TuHS IB Biology I Learning Standards

Semester 1

Unit 1: Cell Biology

Introduction to Cells (1.1)

• According to the cell theory, living organisms are composed of cells
• Organisms consisting of one cell carry out all functions of life in that cell
• Surface area to volume ratio is important in the limitation of cell size
• Multicellular organisms have properties that emerge from the interaction of their cellular components
• Specialized tissues can develop by cell differentiation in multicellular organisms
• Differentiation involves the expression of some genes and not others in a cell’s genome
• The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses

• Application: Questioning the cell theory using atypical examples, including striated muscle, giant algae and aseptate fungal hyphae.
• Application: Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism.
• Application: Use of stem cells to treat Stargardt’s disease and one other named condition.
• Application: Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a newborn baby and from an adult’s own tissues.
• Skill: Use of a light microscope to investigate the structure of cells and tissues, with drawing of cells. Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. (Practical 1)

Ultrastructure of Cells (1.2)

• Prokaryotes have a simple cell structure without compartmentalization
• Eukaryotes have a compartmentalized cell structure
• Electron microscopes have a much higher resolution than light microscopes

• Application: Structure and function of organelles within exocrine gland cells of the pancreas and within palisade mesophyll cells of the leaf.
• Application: Prokaryotes divide by binary fission.
• Skill: Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.
• Skill: Drawing of the ultrastructure of eukaryotic cells based on electron micrograph.
• Skill: Interpretation of electron micrographs to identify organelles and deduce the function of specialized cells.

The Origin of Cells (1.5) 

• Cells can only be formed by division of preexisting cells
• The first cells must have arisen from non-living material
• The origin of eukaryotic cells can be explained by the endosymbiotic theory
• Application: Evidence from Pasteur’s experiments that spontaneous generation of cells and organisms does not now occur on Earth.

Unit 2: Membranes

Membrane Structure (1.3)

• Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules
• Membrane proteins are diverse in terms of structure, position in the membrane, and function
• Cholesterol is a component of animal cell membranes
• Application: Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes.
• Skill: Drawing of the fluid mosaic model.
• Skill: Analysis of evidence from electron microscopy that led to the proposal of the Davson-Danielli model.
• Skill: Analysis of the falsification of the Davson-Danielli model that led to the Singer- Nicolson model.

Membrane Transport (1.4)  

• Particles move across membranes by simple diffusion, facilitated diffusion osmosis and active transport
• The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. Vesicles move materials within cells
• Application: Structure and function of sodium-potassium pumps for active transport and potassium channels for facilitated diffusion axons.
• Application: Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis.
• Skill: Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions (Practical 2).

Unit 3: Molecular Biology

Molecules to Metabolism (2.1)

• Molecular biology explains living processes in terms of the chemical substances involved
• Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist
• LIfe is based on carbon compounds including carbohydrates, lipids, proteins, and nucleic acids
• Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism
• Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions
• Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers
• Application: Urea is an example of a compound that is produced by living organisms but can also be artificially synthesized.
• Skill: Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
• Skill: Identification of biochemicals such as sugars, lipids, or amino acids from molecular diagrams.

Water (2.2)

• Water molecules are polar and hydrogen bonds form between the Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water

• Substances can be hydrophilic or hydrophobic

• Application: Comparison of the thermal properties of water with those of methane.
• Application: Use of water as a coolant in sweat.
• Application: Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.

Carbs & Lipids (2.3)

• Monosaccharides monomers are linked together by condensation reactions to form disaccharides and polysaccharides polymers
• Fatty acids can be saturated, monounsaturated or polyunsaturated
• Unsaturated fatty acids can be cis or trans isomers
• Triglycerides are formed by condensation from three fatty acids and one glycerol
• Application: Structure and function of cellulose and starch in plants and glycogen in humans.
• Application: Scientific evidence for health risks of trans fats and saturated fatty acids.
• Application: Lipids are more suitable for long term energy storage in humans than carbohydrates.
• Application: Evaluation of evidence and the methods used to obtain the evidence for health claims made about lipids.
• Skill: Use of molecular visualization software to compare cellulose, starch and glycogen.
• Skill: Determination of body mass index by calculation or use of nomogram.

Unit 4: Proteins

Proteins (2.4) 

• Amino acids are linked together by condensation to form polypeptides
• There are 20 different amino acids in polypeptides synthesized on ribosomes
• Amino acids can be linked together in any sequence giving a huge range of possible polypeptides
• The amino acid sequence of polypeptides is coded for by genes
• A protein may consist of a single polypeptide of more than one polypeptide linked together
• The amino acid sequence determines the three dimensional conformation of a protein
• Living organisms synthesize many different proteins with a wide range of functions
• Every individual has a unique proteome
• Application: Rubisco, insulin, immunoglobulins, rhodopsin, collagen and spider silk as examples  of the range of protein functions.
• Application: Denaturation of proteins by heat or by deviation of pH from the optimum.
• Skill: Drawing molecular diagrams to show the formation of a peptide bond.

Enzymes (2.5)

• Enzymes have an active site to which specific substrates bind
• Temperature, pH, and substrate concentration affect the rate of activity of enzymes
• Enzymes can be denatured
• Immobilized enzymes are widely used in industry
• Enzyme catalysis involves molecular motion and the collision of substrates with the active site
• Application: Methods of production of lactose-free milk and its advantages.
• Skill: Design of experiments to test the effect of temperature, pH and substrate concentration of the activity of enzymes.
• Skill: Experimental investigation of a factor affecting enzyme activity (Practical 3)  

Metabolism (8.1)

• Metabolic pathways consist of chains and cycles of enzyme-catalysed reactions.
• Enzymes lower the activation energy of the chemical reactions that they catalyse.
• Enzyme inhibitors can be competitive or non-competitive.
• Metabolic pathways can be controlled by end-product inhibition.
• Application: End-product inhibition of the pathway that converts threonine to isoleucine.
• Application: Use of databases to identify potential new anti-material drugs.
• Skill: Calculating and plotting rates of reaction from raw experimental results.
• Skill: Distinguishing different types of inhibition from graphs at specified substrate.

Unit 5: DNA

Cell Division (1.6)

• Mitosis is division of the nucleus into two genetically identical daughter nuclei
• Chromosomes condense by supercoiling during mitosis
• Cytokinesis occurs after mitosis and is different in plant and animal cells
• Interphase is a very active phase of the cell cycle with many processes occurring in the nucleus and cytoplasm
• Cyclins are involved in the control of the cell cycle
• Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumors
• Application: The correlation between smoking and incidence of cancers.
• Skill: Identification of phases of mitosis in cells viewed with a microscope or in a micrograph.
• Skill: Determination of a mitotic index from a micrograph.

Structure of DNA & RNA (2.6)

• The nucleic acids DNA and RNA are polymers of nucleotides
• DNA differs from RNA in the number of strands present, the base composition and the type of pentose
• DNA is a double helix made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs
• Application: Crick and Watson’s elucidation of the structure of DNA using model making.
• Skill: Drawing simple diagrams of the structure of single nucleotides of DNA and RNA, using circles, pentagons and rectangles to represent phosphates, pentoses and bases.

DNA Replication (2.7 & 7.1)

• The replication of DNA is semi-conservative and depends on complementary base pairing
• Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds
• DNA polymerase links nucleotide together to form a new strand, using the preexisting strand as a template
• Nucleosomes help to supercoil the DNA
• DNA structure suggested a mechanism for DNA replication.
• DNA polymerases can only add nucleotides to the 3’ end of a primer.
• DNA replication is continuous on the leading strand and discontinuous on the lagging strand.
• DNA replication is carried out by a complex system of enzymes.
• Some regions of DNA do not code for proteins but have other important functions.
• Application: Rosalind Franklin’s and Maurice Wilkins’ investigation of DNA structure by X-ray diffraction.
• Application: Use of nucleotides containing deoxyribonucleic acid to stop DNA replication in preparation of samples for base sequencing.
• Application: Tandem repeats are used in DNA profiling.
• Skill: Analysis of results of the Hershey and Chase experiment providing evidence that DNA is the genetic material.
• Skill: Utilization of molecular visualization software to analyze the association between protein and DNA within a nucleosome.
• Application: Use Taq DNA polymerase to produce multiple copies of DNA rapidly by the polymerase chain reaction (PCR).
• Application: Production of human insulin in bacteria as an example of the universality of the genetic code allowing gene transfer between species.
• Skill: Use a table of the genetic code to deduce which codon(s) corresponds to which amino acid.
• Skill: Analysis of Meselson and Stahl’s results to obtain support for theory of semi-conservative replication of DNA.

Unit 6: Transcription & Translation

Transcription (2.7 & 7.2)

• Transcription occurs in a 5’ to 3’ direction.
• Nucleosomes help to regulate transcription in eukaryotes.
• Eukaryotic cells modify mRNA after transcription.
• The amino acid sequence of polypeptides is determined by mRNA according to the genetic code
• Codons of three bases on mRNA correspond to one amino acid in a polypeptide
• Splicing of mRNA increases the number of different proteins an organism can produce.
• The environment of a cell and of an organism has an impact on gene expression.
• Transcription is the synthesis of mRNA copied form the DNA base sequences by RNA polymerase
• Gene expression is regulated by proteins that bind to specific base specific base sequences in DNA.
• Skill: Use a table or mRNA codons and their corresponding amino acids to deduce the sequence of amino acids coded by a short mRNA strand of known base sequence.
• Skill: Deducing the DNA base sequence for the mRNA strand.
• Application: The promoter as an example of non-coding DNA with a function.
• Skill: Analysis of changes in the DNA methylation patterns.

Translation (2.7 & 7.3)

• Initiation of translation involves assembly of the components that carry out the process.
• Synthesis of the polypeptide involves a repeated cycle of events.
• Disassembly of the components follows termination of translation.
• Free ribosomes synthesize proteins for use primarily within the cell.
• Bound ribosomes synthesize proteins primarily for secretion or for use in lysosomes.
• Translation can occur immediately after transcription in prokaryotes due to the absence of a nuclear membrane.
• The sequence and number of amino acids in the polypeptide is the primary structure.
• The secondary structure is the formation of alpha helices and beta pleated sheets stabilized by hydrogen bonding.
• The tertiary structure is the further folding of the polypeptide stabilized by interactions between R groups.
• The quaternary structure exists in proteins with more than one polypeptide chain.
• Translation is the synthesis of polypeptides on ribosomes
• Translation depends on  complementary base pairing between codons on mRNA and anticodons of tRNA
• Application: tRNA- activating enzymes illustrate enzyme-substrate specificity and the role of phosphorylation.
• Skill: Identification of polysomes in electron micrographs of prokaryotes and eukaryotes.
• Skill: The use of molecular visualization software to analyze the structure of eukaryotic ribosomes and a tRNA molecule

Semester 2

Unit 7: Genetic Modification and Biotechnology

Genetic Modification and Biotechnology (3.5)

• Gel electrophoresis is used to separate proteins or fragments of DNA according to size.
• PCR can be used to amplify small amounts of DNA.
• DNA profiling involves comparison of DNA.
• Genetic modification is carried out by gene transfer between species.
• Clones are groups of genetically identical organisms derived from a single original parent cell.
• Many plant species and some animal species have natural methods of cloning.
• Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.
• Methods have been developed for cloning adult animals using differentiated cells.

• Application: Use of DNA profiling in paternity and forensic investigations.
• Application: Gene transfer to bacteria using plasmids makes use of restriction endonucleases and DNA ligase.
• Application: Assessment of the potential risks and benefits associated with genetic modification of crops.
• Application: Production of cloned embryos produced by somatic-cell nuclear transfer.
• Skill: Design of an experiment to assess one factor affecting the rooting of stem-cuttings.
• Skill: Analysis of examples of DNA profiles.
• Skill: Analysis of data on risks to monarch butterflies of Bt crops.

Unit 8: Cell Respiration & Photosynthesis

Cell Respiration (2.8 & 8.2)

• Cell respiration is the controlled release of energy from organic compounds to produce ATP
• ATP from cell respiration is immediately available as a source of energy in the cell
• Anaerobic cell respiration gives a small yield of ATP from glucose
• Aerobic cell respiration requires oxygen and give a large yield of ATP from glucose
• Cell respiration involves the oxidation and reduction of the electron carriers.
• Phosphorylation of molecules makes them less stable.
• In glycolysis, glucose is converted to pyruvate in the cytoplasm.
• Oxygen is needed to bind with the free protons to maintain the hydrogen gradient, resulting in the formation of water.
• The structure of the mitochondrion is adapted to the function it performs.
• Glycolysis gives a small net gain of ATP without the use of oxygen.
• In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.
• In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers, liberating carbon dioxide.
• Energy released by oxidation reactions is carried to the cristae of the mitochondria by reduced NAD and FAD.
• Transfer of electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to proton pumping.
• In chemiosmosis protons diffuse through ATP synthase to generate ATP.
• Application: Use of Anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
• Application: Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.
• Skill: Analysis of results from experiments involving measurement of respiration rates in germinating seeds or invertebrates using respirometer.
• Application: Electron tomography used to produce images of active mitochondria.
• Skill: Analysis of diagrams of the pathways of aerobic respiration to deduce where decarboxylation and oxidation reactions occur.
• Skill: Annotation of a diagram of mitochondrion to indicate the adaptations to its function.

Photosynthesis (2.9 & 8.3)

• Photosynthesis is the production of carbon compounds in cells using light energy
• Visible light has a range of wavelengths with violet the shortest wavelength and red the longest
• Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colors
• Oxygen is produced in photosynthesis from the photolysis of water
• Energy is needed to produce carbohydrates and other carbon compounds from carbon dioxide
• Temperature, light intensity and carbon dioxide concentration are possible limiting factors on the rate of photosynthesis
• Light-dependent reactions take place in the intermembrane space of the thylakoids.
• Light-Independent reactions take place in the stroma.
• Reduced NADP and ATP are produced in the light-dependent reactions.
• Absorption of light by photosystems generates excited electrons.
• Photolysis of water generates electrons for use in the light-dependent reactions.
• Transfer of  excited electrons occurs between carriers in thylakoid membranes.
• Excited electrons from Photosystem I are used to contribute to generate a proton gradient.
• ATP synthase in thylakoids generates ATP using the proton gradient.
• Excited electrons from Photosystem II  are used to contribute to generate a proton gradient.
• In the light-independent reactions a carboxylase catalyses the carboxylation of ribulose bisphosphate.
• Glycerate 3-phosphate is reduced to triose phosphate using reduced NADP and ATP.
• Triose phosphate is used to regenerate RuBP and produce carbohydrates.
• Ribulose bisphosphate is reformed using ATP.
• The structure of the chloroplast is adapted to its function in photosynthesis.
• Application: Changes to the Earth’s atmosphere, oceans and rock deposition due to photosynthesis.
• Skill: Drawing an absorption spectrum for chlorophyll and an action spectrum for photosynthesis.
• Skill: Design of experiments to investigate the effect of limiting factors on photosynthesis.
• Skill: Separation of photosynthetic pigments by chromatograph. (Practical 4)
• Application: Calvin’s experiment to elucidate the carboxylation of RuBP.
• Skill: Annotation of a diagram to indicate the adaptations of a chloroplast to its function.

Unit 9: Plant Biology

Transport in the Xylem of Plants (9.1)

• Transpiration is the inevitable consequence of gas exchange in the leaf.
• The cohesive property of water and the structure of the xylem vessels allow transport under tension.
• The adhesive property of water and evaporation generate tension forces in leaf cell walls.
• Active uptake of mineral ions in the roots causes absorption of water by osmosis.
• Plants transport water from the roots to the leaves to replace losses from transpiration.
• Application: Adaptations of plants in deserts and in saline soils for water conservation.
• Application: Models of water transport in xylem using simple apparatus including blotting of filter paper, porous pots and capillary tubing.
• Skill: Drawing the structure of primary xylem vessels in sections of stems based on microscope images.
• Skill: Measurement of transpiration rates using potometers. (Practical 7).
• Skill: Design of an experiment to test hypotheses about the effect of temperature or humidity on transpiration rates.

Transport in the Phloem of Plants (9.2)

• Plants transport organic compounds from sources to sinks.
• Incompressibility of water allows transport along hydrostatic pressure gradients.
• High concentrations of solutes in the phloem at the source lead to water uptake by osmosis.
• Raised hydrostatic pressure causes the contents of the phloem to flow towards sinks.
• Active transport is used to load organic compounds into phloem sieve tubes at the source.
• Application: Structure-function relationships of phloem sieve tubes.
• Skill: Identification of xylem and phloem in microscope images of stem and root.
• Skill: Analysis of data from experiments measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide.

Growth in Plants (9.3)

• Undifferentiated cells in the meristems of plants allow indeterminate growth.
• Mitosis and cell division in the shoot apex provide cells needed for extension of stems and development of leaves.
• Plant hormones control growth in the shoot apex.
• Plant shoots respond to the environment by tropisms.
• Auxin influences cell growth rates by changing the pattern of gene expression.
• Auxin efflux pumps can set up concentration gradients of auxin in plant tissue.
• Application: Micropropagation of plants using tissue from the shoot apex, nutrient agar gels and growth hormones.
• Application: Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species.

Reproduction in Plants (9.4)

• Flowering involves a change in gene expression in the shoot apex.
• Most flowering plants use mutualistic relationships with pollinators in sexual reproduction.
• Skill: Drawing internal structure of seeds.
• Skill: Drawing of half-views of animal-pollinated flowers.
• Success in plant reproduction depends on pollination, fertilization and seed dispersal.
• Application: Methods used induce short-day plants to flower out of season.
• Skill: Design of experiments to test hypotheses about factors affecting germination.
• The switch to flowering is a response to the length of light and dark periods in many plants.

Unit 10: Evolution & Biodiversity

Evidence for Evolution (5.1)

• Evolution occurs when heritable characteristics of a species change.
• The fossil record provides evidence for evolution.
• Selective breeding of domesticated animals shows that artificial selection can cause evolution.
• Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.  
• Populations of a species can gradually diverge into separate species by evolution.
• Continuous variation across the geographical range of related populations matches the concept of gradually divergence.
• Application: Development of melanistic insects in polluted areas.
• Application: Comparison of the pentadactyl limb of mammals, birds, amphibians and reptiles with different methods of locomotion.

Natural Selection (5.2)

• Natural selection can only occur if there is variation among members of the same species.
• Mutation, meiosis and sexual reproduction cause variation between individuals in a species.
• Adaptations are characteristics that make an individual suited to its environment and way of life.
• Species tend to produce more offspring than the environment can support.
• Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.
• Individuals that reproduce pass on characteristics to their offspring.
• Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.
• Application: Changes in beaks of finches on Daphne Major.
• Application: Evolution of antibiotic resistance in bacteria.

Cladistics (5.4)

• A clade is a group of organisms that have evolved from a common ancestor.
• Evidence for which species are part of a clade can be obtained from the base sequences of a gene or the corresponding amino acid sequence of a protein.
• Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor.
• Traits can be analogous or homologous.
• Cladograms are tree diagrams that show the most probable sequence of divergence in clades.
• Evidence from cladistics has shown that classifications of some groups based on structure did not correspond with the evolutionary origins of a group or species.
• Application: Cladograms including humans and other primates.
• Application: Reclassification of the figwort family using evidence from cladistics.
• Skills: Analysis of cladograms to deduce evolutionary relationships.

Gene Pools & Speciation (10.3)

• A gene pool consists of all the genes and their different alleles, present in an interbreeding population.
• Evolution requires that allele frequencies change with time in populations.
• Reproductive isolation of populations can be temporal, behavioral or geographic.
• Speciation due to divergence of isolated populations can be gradual.
• Speciation can occur abruptly
• Application: Identifying examples of directional, stabilizing, and disruptive selection
• Application: Speciation in the genus Allium by polyploidy
• Skill: Comparison of allele frequencies of geographically isolated populations

Unit 11: Ecology

Species, Communities & Ecosystems (4.1)

• Species are groups of organisms that can potentially interbreed to produce fertile offspring.
• Members of a species may be reproductively isolated in separate populations.
• Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods).
• Consumers are heterotrophs that feed on living organisms by ingestion.
• Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
• Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.
• A community is formed by populations of different species living together and interacting with each other.
• A community forms an ecosystem by its interactions with the abiotic environment.
• Autotrophs obtain inorganic nutrients from the abiotic environment.
• The supply of inorganic nutrients is maintained by nutrient cycling.
• Ecosystems have the potential to be sustainable over long periods of time.
• Skill: Classifying species as autotrophs, consumers, detritivores or or saprotrophs from a knowledge of their mode of nutrition.
• Skill: Setting up sealed mesocosms between two species to try to establish sustainability (Practical 5, not on quiz)
• Skill: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling (will not be asked on a quiz).
• Skill: Recognizing and interpreting statistical significance [of chi-squared test] (will not be asked on a quiz).

Energy Flow (4.2)

• Most ecosystems rely on a supply of energy from sunlight.
• Light energy is converted to chemical energy in carbon compounds by photosynthesis.
• Chemical energy in carbon compounds flows through food chains by means of feeding.
• Energy released from carbon compounds by respiration is used in living organisms and converted to heat.
• Living organisms cannot convert heat to other forms of energy.
• Heat is lost from ecosystems.
• Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels.
• Skill: Quantitative representations of energy flow using pyramids of energy.

Carbon Cycling (4.3)

• Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds.
• In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen carbonate ions.
• Carbon dioxide diffuses from the atmosphere or water into autotrophs.
• Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere.
• Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground.
• Methane is oxidized to carbon dioxide and water in the atmosphere.
• Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.
• Partially decomposed organic matter from past geological eras was converted either into oil and gas that accumulate in porous rocks.
• Carbon dioxide is produced by the combustion of biomass and fossilized organic matter.
• Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilized limestone.
• Application: Estimation of carbon fluxes due to processes in the carbon cycle.
• Application: Analysis of data from air monitoring stations to explain annual fluctuations.
• Skil: Construct a diagram of the carbon cycle.

Climate Change (4.4)

• Carbon dioxide and water vapor are the most significant greenhouse gases.
• Other gases including methane and nitrogen oxides have less impact.
• The impact of a gas depends on its ability to absorb long wave radiation as well as on its concentration in the atmosphere.
• The warmed Earth emits longer wavelength radiation (heat).
• Global temperatures and climate patterns are influenced by concentrations of greenhouse gases.
• There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution 200 years ago and average global temperatures.
• Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilized organic matter.
• Application: Threats to coral reefs from increasing concentrations of dissolved carbon dioxide.
• Application: Correlations between global temperatures and carbon dioxide concentrations on Earth.
• Application: Evaluating claims that human activities are not causing climate change.

Classification of Biodiversity (5.3)

• The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.
• When species are discovered they are given scientific names using the binomial system.
• Taxonomists classify species using a hierarchy of taxa.
•  All organisms are classified into three domains.
• The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus, and species.
• In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species.
• Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.
• Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.
• Application: Classification of one plant and one animal species from dominant to species level.
• Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.
• Application: Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda and chordata.
• Application: Recognition of features of birds, mammals, amphibians, reptiles and fish.
• Skill: Construction of dichotomous keys for use in identifying specimens.