensory Systems - Visual, Detects light and enables sight, ( Organs involved: Eyes, Optic nerve, Brain) - Auditory, Detects sound and enables hearing, ( Organs Involved: Ears, auditory nerves, Brain) - Touch, Detects touch, pressure, temperature and pain, ( Organs involved: Skin, muscles , joints, spinal cords, Brain) - Olfactory, detects odours and enable smell ( organs involved, Nose, olfactory nerves, Brain) - Gustatory, Detects taste and enables taste ( organs involved, Tongue, mouth, facial nerves and the Brain) Nervous System A highly complex human system that coordinates human actions and sensory information by transmitting electrical signals to and from different parts of the body. The Central Nervous System: consists of the spinal cord and the brain, which are responsible for processing information from the Peripheral Nervous System: consists of all the other nerves and is responsible for detecting stimuli and initiating response that comes from the CNS. The Somatic Nervous System is a component of the PNS associated with the voluntary control of body movements via skeletal muscles (moving arms, legs, and other body parts) It is made up of afferent nerves which are made of sensory neurons (send information to brain and spinal) and efferent nerves made of motor neurons (send information from the brain) The Autonomic Nervous System is a component of the PNS that regulates involuntary physiologic (functions of the body) processes. ( eg, Heart rate, digestion)  Part of the ANS, Sympathetic carries signals that put your system on alert or flight-or-fight response (increase heartbeat, inhibit salvation and dilate pupils) Part of the ANS, Parasympathetic carries signals that put relax the body or “rest and digest” (slow heartbeat, stimulate saliva and constrict pupils) Difference between ANS and SNS Feature ANS SNS Control Involuntary Voluntary Targets Internal Organs Skeletal Organs Functions Heart rate, digestion, Movement, sensation respiration Divisions Sympathetic, Sensory, motor parasympathetic Relationship b/w the stimulus, receptor and response The stimulus refers to the a change in the environment (either external or internal) The receptor transduces the environmental stimuli into electrical impulses → travels to CNS via neurons, decision made, travels to effectors via neurons The response refers to the change in the organism resulting from the detecting of the stimulus Diagram of the nervous system Brain The human brain is a complex organ that controls all of our thoughts, emotions, and behaviours. It is composed of billions of neurons, which are specialised cells that transmit electrical and chemical signals. The brain consists of the forebrain, midbrain and the hindbrain which controls different part of the body via the different types of neurons ​ Neurons Neurons, often referred to as nerve cells, are the fundamental units of the nervous system. They are specialised cells that transmit electrical and chemical signals throughout the body. Large cell body: where the nucleus is found, which connects to a long thin axon on one side and dendrites on the other side. Dendrites: nerve endings that branch out of the cell body, receive information and form contacts with axons of other neurons, allowing messages to be transmitted. Axons are long thin tubes- like things that pass information from dendrites to dendrites. Many neurons can be myelinated, meaning they are covered with a fatty layer. This greatly increases the speed of signals being transmitted. A tiny gap separates neurons where signals cannot be transmitted, called synaptic gap. → releases neurotransmitters, triggering a new electrical impulse in the second cell to continue the message. 18. Explain the relationship between sensory organs, sensory neurons, motor neurons and effectors 1. Sensory neurons receive stimuli from sensory organs that monitor the external and internal environment of the body. 2. Sensory neurons provide information to the CNS 3. The CNS gives messages to the motor neuron. 4. Motor neurons carry these messages to the effectors, leading to a change. Reflex Arc The stimulus is first captured by the receptor ( e.g. eyes capturing the light) and then the information is transformed into electrical signals and gets sent to the brain via the sensory neurons. The brain then processes the information and eventually gives an order back to the organs via motor neurons, where then the effector gives a response to the stimulus. The other situation is when the whole process skips the brain processes, but to give a response straightaway from the sensory signal to the motor signal. ( Called spinal reflex arc) This action is quicker than normal reflex arc and is involuntary. Endocrine System Hormone: a chemical secreted by a gland (tissue that secretes a hormone) that triggers a response in specific cells. Diagram of Endocrine System: Pineal Gland: receives information about the day-night cycle from the retina and then produces / releases melatonin which plays a role in sleep Hypothalamus: the main function is to keep the body in a state of homeostasis by producing hormones that regulate body temperature, heart rate and mood Pituitary Gland: produces hormones essential for metabolism, water balance and reproduction. Parathyroid Gland: produces the parathyroid hormone which regulates calcium levels in the bloodstream. (calcium homeostasis) Thyroid Gland: responsible for the formation and secretion of thyroid hormones which is important for controlling the body’s metabolic rate Thymus: produces several hormones which fuel the production of T-cells and keep the immune system working. Adrenal Gland: Produces 1. Cortisol, produced when stressed increasing the glucose in the bloodstream and substances for tissue repair → body is preparing itself 2. Adrenaline makes the heart beat quicker, lungs breathe more efficiently, more blood to muscles, pupils dilate, more alert → in stressful situations 3. Aldosterone manages blood pressure by controlling salt and water levels in the body Pancreas: produces the hormone insulin and glucagon which regulates blood sugar levels Kidneys: produce various hormones needed in the body Testes (male): produces the male sex hormone, testosterone (stimulates the development of male reproductive organs) and sperm. Ovaries (female): releases female sex hormones such as estrogen (stimulates development of female reproductive organs) Homeostasis Homeostasis refers to the process of maintaining a stable internal environment in the body What is the role of homeostasis in the human body? - Keeping blood pH, glucose and internal temperature levels in a certain range - Maintain a certain range of nutrients in the bloodstream such as sodium, potassium and calcium - Maintain water levels in the body between a certain range Specific example - body temperatures are maintained by dissipating excess heat outside the body - Vasodilation (widening of blood vessels) increases the amount and speed of blood flow, allowing more heat to be lost. (hot) - Vasoconstriction (narrowing of blood vessels) decreases the amount and speed of blood flow, leading to less heat being lost (cold)