Evidence for EvolutionTeachers Pet2015-04-21 | Learn about the key pieces of evidence for evolution: fossils, anatomical evidence, embryology and biochemical evidenceOcean AcidificationTeachers Pet2021-05-13 | Learn about the chemistry of ocean acidification and how it affects ocean life in this video!Counting AtomsTeachers Pet2020-09-08 | Learn to count the atoms in a chemical formula in this video!Gene Flow and SpeciationTeachers Pet2019-12-10 | This video coordinates with IB Biology topic 10.3 Gene Flow and SpeciationTranslation (advanced)Teachers Pet2019-11-10 | Learn about translation and protein structure in this video! (Corresponds with IB Biology HL topic 7.3)Transcription and Gene ExpressionTeachers Pet2019-11-06 | Learn about the factors effecting gene expression and the control of gene expression during and after transcription in this video! (Correlates with IB Biology AHL topic 7.2)DNA Replication and SequencingTeachers Pet2019-11-05 | (advanced) Learn about DNA replication in prokaryotes and the enzymes involved, and how DNA is sequenced by scientists in this video! (Correlates with parts of IB Biology HL topic 7.1)Uncovering the Structure of DNATeachers Pet2019-11-04 | Learn about the Hershey Chase experiment, Rosalind Franklin’s X-ray diffraction and the formation of nucleosomes in this video! (Correlates with parts of IB Biology HL Topic 7.1)Photosynthesis (advanced)Teachers Pet2018-11-27 | Learn about the light dependent and independent reactions of photosynthesis in this video!Cellular Respiration (advanced)Teachers Pet2018-11-08 | Learn a detailed account of aerobic cellular respiration in this video!Energy Conversions in BiologyTeachers Pet2018-11-06 | Learn about phosphorylation and oxidation/reduction in this video!Enzyme ActionsTeachers Pet2018-10-29 | Learn about enzymes and inhibitors in this video!Drugs and the Nervous SystemTeachers Pet2018-10-13 | Learn about how various drugs affect the nervous system in this video!Action of NeurotransmittersTeachers Pet2018-10-11 | Learn about the excitatory and inhibitory actions of fast and slow neurotransmitters in this video!ReflexesTeachers Pet2018-10-01 | Learn about reflexes and reflex arcs in this video!The EarTeachers Pet2018-09-25 | Learn about the ear, it’s components and functions in this video!The EyeTeachers Pet2018-09-24 | Learn about the eye and how vision is processed in the brain in this video!
Eye diagram modified from http://open.umich.edu/education/med/resources/second-look-series/materialsSensory ReceptorsTeachers Pet2018-09-22 | Learn about 4 types of sensory receptors, their location, and function in this video!Cerebral HemispheresTeachers Pet2018-09-17 | Learn about the cerebral hemispheres in this video!
Mammal Brains Image modified from: CNX OptenStax http://cnx.org/contents/GFy_h8cuBrain Development and FunctionTeachers Pet2018-09-11 | Learn about the brain and many functions of the brain in this video!
Images used and modified: Embryo photo -Anatomist90 CC upload.wikimedia.org/wikipedia/commons/9/9c/Human_embryo.jpg External brain - James.mcd.nzcommons.wikimedia.org/wiki/File:Brain_Surface_Gyri.SVG Brain cross section - Fvasconcellos CC frcemsuccess.com/cerebellumSynapsesTeachers Pet2018-08-28 | Learn about synapses and how neurotransmitters are used to send messages in this video!Action PotentialsTeachers Pet2018-08-27 | Learn about the propagation of action potentials in a neuron in this video!Neuron Structure and FunctionTeachers Pet2018-08-24 | Learn about the structure and function of neurons (the cell of the nervous system) in this video!Isomers and Structural ShorthandTeachers Pet2018-01-18 | Learn the basics of isomers, some common mistakes to avoid and how to write organic chemicals in structural shorthand!ConvectionTeachers Pet2017-09-25 | Learn about convection, it’s driving force and how it works in the atmosphere, ocean and in Earth’s mantle!DensityTeachers Pet2017-09-20 | Learn about density, how to calculate it, its units and how temperature and addition of solute can change it in this video!Percent YieldTeachers Pet2017-03-21 | Learn how to calculate percent yield from a stoichiometry problem.Collision TheoryTeachers Pet2017-02-03 | Learn about the three parts of collision theory and what it takes for a reaction to occur in this video!Types of Chemical ReactionsTeachers Pet2017-01-14 | Learn about the five types of chemical reactions (combination, decomposition, single replacement, double replacement and combustion) in this video!Atomic MassTeachers Pet2016-09-14 | Learn about atomic mass and how to calculate atomic mass in this video!Radiation and RadioactivityTeachers Pet2015-09-14 | Learn about the types of radiation, radioactive decay, half-lives and medical uses of radiation in this video!Fission and FusionTeachers Pet2015-09-09 | Learn about the basics of fission and fusion, chain reactions, nuclear reactors and nuclear weapons in this video!The NucleusTeachers Pet2015-09-08 | In this video you’ll learn about the parts of the nucleus, how it stays together and how to write in isotope notation.History of Evolutionary ThoughtTeachers Pet2015-04-21 | Learn about Jean Baptiste de Lamarck, Darwin and Wallace in this video!Solubility EquilibriumTeachers Pet2015-04-21 | Learn about solubility, solubility product constants, common ion effect and predicting if a precipitate will form in this video!SpeciationTeachers Pet2015-04-20 | Learn about speciation and patterns of evolution in this video!Types of Natural SelectionTeachers Pet2015-04-20 | Learn about the types of natural selection (directional, stabilizing and disruptive) in this video!Equilibrium ConstantsTeachers Pet2015-04-17 | Learn about how to write equilibrium constant expressions and interpret their meaning in this video!Disruption of Genetic EquilibriumTeachers Pet2015-04-16 | Learn about the disruption of Hardy-Weinburg equilibrium in this video! Includes information about mutation, migration, gene flow, genetic drift, small populations, sexual selection and artificial selection.Le ChâtelierTeachers Pet2015-04-15 | Learn about Le Châtelier’s principle and how to apply it to reversible reactions in this video!Reversible ReactionsTeachers Pet2015-04-15 | Learn about reversible reactions in dynamic equilibrium in this video!Allele FrequenciesTeachers Pet2015-04-14 | Learn about the simple calculation of allele frequencies in a gene pool, hardy-weinberg assumptions and the difference between acclimation and adaptation in this video!Population GeneticsTeachers Pet2015-04-13 | Learn about the very basics of population genetics (microevolution) in this video!SuccessionTeachers Pet2015-03-26 | Learn about the types of succession (primary and secondary) and the process of succession in this video!Salts in SolutionTeachers Pet2015-03-26 | Learn about salts in solution, equivalence points other than 7 and buffers in this video!
transcript _______________ Salts contain an anion from an acid and a cation from a base Acids and bases mix to produce salts, but not always a neutral solution. Some salts actually cause water to break up into further ions. In general, salts that produce acidic solutions contain positive ions that release protons to water. Salts that produce basic solutions contain negative ions that attract protons from water. in salt hydrolysis, the cations or anions of a dissociated salt remove hydrogen ions from or donate hydrogen ions to water. Not all salts will do this, only some will. whenever we have a strong acid with a strong base, we get a neutral solution with salts that don’t do salt hydrolysis. when we mix a strong acid and a weak base, we end up with an acidic solution. a weak acid and a strong base will produce a basic solution. Here is a graph of a titration of a strong acid and a strong base, sodium hydroxide. you can dee that the equivalence point is right in the middle of the vertical section of the graph, at a pH of 7. But if we look at a graph of a titration of a weak acid and a strong base, the equivalence point is slightly more basic, at almost a pH of 9. The salt produced cases more hydroxide ions to be produced, resulting in a more basic equivalence point. A buffer is a solution of a weak acid and one of its salts, or a solution of a weak base and one of its salts. The pH of a buffer remains relatively constant when small amounts of acid or base are added. The buffer capacity is the amount of acid or base that can be added to a buffer solution before a significant change in pH occurs. This graph shows that happens where more HCl is added to pure water over time. The pH is steadily decreasing. But when we have a buffer solution and we add HCl, the pH remains steady for a long time, then begins to change eventually, but nowhere near as drastically. Buffers keep the pH steady, and this is very important for many living systems, like the pH of your blood.Species InteractionsTeachers Pet2015-03-26 | Learn about predator-prey relationships, interspecific competition, infraspecific competition, competitive exclusion principle, resource partitioning and symbiosis (mutualism, commensalism and parasitism) in this video!TitrationsTeachers Pet2015-03-25 | Learn about the basics of titrations and the steps to perform them in this video!
transcript ___________________ when a strong acid and a strong base are mixed together, a neutralization reaction occurs. They end up forming water and a salt. at the end of the reaction, if the molar ratio of reactants was balanced, we’ll get a solution with a pH of 7, neutral. When an acid and base are mixed, the equivalence point is when the number of moles of hydrogen ions equals the number of moles of hydroxide ions. with strong acids and bases reacting, the reaction produces a neutral solution with a pH of 7. when we do a titration where we add an acid or base with a known concentration, called the standard solution, to a base or acid with an unknown concentration, we need a way to know when the equivalence point has been reached. to do this we use an indicator. Indicators are often used to determine when enough of the standard solution has been added to neutralize the acid or base. the indicator needs to change color near the equivalence point. The point at which the indicator changes color is the end point of the titration. the end point is not the same as the equivalence point, but it’s usually very near it on the pH scale. A measured volume of an acid solution of unknown concentration is added to a flask. Then several drops of the indicator are added to the solution while the flask is gently swirled. Then measured volumes of a base of known concentration are mixed into the acid until the indicator just barely changes color. the equivalence point (equal [H+] and [OH-]) is not exactly the same as the end point. The end point is where the indicator changes color. The standard solution should change the indicator color so that the end point can be determined. You want to see the color change usually just after the equivalence point has been reached. for example, phenophthalein turns pink with a base around a pH of 8, so the end point of a titration with a base will be measured when the solution just turns pink.Strength of Acids and BasesTeachers Pet2015-03-25 | Learn about how the strength of acids and bases are determined in this video!
transcript ____________________ not all acids and bases are the same. Some are stronger some are weaker. We can figure out the strength of an acid using this acid dissociation constant. An acid dissociation constant (Ka) is the ratio of the concentration of the dissociated (or ionized) form of an acid to the concentration of the undissociated (nonionized) form. the same basic formula is used to find the strength of the base with the ratio of the concentration of the dissociated or ionized form of the base to the concentration of the undissociated base. So how does this constant tell us if it’s a strong or weak acid or base? strong acids and bases dissociate completely, weak acids and bases dissociate partially, so strong acids have a have a higher Ka value, and weak acids have a smaller Ka value. the same is true of bases. acetic acid is weak but hydrochloric acid is strong, ammonia is a weak base, but sodium hydroxide is strong. remember, strength of an acid or base is based on how much the ions dissociate, but concentration tells you how many ions are in solution. it is possible to have highly concentrated weak base, which could actually do a lot of damage to your tissues, and it’s possible to have a dilute strong base, which is much less harmful to your tissues because it’s so diluted.Population DynamicsTeachers Pet2015-03-24 | Learn how to calculate growth rate, interpret growth diagrams, survivorship curves, population pyramids (age structures), exponential and logistic growth in this video!