Biology Concepts Study Sheet

THE BASIC PRINCIPLES OF BIOLOGY

BASIC CONCEPTS FOR STUDENTS PREPARING FOR THE C.A.P.T. TEST

I. BIOLOGICAL SCIENCE: THE STUDY OF LIFE
        A. THE SCIENTIFIC METHOD: HOW SCIENTISTS STUDY BIOLOGY

  1. Observe phenomena and formulate stable and falsifiable (in case they are wrong) hypotheses
  2. Test hypotheses, collect data, and analyze statistically (if necessary)

II. EVOLUTION: The concept that all organisms are related to each other by common ancestry:
THE UNIFYING THEME IN BIOLOGY
        A. NATURAL SELECTION - A MECHANISM FOR HOW EVOLUTION OCCURS

  1. Survival of those offspring best adapted to the conditions in which they live:

    a. There is variation (based on genetic differences) in every population.
    b. Organisms (individuals) compete for limited resources.
    c. Organisms (individuals) produce more offspring than can survive.
    d. Organisms (individuals) pass genetic traits on to their offspring.
    e. Organisms (individuals) with the most beneficial traits (i.e. adaptations), are more likely to survive to the age of reproduction and thus pass their genes on to the next generation. This is called NATURAL SELECTION.
    Thus, nature is selecting offspring and shaping the evolution of species.

  2. Charles Darwin and Alfred Wallace, 19th century biologists, formulated the concept of natural selection independent of each other (although Darwin was first).
  3. IN SOME CASES THE BENEFICIAL TRAIT IS BEHAVIORAL: This is true for both instinctive and learned behaviors. In the case of humans, as a result of the evolution of our brains, learning and behavior -- and thus culture -- are particularly important to the survival of our species.

ORGANIC MOLECULES

ORGANIC MOLECULES: Molecules, made by living things, which contain carbon.
1. THE FOUR MOST COMMON ELEMENTS: H = Hydrogen, O = Oxygen, N = Nitrogen, C = Carbon
2. THE USE OF REPEATING UNITS:
A. MONOMER: a single repeating unit in a larger molecule (polymer)
B. POLYMER: a large molecule made of many monomers
3. THE FOUR TYPES:
A. CARBOHYDRATES: used for energy storage (sugars & starches)
B. PROTEINS: used as enzymes, hormones, and structural molecules

  1. ENZYMES: organic catalysts which speed up chemical reactions by lowering

CYTOLOGY: THE STUDY OF CELLS

I. CELL THEORY: All living things are composed of cells - cells are the basic unit of structure and function - all cells come from preexisting cells.
A. CELL SIZE: small to maximize surface area to volume ratio (SA/V) for regulating internal cell environment. As a cell's volume increases, the SA/V decreases.
B. CELL (PLASMA) MEMBRANE: composed of fluid-like phospholipid bilayer, proteins, and glycoproteins
C. CELL WALL: outside of cell membrane in some organisms. Composed of carbohydrate (e.g. cellulose or chitin) or carbohydrate derivative (e.g., peptidoglycan)
D. CYTOPLASM: Material outside nucleus

  1. Site for metabolic activity
  2. Cytosol: Solutions with dissolved substances such as glucose, C02, 02, etc.
  3. Organelles: (membrane-bound subunits of cells with specialized functions)

II. EUKARYOTIC CELLS: Complex cellular organization, larger than prokaryotes, and have membane-bound organelles (Nucleus, chloroplasts, mitochondria, vacuoles, Smooth & Rough E.R. [endoplasmic reticulum], Golgi bodies, lysosomes, vacuoles, etc.)

  1. Nucleus - DNA, chromosomes control cellular activities via genes
  2. Chloroplast - site of photosynthesis
  3. Mitochondrion - site of respiration (ATP production)
  4. Vacuole - general storage and space filling structure
  5. Ribosomes (no membrane) - site of protein synthesis

III. PROKARYOTIC CELLS: Simpler cellular organization with no nucleus or other membrane-bound organelles (they do have ribosomes).

ENERGY AND LIFE

I. OUR SUN: Most organisms must use the sun's energy (directly or indirectly) to become and remain in an organized state.
A. METABOLISM - Series of chemical reactions involved in storing (anabolism) or releasing (catabolism) energy, much of this through the use of enzymes
B. ADENOSINE TRIPHOSPHATE (ATP) - A high-energy molecule that is used by cells.
II PHOTOSYNTHESIS: Sunlight or radiant energy is captured by chlorophyll and carotenoid photopigments (found in cytoplasm in prokaryotes and chloroplasts in eukaryotes) and converted into sugar (glucose).
THE FORMULA:     6 CO2 + 12 H2O ----> C6H1206 + 6 02 + 6 H20
III. CELL RESPIRATION: Glucose is broken down in the mitochondria of eukaryotic cells, and the cytoplasm of prokaryotic cells, to produce ATP.
THE FORMULA:     C6H1206 + 6 02 ----> 6 CO2 + 6 H20
A. With O2 the energy yield from one molecule of glucose is 36 ATP; Without O2 the energy yield from one molecule of glucose is 2 ATP. O2 is thus very important in terms of energy.
B. In the absence of O2 a cell needs to perform a process known as fermentation, despite the fact that there is no net gain of energy.

  1. Lactic acid fermentation: produces 2 lactic acids (in yogurt, and anaerobic muscle use)
  2. Alcoholic fermentation: produces 2 alcohol molecules and 2 C02 molecules (hence the bubbles in champagne!)

CELL TRANSPORT:
HOW SUBSTANCES ENTER & LEAVE

I. PASSIVE TRANSPORT
A. RELIES ON THERMAL ENERGY OF MATTER; THE CELL DOES NOT USE ENERGY.

  1. Diffusion - movement from an area of high to low concentration
  2. Osmosis - Diffusion across a semi-permeable membrane

II. ACTIVE TRANSPORT
A. OPPOSITE DIRECTION FROM DIFFUSION;THE CELL DOES USE ENERGY.

CELL REPRODUCTION

CELLS REPRODUCE IN 2 STEPS
A. MITOSIS - division of nuclear material
B. CYTOKINESIS - division of remaining cellular contents of the cytoplasm
I. CELL CYCLE - steps B, C, D, & E together are called MITOSIS.
A. INTERPHASE - the main part of a cell's life, during which a cell grows and copies it's DNA.
B. PROPHASE - chromosomes condense and organize; nuclear membrane and nucleoli disappear, spindle apparatus assembled and attached to centromeres of duplicated chromosomes.
C. METAPHASE - spindles line up duplicated chromosomes along equator of cell, one spindle to each half or chromatid of duplicated chromosome.
D. ANAPHASE - centromere of each duplicated chromosome is separated and sister chromatids are pulled apart.
E. TELOPHASE - chromosomes uncoil, nucleoli reappear, cytokinesis occurs and two genetically identical daughter cells are produced.

ORGANISMAL REPRODUCTION AND MEIOSIS

I. SEXUAL PROCESSES: This greatly icreases the genetic variation in populations.
A. SEXUAL REPRODUCTION - involves the fusion of genetic material (gametes) from two parental organisms.
B. TO ENSURE THE PROPER CHROMOSOMAL NUMBERS IN THE ZYGOTE (FERTILIZED EGG), EACH GAMETE MUST HAVE HALF OR HAPLOID (n) OF THE ORIGINAL DIPLOID (2n) AMOUNT OF DNA.
C. MEIOSIS - Reduces the chromosome number by half and results in new genetic combinations in the gametes (which is enhanced further by crossing over).

GENETICS & MENDEL

INTRODUCTION:
A. GENETICS: The study of traits and their inheritance
B. 19TH CENTURY BIOLOGISTS BELIEVED THAT TRAITS BLENDED. If blending occurred, things would become more similar not different. Darwin and Wallace stated that variations or differences in offspring were necessary for natural selection to occur.
C. GREGOR MENDEL PROVIDED THE MOST PLAUSIBLE HYPOTHESIS FOR GENETICS:
MENDELIAN GENETICS - TWO LAWS were developed by using statistics to analyze results of crosses involving distinguishing traits of garden peas.
I. LAW OF SEGREGATION OF ALTERNATE FACTORS; DEVELOPED BY MENDEL USING SINGLE -TRAIT CROSSES
A. SINGLE-TRAIT CROSS BREEDING:
P1 (parents): RR x rr (true breeders) gametes R x r
F1 (offspring): Rr x Rr (monohybrids) gametes R and r x R and r
F2 (offspeing of 2 F1 organisms:
Genotypic ratios (the genetic makeup) - 1 : 2 : 1 of RR to Rr to rr
Phenotypic ratios (the trait shown)- 3 : 1 of
Round (dominant) to Wrinkled (recessive)
B. MENDEL'S FIRST CONCLUSIONS: Discrete factors (now known as genes) were responsible for the traits and these factors were paired, separated (which occurs during meiosis) and recombined (during fertilization). Alternate forms of factors or genes exist called alleles. The F1 individuals had two alleles, their genotype consisted of a dominant and recessive allele (e.g., Rr with R for round and r for wrinkled seed). Thus, the Fl's were hybrids. Their phenotype was similar to only one of original parents, the one with the dominant trait (e.g., round seed).
II. LAW OF INDEPENDENT ASSORTMENT: MENDEL CONCLUDED STATISTICALLY THAT THESE RESULTS OCCURRED BECAUSE ALLELES FOR ONE TRAIT OR GENE DID NOT AFFECT THE INHERITANCE OF ALLELES FOR ANOTHER TRAIT.
III. MENDEL UPDATED
A. GENES ARE FOUND ON CHROMOSOMES, AND THUS MULTIPLE TRAITS ASSORT INDEPENDENTLY AS LONG AS THEY ARE LOCATED ON DIFFERENT CHROMOSOMES. Mendel studied traits in peas that were each on separate chromosomes. Genes on the same chromosome are linked and thus will not normally assort independently.
B. INTERACTIONS BETWEEN ALLELES

  1. Complete Dominance - one allele dominates another allele

    a. R - this trait is called Dominant and shows up with either:
    two alleles RR = homozygous dominant or
    one allele Rr = heterozygous
    b. r - this trait is called Recessive and shows up only with:
    one allele rr = homozygous recessive
    c. Human Disorders:

    1. Huntington's Chorea: Dominant allele
    2. Achondroplasia (dwarfism): Dominant allele
    3. Sickle Cell Anemia: Recessive allele
    4. Cystic Fibrosis: Recessive allele
  2. Incomplete Dominance - neither allele is expressed fully
  3. Codominance - both alleles are expressed fully
  4. Multiple Alleles- more than two alleles for a gene are found within a population
  5. Epistasis - one gene alters the affect of another gene
  6. Polygenic Inheritance - many genes contribute to a phenotype
  7. Pleiotropy - one gene can affect several phenotypes
  8. Environmental Influences - genotype and environment interact to form a phenotype

IV. CHROMOSOMES AND SEX DETERMINATION
A. IN MANY ANIMALS SPECIAL SEX CHROMOSOMES DETERMINE GENDER. THE REMAINING CHROMOSOMES ARE CALLED AUTOSOMES.
B. IN HUMANS THERE ARE 44 AUTOSOMES AND TWO SEX CHROMOSOMES:
X AND X IN FEMALES & X AND Y IN MALES.
V. SEX-LINKED TRAITS: IN HUMANS, THE Y CHROMOSOME CONTAINS THE DETERMINANT FOR MALENESS, THE X CONTAINS MANY GENES. IF A MALE GETS A RECESSIVE (OR DOMINANT) ALLELE ON THE X CHROMOSOME FROM HIS MOTHER, HE WILL EXPRESS THE TRAIT. THEREFORE MALES ARE FREQUENTLY AFFLICTED WITH X-LINKED DISORDERS. A FEMALE MUST INHERIT A RECESSIVE ALLELE FROM BOTH PARENTS IN ORDER TO EXPRESS A RECESSIVE X-LINKED DISORDER.
A. Human Disorders:

  1. Colorblindness: Recessive allele on the X chromosome
  2. Hemophilia: Recessive allele on the X chromosome

MOLECULAR GENETICS

I. GENES, DNA & NUCLEIC ACIDS
A. GENE FUNCTIONS:

  1. To be preserved and transmitted
  2. To control various biological functions through the production of proteins (i.e., large, complex sequences of amino acids) and RNA.

II. THE CENTRAL PRINCIPAL
A. REPLICATION -

  1. DNA is copied from other DNA, by unzipping the Hydrogen bonds holding the two sides of the helix and pairing new nucleotides with the proper bases (i.e., A with T and C with G) on each separated side of the original DNA.

III. MUTATIONS: ANY RANDOM, PERMANENT CHANGE IN THE DNA MOLECULE. MANY ARE HARMFUL, SOME HAVE NO EFFECT, AND A FEW ACTUALLY BENEFIT THE ORGANISM. MUTATIONS PROVIDE THE RAW MATERIAL FOR EVOLUTION BY ADDING TO THE VARIATION IN EVERY POPULATION. NATURE SELECTS THOSE MUTATIONS THAT ARE BENEFICIAL OR ADAPTIVE IN ORGANISMS TO HELP SHAPE THE COURSE OF EVOLUTION.

POPULATION GENETICS

I. GENES IN POPULATIONS VERSUS INDIVIDUALS
A. POPULATIONS EVOLVE JUST AS DO SPECIES
B. GENOTYPE - Genetic composition of an individual
C. GENE POOL - Genetic composition of a population of individuals. That is, all alleles for all genes in a population. A small gene pool increases the chances of dangerous recessive alleles combining and being expressed in an individual.
D. EVOLUTION INVOLVES CHANGES IN GENE POOLS OVER TIME. To understand changes in gene pools as populations evolve, an understanding of non-evolving populations is necessary
E. BOTH ALLELIC FREQUENCIES AND GENOTYPIC RATIOS (I.E., GENE POOLS) REMAIN CONSTANT FROM GENERATION TO GENERATION IN SEXUALLY PRODUCING POPULATIONS, IF THE FOLLOWING CONDITIONS OF EQUILIBRIUM EXIST:

  1. Mutations do not occur.
  2. No net movement of individuals out of or into a population occurs.
  3. All offspring produced have the same chances for survival and mating is random. That is, no natural selection occurs.
  4. The population is large so that chance would not alter frequencies of alleles.

PHYLOGENETIC GROUPINGS

ORGANISMS ARE GROUPED ACCORDING TO SHARED CHARACTERISTICS. IN THE PAST THE GROUPINGS WERE DETERMINED BY SHARED PHYSICAL CHARACTERISTICS. THE ADVANCES IN BIOCHEMISTRY THIS CENTURY HAS ADDED TO THE SOPHISTICATION OF THESE GROUPINGS.
1. THE GROUPS, IN ORDER OF SIZE: with the group names for human included
A. KINGDOM - Animalia (The LARGEST grouping)
B. PHYLUM - Chordata
C. CLASS - Mammalia
D. ORDER - Primata
E. FAMILY - Hominidae
F. GENUS - Homo
G. SPECIES - sapiens (The smallest grouping)
2. SCIENTIFIC NAME (BINOMIAL NOMENCLATURE): This is used to avoid confusion between scienctists all over the world by establishing a universal name for every organism, which consists of the Genus & Species names (e.g., humans are Homo sapiens).
3. THE SIX KINGDOMS:
A. ANIMALIA: motile, multicellular, eukaryotic consumers.
B. PLANTAE: sessile, multicellular, eukaryotic producers.
C. FUNGI: sessile, multicellular, eukaryoticdecomposers.
D. PROTISTA: unicellular eukaryotes, which may be producers or consumers.
E. EUBACTERIA: unicellular prokaryotes, which may be producers, consumers, or decomposers.
F. ARCHAEBACTERIA: unicellular prokaryotes which can be found living in conditions that are similar to the earliest environments on earth (deep sea themal vents, hot springs, etc.). This kingdom is genetically quite different from all other bacteria, and is considered to be among the oldest group of organisms on earth.

ECOLOGY

I. PRODUCERS, CONSUMERS, & DECOMPOSERS
A. PRODUCERS: These organisms, also called AUTOTROPHS, produce their own food through either photosynthesis or chemosynthesis.
B. CONSUMERS: These organisms, also called HETEROTROPHS, eat the material that is made by producers, or other consumers.
C. DECOMPOSERS: These organisms, a special form of HETEROTROPH, break down dead organisms and return their nutrients to the soil, thus recycling the elements necessary for life.
II. FOOD CHAINS, FOOD WEBS, & TROPHIC LEVELS:
A. FOOD CHAINS vs. FOOD WEBS:

  1. FOOD CHAIN: It illustrates the fact that smaller organisms are eaten by larger organisms, who in turn are eaten by even larger ones.
  2. FOOD WEB: An even more accurate view that accounts for the fact that many organisms will eat a large variety of other organisms, forming an interconnected web.

III. CYCLES: These illustrate the way materials are recycled in ecosystems.
A. WATER: Water enters the atmosphere through evaporation, and transpiration (through the leaves of plants) -- it falls to the earth as precipitation (rain, snow, etc.) -- and it is absorbed into the groundwater, and enters lakes, rivers, etc.
B. CARBON: Carbon in the atmosphere (as CO2) is absorbed by plants & algae for photosynthesis -- the carbon becomes a part of these producers, as well as the consumers who eat them -- when all these organisms die they are broken down by decomposers who release CO2 into the atmosphere.
C. NITROGEN: N2 gas in the atmosphere is absorbed by nitrogen-fixing bacteria in the soil (in the roots of legumes) where the triple covalent bond is broken -- the nitrogen becomes a part of producers, as well as the consumers who eat them -- consumers release nitrogenous wastes which are broken down by bacteria in the soil -- when all these organisms die they are broken down by decomposers who release nitrogen into the soil -- some soil bacteria ultimately release N2 from these processes back into the atmosphere.
IV. POPULATIONS, COMMUNITIES & ECOSYSTEMS
A. POPULATION: All of the organisms of a single species in a given area. Many biologists are exploring the idea of the evolution of populations rather than individuals.
B. COMMUNITY: All of the organisms of all different species in a given area. This is an important ecological concept in that organisms have an effect on other organisms in their environment in both the large scale and the small (e.g., intestinal bacteria, parasites, etc.).
C. ECOSYSTEM: All of the living and non-living things in a given area. Organisms also have an effect on the non-living parts of their environment (e.g., plants greatly increased the amount of O2 gas in the atmosphere), and vice versa.
V. THE BIOSPHERE & GLOBAL WARMING:
A. THE BIOSPHERE: is the planet as a whole. It is made up of several biomes (regions with a characteristic types of ecosystems: desert, rain forest, etc.). It is so called because the effect of organisms on their environment can have GLOBAL consequences (as in the O2 example above).
B. GLOBAL WARMING: This phenomenon ic also called THE GREENHOUSE EFFECT. One of the reasons life can survive at all on this planet has to do with the way gasses in the atmosphere retain some of the heat energy from the sun. CERTAIN GASES, SUCH AS CO2 RELEASED FROM THE BURNING OF FOSSIL FUELS, HAVE RESULTED IN A CHANGE IN THE AVERAGE GLOBAL TEMPERATURE THIS CENTURY. THIS WILL ULTIMATELY RESULT IN THE MELTING OF THE POLAR ICE CAPS, AND SEVERE CLIMATE CHANGES, WHICH CAN ULTIMATELY HAVE SOCIAL & POLITICAL CONSEQUENCES AS AGRICULTURAL REGIONS LOSE THEIR ABILITY TO HARVEST CROPS.
C. THE OZONE LAYER: This is a different phenomenon in which O3 gas, known as OZONE, absorbs the energy from UV (Ultra Violet Light) Radiation and is converted into O2 gas. O2 gas is then transformed into O3 gas (OZONE) by UV radiation. This recycling process protects organisms from the harmful mutagenic effects of UV Radiation. CFC's (Chloroflurocarbons, SUCH AS FREON IN AIR CONDITIONERS) DESTROY THE OZONE LAYER, THUS INCREASING THE RISK OF SKIN CANCER.

BODY SYSTEMS
(mnemonic device: SLIC MEN R RED)

LARGER, MORE COMPLEX ORGANISMS ARE DIVIDED INTO GROUPS OF ORGANS, KNOWN AS ORGAN SYSTEMS, WHICH PERFORM SIMILAR TASKS. ALTHOUGH THESE ARE TAKEN FROM THE EXAMPLE OF HUMANS, SIMILAR SYSTEMS (OR FUNCTIONS) CAN BE FOUND IN MANY OTHER SPECIES OF ANIMAL; IN THE CASE OF THE SYSTEM FUNCTIONS, EQUIVALENTS CAN BE FOUND AS WELL IN MEMBERS OF OTHER KINGDOMS.

I. SKELETAL - The support structure.

A. 206 Bones:

  1. Axial - skull, spine, & ribcage
  2. Appendicular - shoulders, arms & hands, hips, legs & feet

II. LYMPHATIC (& IMMUNE) - The drainage (and defense) system.

A. Fluids and nutrients released by diffusion from the bloodstream are returned to the blood via the tubes of this system.
B. These fluids are filtered in Lymph Nodes where pathogens (disease-causing agents) are removed and destroyed.
C. EQUIVALENTS: xylem & phloem of plants, open circulatory systems of arthropods, etc.

III. INTEGUMENTARY - SKIN: the first line of defense.

A. Barrier to pathogens.
B. Regulation of body temperature through blood flow.
C. Production of Vitamin D.
D. EQUIVALENTS: cell walls of monerans & plants, bark of trees, etc.

IV. CARDIOVASCULAR - The delivery system.

A. Heart & Blood Vessels (Aorta, arteries, arterioles, capillaries, venules, vein, Vena Cava)
B. Blood carries many essential materials throughout the body: H2O, O2, CO2, nutrients, hormones, etc.
C. The action of the Heart (2 chambers in Fish, 3 chambers in Amphibians, 4 chambers in birds & mammals) pumps the blood through the blood vessels. The 4-chambered heart separates the oxygenated blood (from the lungs) and the deoxygenated blood (on the way to the lungs), thus maximizing the amount of O2 that reaches the body tissues.
D. EQUIVALENTS: xylem & phloem of plants, open circulatory systems of arthropods, etc.

V. MUSCULAR - The means of movement.

A. Over 600 muscles in the human body, many of which are arranged in antagonistic pairs.

  1. Antagonistic Pairs: muscles that do the opposite motion to each other (e.g., flexion of the Biceps & extension of the Triceps).

VI. ENDOCRINE - The SLOW control of the body.

A. Hypothalamus (master gland), pituitary, thyroid, parathyroid, thymus, adrenal, ovaries, testes, pancreas
B. Slow control of the body's functions through chemical means (via hormones). These hormones travel through the blood stream, and control everything from growth & development to blood-sugar levels.
C. EQUIVALENTS: plant growth hormones, insect hormones (used in metamorphosis), etc.

VII. NERVOUS - The RAPID control of the body.

A. Central Nervous System (CNS): Brain & Spinal Cord / Peripheral Nervous System (PNS): cranial, spinal, and other peripheral nerves.
B. Controls body movement, peristalsis & digestion of food, interpretation of sensory input, heartbeat, breathing, etc.
C. Sympathetic: controls body reactions to stress / Parasympathetic: slows down the body in the absence of stress.
D. EQUIVALENTS: nerve nets of cnidarians, ganglia of worms, etc.

VIII. RESPIRATORY - The means of gas exchange.

A. Epigliottis (prevents food blockage of trachea = choking) larynx (voice box), trachea, bronchi, lungs (bronchioles and alveoli).
B. Controls the intake of O2 and the release of CO2 (which is a waste) from the blood.
C. Breathing rate increases during exercise due to the greater need for O2, which is used to convert glucose into ATP.
D. EQUIVALENTS: cell membranes of monerans & protists, plant leaf stoma, gills of fish, etc.

IX. REPRODUCTIVE - The means of continuing the species.

A. Females: ovaries, fallopian tubes, uterus, vagina. Males: testes, vas deferens, prostate & cowpers glands, urethra, penis.
B. Haploid (n) gametes are produced in the ovaries (ovum), and testes (sperm).
C. Fertilization of the ovum by the sperm (thus producing the diploid [2n] zygote) occurs in the fallopian tubes.
D. Implantation and development of the zygote (now a blastocyst) into an embryo and then a fetus, occurs in the uterus over a period of nine months (divided into 3 trimesters).
E. The greatest period of development occurs in the 1st trimester, during which the embryo/fetus is the most vulnerable to birth defects by chemicals (teratogens). The 3rd trimester is largely one of growth in the fetus, although some development still occurs (especially in the lungs).
F. EQUIVALENTS: binary fission of monerans & protists, budding of yeast, plant flowers, etc.

X. EXCRETORY (URINARY) - The system of fluid waste removal.

A. Kidneys, ureters, urinary bladder, urethra.
B. Blood is filtered of wastes in the kidneys. A balance of solutes and body fluids is thus regulated by the production and release of urine.
C. EQUIVALENTS: cell membranes of monerans & protists, nephridia of annelids, green glands of arthropods, etc.

XI. DIGESTIVE - The system for breakdown and absorption of nutrients.

A. Primary Organs (through which food passes): mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus. Accessory Organs (provide digestive enzymes and, in the case of the liver, processes some of the food absorbed): salivary glands, liver, gall bladder, pancreas.
B. Through Mechanical Digestion (mouth & stomach) the food gets broken into smaller pieces, but the actual organic molecules remain the same.
C. Through Chemical Digestion (proteins start in the stomach, just about everything else is in the small intestine) the organic molecules are broken down from polymers to monomers.
D. These monomers are now able to absorbed in the small intestine for delivery by the blood stream. The water is absorbed by the large intestine.
E. EQUIVALENTS: cell membranes of monerans & protists, phagocytosis of amoeba, two-way digestive tract of cnidarians & flatworms, one-way digestive tracts of insects, vertebrates, etc.

IF YOU ARE INTERESTED IN MORE BIOLOGY (BEYOND THE C.A.P.T. TEST) . . .

A great deal more exists in the realm of biology. Every area above can be studied in a great deal more depth, especially in the area of biochemistry, where our understanding of the intricacies of how cells function chemically is growing at a tremendous rate. Students interested in this area of study should consider taking BIOTECHNOLOGY or A.P. BIOLOGY.
In Zoology ,Botany, & Microbiology there is a great deal of information to be learned about each of the phyla, as well as individual species from each group! Botany is discussed, and practiced , in HORTICULTURE. Zoology & Microbiology are discussed in A.P. BIOLOGY (both), ANATOMY & PHYSIOLOGY (some comparative Zoology), and MARINE BIOLOGY (Zoology).
Medicine is a growing field that deals with the intricacies of the human body. Those interested in such topics, and who are comfortable with dissection, should consider taking ANATOMY & PHYSIOLOGY.
Ecology is also a growing field. Some ecology is covered in ENVIRONMENTAL STUDIES and  A.P. ENVIRONMENTAL SCIENCE.

Science Department