Biology SOL Review Notes

Scientific Investigation

A. Steps of the Scientific Method

  1. Make observations/Do research: Determine the problem to address.

  2. Develop a Research Question: Specify the focus of the investigation.

  3. Develop a hypothesis: Formulate a testable prediction based on research.

    • a. Scientific journals: Best for current findings on new technologies.

    • b. Encyclopedias: Useful for information on extinct species or historical theories.

    • c. State/local agencies: Help with local policies or research (e.g., pesticide effects on squirrels).

  4. Conduct a Controlled Experiment: Test the hypothesis and collect data.

  5. Interpret and Analyze Data: Use tables and graphs to analyze.

  6. Draw Conclusions: Suggest improvements for future experiments.

  7. Communicate Results: Share findings for others to build upon.

B. Terms

  1. Hypothesis: An educated guess/prediction in “IF…THEN” form.

  2. Variables: Factors that are measured in an experiment.

  3. Independent Variable: The variable that is purposely changed (the “I” change).

  4. Dependent Variable: The variable that changes as a result of changing the IV.

  5. Control: The baseline measurement used for comparison.

  6. Constants: The factors that are purposely kept the same in the experiment.

  7. Experiment: A structured way to test a hypothesis.

Scientific Tools

C. Scientific Tools

  1. Balance: Used for measuring mass.

  2. Electron Microscope: Used for examining extremely small specimens.

  3. Light Microscope: Used for examining small specimens; led to the discovery of cells.

  4. Graduated Cylinder: Used for measuring precise volumes of liquids.

  5. Beaker: Less accurate tool for measuring volume.

D. Microscope Parts and Function

  1. Course Focus: Used to make large changes in focus.

  2. Diaphragm: Adjusts the amount of light.

  3. Revolving Nosepiece: Changes the magnification.

  4. Stage Clips: Holds down the slide.

  5. Ocular Lens: The lens you look through.

*Coverslip Application: A diagram should illustrate the proper technique to apply a coverslip to avoid bubbles.

Total Magnification Calculation:

  • Total Magnification = Ocular Lens x Objective Lens

  • Example: Ocular (10x) x Objective (100x) = Total (1,000x)

Characteristics of Living Things

A. 7 Themes of Biology

  1. Cells: The smallest unit of all life.

  2. Metabolism: Getting and using energy to carry out life functions.

  3. Interdependence: Organisms rely on each other to survive.

  4. Reproduction: Either asexually or sexually.

  5. Homeostasis: Maintaining a constant internal environment (e.g., body temperature).

  6. Heredity: Passing on traits to offspring.

  7. Evolution: Populations of organisms change over time.

B. Biological Terms (Smallest to Largest)

Cell → Tissue → Organ → Organ System → Organism → Population → Species → Community → Ecosystem → Biosphere

  1. Cell: The smallest unit of life.

  2. Tissue: A group of cells that carry out a similar function.

  3. Organ: A group of tissues that carry out a specialized function in the body.

  4. Organ System: A group of organs that work together to perform body functions.

  5. Organism: A single living thing.

  6. Population: A group of organisms of the same species that live in the same area and can interbreed.

  7. Species: A group of organisms that look similar and can produce fertile offspring.

  8. Community: A group of different species that live in the same habitat and interact with one another.

  9. Ecosystem: A community of organisms and their non-living environment.

  10. Biosphere: All of the world and its atmosphere that supports life.

Life at the Molecular Level

A. Inorganic Compounds (Typically DO NOT contain carbon)

1. Water

  • a. Water molecules have an unevenly distributed charge, making the molecule polar.

  • b. Hydrogen bonding is the attraction between the positive end of one water molecule and the negative end of another.

  • c. Many unique properties of water are caused by hydrogen bonding:

    • Capillary action: The movement of water up thin tubes, due to cohesion (water molecules ‘stick’ to each other) and adhesion (water molecules ‘stick’ to other substances).

    • Surface tension: Allows bugs to stand on water.

    • Ice floats because water expands when it freezes.

    • High heat capacity: Takes a lot of energy to raise or lower its temperature, helping organisms maintain homeostasis by keeping a constant body temperature.

  • d. Water is the universal solvent because it is a polar molecule and can dissolve many substances.

  • e. Cells are mostly water, therefore much of your body is made of water.

    • The pH scale ranges from 0-14.

    • Acids range from 0-6.

    • Bases range from 8-14.

    • A neutral solution has a pH of 7.

2. The Water Cycle

  • a. Water falls to the ground in the form of precipitation (letter unspecified in transcript, assumed 'A').

  • b. Water percolates through the soil to make ground water (letter unspecified in transcript, assumed 'B').

  • c. Water that doesn’t go into the ground is called runoff (letter unspecified in transcript, assumed 'C').

  • d. Water is taken into plants through the roots by capillary action.

  • e. Transpiration releases water vapor into the atmosphere from plant leaves (letter unspecified in transcript, assumed 'E').

  • f. Evaporation puts water from oceans and lakes into the atmosphere (letter unspecified in transcript, assumed 'F').

  • g. Water in the atmosphere forms droplets in clouds by condensation (letter unspecified in transcript, assumed 'G').

3. The Carbon Dioxide/Oxygen Cycle

  • a. Autotrophs use organelles called chloroplasts in their leaves to collect solar energy.

  • b. Photosynthesis occurs so plants can make glucose to use for energy.

  • c. Photosynthesis converts solar energy into chemical energy.

  • d. Photosynthesis uses CO2, water, and solar energy to form glucose & O2.

  • e. Animals cannot make their own food; therefore, they are called heterotrophs.

  • f. All organisms use organelles called mitochondria to perform a process called respiration, which breaks down food molecules to produce ATP for energy.

  • g. Respiration uses O2 and glucose to produce CO2 and water.

  • h. The gas made by respiration is CO2; the gas taken in by photosynthesis is CO2.

  • i. The gas taken in by respiration is O2; the gas produced by photosynthesis is O2.

B. Organic Compounds (Contain Carbon)

1. Carbohydrates

  • a. Carbohydrates are built to store energy in plants and are broken down to be used as cellular energy to accomplish the characteristics of life.

  • b. Monosaccharides are the building blocks of carbohydrates; example: glucose.

2. Lipids

  • a. Lipids are organic compounds that include fat, oil, and wax.

  • b. Lipids are used to store energy in animals.

  • c. Leaves have a protective lipid layer called the cuticle that prevents water loss.

  • d. Lipids, like those in whale blubber and human fat, help insulate organisms, protecting them and keeping them warm.

3. Proteins

  • a. Proteins are made up of amino acids joined together by peptide bonds.

  • b. Enzymes are a special group of proteins that speed up reactions.

  • c. Enzymes have active sites with specific shapes that allow them to interact with only one type of substrate.

  • d. Enzymes are unchanged during reactions.

4. Nucleic Acids

  • a. The two types of nucleic acids are DNA and RNA.

  • b. The building block of a nucleic acid is a nucleotide, which is made of a sugar, a phosphate, and a nitrogen base.

  • c. DNA is common to all living things and it stores genetic information.

  • d. In DNA, adenine bonds with thymine and guanine bonds with cytosine.

  • e. The nitrogen bases are held together by hydrogen bonds.

  • f. The shape of a DNA molecule is a double helix, discovered by Watson & Crick.

  • g. Rosalind Franklin took X-ray photographs of DNA that helped determine DNA’s structure.

  • h. Replication is a process that makes an exact copy of DNA.

  • i. The sugar in DNA is deoxyribose, but the sugar in RNA is ribose.

  • j. In DNA, adenine bonds with thymine, but in RNA it bonds with uracil.

  • k. RNA is single-stranded, and DNA is double-stranded.

  • l. DNA is copied by RNA, which becomes the pattern for making proteins.

  • m. Genetic engineering involves inserting foreign DNA into host DNA to make recombinant DNA.

Life at the Cellular Level

A. The Parts of the Cell Theory

(The specific parts of the cell theory are not provided in the transcript but implied as requiring a defined list of elements.)

B. Development of the Cell Theory

  1. Leeuwenhoek - First to observe living microorganisms through a microscope.

  2. Hooke - Observed cork and named cells.

  3. Schleiden - Studied plant cells.

  4. Schwann - Studied animal cells.

  5. Virchow - Concluded that all cells come from preexisting cells.

C. Types of Cells

  1. Eukaryotes - Have a nucleus

  2. Eukaryotes - Have organelles

  3. Prokaryotes - Includes the kingdom Eubacteria and Archaebacteria

  4. Prokaryotes - Do not have organelles (mini-organs)

  5. Eukaryotes - Includes Protists, Fungi, Plants, and Animals

  6. Both - Have DNA (HINT: ALL kingdoms have this in common)

  7. Eukaryotes - Go through mitosis

  8. Prokaryotes - Go through binary fission

  9. Both - Have ribosomes to synthesize (make) proteins

D. Cellular Organelles

  1. Nucleus - Command center of the cell; DNA in the form of chromosomes is here.

  2. Nucleolus - Small organelle in the nucleus that makes ribosomes.

  3. Ribosomes - The site of protein synthesis in prokaryotes and eukaryotes.

  4. Endoplasmic Reticulum - Transport system of the cell.

  5. Golgi Body/Apparatus - Collects, packages, and distributes proteins.

  6. Lysosomes - Contains digestive enzymes to break down old cell parts.

  7. Vacuole - Storage tank of the cell.

  8. Mitochondria - Organelle that conducts ‘respiration’ for the cell; the powerhouse of the cell.

  9. Chloroplast - Organelle that conducts ‘photosynthesis’ for plant cells.

  10. Centriole - Assists in cell division in animal cells only.

  11. Cytoplasm - The jelly-like material in which organelles float inside a cell.

  12. Cell Wall - Made of cellulose (plants) or chitin (fungi); boundary outside of the cell membrane in some cells.

  13. Cell Membrane - Encloses cell, controls what gets into and out of the cell.

  14. Mitochondria - Numerous in heart muscle cells because of the need for energy.

  15. Ribosomes - Numerous in cells that produce large quantities of proteins.

E. Differences Between Plant and Animal Cells

(The transcript indicates a table to be completed regarding plant and animal cell differences. Shape and Unique Parts are the two explicit categories. A comprehensive difference cannot be accurately extracted from the given source.)

F. The Fluid Mosaic Model and Movement Through the Cell Membrane

  1. The cell membrane is composed of phospholipids, proteins, and carbohydrates.

  2. The Fluid Mosaic Model describes the cell membrane.

  3. Passive transport is also called diffusion and it doesn’t require energy.

  4. Passive transport moves molecules from areas of high to low concentration.

  5. Facilitated diffusion - diffusion where carrier proteins help molecules across the membrane.

  6. Osmosis is a type of diffusion involving only the movement of water molecules.

  7. The type of transport that requires energy is active transport.

  8. The movement that requires energy moves molecules from low to high concentrations.

  9. Active transport that moves substances into the cell is called endocytosis.

  10. Moving solid particles into the cell is called phagocytosis.

  11. Moving liquids into the cell is called pinocytosis.

  12. Active transport that moves substances out of the cell is called exocytosis.

  13. Molecules are transported across the cell membrane by carrier proteins.

Cell Division

A. Mitosis

  1. A chromosome is made of two identical parts called chromatids.

  2. The parts of a chromosome are held together by a centromere.

  3. Only animal cells have centrioles to help with chromosome movement.

  4. During anaphase, sister chromatids are separated at the centromere and are pulled to opposite ends of the cell.

  5. DNA is replicated during interphase so each cell will have the same information.

  6. Chromosomes line up along the equator of the cell in metaphase.

  7. Loose or uncoiled chromosomes are actually DNA in the form of chromatin.

  8. During anaphase, spindle fibers shorten, which pulls chromosomes to the poles.

  9. After the nucleus divides, cytokinesis occurs: the division of the cytoplasm.

  10. In plant cells only, a cell plate forms during cytokinesis.

  11. In animal cells only, a cell furrow forms during cytokinesis.

  12. Spindle fibers are attached to chromosomes at the centromere

  13. Prophase - chromosomes become visible

  14. Telophase - nuclear membrane forms around each chromosome set

  15. Prophase - nuclear membrane begins to disappear

  16. Telophase - two daughter cells are formed

  17. (Diagram labeling of mitosis phases implied, but specific labels were not provided in the transcript.)

B. Meiosis

  1. Meiosis is a type of cell division that makes sex cells or gametes.

  2. The two types of sex cells are eggs and sperm.

  3. Mitosis consists of 1 division(s), while meiosis consists of 2 division(s).

  4. Mitosis makes cells with the same number of chromosomes as the parent cell, but meiosis produces cells with half the number of chromosomes as the parent cell.

  5. A human’s body cells have 46 chromosomes; sex cells or gametes have 23.

  6. For every chromosome your mother gave you, there is a homologous chromosome from your father with information regarding the same trait(s).

  7. When a cell has a full complement of homologous chromosomes from each parent (2 complete sets of chromosomes), the cell is said to be diploid.

  8. Sex cells have only ONE set of chromosomes; they are called haploid.

  9. When an egg and a sperm combine during fertilization, the zygote that is formed has the normal diploid number of chromosomes.

  10. Homologous chromosomes exchange information during prophase, which adds to diversity.

C. Making Proteins

  1. Almost everything in a living organism is made of or made by proteins.

  2. The process of protein synthesis consists of transcription and translation.

  3. During transcription, the genetic code is copied from DNA to mRNA.

  4. Because DNA can’t leave the nucleus, the message is carried out to the cytoplasm by mRNA.

  5. Once the message from DNA is copied, the mRNA leaves the nucleus and travels to a ribosome in the cytoplasm.

  6. A sequence of 3 bases on mRNA is called a(n) codon, but 3 bases on a tRNA molecule are called a(n) anticodon.

  7. Each codon is matched with an anticodon, and the tRNA transfers the amino acid to the ribosome.

  8. Each amino acid is linked together by peptide bonds to form proteins.

  9. Another name actually making proteins is translation.

  10. The sequence of nitrogen bases on DNA carry the genetic code.

D. Transcription and Translation

  1. mRNA: (Requires transcription of given DNA sequence: GGCCATTTCGATTTGAGC. Accurate mRNA not provided in document)

  2. Amino acids: (Requires translation of transcribed mRNA sequence. Accurate amino acid sequence based on provided DNA is not provided in document)

  3. This protein is made of (Number) amino acids. (Requires prior translation of mRNA sequence to accurately determine this number. Accurate number not provided in document)

E. DNA Technology

  1. DNA fingerprinting is used to identify crime suspects (such as murder and rape).

  2. Using gel electrophoresis, scientists can determine an individual’s DNA fingerprint. No two people have the same fingerprint, except for identical twins.

  3. The Human Genome project is considered a collaborative effort because 13 countries worked on it.

  4. The objective of the Human Genome Project was to understand the human DNA sequence.

  5. Scientists wanted to determine the sequence of bases to ultimately find the genes responsible for certain diseases and human traits.

Genetics

A. Vocabulary

  1. Heterozygous - Two different alleles, a hybrid (Tt)

  2. Heredity - Is the passing of characteristics from parent to offspring

  3. Genotype - Is the type of genes or alleles present in an organism’s genome

  4. Dominant - Form of gene that always shows even in the presence of recessive allele.

  5. Genome - All of the genes in an organism

  6. Alleles - Are different forms of the same gene (ex: tall vs. short)

  7. Homozygous - Two alleles of the same form that make up a genotype, pure breed (TT or tt)

  8. Gregor Mendel - Is the Father of Modern Genetics

  9. Recessive - Form of a gene only expressed in a homozygous state

  10. Trait - Is an inherited characteristic

  11. Phenotype - Is an organism’s physical appearance

  12. Genetics - Is the study of heredity

  13. Gene - Is a segment of DNA located on a chromosome that codes for a particular protein

B. Mendelian Genetics

  1. Punnett square - Table used to diagram the probability of getting certain genotypes

  2. A monohybrid cross looks at only one trait

  3. A dihybrid cross looks at two traits at a time

  4. The first generation of a ‘cross’ is the P or parental generation

  5. The offspring of the P generation is the F1 generation

  6. The offspring of the F1 generation is the F2 generation

  7. The Law of independent assortment states that each gene is inherited separately from others if they are on different chromosomes

  8. The Law of segregation states the 2 alleles for each trait separate as gametes form

  9. Incomplete dominance is blending of traits; red flowers + white flowers = pink

  10. Codominance - Both alleles are expressed equally, as in blood typing (A+B = AB)

  11. Sex-linked traits - Controlled by genes on sex chromosomes and are often more common in males than in females; colorblindness, hemophilia

C. Mutations

1. Gene Mutations

  • a. A gene mutation is a change in one or more nucleotide bases of DNA.

  • b. Mutations are caused by mutagens like UV light or chemicals

  • c. A point mutation is when 1 nucleotide base in DNA is changed

  • d. A frameshift mutation occurs if 1 or more nucleotides in DNA are added or deleted; this causes the codon sequence to be shifted.

    • Original DNA: ATAACGCCTATT

    • Number of codons: 4

    • mRNA sequence: UAUUGCGGAUAA

    • DNA with “G” deleted: ATAACCCCTATT

    • Number of complete codons: 4

    • mRNA sequence: UAUUGG GGAUAA

    • DNA with “C” added to the beginning: CATAACGCCTATT

    • Number of complete codons: 4

    • mRNA sequence: GUA UUGCGGAUAA

2. Chromosomal Mutations

  • a. A chromosomal mutation occurs if there is a change in the number or structure of a single chromosome or whole sets of chromosomes

  • b. Nondisjunction - Chromosomes don’t separate during meiosis

  • c. Translocation - Chromosome pieces are moved onto another chromosome

  • d. Inversion - Chromosome segment is inserted in reverse order

  • e. Duplication - A segment of a chromosome is repeated

  • f. Deletion - Segment of a chromosome is removed

  • g. Insertion - Segment of chromosome is inserted into another

  • h. Polyploidy - Whole extra sets of chromosomes in the same cell

  • i. In plants and animals, sex cells are haploid which means that they have half the number of chromosomes that a body cell has

  • j. Diploid - a cell with 2 sets of chromosomes (1 from mother; 1 from father)

  • k. Triploid - a cell with 3 sets of chromosomes

D. Genetic Disorders

  1. Only a karyotype detects mutations affecting the number of chromosomes

  2. Down Syndrome is trisomy on the 21st chromosome pair

  3. Trisomy occurs when there is an extra copy of a chromosome in a diploid cell

  4. Turner Syndrome is caused by only have one sex chromosomes, one X. pair. This condition is called a Monosomy.

Taxonomy

A. Classification

Rank

Classification Level

Trick to Remember

Implied Order

Correct Order

Taxonomic Rank

Notes

1.

Domain

Largest, most inclusive

2.

Kingdom

3.

Phylum

4.

Class

5.

Order

6.

Family

7.

good

Genus

8.

Species

Smallest, most specific

Note: The “Trick to Remember” column suggests a mnemonic, but no specific mnemonic is provided in the source document.

B. Naming Organisms

  1. Binomial nomenclature, or ‘2 name naming’ was developed by Linneaus.

  2. An organism’s scientific name is made of its genus then its species

  3. If 2 organisms are in the same genus, they must be in the same family

  4. Clostridium tetani and Clostridium botulinum are two types of bacteria from the Eubacteria kingdom. They are in different species, but they are in the same genus

  5. The Class of Mammals includes organisms such as rabbits and elephants which are in the same phylum but different species

  6. Only organisms that interbreed and produce fertile offspring are in the same species.

C. Kingdoms

Kingdom

Cell Type

Cell Structure

Number of cells

Nutrition

Examples

Eubacteria

Prokaryotic

Cell wall (Peptidoglycan)

Unicellular

Autotroph/Heterotroph

All common bacteria

Archeabacteria

Prokaryotic

Cell wall

Unicellular

Autotroph/Heterotroph

Extremophiles

Protista

Eukaryotic

Mixed

Uni/Multicellular

Autotroph/Heterotroph

Ameoba, Paramecium

Fungi

Eukaryotic

Cell wall (chitin)

Uni/Multicellular

Heterotroph

Mushrooms, yeast

Plantae

Eukaryotic

Cell Wall (cellulose)

Multicellular

Autotroph

Grass, Flowers

Animalia

Eukaryotic

No cell wall

Multicellular

Heterotroph

Cats, Jellyfish, Giraffe

Giraffa camelopardalis (genus) (species)

D. Viruses

  1. Viruses are considered nonliving because they cannot perform the characteristics of life without a host

  2. Viruses are made of only 2 organic compounds, DNA, and a capsid made of protein.

  3. A virus infects a cell by injecting DNA into a cell

  4. The cold, the flu and HIV are caused by a virus. (Note: the original document indicates a missing term to fill in, corrected as 'virus' here.)

  5. Antibiotics are typically used to fight bacterial infections. The word antibiotic literally means against life. Because viruses are considered nonliving, antibiotics don’t work against viruses

  6. Vaccines are used to help organisms make antibodies to build immunity. Vaccines are made from destroyed or weakened forms of a virus.

F. Sexual Reproduction in Plants

  1. ONLY the most complex kingdoms, like animals and plants regularly use sexual reproduction which requires 2 distinct gametes called sperm and eggs

  2. Body cells of a plant are made by mitosis, while sex cells are made by meiosis

  3. In sperm, the nucleus is located inside a pollen grain which will fertilize an egg

  4. The female part of a flower that contains ovules or eggs is called the pistil

  5. Pollen is located on the anther or stamen, which is the male part of a flower

  6. Pollination occurs when pollen from the stamen is deposited on the pistil, which can happen by wind, insects, and birds

Evolution

A. Origin of Life – Scientists Hypotheses

1. Disproving Spontaneous Generation

  • a. Through the early 1800s, people believed organisms could spontaneously develop, an idea know as spontaneous generation

  • b. In 1668, many believed maggots spontaneously generated from rotting meat. Francis Redi’s experiment disproved this by experimenting with meat in open jars, sealed jars and jars covered with gauze

  • c. It was also believed that bacteria spontaneously generated in broth. Lazzaro Spallanzani removed the air from a flask, boiled the broth and sealed the flask. No bacteria generated without exposure to the air

  • d. Some people still supported spontaneous generation but thought that air was a vital force, necessary for it to occur

  • e. In 1859, Louis Pasteur completely disproved spontaneous generation by using a special flask that allow air in but captured bacteria before it could get to the broth. No bacteria grew in the flask after boiling = no spontaneous generation

2. First Life

  • a. Earth’s atmosphere had to be very hot and with little oxygen for the first organic molecules to first form

  • b. Organic molecules clumped together for form self-replicating structures that later evolved into cells

  • c. Prokaryotic cells were the first to evolve

  • d. When cells gained the ability to do photosynthesis, they used up carbon dioxide and put more oxygen into the atmosphere

  • e. With more oxygen in the atmosphere, a wider variety of organisms evolved on land

  • f. Some cells engulfed each other leading to the formation of more complex cells that we now call eukaryotes.

B. Early Theorists

1. Lamarck

  • a. Law of Use and Disuse - if you don’t use it, you lose it

  • b. Lamarck believed that giraffe’s long necks were a result of being stretched because they were trying to reach tall trees, and the one’s who didn’t stretch died out

  • c. Inheritance of Acquired Traits - was his belief that if a characteristic occurs and is beneficial to an organism’s survival, then it will be passed on; ex. if a toe gets cut off and it’s helpful, then that trait gets passed on to offspring

  • d. NO evidence to support this theory so it was thrown out

2. Charles Darwin

  • a. Natural Selection - only the organisms that are best suited to their environments will survive

  • b. The Galapagos Islands were a cluster of islands that had different food sources. Because of this, the finches had different beaks to help eat the food

  • c. The Origin of Species was his book that compiled his evidence for evolution

C. Rates of Evolution

  1. Gradualism - organisms evolve as a result of small adaptive changes over time

  2. Punctuated equilibrium - short periods of rapid change followed by long periods of little or no change

D. Evidence of Common Ancestry

  1. Homologous structures: A bat’s wing, whale’s flipper, and human arm have the same number, type, and arrangement of bones; considered to have a common evolutionary origin

  2. The presence of the same number & type of bones in the wing of a bat and the arm and hand of a human suggests that a bat and a human must share common ancestors

  3. DNA sequence - similar amino acid sequences in proteins of horses and humans provides evidence of similar origin, this is the most specific way to compare organisms

  4. The fact that the DNA of humans and that of monkey species are 99% similar suggests that they probably share common ancestors

  5. The most specific way to provide evidence of common ancestry is by using DNA sequence

  6. Embryology - embryos of different organisms (chicken, human, rabbit) look similar at certain early stages, which means the same genes are working at those times

  7. The embryological development of the stages in the green box suggest that fish and rabbits are more closely related because they look alike (Note that gorillas wasn't an option in this case)

  8. Vestigial organs - are structures that have no apparent use; the appendix in humans may be a remnant of a digestive organ still found in other organisms and the pelvis and femur in a whale may be remnants of when whale ancestors had legs

  9. According to relative dating of fossils: the deeper under ground the fossil is, the older it is

  10. Absolute dating uses radioactive isotopes to determine an estimated age for fossils

Ecology

A. Ecological Succession

  1. Ecological succession is the sequential replacement of one ecological community with another. Succession is complete when a stable climax community is established

  2. Succession often begins after all life in a climax community is destroyed by fire. The result of this fire could be represented in the pictures to the right by letter (assuming W as the start point).

  3. Primary succession occurs as plants such as mosses and grasses begin to grow on bare surfaces. This could be represented by picture (assuming X to follow the destruction). *(Note: The original document