Biology Lecture Notes Review

Characteristics of Life

• All prokaryotic and eukaryotic organisms share certain characteristics:

  • Made of Cells

  • Heredity

  • Maintain Homeostasis

  • Respond to Stimuli

  • Maintain Metabolism

  • Grow and Develop

  • Reproduce

Comparison of Cellular Structures

• Prokaryotes

  • Lack organelles.

  • Contain ribosomes.

  • Lack a nucleus.

  • Single-celled.

• Eukaryotes

  • Contain organelles.

  • Contains a nucleus.

  • Contain ribosomes.

  • Single and/or multi-celled.

Organelles and Their Functions

• Nucleus: Contains DNA, controls the cell's activities.

• Nucleolus: Site of ribosome synthesis, found in the nucleus.

• Mitochondria: Breaks down carbohydrates to produce ATP (usable energy).

• Rough Endoplasmic Reticulum: Transports proteins and other substances within the cell.

• Smooth Endoplasmic Reticulum: Creates lipids.

• Ribosomes: Protein synthesis.

• Chloroplast: Synthesizes carbohydrates using light energy.

• Golgi Apparatus: Protein packaging.

• Cytoplasm: Supports and protects organelles.

• Centrioles: Paired cylindrical organelles utilized in cell division.

• Cytoskeleton/Microtubules: Supports the cell, provides shape, and used in cell movement.

• Lysosome: Breaks down food molecules and old organelles.

• Vacuoles: Storage, digestion, and waste removal.

  • Contractile Vacuole: Pumps water out of the cell.

• Vesicle: Moves proteins, lipids, and carbohydrates through the cell.

• Cell Membrane: Protects the contents of the cell, controls what enters and leaves the cell.

• Cell Wall: Protects the contents of the cell and prevents cells from bursting.

Biological Organization

• Relationships between structure and function at various levels:

  • Organelles → cells → tissues → organs → organ systems → multi-cellular organisms

Cell Cycle

• Interphase

  • G1 Phase: Cell grows.

  • S Phase: DNA is copied.

  • G2 Phase: Cell continues to grow, organelles are copied.

• Mitosis

  • Prophase: Spindle fibers form, nuclear envelope dissolves, chromosomes become visible.

  • Metaphase: Chromosomes align at the cell's equator, spindle fibers attach to chromosomes.

  • Anaphase: Spindle fibers pull chromatids apart at the centromere, chromatids move to opposite poles.

  • Telophase

• Meiosis

  • Prophase I: Chromosomes become visible, Nuclear envelope disappears, Crossover occurs

  • Metaphase I: Homologous chromosomes move to equator

  • Anaphase I: Homologous chromosomes move to opposite poles

  • Telophase I: Cytoplasm divides

  • Prophase II: New spindle fibers form around the chromosomes

  • Metaphase II: Chromosomes align up at the equator

  • Anaphase II: Centromeres divide, Chromatids move to opposite poles

  • Telophase II: Nuclear envelope reforms around each set of chromosomes, Cytoplasm divides

• Cytokinesis: Splitting of the cell membrane into two separate cells.

Mitosis vs. Meiosis

• Mitosis: One division into two identical diploid cells.

• Meiosis: Two divisions, resulting in 4 haploid cells after the second division.

DNA Replication

• Process of making an exact copy of DNA.

• Occurs in the S phase of the cell cycle.

• Produces two exact daughter strands of DNA from the parent strand.

• One strand will be moved into each of the new daughter cells after cytokinesis occurs.

DNA, Genes, Alleles, and Chromosomes

• Chromosomes: Long strands of DNA.

• DNA: Genetic material that codes for the hereditary traits of organisms.

• Genes: Segments of DNA located in a chromosome that code for a specific hereditary trait.

• Alleles: Alternative forms of a gene that govern a characteristic, such as hair color.

Unique Properties of Water

• 70-75% of the human body is made of water.

• Water can be found in all three states of matter: solid, liquid, and gas.

• Due to water's polarity, it makes a great solvent.

  • Almost all polar molecules and ions can dissolve in water.

• Cohesion: Attraction between water molecules due to polarity.

  • Causes "surface tension," allowing small, dense items to be held on the surface of the water.

• Adhesion: Water tends to cling to other polar molecules.

• Capillary movement involves adhesion, cohesion, and surface tension.

  • Adhesion is the attraction of water for a wettable surface.

  • Cohesion is the attraction of one water molecule for another water molecule.

  • Surface tension minimizes surface area.

  • Water is attracted along the walls by adhesive forces inside a small diameter tube.

  • Surface tension and cohesion drag more water molecules along behind.

  • Water movement stops when cohesive forces, tube size resistance to movement, and gravity become too great.

• High specific heat: Water absorbs significant energy before showing temperature change.

  • Water boils at 212^{\circ}F (100^{\circ}C).

  • Water freezes at 32^{\circ}F (0^{\circ}C).

  • Energy added increases molecular vibration and breaks hydrogen bonds.

  • Evaporation occurs when water molecules break from all hydrogen bonds and escape into the atmosphere, cooling the organism by pulling heat from it.

• Water is a good hydraulic fluid, used to expand and hold cells rigid and erect.

Carbon's Role in Macromolecules

• Organic compounds contain both carbon and hydrogen.

• Carbon, atomic number six, has six electrons; two in the first shell and four in the second.

• Carbon shares four electrons with other atoms to fill its outermost electron shell and attain a stable configuration.

• Carbon can share electrons with various elements found in organic compounds, including other carbon, hydrogen, and oxygen atoms.

Formation of Biological Macromolecules

• Four Biological Macromolecules (Polymers) → Made of → Monomers

  • Carbohydrates: Monosaccharides (Monomer) → Disaccharides → Polysaccharides (Polymer/Macromolecule)

  • Proteins: Amino Acid (Monomer) → Polypeptide Chains → Protein (Polymer/Macromolecule)

  • Lipids: wide range of monomers depending on the type of lipid

  • Nucleic Acid: Nucleotide (Monomer) → DNA/RNA (Polymer/Macromolecule)

Structure and Function of Macromolecules

• Carbohydrates

  • Organic compounds made of carbon, hydrogen, and oxygen in a 1:2:1 ratio.

  • Key source of energy, found in fruits, vegetables, and grains.

  • Monosaccharides: Examples include glucose and fructose.

  • Disaccharides: Example: Sucrose.

  • Polysaccharides: Examples include starch (found only in plants to store energy), cellulose (found only in plants used for structural support), and glycogen (found only in animals for energy storage).

• Lipids

  • Nonpolar molecules that aren't soluble in water.

  • Fatty acids tend to be the monomer of larger, more complex lipids.

  • Phospholipids: Make up the lipid bilayer of cell membranes.

  • Sterols: Hormones or signaling molecules like cholesterol, estrogen, and testosterone.

  • Glycerol: Stores a large amount of energy.

  • Fats found in foods:

    • Dietary fats: Facilitate absorption of fat-soluble vitamins (A, D, E, and K) and carotenoids.

    • Omega-3 fatty acids: Help infant development, cancer, cardiovascular diseases, and mental illnesses like depression, ADHD, and dementia.

    • Saturated fats: Increase bad cholesterol (LDL), clogging arteries.

    • Unsaturated fats: Increase good cholesterol (HDL), taking bad cholesterol (LDL) to the liver to be broken down.

    • Trans fats:

      • Produced during vegetable oil production.

      • Risk for cardiovascular disease.

• Proteins

  • Building blocks for many structures in the body.

  • Amino acids (monomer) → Polypeptide chains → Proteins (Polymer/macromolecule)

  • 20 different amino acids make up 2 million different proteins in the human body.

  • Function of proteins:

    • Antibodies: Travel through the bloodstream and are utilized by the immune system to identify and defend against bacteria, viruses, and other foreign intruders.

    • Enzymes: Catalysts that speed up chemical reactions.

      • Most enzymes end with the suffix -ase. Lactase breaks down lactose; Fructase breaks down fructose.

    • Hormones: Messenger proteins that coordinate bodily activities. Examples include insulin and oxytocin.

    • Structural proteins: Provide support. Examples include keratin (hair and feathers) and collagen (tendons and ligaments).

    • Transport proteins: Move molecules around the body. Example: Hemoglobin in red blood cells.

• Nucleic acids

  • Used for protein production and hereditary information storage.

  • Nucleotides (Monomer) → Nucleic acids (Polymer/Macromolecule)

  • Two types:

    • DNA: Deoxyribonucleic Acid

      • Stores hereditary information.

      • Two strands of nucleotides twisted around each other.

    • RNA: Ribonucleic Acids

      • Used in the manufacturing of proteins.

      • Single strand of nucleotides that code for a specific protein to be made by the cell.

Enzymes as Catalysts

• Enzymes reduce the activation energy needed to start chemical reactions.

• Enzymes increase the speed of chemical reactions.

• Without enzymes, chemical reactions would not occur quickly enough to sustain life.

• The substrate is the molecule that an enzyme acts on.

• Substrate molecules are changed, and product is formed.

• The enzyme molecule is unchanged after the reaction and can continue to catalyze the same type of reaction.

• Enzymes are substrate-specific.

• The enzyme fits into the substrate's active site like a key into a lock.

• Each substrate has a different active spot, causing it to have a different enzyme.

• Starch can only be broken down into glucose with the enzyme amylase.

• Lipase breaks lipids down into fatty acids and glycerol.

Factors Affecting Enzyme Function

• pH effects:

  • Each enzyme functions best in a specific pH range.

  • pH changes distort the active site, affecting enzyme function.

• Temperature effects:

  • Reactions speed up as temperature increases.

  • Each enzyme has a temperature optimum; beyond this point, the enzyme's shape is lost.

  • Boiling temperatures will denature most enzymes.

• Concentration effects:

  • Increasing substrate and/or enzyme concentration increases the rate of reaction.

Patterns of Inheritance

• Punnett squares are used to predict offspring appearance from known parents.

• Dominant genes: Always expressed if present in an organism's genotype.

  • Genotype: The pair of alleles an organism receives from its parents (e.g., AA, Aa, aa).

    • Homozygous genotype: Alleles are the same (Ex: AA - Homozygous dominant, aa - Homozygous recessive).

    • Heterozygous genotype: Alleles are different (Ex: Aa - Heterozygous dominant).

  • Phenotype: The physical expression of the pair of alleles for a specific trait (e.g., purple flowers or white flowers).

• Recessive genes: Only expressed if dominant genes aren't present.

• Exceptions to simple inheritance:

  • Polygenic traits: Determined by the combined effect of more than one pair of genes. Varying degrees of intermediate conditions. Examples: Human hair color, eye color, height, weight.

  • Incomplete dominance: Results in an intermediate expression of a trait in heterozygous individuals. For example, red or white flowers are homozygous while pink flowers are heterozygous.

  • Multiple alleles: Genes with three or more alleles. An individual can only have two of the possible alleles. Example: Human blood type - I^A, I^B, i°.

  • Codominance: Two dominant alleles are expressed at the same time. Both dominant phenotypes are expressed at the same time.

    • Example: Human Blood Type - Parent one with I^A I^B blood type has a baby with parent two who has I. They will have a child with AB blood type, because the A and B allele are both dominant.

• Sex-linked traits: A gene found only on the X chromosome and not the Y chromosome. Females have two copies, males have one copy.

  • Males only need one recessive gene to have a sex-linked trait.

  • This is why males exhibit some traits more frequently than females.

Chromosome Alterations

• Crossing Over: Exchange of genetic material between homologous chromosomes during Prophase I of meiosis.

  • Shuffles allele content between homologous chromosomes.

  • Creates more possible combinations of offspring outcomes.

• Nondisjunction: Failure of chromosome pairs to separate properly during meiosis.

  • Results in a gamete with an imbalance of chromosomes.

  • Loss of a single chromosome (monosomy) is usually lethal, except for Turner Syndrome (women missing one X chromosome).

  • Gaining a single chromosome (trisomy). Examples: Trisomy 21 (Down Syndrome), Trisomy 18 (Edward's Syndrome), Triple X Syndrome, XXY (Klinefelter Syndrome).

• Common chromosomal mutations:

  • Insertion: Add one or more extra nucleotides into the DNA, altering the reading frame. Example: Original strand ATCGAT New strand ATCIGAT

  • Deletion: Removal of one or more nucleotides from the DNA, altering the reading frame. Example: Original strand ATCGAT New strand ATAT

  • Duplication: Leading to multiple copies of all chromosomal regions, increasing the dosage of the genes located within them. Example: Original strand ATCGAT New strand ATCATCGAT

  • Inversion: A segment of a chromosome is reversed end to end. Example: Original strand ATCGAT New strand CTAGAT

  • Translocation: Rearrangement of parts between nonhomologous chromosomes. Common in cancer.

    • Balanced: An even exchange of material with no genetic information extra or missing. full functionality

    • Unbalanced: The exchange of chromosome material is unequal resulting in extra or missing genes.

Genetic Mutations and Phenotype

• Point mutations: Exchange a single nucleotide for another.

  • Silent mutations: Do not result in a change to the amino acid sequence of a protein.

  • Nonsense mutations: Result in a premature stop codon.

  • Missense mutations: Single nucleotide is changed, resulting in a codon that codes for a different amino acid.

• Frameshift mutations: Will cause the reading of the codons after the mutation to code for different amino acids. Can cause the polypeptide being created could be abnormally short or abnormally long, and will most likely not be functional.

Genetic Mutations and Population Variation

• A mutation is a change in DNA, the hereditary material of life. Affects how it looks, how it behaves, and its physiology.

• New phenotypic expressions arise from mutations in the genes. This is an important source of variation that allows organisms to adapt to new environments.

Transcription and Translation

• Occur in all organisms; process is similar, but differs in prokaryotes and eukaryotes.

• In prokaryotes, both transcription and translation take place in the cytoplasm.

• In eukaryotes, transcription occurs in the nucleus and translation in the cytoplasm.

• Transcription = DNA → RNA

• Translation = RNA → protein

• mRNA: Transcribed from DNA for protein synthesis.

• Translation: mRNA produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein.

• Prokaryotes: Translation occurs in cell's cytoplasm.

• Eukaryotes: Translation occurs across the membrane of the endoplasmic reticulum in a process called vectorial synthesis.

• Ribosomes induce the binding of tRNAs to mRNA, carrying specific amino acids that are chained together into a polypeptide as the mRNA passes through.

Organelles in Protein Production

• Ribosomes: Translate mRNA genetic code to a specific sequence of amino acids.

  • tRNAs transport amino acids to the ribosome and possess an anticodon.

• Endoplasmic reticulum: Found only in eukaryotic cells. Ribosomes binds to the rough ER, the polypeptide chain that is produced by the ribosome is then released into the endoplasmic reticulum. Then ER transports the polypeptide change to the area of the cell where it will be used.

• Golgi Apparatus: Composed of flattened fluid-filled sacs; controls the flow of molecules in a cell; produces glycoprotein.

  • Carbohydrates are added to translated proteins.

  • Glycoprotein is transported by a vesicle to the cell membrane.

  • The vesicle binds to a receptor on the surface and excretes the protein.

• Nucleus: Directs protein synthesis by synthesizing mRNA according to instructions provided by the DNA.

Genetic Engineering

• Selective Breeding: Breeding plants and animals for particular traits. Benefits: High crop yields & resistance to disease. Negative Impacts: Disrupts the food chain and natural order of life

• Gene splicing: Cutting the DNA from one organism and attaching it to the DNA of another organism causing the host organism to demonstrate a new phenotype. Example: attaching the insulin gene to bacteria to mass produce the drug.

• Cloning: Producing similar populations of genetically identical individuals that occurs in nature when organisms reproduce asexually.

  • Benefits: Can provide a viable solution to infertility in organisms. Disadvantages: Cloning raises a concerning probability of deliberate reproduction of undesirable traits in organisms.

• Gene therapy: DNA can be used to supplement or alter genes within an individual's cells as a therapy to treat disease.

  • Stem cell therapy: an intervention strategy that introduces new adult stem cells into damaged tissue in order to treat disease or injury

Plastids and Mitochondria in Energy Transformation

• Plastids: Only found in plants; composed of stacks of thylakoid sacks. Light is converted into glucose, where it is then used by the mitochondria to make ATP molecules Through Photosynthesis.

• Mitochondria: Found in all eukaryotic cells; produce and store adenosine triphosphate (ATP) molecules - Result of cellular respiration and requires a food source.

  • Covered in cristae to maximize surface area.

  • Performs many chemical reactions, transports molecules into the matrix, where oxygen combines with food molecules to create energy.

Photosynthesis vs. Cellular Respiration

• Photosynthesis: Plants use solar energy to convert carbon dioxide (CO2) and water (H2O) into glucose (C6H{12}O_6).

  • Oxygen gas is produced as the byproduct

  • Occurs in the chloroplasts of plants. General chemical equation:

6H2O + 6 CO2 + solar energy \rightarrow C6H{12}O6 + 6O2

• Cellular respiration: Release of energy from energy-storing compounds.

  • Cells require a continuous supply of energy.

  • Occurs in the mitochondria of eukaryotes. Chemical equation:

C6H{12}O6 + 6 O2 \rightarrow 6 CO2 + 6H2O + energy

cellular respiration is essentially the reverse of photosynthesis.

Role of ATP

• ATP (Adenosine Triphosphate) is a nucleotide used for energy storage.

  • Composed of: Adenine nitrogen base, Ribose sugar molecule, Phosphate group(s).

  • Number of phosphate groups determines the power of the nucleotide.

    • AMP: Adenosine monophosphate - 1 phosphate group - acts like a very weak battery

    • ADP: Adenosine diphosphate - 2 phosphate groups - acts like a dollar store battery (has power but not the best)

    • ATP: Adenosine triphosphate - 3 phosphate groups - acts like a Duracell lithium battery

  • ATP is fuel for cells

  • ATP transports chemical energy within cells for metabolism.

  • ATP is produced in: Photophosphorylation, Cellular respiration, Fermentation.

  • ATP is used by: Enzymes function & Structural proteins in many cellular processes, including metabolism, motility, and cell division.

Natural Selection and Allele Frequencies

• Natural selection can increase the frequencies of alleles if they are advantageous to a species' survival and reproductive abilities. If they somehow produce a phenotype that is not a selective advantage, their frequency will decrease.

Development of New Species

• Prezygotic mechanisms: Prevent individuals from mating.

  • Geographic isolation: Species occur in different areas.

  • Temporal isolation: Individuals do not mate because they are reproductively active at different times.

  • Ecological isolation: Individuals only mate in their preferred habitat.

  • Behavioral isolation: Individuals of different species may meet, but one does not recognize any sexual cues that may be given

  • Mechanical isolation: Copulation may be attempted but transfer of sperm does not take place

  • Gametic incompatibility: Sperm transfer takes place, but the egg is not fertilized.

• Postzygotic isolating mechanisms: Genomic incompatibility, hybrid inviability or sterility.

  • Zygotic mortality: The egg is fertilized, but the zygote does not develop.

  • Hybrid inviability: Hybrid embryo forms, but is not viable.

  • Hybrid sterility: Hybrid is viable, but the resulting adult is sterile.

  • Hybrid breakdown: First generation (F1) hybrids are viable and fertile, but further hybrid generations (F2 and backcrosses) are inviable or sterile.

• Genetic Drift: In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals. Types of genetic drift: Bottleneck effect & Founders effect.

• Effects of genetic drift:

  • Drift reduces genetic variation in populations

• Types of genetic drift:

  • Bottleneck effect:

  • Founders effect occurs when a new colony is started by a few members of the original population

Evidence Supporting Evolution

• Fossil: Provides an actual record of Earth's past life-forms - Most direct evidence that evolution takes place.

• Anatomical: comparisons of the different types of organisms often reveal basic similarities in body structures even though the structure's function may differ between organisms.

  • Vestigial structures: structures present in organisms, but are reduced in size and either have no or little function than in other related species.
    Examples: Human appendix, whale hip bone

  • Homologous structures: structures derived from a common ancestor or same evolutionary or developmental origin.
    Examples: The forearm of the crocodile, cat, bat and bird

  • Analagous Structures: Structures of different species having similar or corresponding function but not from the same evolutionary origin.
    Examples: The wings of a bat and a butterfly.

• Embryological: At some time in development, all vertebrates have a tail, buds that become limbs, and pharyngeal pouches.

• Biochemical: With the increase of anatomical differences, protein and DNA differences also increase.

Scientific Terms

• Hypothesis: Is a proposed explanation for a phenomenon. An idea about the solution to a problem utilizing knowledge & research. Used to help guide scientists through the experimental process.

• Inference: Is a conclusion drawn from specific observations.

• Law: Is the summarizing statement of observed experimental facts that have been tested many times and is generally accepted to be true.

• Theory: which has been confirmed through repeated experimental tests.

• Principle: A basic truth, law, or assumption.

• Fact: Something demonstrated to exist or known to have existed.

• Observation: An inference or a judgment that is acquired from or based on observing. Typically, the first step in a scientific process.

Plasma Membrane Structure

• Plasma membranes are sheet-like structures composed mainly of lipids and proteins.

• Membrane lipids are organized in a bilayer (two sheets of lipids making up a single membrane).

• serve as the attachment surface for several extracellular structures

Transport Across Plasma Membrane

• Passive Transport: substances move from an area of high concentration to an area of low concentration.

  • No energy is required to move from high to low concentrations.
    Passive transport: diffusion, osmosis, facilitated diffusion;

  • Diffusion: Some substances (small molecules, ions) such as carbon dioxide (CO2), oxygen (O2), and water, can move across the plasma membrane

  • Osmosis: is the diffusion of water from areas of high concentration to areas of low concentration.

  • Facilitated diffusion: is the spontaneous passage of molecules or ions across a biological membrane passing through specific trans-membrane integral proteins

  • Active transport: moves molecules from areas of low concentration to areas of high concentration.

  • This movement uses energy (typically ATP).
    transport - pumps, endocytosis, exocytosis

• Types of active transport:

  • Sodium-potassium pumps: is responsible for cells containing relatively high concentrations of potassium ions but low concentrations of sodium ions Sodium-potassium pumps; endocytosis

• Endocytosis: is the process in which cells absorb molecules by engulfing them.
  Types of endocytosis: Phagocytosis - cell eating & Pinocytosis - cell drinking

• Exocytosis: occurs in various cells to remove undigested residues of substances brought in by endocytosis.

Organelles Facilitating Transport

• Endoplasmic reticulum: the transportation system of the eukaryotic cell. Proteins move from the rough ER to the Golgi apparatus.

• Golgi apparatus: Vesicles transported to the Golgi apparatus, where they fuse with the Golgi membrane and empty their contents into the lumen.

• The Golgi complex modifies many products from the ER including proteins and phospholipids

Maintaining Homeostasis

• Behavioral - where we consciously change our behavior - Physiological - where our body automatically alters its functioning without conscious control.

• The body relies upon a constant fluid level to ensure metabolic reactions within cells can proceed.

• Single-celled organisms really upon their cell membrane to regulate diffuse of essential molecules.

Ecological Organization

• In order from smallest to greatest:

  • Organism: individual living creature.

  • Population: A group of organisms of one species that interbreed and live in the same place at the same time (e.g. muted swan population).

  • Community: An group of organisms or a population of different species occupying a particular area.
    ecological organization (i.e., organism, population, community, ecosystem, biome, biosphere

• Ecosystem: A system that includes all living organisms (biotic factors) in an area as well as its physical environment (abiotic factors) functioning together as a unit.

  • Biome: A major ecological community of organisms adapted to a particular climatic or environmental condition on a large geographic area in which they occur. (Ex: Savanna, Tropical rainforest)

  • Biosphere: The part of the earth where living things exist

• Abiotic: is a nonliving (NEVER has lived) physical and chemical attribute of a system, for example light, temperature, wind patterns, rocks, soil, pH, pressure, etc. in an environment
  Flow of Matter & Energy: food chains, food webs, energy pyramids & Symbiosis

Biotic Interactions

• Symbiosis: a long-term relationship between two different species.

• Competition: A symbiotic relationship between or among living things for resources, such as food, space, shelter, mate, ecological status, etc.
  Two male lions fighting for a mate Mutualism: in this type of symbiosis, both organisms of different species rely on one another for nutrients, protection and other life functions, hence, they are usually found living in close proximity

• Commensalism: A form of symbiosis between two organisms of different species in which one of them benefits from the association whereas the other is largely unaffected or not significantly harmed or benefiting from the relationship Predation: A form of symbiotic relationship between two organisms of unlike species in which one of them acts as predator that captures and feeds on the other organism that serves as the prey

• Ex: An owl killing a mouse for food Parasitism: A form of symbiosis in which one organism (called parasite) benefits at the expense of another organism usually of different species (called host).

Recycling of Matter

• Water, Carbon, Oxygen & Nitrogen cycle. Cycle's energy supplied by the sun Water returns to the atmosphere by: Evaporation & This special case is called transpiration.*

• Carbon Cycle: Meteorite

  • The chief reservoirs for carbon dioxide are in the oceans and in rock* Through combustion of organic material, which oxidizes the carbon

• Burning fossil fuels such as coal, petroleum products, and natural gas releases carbon that has been stored in the geosphere for millions of years
  n Nitrogen Cycle:
  Nitrogen gas in the atmosphere is composed of two nitrogen atoms bound to each other