Biology 30 Final Review January 2025 PDF

Biology 30 - Final Review – January 2025 Unit One - What is Life? Chapter Fourteen - How Did Life Begin? 1. List and describe the THREE parts of the cell theory- Cells are basic units of life, all living things are made of cells, cells come from other cells. 2. Define spontaneous generation (abioge...

Biology 30 - Final Review – January 2025 Unit One - What is Life? Chapter Fourteen - How Did Life Begin? 1. List and describe the THREE parts of the cell theory- Cells are basic units of life, all living things are made of cells, cells come from other cells. 2. Define spontaneous generation (abiogenesis) and give TWO examples of it from prior to the seventeenth century- Spontaneous generation states that living things could arise from nonliving things. Examples of spontaneous generation include maggots appearing on rotting meat, and fish which appeared in ponds that were previously dried out. 3. Describe, in DETAIL, Redi's, Spallanzani and Pasteur's experiments (as well as their accompanying conclusions.- Redi noticed and described the different developmental forms of flies. Using glass jars and meat, Redi assigned uncovered jars as the control group and covered groups as the experimental group. During observation, Redi noticed that tiny wormlike maggots turned into sturdy oval cases (eggs), from which flies later hatched from. Another observation he had was that maggots seemed to appear where adult flies had previously landed. These observations led Redi to question the commonly held belief that flies generated spontaneously from rotting meat. Spallanzani hypothesized that microorganisms formed from other microorganisms and not air. He conducted an experiment by testing the growth of microorganisms within meat broth. He reasoned that boiling the brother would kill all organisms within the flask. Once he boiled he then sealed the bottles once they filled with steam. He had a control group which he left open, and an experimental flask in which he melted closed. In the end of the experiment he concluded that the boiled broth which was left over was contaminated. Pasteur followed Spallanzani's experiment but added his own factor which was a curved neck flask. This flask allowed the air from inside and outside to mix but prevented microorganisms from entering the flask. Broth within the flask stayed clear for a year until pasteur broke the the neck of the flask. A day after the neck had been broken, the broth became cloudy and contaminated with microorganisms, Pasteur reasoned that the contamination was due to microorganisms in the air. 4. Describe the first cellular life on Earth (Origin of Life Assignment, C #5)- The first bacteria being cyanobacteria was photosynthetic, meaning it did not need oxygen to survive but it produced oxygen. Until the cyanobacteria, there was no oxygen present. 6. Define autotroph, heterotroph – as well, give an example of each.- Autotrophs are organisms which are able to make their own food, such as grass, heterotrophs are organisms which eat other organisms, such as a cow. 5. Describe in DETAIL prokaryote and eukaryote cells. Additionally, be able to compare and contrast them – how are they the same? How are they different? Which kingdom(s) are prokaryotic? Which kingdom(s) are eukaryotic?- Prokaryotic cells- do not have a nucleus or other membrane bound organelles. DNA is suspended in the cytoplasm. Most are microscopic single celled organisms.​Belong to the bacteria kingdom. Eukaryotic cells- have a nucleus and other membrane bound organelles. The nucleus, the largest organelle, encloses genetic information. May be multi or single celled. Belongs to kingdoms Animalia (Metazoa), Plantae, Fungi and Protista. They BOTH have genetic information and cell membranes. 6. Describe Lynn Margulis' research in the late 1900s that suggested how prokaryotes evolved into the first eukaryotes (Origin of Life Assignment, C #9) – as well as describe the scientific evidence that supports this theory. (Origin of Life Assignment, C #10)- Lynn researched these cells and found that about 1.5-2 billion years ago a small aerobic prokaryote entered and began to live and reproduce inside larger anaerobic cells. Lynn proposed that this was an invasion turned into a mutually beneficial relationship called endosymbiosis. It is thought the aerobic prokaryote eventually gave rise to the modern mitochondria. Chloroplasts and the mitochondria replicate independently from the replication cycle that contains them. Chloroplasts and the mitochondria contain some of their own cells and ribosomes. they can copy themselves independently within the cell in which they are found. Chapter Fifteen - Evolution: Evidence and Theory 1. Describe Lamarck’s Theory of Evolution and explain why we still study it. What points did he get “right? What did he get “wrong” - Why is his theory no longer supported by the scientific community?- Lamarck's Theory of Evolutions hypothesized that traits acquired over a lifetime ate passed onto offspring and that structures formed through repetitive use or structures could be lost through lack of use. We still study him because he was the first to state that organisms change overtime and that physical characteristics could be inherited and were driven by environmental changes. What he got wrong was that there was a “need” to change as the world was changing. What he got right, although he stated it incorrectly, was that traits are passed down from generation to generation. 2. State the THREE points of Darwin's theory of Descent with Modification.- States that newer forms appearing in fossil records are actually modified descendants of older species. Stated that all living things descended from one or a few common ancestors. Accounted for the fact that similar organisms arise in the same geographical location. 3. State the THREE points of Darwin's theory of Natural Selection.- Overproduction- More organisms are born than can survive. Variation- When organisms are born, they are ot all the same. Adaptation- the “strong” of the “best suited” that are selected by the environment survive and pass down these traits to their offspring. 4. List and thoroughly describe FIVE things that are evidence of evolution (see “Evolution in Process” assignment).- The beaks of birds (homologous), the wings of hummingbirds and humming moths (analogous), appendix and tailbone of a human (vestigial), the early stages of certain animals in utero (embryology), many species have the red blood cells (macromolecules). 5. Be familiar with the following terms from the “Evolution in Process” assignment: Homologous structures- Similar features that originated in a shared ancestor Analogous structures- Serve identical functions and look somewhat alike, however, they may have very different internal anatomy Coevolution- The change of two or more species in close association Convergent evolution- When the environment selects similar phenotypes, even though the ancestral types were very different Divergent evolution- Two or more related populations or species become more and more dissimilar Adaptive radiation- Many different related species evolve from one single ancestral specie Artificial selection- The artificial process in which divergence can be sped up 6. Know the theory of continental drift/plate tectonics, what scientist was responsible for this theory, and how it explained the geographical distribution of species such as marsupials.- German scientist Wegener suggested that the present continents had once been joined in a supercontinent called Pangaea. The thought was that these big land masses were floating apart over the Earth's hot liquid interior. Molten rock would rise to the ocean floor and cool where it meets the land it is forced beneath the continent. It explains geographical distribution because new islands were formed such as the Galapagos which formed new environments for new species. 7. From the notes “What Causes Variation”: a)​ Define isolation- The separation of once two coliving species b)​ Identify what isolation can lead to- Can lead to genetic divergence c)​ List and describe the types of isolation that can occur- Geographic isolation- physical separation of members from a population Reproductive isolation- results from barriers to successful breeding groups in the same area Temporal isolation- exists when timing prevents reproduction between populations Behavioural isolation- isolation caused by different courtship or mating behaviours 8. What does LUCA stand for? How can you identify LUCA on a cladogram?- LUCA- Last Universal Common Ancestor. You can identify the LUCA by looking at the root of the cladogram. Chapter Sixteen - Speciation 1. Define homeobox genes and give an example.- Homeobox genes- Any of the developmental control genes that define the head to tail pattern of development in animal embryos. An example is when a fruit flie grows a leg out of where its antenna should be. 2. Define epigenetics and be able to describe how it affects DNA. - Epigenetics- Refers to external modifications to DNA that turn genes “on” and “off”. Epigenetics refer to the idea that environmental factors can change how a DNA sequence is expressed. Unit Two - Cell Structure and Function Chapter Four - Structure and Function of the Cell 1. ​Give the major function of each of the following cell parts: Mitochondria- Transfers energy from organic compounds to ATP Endoplasmic Reticulum- Prepares proteins for export (rough er); synthesizes steroids, regulates calcium levels, breaks down toxic substances (smooth er). Golgi Apparatus- Processes and packages substances produced by the cell Nucleus- Stores hereditary information in DNA; synthesizes RNA and ribosomes Cell membrane- Supports and protects the cell 2. ​Given diagrams of plant and animal cells, be able to label the organelles listed in #1. 3. ​Be able to identify the THREE organelles that are unique to plant cells: Chloroplast- Stores food or pigments: one type (chloroplast) transfers energy from light to organic compounds Central Vacuole- Stores enzymes and waste products Cell wall- Supports and protects the cell Chapter Five - Homeostasis and Transport 1. ​Cell membrane – what are the parts of the cell membrane? What is the function of each? What does semipermeable mean?- The parts of the cell membrane consist of two layers of phospholipids interspersed with various other molecules. A phospholipid contains three parts, a charged phosphate group, glycerol, and two fatty acid chains. The phosphate and glycerol form the head while the two fatty acid chains form the tail. The heads are polar so they therefore repel and the tails attract. This creates a boundary between the cell and the external environment. Semipermeable means to allow certain substances through while blocking others, for example allowing the passage of a solvent but not the solutes. 2. ​Active and passive transport: a)​ Describe each b)​ Identify the energy requirements of each c)​ Identify the direction with relation to the concentration gradient for each Active transport- drives molecules across a membrane from a region of lower concentration to a region of higher concentration, this process requires energy, moves from low to high concentration aka up the concentration gradient. Passive transport- the movement of molecules across a cell membrane WITHOUT energy input from the cell, requires no energy, moves from high to low concentration aka down the concentration gradient.​ 3. ​Define hypotonic, hypertonic & isotonic- Hypotonic- cells shrink and shrivel as the water diffuses out Hypertonic- cells swell and eventually burst as the water diffuses in Isotonic- when there is equal concentration 4. ​Label each of the following situations as hypotonic, hypertonic or isotonic, then state what will happen to the potato if the solution is left overnight. a) ​distilled water and potato- Start- Isotonic End- Hypotonic b) ​tap water and potato- Start- Isotonic End- Isotonic/Hypertonic c) ​salt water and potato- Start- Isotonic End- Hypertonic 1. ​Explain facilitated diffusion. What types of molecules use it? What is the role of carrier proteins?- Is the diffusion of molecules across a cell membrane with the help of carrier proteins. Molecules such as glucose would aid from a carrier protein. The task for a carrier protein is to aid in the diffusion of a molecule. Chapter Six - Photosynthesis 1. ​Give the chemical equations representing photosynthesis and cellular respiration. Photosynthesis- 6CO2 + 6H2O + light energy -> organic compounds + 6O2 Cellular respiration- Organic compounds + 6O2 -> 6CO2 + 6H2O + energy 2. ​In what organelle (as well as location within that organelle) do light reactions take place? Dark reactions?- Light reactions take place in the chloroplast thylakoids Dark reactions take place in chloroplast stroma 3. ​Explain why plants look green.- In the thylakoids, is a pigment called chlorophyll - the two most common types are chlorophyll a or chlorophyll b. Neither a nor b a absorbs much green light, the green light is reflected or transmitted, that's why plants look green 4. ​What is the end result of electron transport (in the light reaction phase of photosynthesis)?- The end result is 34 ATP 5. ​Explain how ATP is made during chemiosmosis. You may draw diagrams as part of your explanation.- the movement of hydrogen ions across the membrane via ATP synthase, produces ATP. 6. ​What TWO names does the second part of photosynthesis have? In one sentence, what occurs in this phase?- Two names in which the second part of photosynthesis go by is, The Dark Reactions, or, The Light Independent Reactions 7. ​What does the rate of photosynthesis depend on? (There are THREE factors that you need to list and describe!)- Light intensity- as light increases so does the rate of photosynthesis Temperature- if temperature increases the rate of photosynthesis drops CO2 Level- As the rate of CO2 increases the rate of photosynthesis also increases Chapter Seven - Cellular Respiration 1. ​In a diagram, show the pathway that pyruvic acid follows after the Calvin Cycle - make sure to include when oxygen is present and when oxygen is absent. 2. ​Summarize the process of cellular respiration in one sentence OR sketch it.- Complex process by which cells make ATP and release energy by breaking down organic compounds like sugars 3. ​What does glycolysis produce? (What are the end products of glycolysis?)- Glycolysis produces pyruvate and energy totalling 2 ATP 4. ​When and where does fermentation (anaerobic respiration) occur?- Fermentation takes place in the cytosol when no oxygen is present, or in the muscle cells when the cells cannot get enough oxygen 5. ​Use the pathway of lactic acid fermentation to explain muscle pain during strenuous exercise.- Happens during strenuous activity oxygen is used more quickly than it can be delivered and the muscle cells switch from aerobic respiration to lactic acid fermentation 6. ​Use the alcoholic fermentation pathway to explain how alcohol is made.- Yeast cell are added to the fermentation mixture to provide the enzymes needed for alcoholic fermentation 7. ​Why does fermentation occur primarily in smaller organisms?- 8. ​Where (which organelle) and when does aerobic/cellular respiration occur?- In the mitochondria 9. ​What does Krebs Cycle break down and produce?- takes in acetyl COA and produces CO2, NADH, FADH2, and ATP. 10. Where (which organelle) does the second stage of aerobic respiration occur? What does it produce?- Occurs in the mitochondrial matrix, produces NADH and FADH 11. In what organelle (as well as location in that organelle) does the Kreb’s Cycle take Place? The ETC?- The Krebs cycle occurs in the matrix of the mitochondria. The ETC occurs in the cristae of the mitochondria. 12. Go back to #1 above and label the amount of ATP made at each step of the pathway.- Listed on chart. (Both Photosynthesis and Cellular Respiration) 12. In a table, be able to compare photosynthesis and cellular respiration with regards to: Photosynthesis Cellular Respiration Chemical Formula 6CO2 + 6H2O + light energy Organic compounds + 6O2 -> -> organic compounds + 6O2 6CO2 + 6H2O + energy name and location of first light dependent reactions, the Krebs Cycle, takes place process take place in the thylakoid in the mitochondrial matrix membrane main products of first ATP, NADH CO2, NADH, FADH+, ATP process name and location of second the Calvin Cycle, takes place the ETC, takes place in the process in the stroma mitochondria main products of second glucose NAD+, FAD, water, and ATP process Unit Three - DNA, RNA & Biotechnology Chapter Eight - Cell Reproduction 1. ​Briefly describe the FIVE stages of the cell cycle and know in which order they occur. - Gap 1- a cell carries out its normal functions. Depending on certain factors, the cell will do certain things. In G1 cells increases in size organelles increase in number. Most time is spent G1 but length of time depends on cell type. Certain things must happen in G1, before the cell can move onto synthesis. Synthesis- “the combining of parts to make a whole” the cell makes a copy of its nuclear DNA. By the end of this stage there will be 2 complete sets of DNA. Gap 2- like G1, cells carry out their normal functions and additional growth occurs. This stage also includes a checkpoint, everything must be in order- adequate cell size, undamaged DNA- before the cell goes through mitosis and division. Mitosis- includes two processes: mitosis and cytokinesis. Mitosis is the division of the cell nucleus and its contents. During this process, the nuclear membrane dissolves the duplicated DNA condenses around proteins and separates, and two new nuclei form. Cytokinesis- divides the cell's cytoplasm. The result is two daughters identical to the original cell. 2. ​List and describe the FOUR stages of mitosis. Draw a sketch of each one and of cytokinesis.- Prophase- the stage of mitosis where chromatin condenses, the nucleus breaks down, the centrioles move apart, spindle fibers form Metaphase- the stage of mitosis where the chromosomes are pulled to the middle of the cell Anaphase- the stage of mitosis where the chromosomes are pulled apart at the centromere with each sister chromatid moving to the opposite side of the cell Telophase- the stage of mitosis where spindle fibers dissolves and the nucleus reforms around each set of chromosomes 3. ​Define haploid and diploid cells – be able to provide an example of each type of cell, as well as the number of chromosomes in each type of cell (for humans).- Haploid- Having only one chromosome of each homologous pair, represented as n, example is egg and sperm cells, 23 haploid cells Diploid- a cell that contains both chromosomes of a homologous pair, represented as 2n, example is blood cells, 46 diploid cells in human 4. ​Fill in the blanks in the chart below comparing mitosis and meiosis 5. Is mitosis or meiosis responsible for creating genetic diversity? Explain.- Meiosis is responsible for genetic variation because it is responsible for sex cells along with traits from mom or dad 6. ​Explain how one cell becomes four gametes. (A sketch may be easiest.)- Through meiosis Chapter Ten - Nucleic Acids and Protein Synthesis 1. ​Define DNA.- The primary function of DNA is to store and transmit the genetic information that tells cells which proteins to make and when to make them. 2. ​Define RNA.- The most abundant form of RA.rRNa consists of RNA nucleotides in globular form. Joining b protein, rRNA makes up the ribosomes where proteins are made. 3. ​Briefly describe and sketch the three parts of the nucleotide structure of a DNA molecule.- DNA is a nucleic acid, each DNA molecule consists of 2 long chains of nucleotides. DNA has three parts in each nucleotide, i) sugar molecule ii) phosphate group iii) nitrogenous base (adenine, guanine, cytosine, thymine) 4. ​What THREE structural differences exist between DNA and RNA?- DNA RNA -double stranded helix -single stranded -adenine, guanine, cytosine, thymine -adenine, guanine, cytosine, uracil -deoxyribose sugar -ribose sugar 5. ​What THREE types of RNA did we cover in class, and what is the role of each?- messenger- carries information from the DNA in the nucleus to the cytosol of a eukaryotic cell transfer- decodes mRNA into a protein sequence ribosomal- makes up ribosomes where proteins are made 6. ​What is a codon?- a group of three sequential nitrogen bases of an mRNA molecule 7. ​What are the base pairing rules for DNA? RNA?- DNA (A-T), (C-G), RNA (A-U) (C-G) 8. ​Define replication and know its location in the cell. What is an error in replication called?- Replication- the process of copying DNA in a cell, happens in the nucleus, errors are called mutations 9. ​Define transcription and know the location of this process in the cell.- Transcription- the process by which genetic info is copied from DNA to RNA, happens in the cytoplasm 10. ​ Define translation and know the location of this process in the cell.- Translation- the process of genetic code-> amino acid -> protein, happens in the ribosomes 11. ​ A segment of DNA has the following sequence. AAC TAC GGT CTC a) ​Write the mRNA transcript of this sequence of DNA.- UUG AUG CCA GAG b) ​Write the list of codons and give the names of the amino acids coded by them (using the table on page 194 of your old text).- UUG-leucine AUG-start CCA-proline GAG-aspartic acid Biotechnology 1. Define the terms: Biotechnology- a business sector and scientific discipline which deals with the use of living organisms or their products in industrial processes. Gene Therapy- a process of inserting genes directly into selected cells to correct a genetic defect or disease. GMOs- an organism that has had its genetic material altered in order to give the organism new characteristics that are not naturally present in the organism. Recombinant DNA- a combination of DNA from two different species that are joined. Artificial Selection- an intentional breeding by humans towards a desirable trait which is of value Transgenic- an organism that has had genes from another organism put into its genome through recombinant DNA technology. Mutagenesis- the formation of mutations in DNA molecules. 2. Explain what stem cells are and list some of their uses.- Stem Cells- a class of undifferentiated cells that are able to differentiate into specialized cells. Used to treat cancers, immune deficiencies, sickle cell anemia, possibly Parkinson 3. Explain two pros and two cons to genetically modified organisms.- Pros- less pesticides, more nutritious food Cons- Allergic reactions, possible antibiotic resistance Unit Four - Genetics Chapter Nine - Fundamentals of Genetics 1. Who was Gregor Mendel? Explain how his life/vocation led to his scientific contributions in the field of genetics.- Mendel was a monk who tended a garden in the monastery. He watched many plants grow and saw how traits from some plants would happen on others, he was the first to research how cross pollination affected the transmission of the traits. 2. Define the following terms and be able to give an example of each; a)​ Dominant- refers to an allele that masks the presence of another allele for the same trait b)​ Recessive- refers to an allele that has its presence masked by another allele c)​ Homozygous- When two alleles in the pair are similar d)​ Heterozygous- When two alleles in the pair are different e)​ Genotype- Genetic makeup of an organism f)​ Phenotype- Appearance of an organism 3. Incomplete dominance and codominance: a)​ How do you distinguish between them?- Incomplete dominance will mix while codominance will have the appearance of both b)​ What is an example of each?- Incomplete dominance- a red and white flower makes a pink flower. Codominance- A red and white flower produce a flower with both red and white stripes 4. For each of the following questions, give: - the parent’s genotypes - the gametes, ​ - complete a Punnett square  - summarize the phenotype(s) of the offspring - summarize the genotype(s) of the offspring a)​ Cross a heterozygous tall pea plant with a homozygous short pea plant. b)​ Cross a heterozygous smooth, homozygous yellow SEED color pea plant with a homozygous wrinkled, heterozygous yellow SEED pea plant. c)​ A red flowered plant is crossed with a white flowered plant. The result is pink flowers. What type of inheritance is this? What would be the result of crossing two pink flowers? - this is incomplete codominance Chapter Twelve - Inheritance Patterns and Human Genetics 1. ​Sex chromosomes and autosomes: a)​ give an example of each- egg and sperm for sex cell, blood cell for autosome b)​ identify how many chromosomes are present in each (for humans).- 2 sex chromosomes, 44 autosomes 2. ​Karyotype: a) Definition- a picture of an individual's chromosomes b) Given a karyotype, be able to tell if an individual is: ✔​ Biologically male or biologically female ✔​ Affected by a particular disorder 3. ​Cross a mother who is normal (not a carrier) and a father who is a hemophiliac. Give: -​ the parent’s genotypes -​ the gametes -​ complete a Punnett’s square -​ summarize the genotype(s) of the resulting offspring. -​ summarize the phenotype(s) of the resulting offspring. 4. ​Define and describe the effects of the following mutations: germ cell mutations- The change in the DNA of a sex cell somatic mutation- The mutation that occurs in a body cell. lethal mutation- A genetic alteration that occurs in a germ cell, such as a sperm or egg, leading to the death of the fertilized egg or embryo. chromosome mutations- Changes in the number or structure of the chromosomes  gene mutations- A change in one or more genes. 5. ​Answer the following blood type questions: a)​ Can a type A blood parent and a type B blood parent have a type O blood baby? b)​ Can a type A blood parent and a type AB blood parent? In your answer for (a) and (b) above, please identify: -​ the parent’s genotypes -​ the gametes -​ complete a Punnett’s square -​ summarize the genotype(s) of the resulting offspring. -​ summarize the phenotype(s) of the resulting offspring. a) b) 6. What is a universal blood donor? A universal blood acceptor?- Universal donor is blood type O, universal acceptor is AB Unit Five - Organization of Life 1. Define taxonomy.- Taxonomy is the science of naming and classifying organisms. It gives scientists a standard way to refer to species and organize the diversity of living things. 2. a) Describe Aristotle’s classification system.- Greek philosopher Aristotle classified things as either plants or animals. He went into further detail by classifying animals as land dwellers, water dwellers, and air dwellers. He did similar groupings of plants based on the differences in their stems. b) Explain why Aristotle’s classification system was replaced.- Aristotle's system of classification was replaced because modern science was developing and there was a period of rapid scientific explorations where many new organisms were discovered. Due to all of this new information, Aristotle's system was no longer adequate for the world of modern science. c) Why have biological classification systems changed over time?- New organisms are constantly being discovered therefore we need updated systems 3. Explain Linnaeus’s system of classification and identify the main criterion/basis he used to classify organisms. Don’t forget binomial nomenclature – what is it? What is an example?- The Linnaean system of classifications has seven levels, or taxa. From general to most specific they are as follows; kingdom, phylum, class, order, family, genus, and species. A kingdom contains one or more phyla, a phylum contains one more class and so on. For example the classification of the gray wolf goes from the top level representing all of the species in the Animalia kingdom. As you move down the levels, they will get more specific with less species. Linnaeus created this system based on physical similarities alone before technological advancements were made to allow us to study at the molecular level. This system did not account for species being closely related due to similarities. 5. List Linnaeus’s SEVEN levels of classification from the most general to the most specific.- kingdom, phylum, class, order, family, genus, and species 6. What are the FIVE kingdoms? Give an example of a common organism from each kingdom. Animal (dog), plant (grass), fungi (mushroom), protista (algae) and monera (eubacteria) 7. What is the biological definition of a species? Do donkeys and horses belong to the same species? Why or why not?- Species- a group of organisms that can reproduce with one another in nature and produce fertile offspring. Horses and donkeys do not belong to the same species due to the fact that a mule is not fertile. 8. Cladogram a)​ What is a cladogram?- a diagram that shows evolutionary relationships based on observable traits b)​ Be able to identify organisms using a cladogram.- 9. For each of the 5 kingdoms, know: a)​ Cell type (prokaryotic or eukaryotic) b)​ Number of cells (unicellular, multicellular or both) c)​ How nutrition is obtained (autotroph, heterotroph or both) d)​ Examples of common organisms in that kingdom animal- a) prokaryote b) multicellular c) hetero d) dog plant- a) prokaryotes b) multicellular c) auto d) grass fungi- a) eukaryotic b) multi c) hetero d) mushroom protista- a) eukaryotic, includes what does not fit in to the three above categories d) algae monera- a) prokaryotes b) uni c) heterotroph d) eubacteria 10. Dichotomous key: a)​ Define- A dichotomous key is an important scientific tool, used to identify different organisms, based on the organism's observable traits. Dichotomous keys consist of a series of statements with two choices in each step that will lead users to the correct identification. b)​ Know how to identify an organism using a dichotomous key- c)​ Be able to construct a dichotomous key for a group of organisms