Biology SOL Review Notes

CELL

• SYSTEM OF ORGANS
• ORGAN
• ORGANISM
• POPULATION
• TISSUE
• BIOSPHERE
• CELL ORGANELLES
• MOLECULE
• ATOM
• BIOMA
• BIOCENOSES
• ECOSYSTEM

Scientific Investigation

• Prior to formulating a hypothesis, an observation is made.
• Hypothesis:
  • Prediction of what will happen based on observation.
• Control:
  • Standard used for comparison in an experiment.
• Independent variable:
  • What is changed in an experiment.
• Dependent variable:
  • What is measured in an experiment.
• Constant:
  • Conditions that remain consistent throughout the experiment (e.g., temperature, sunlight, type of soil).

Data

• Qualitative Data
  • Physical description without using numbers.
  • Example: The cup is red.
• Quantitative Data
  • Using numbers.
  • Example: 5 cups.

Hypothesis

• Can be supported, modified, or rejected based on data collected.
• Tentative explanation that accounts for a set of facts that can be tested by further investigation.

Scientific Theory

• An accepted explanation of a large body of information, both experimental and inferential.
• Serves as an overarching framework for numerous concepts.
• Subject to change as new evidence becomes available.

Scientific Law

• A statement of fact meant to describe, in concise terms, an action.
• Generally accepted to be true and universal.

Experiment

• For an experiment to be valid, there must be:
  • A control.
  • One independent variable.
  • Repeatability.

Graphing the variables

• DV = Results
• IV = Change

Biochemistry

Water

• Absorbs heat when it evaporates, allowing organisms to release excess heat.
• Less dense when frozen (ice floats), preventing lakes and oceans from freezing solid.
• Water molecules are both cohesive and adhesive due to hydrogen bonding.
  • Cohesion: water sticking to itself.
  • Adhesion: water sticking to other molecules.
  • Capillary action: properties of adhesion and cohesion working together.
    • Example: water moves up a paper towel because water sticks to itself and other molecules in the towel.
• Two thirds of the mass of a cell is made up of water.
• Most biochemical processes of life occur in water solutions.
• Water is a universal solvent, dissolving many substances due to its polarity.
  • Water inside and outside of cells carries nutrients into cells and wastes away.

Water

• Solvent:
  • The dissolving agent.
• Solute:
  • The substance or particles being dissolved.
• Solute + solvent = solution
• The polarity of water creates a slightly positive charge on the hydrogen end and a slightly negative charge on the oxygen end.

pH

• Organisms can tolerate only small changes in pH because every cell has a particular pH at which it functions best.
• Changes in pH cause changes in enzyme conformation (shape), resulting in a change in activity.
• Most cells function best within a narrow range of temperature and pH.
• The pH of pure water is 7.
• Substances added to water can lower or raise the pH.
• At very low temperatures, reaction rates are too slow.
• High temperatures or extremes of pH can irreversibly change the structure of proteins and alter their function.
• Fluids in and around the cells have nearly constant pH.
• The most important way to maintain pH is through a buffer system.

Biomolecules (Macromolecules)

*4 Biomolecules
*Proteins
*Monomers: Amino acids
*Lipids
*Monomers: Fatty acid + glycerol
*Carbohydrates
*Monomers: Monosaccharide
*Nucleic Acid
*Monomers: Nucleotide

Proteins

• Polymer that links amino acids together.
• Carry out most of the cells' work.
• Functions:
  • Vary depending on shape.
    • Structural (hair, nails).
    • Transport (hemoglobin).
    • Movement (muscle fibers + cytoskeleton).
    • Regulates cellular function (hormones + enzymes).
    • Defense (antibodies).

4 levels of protein structure

• Primary structure
  • Primary sequence of amino acids
• Secondary structure
  • Secondary interactions between adjacent amino acids
• Tertiary structure
  • 3D folding of the polypeptide
• Quaternary structure
  • Arrangements of multiple polypeptides

Proteins - Enzymes

• Act as catalysts that speed up chemical reactions and control the rate of metabolic reactions.
• Control the chemical reactions that occur inside cells.
• Enzyme function depends on their shape.
• Three-dimensional shape allows it to recognize and bind with its substrate.

Lipids

• Primary Function
  • Insulation
  • Energy storage
  • Make up the cell membrane (phospholipid bilayer)
• Structure
  • Fats, Oils, Waxes
  • Provide energy for cells, cell structure, insulation
• Lipids & Proteins compose the cell membrane
• Cholesterol: gives cell membrane flexibility
• Structure (2 parts):
  • "Head" = glycerol
  • "Tails" = fatty acids
  • Monomer: Fatty Acid
  • Polymer: Lipid
  • hydrophilic head
  • Phospholipid
  • hydrophobic tail

Carbohydrates

• Primary Function
  • Energy storage

Nucleic Acids

• Primary Function
  • Controls cell activities by directing protein synthesis
  • DNA and RNA

Cells

• Cell Theory
  • All living organisms are composed of cells
  • All cells come from existing cells
  • Cells are the basic unit of structure and functions of living organisms
  • Cells contain specialized structures to perform functions necessary for life
• Modern Cell Theory
  • The modern cell theory also includes;
    • Energy flow (metabolism and biochemistry) occurs within cells
    • Cells contain hereditary information (DNA) passed from cell to cell during cell division
    • All cells are basically the same in chemical composition in organisms of similar species
• Scientists - Cell Theory
  • Anton van Leeuwenhoek -1673-used a microscope to view living organisms, he called these organisms “animolecules.”
  • Robert Hooke -1665- used the word “cell” to describe compartments he saw in a cork under a microscope.
  • Matthias Schleiden -1834- concluded that plants are multicellular organisms
  • Theodor Schwann - 1839- stated that animals are multicellular organisms
  • Rudolph Virchow - 1858 - studied reproduction of cells, stated that cells come from existing cells

Prokaryotic Cells

• Prokaryotic Cells
  • Earth’s first cells were prokaryotes
  • Prokaryotic cells are Earth’s most abundant inhabitants
  • They can survive in a wide range of environment
  • Two major forms - Eubacteria and Archaebacteria
  • Eubacteria are more know two us
  • Archaebacteria are located in more extreme environments
  • Contain DNA (within a nucleoid region)
  • Cell membrane, ribosomes,

Prokaryotes vs. Eukaryotes

• Eukaryotes differ from prokaryotes based on size, genetic material, surrounded by a nuclear membrane, and the addition of membrane bound organelles.
• Eukaryotes arose from prokaryotes and developed into larger, more complex organisms, from single celled protists to multicellular protists, fungi, plants, and animals.

Eukaryotic Cells

• Eukaryotic Cells
  • More complex than prokaryotic cells
  • Nucleus
  • Contain membrane bound organelles that carry out specialized functions
  • Some unicellular, most multicellular

Organelles and Functions

• Nucleus:
  • Contains DNA.
  • Controls cell activity.
• Nucleolus:
  • Site of ribosomal synthesis.
• Ribosomes:
  • Site of protein synthesis.
  • In cytoplasm or attached to RER.
• Mitochondria:
  • Site of cellular respiration.
  • Energy (ATP) is made.
• Chloroplast:
  • Site of photosynthesis (plant cell).
• Endoplasmic Reticulum (ER):
  • Transports materials through the cell.
• Golgi:
  • Site where cell products are packaged for export.
• Function of:
  • Lysosome - contains digestive enzymes
  • Cell membrane - controls what enters and leaves the cell
  • Cell wall -provides support - contains connective channels -plasmodesmata
  • Vacuole - storage - larger in plant cells
  • Cytoplasm - contains organelles and site of many chemical reactions
  • Centriole -organizes spindle fibers in animal cells - aids in cell division

Organelles & Functions

• Cytoskeleton (protein fibers)
  • Microtubules
  • Microfilaments
  • Intermediate filaments

Cellular Energy

• Adenosine Triphosphate (ATP) -energy used for cellular processes.

Photosynthesis

*Photosynthesis Converts solar energy in to the chemical energy of a carbohydrate
*Includes plants, algae, and cyanobacteria (autotrophs)
*Autotrophs – produce their own food (producers)

Chloroplasts

• Photosynthesis occurs in the chloroplast
• Carbon dioxide in the air enters a leaf through the stomata (small opening)
• Carbon dioxide and water diffuse into chloroplasts

Components of a Chloroplasts

• Stroma –fluid filled interior
• Thylakoids – flattened sacs within the stroma – contains chlorophyll and other pigments
• Grana – stacks of thylakoid membranes
• Chlorophyll- photosynthetic pigments that absorb solar energy

Photosynthetic Reaction (equation)

• $6 CO<em>2 + 6 H</em>2O \rightarrow C<em>6H</em>{12}O<em>6 +6 O</em>2$
  • Carbon dioxide + water yields glucose + oxygen gas

Two Sets of Reactions

• Light Reactions
  • Chloroplast
• Calvin Cycle (dark reaction or light independent reactions)

Light – dependent reactions

• The light – dependent reactions produce oxygen gas and convert ADP and NADP+ into the energy carriers ATP and NADPH.
• Occurs in the thylakoid membrane
• The pigments within the thylakoid membrane absorb solar energy

Light – dependent reactions

• Two types of pigments
  • Chlorophyll a – absorbs light in the violet and red regions of the visible spectrum
  • Chlorophyll b – absorbs light in the blue and red regions of the visible spectrum
    • Chlorophyll does not absorb light well in the green region of the spectrum so it reflects green
• Products of light – dependent reactions
  • ATP, NADPH and Oxygen

Calvin Cycle

• Also called light-independent reactions, C3 cycle, and dark reactions.
• Uses ATP and NADPH to produce high-energy sugars (carbohydrate).
• A series of reactions that uses carbon dioxide from the atmosphere to produce carbohydrates.
• Takes place in the stroma of chloroplasts.
• Does not require light.

Calvin Cycle

• Stage 1: Carbon dioxide fixation
• Stage 2: Carbon dioxide reduction -
• Stage 3: RuBP regeneration -

Calvin Cycle: Stage I

• Carbon dioxide fixation
• First step
• Carbon dioxide from the atmosphere is attached to RuBP, a 5- carbon molecule
• Results in a one 6- carbon molecule, which splits into two 3 -carbon molecules

Calvin Cycle: Stage 3

• Regeneration of RuBP
• Five molecules of G3P becomes three molecules of RuBP, three molecules of ATP become three molecules of ADP + P
• RuBP is needed to start the Calvin cycle

Calvin Cycle: Stage 2

• Reduction stage
• Reduction of carbon dioxide to a carbohydrate
• Energy and electrons needed for this reduction reaction
  • ATP and NADPH + H+ from the light reactions.

Cellular Respiration

• Cellular Respiration Reaction
• $C<em>6H</em>{12}O<em>6 + 6O</em>2 \rightarrow 6CO<em>2 + 6H</em>2O +ATP$
  • Glucose + Oxygen yields Carbon Dioxide + Water + Energy

Cellular Respiration

• Process that releases energy by breaking down (food mol glucose in the presence of oxygen: Three Steps
  • Glycolysis,
  • Krebs cycle
  • Electron transport chain
• Glycolysis
  • the first step in cellular respiration
  • Occurs in the cytoplasm
  • breaks glucose down into two molecules of pyruvic acid
  • produces a total of 4 ATP, two are used with a net gain of 2ATP

Cellular Respiration Step Two

• Krebs Cycle
  • Second stage of cellular respiration
  • Two pyruvic acid are broken down into carbon dioxide in a series of energy- extracting reactions
  • Produces 2ATP

Cellular Respiration Step Three

• Electron Transport Chain
  • Last stage in cellular respiration
  • uses high-energy electrons from the Kreb Cycle to convert ADP into ATP (32 ATP)
  • Total ATP from cellular respiration 38 ATP produced, but a net gain of 36 ATP

Anaerobic Respiration

• When oxygen is not present glycolysis is followed by fermentation.
• Fermentation
  • a process by which cells release energy without oxygen
  • Types of Fermentation
    • Alcoholic Fermentation
    • Lactic Acid Fermentation

Fermentation

• Alcoholic
  • occurs in yeasts and other microorganisms, produces carbon dioxide and alcohol when oxygen is not present
• Lactic Acid
  • occurs in the muscle cells, no oxygen is present, converts glucose into lactic acid and produces 2ATP

Cellular Transport

• Cell Membrane
  • The Fluid Mosaic Model

Cell Membrane

• Homeostasis of a cell is maintained by the plasma membrane
• Controls the movement of materials in and out of the cell
• Communication between cells
• Cell recognition to facilitate multiple metabolic functions

Cellular Transport

• Passive transport
  • cellular transport that does not require energy
  • Types
    • Diffusion
    • Osmosis
    • Facilitated diffusion
• Active transport
  • cellular transport that requires energy in the form of ATP
  • Types
    • Sodium-potassium pump
    • Endocytosis
    • Exocytosis

Passive Transport (no energy)

• Osmosis
  • the movement of water across a semipermeable membrane
• Facilitated diffusion
  • does not require energy but requires the use of protein channels embedded in the membrane to move substances
• Diffusion
  • movement of a substance from an area of high concentration to an area of low concentration

Osmosis Tonicity

• Hypotonic solution
  • in a hypotonic solution water will move inside of the cell causing the cell to swell
• Isotonic solution
  • in an isotonic solution water moves at an equal rate inside and outside the cell
• Hypertonic solution
  • in a hypertonic solution water will move outside the cell causing the cell to shrink

Active transport (requires energy)

• Endocytosis
  • requires energy, when the cell engulfs substances that are too large to pass through (vesicles)
• Exocytosis
  • requires energy, when the cell expels waste or larger molecules out of the cell through vesicles
• Sodium-potassium pump
  • requires energy (ATP). the protein pumps Na+ ions out of the cell and K+ ions into the cell

Cell Cycle and Mitosis

• Cell cycle
  • - a series of events that cells go through as they grow and divide

Interphase

• Growth Stage 1 (G1) – First growth phase
• Synthesis Stage (S) – replication of DNA
• Growth Stage 2 (G2) – Second growth phase, preparation for mitosis/cell division

Mitosis

• Mitosis
  • the part of cell division during which the nucleus divides
  • Occurs in somatic cells
    • Stages of Mitosis
      • Prophase
      • Metaphase
      • Anaphase
      • Telophase
    • Cytokinesis
      • division of the cytoplasm during cell division

Prophase

• Nucleus disappears
• Duplicated chromosomes become visible
• Spindle fibers start to form
• Centromeres are present

Metaphase

• Centromeres of duplicated chromosomes align at the metaphase plate (in the middle)
• Spindle fibers attach to the sister chromatids

Anaphase

• Sister chromatids move apart and become daughter chromosomes
• They move to opposite poles
• They receive the same number and chromosomes as the parental cell

Telophase

• Nuclear Envelope reforms
• Nucleoli reappear
• Chromosomes uncoil
• Spindle fiber disappears

Cytokinesis

• Cytoplasm divides
• Cell division takes place
• Two new identical daughter cells form

Control of the Cell Cycle

• Enzymes (proteins
  • Some trigger cell division
  • Some inhibit cell division
  • Production of enzymes are controlled by a gene
    • Gene
      • portion of DNA that controls the production of one protein
• Cell-to-cell communication
  • Contact inhibition- cells will continue to grow in a given space until they touch each other (normal case).
  • Cells produce certain chemicals to tell each other when to stop dividing
  • Chemicals are also controlled by genes. How is the cell cycle normally controlled?

Abnormal control of cell division

• Cancer
  • Cell death or uncontrolled division of cells
  • Affect normal cells by depriving them of nutrients
  • In late stages of cancer, cancer cells enter the bloodstream and deposit in organs (metastasis) and disrupts normal organ function
• Why does cancer occur?
  • Changes occur in genes that control the production of the enzymes and chemicals that control the cell cycle
• What causes changes in gene mutations?
  • Genetics- people are born with mutations, Environmental - carcinogens - substance that is classified as cancer causing

Meiosis

*Process of reduction division
*Chromosome number cut in half through separation of homologous chromosomes
*Results in 4 genetically different haploid cells

Meiosis - Important terms

• Homologous chromosomes - two chromosomes that both carry genes controlling the same characteristics
• Genome- a complete (haploid) set of an organism's genes
• Haploid cell
  • (n) a cell with a single set of chromosomes
• Diploid cell
  • (2n) contains two homologous sets of chromosomes
• Gametes
  • sex cells, egg or sperm (haploid)
• Zygote
  • fertilized egg (diploid)
• Sex chromosomes
  • chromosomes that determine the sex of an individual

Interphase (Prior to Meiosis)

• Chromosomes duplicate
• Chromosomes consist of two genetically identical sister chromatids attached together
• Chromosomes aren't visible under a microscope except as a mass of chromatin

Meiosis 1

• Meiosis 1 Prophase 1
  • Each chromosome pairs with its corresponding homologous chromosome (synapsis) to form a tetrad
  • During synapsis, chromatids of homologous chromosomes exchange segments in a process called crossing over
  • Tetrad - contains 4 chromatids

Meiosis 1 Metaphase 1

• Spindle fibers attach to the chromosomes
• Homologous chromosome pairs align at the metaphase plate
• Homologous chromosomes are held together at sites of crossing over

Meiosis 1 Anaphase 1

• Homologous chromosomes separate, and are pulled to opposite poles by the centromeric spindle fibers
• Sister chromatids remain attached at the centromere

Meiosis 1 Telophase 1

• Nuclear membranes form
• Cell separates into two haploid daughter cells
• Each having one chromosome from each homologous pair

Meiosis II

• Meiosis II is very similar to mitosis

Meiosis II Prophase II

• Meiosis 1 results in 2 haploid daughter cells each with half the number of chromosomes as the original cell
• Cells have one chromosome from each homologous pair

Meiosis II Metaphase II

• The chromosomes align on the metaphase plate

Meiosis II Anaphase II

• Sister chromatids separate and move toward opposite ends of the pole

Meiosis II Telophase II

• Spindle disappears
• Nuclei form
• Cytokinesis takes place
• Meiosis results in four haploid (4n) daughter cells

DNA, RNA & Protein Synthesis

*DNA Scientists
* Watson & Crick
* Completed the double helical, semiconservative model of DNA
* Rosalind Franklin & Maurice Wilkins
* X-ray crystallography
* Erwin Chargaff
* percent of nitrogen bases A-T, and G-C
* Hershey & Chase
* Concluded that the genetic material in a bacteriophage was DNA not protein
* Avery, McCarty, & MacLeod
* Discovered that DNA is the nucleic acid that stores and transmits the genetic Information from one generation of an organism to the next.
* Griffith
* Transformation
* he mixed the heat-killed, disease causing bacteria with live harmless bacteria and injected the mixture into the mice, they developed pneumonia and died. Their lungs were filled with disease-causing bacteria.
* Meselson & Stahl
* semiconservative model
* in DNA replication half of the DNA is the from the original in the two copies of DNA.

DNA Structure

• Composed of nucleotides
  • Deoxyribose (5-Carbon Sugar)
  • Nitrogen base
    • Adenine, Thymine, Cytosine, and Guanine
• Phosphate Group

DNA Structure

• Double helix (twisted ladder)
• Sugar phosphate backbone
• Rungs of the ladder are the nitrogen bases
• Nitrogen bases held by hydrogen bonds

DNA Replication

• Occurs in the S phase of the cell cycle during interphase
• The parent strand of DNA is unzipped by the enzyme helicase
• New strands are added by the enzyme DNA polymerase in the 5’ to 3’ directions.
• When the DNA is copied, both copies have one parent strand and one original strand

RNA

• RNA
  • Cytosine
  • Uracil
  • Guanine
  • Adenine
  • Single stranded
  • The nitrogen base Uracil replaces Thymine
    • Adenine - Uracil
    • Guanine - Cytosine

Types of RNA

• mRNA- messenger RNA
  • carries the DNA code to the ribosome
• tRNA - transfer RNA
  • -transfers the code to the amino acid
• rRNA - ribosomal RNA
  • - ribosome - site of protein synthesis -

Protein Synthesis

• Transcription
  • DNA --→ RNA
    • synthesizing mRNA from the DNA strand

Protein Synthesis

• Translation
  • RNA --→ Protein
    • translates the code from the mRNA(codon), attached to the tRNA(anticodon), and translates to the amino acid to build the protein
• Codon
  • triplet that codes for the amino acid (on the mRNA)
• Anticodon
  • on the tRNA, attaches to and reads the code from the mRNA to find the correct amino acid

DNA Technologies

• DNA technologies allow scientists to identify, study, and modify genes. Forensic identification is an example of the application of DNA technology.
• Genetic engineering techniques are used in a variety of industries, in agriculture, in basic research, and in medicine. There is great benefit in terms of useful products derived through genetic engineering (e.g., human growth hormone, insulin, and pest- and disease -resistant fruits and vegetables).
• The Human Genome Project is a collaborative effort to map the entire gene sequence of organisms. This information may be useful in detection, prevention and treatment of many genetic diseases. The potential for identifying and altering genomes raises practical and ethical questions.
• Cloning is the production of genetically identical cells and/or organisms

Mutations

• Chromosomal Mutations
  • May Involve changing the structure of a chromosome, or the loss or gain of part of a chromosome
    • Types
      • Inversion - a segment of the chromosome breaks of flips upside down and reattached in the chromosome
      • Deletion -a section of the chromosome breaks off

Types of Chromosomal Mutations continued

• Duplication
  • when a section in of the DNA is duplicated in the chromosome
• Translocation
  • •Involves two chromosomes that aren’t homologous, part of one chromosome is transferred to another chromosomes
• Nondisjunction
  • failure of chromosomes to separate during meiosis, causes gamete to have too many or too few chromosomes

Gene Mutations

• Change in the nucleotide sequence of a gene that only change one protein
  • Point mutations - Change of a single nucleotide includes the deletion, insertion, or substitution of one nucleotide in a gene
  • Frameshift mutation - gene mutation that occurs if one or more nucleotides are inserted or deleted, this changes the entire reading frame

Genetics

• Gregor Mendel
  • Austrian monk, who lived in a monastery
  • Father of Genetics
  • Studied patterns of inheritance
  • Used pea plants

Important Terms

• Genetics
  • the study of heredity
• True Breeding
  • organisms that produce offspring identical to themselves if allowed to self-pollinate
• Cross pollination
  • cross pollinated pea plants
    • joined male and female reproductive cells combining tall and short pea plants
• Hybrid
  • the offspring of crosses between parents of different traits
• Allele
  • different forms of a gene
• Dominant
  • ( T ) allele that is expressed if present
• Recessive
  • ( t )alleles that are not expressed if a dominant allele is present

Terms

• Homozygous
  • two identical alleles for a particular trait example; T T or t t
• Heterozygous
  • two different alleles for the same trait example: Tt
• Punnett Square
  • genetic cross that shows the possible gene combinations
• First filial
  • ( F1 ) is the offspring of the P, or parental generation
• Phenotype
  • Physical characteristic of traits (Tall, Tall, Short)
• Genotype
  • alleles for different traits ( T T), (Tt), or (tt)
• Genes
  • the chemical factors that determine traits
• Trait
  • specific characteristics that varies from one individual to the next
• Heredity
  • passed from one generation to the next

The law of segregation

• Each individual has two factors for each trait.
• The factors segregate (separate) during the formation of gametes.
• Each gamete contains only one factor from each pair of factors.
• Fertilization gives each new individual two factors from each trait.

Patterns of Inheritance

• Sex-linked inheritance
  • traits controlled by genes on the sex chromosomes, female x-linked, male Y-linked, Example: color-blindness, X-linked
• Polygenic inheritance
  • occurs when a trait is governed by two or more sets of alleles, Example: Skin color

Classification of Living Things

• Classifications
  • Domains
    • Archaea
    • Eubacteria
    • Eukarya
  • Kingdoms
    • Archaebacteria
    • Eubacteria
    • Protista
    • Fungi
    • Plantae
    • Animalia

Basis for modern taxonomy

• Homologous structures (same structure, different function)
• Similar embryo development
• Molecular Similarity in DNA, RNA, or amino acid sequence of Proteins

Viruses

• Not living
• Contain DNA
• Nucleic acid core surrounded by a protein coat
• Reproduce inside living cells (host required)

Viral Reproduction

*A virus must insert its genetic material into the host cell.
*The viral genetic material takes control of the host cell and uses it to produce viruses.
*The newly formed viruses are released from the host cell.

Evolutionary Scientists

• Charles Darwin
  • -Theory of evolution through natural selection, species changing over time
• Ernst Mayr
  • proposed that when a population of organisms becomes separated from the main group by time or geography, they eventually evolve different traits and can no longer interbreed
    • speciation
• Jean Baptiste Lamarck
  • -inheritance of acquired traits
  • during an organism's lifetime through use or disuse.
• Stephen Jay Gould
  • his idea of punctuated equilibrium proposes that organisms may undergo rapid (in geologic time) bursts of speciation followed by long periods of time unchanged.
    • This view is in contrast to the traditional evolutionary view of gradual and continuous change

Adaptation

• Natural selection is a process by which organisms with traits well suited to an environment survive and reproduce at a greater rate than organisms less suited to that environment, and is governed by the principles of genetics.
• The change in frequency of a gene in a given population leads to a change favoring maintenance of that gene within a population and if so, may result in the emerging of a new species. Natural selection operates on populations over many generations.
• Depending on the rate of adaptation, the rate of reproduction, and the environmental factors present, structural adaptations may take millions of years to develop.

Adaptations

• Adaptations sometimes arise abruptly in response to strong environmental selective pressures for example, the development of antibiotic resistance in bacterial populations, morphological changes in the peppered moth population, and the development of pesticide resistance in insect populations.

Genetic mutations

• Genetic mutations and variety produced by sexual reproduction allow for diversity within a given population.
• Many factors can cause a change in a gene over time.
• Mutations are important in how populations change over time because they result in changes to the gene poole

Fossil age

• Relative dating
  • - estimated age in comparison to other fossils, determined by comparing its placement with that of fossils in other layers of rock
• Radioactive dating
  • the use of half-lives to determine age sample
    • In radioactive dating, scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.
• Half-life is the length of time required for half of the radioactive atoms in a sample to decay.

Ecology

• The study of living organisms and their interactions with their nonliving environment. (ecosystem)
• Biotic - living organisms in an environment
• Abiotic -nonliving factors in an environment

Ecological Levels of Organization

• Organisms
  • individual species
• Population
  • group of species living together, mating
• Community
  • collection of interacting populations
• Ecosystem
  • consists of all the interacting species and the abiotic environment in a given geographic area
• Biosphere
  • all the ecosystems together

Ecosystem

• All matter including essential nutrients cycle through an ecosystem.
• The most common examples of such matter and nutrients include carbon, nitrogen, and water.

Biogeochemical Cycle

• Main processes in the water cycle
  • Evaporation
  • Transpiration
  • Condensation
  • Precipitation

Energy Flow

• Food Chain

Climax Community

*A climax community occurs when succession slows down and a stable community is established.
*The climax community in most of Virginia is a deciduous oak-hickory (hardwood) forest.

Ecological Succession

• Primary succession
  • Succession that occurs on surfaces where no soil exists.
• Secondary succession
  • Succession that occurs after a natural disaster without removing the soil.
• Succession
  • - a predictable change in the sequence of species that establish in a particular area over time.

Human Impact

• As the human population increases, so does human impact on the environment.
• Human activities that have changed Earth’s land, oceans, and atmosphere. Some of these changes have decreased the capacity of the environment to support some life forms.
• reducing the amount of forest cover
• Increasing the amount and variety of chemicals released into the environment
• Intensive farming

Body Functions

• Human beings are composed of a group of cells that are specialized to provide the human organism with the basic requirements for life;
  • Obtaining food
  • Deriving energy from food
  • Maintaining homeostasis
  • Coordinating body functions
  • Reproducing