SBI 3U Exam Review - Biology PDF

SBI 3U: Exam Review – Topics of Study ***IF THE TOPIC IS NOT LISTED THEN DO NOT STUDY IT FOR THE FINAL EXAM** A) Diversity Unit Review (chapters 1, 2 and 3) Chapter 1: Classifying Life’s Diversity binomial nomenclature -​ The first word is the genus name and the second word identifies the...

SBI 3U: Exam Review – Topics of Study ***IF THE TOPIC IS NOT LISTED THEN DO NOT STUDY IT FOR THE FINAL EXAM** A) Diversity Unit Review (chapters 1, 2 and 3) Chapter 1: Classifying Life’s Diversity binomial nomenclature -​ The first word is the genus name and the second word identifies the particular species -​ The scientific name is italicized when typed with the genus name capitalized and species name lower case -​ When written by hand, both parts are underlined species concepts – definitions of ; advantages and disadvantages of each The morphological species The biological species concept The phylogenetic species concept focuses on defines species on the basis of concept examines the phylogeny, morphology—body shape, size, whether two organisms can or evolutionary history, of and other structural features. produce fertile offspring. organisms. Advantage: This species concept is Advantage: This species concept is Advantages: The phylogenetic simple and widely used, widely used by scientists. species concept applies to extinct particularly for plants. Disadvantages: It cannot be species and incorporates DNA Disadvantage: It can be difficult to applied to physically separated analysis, aiding in identifying new define acceptable variation, as populations, asexual organisms, species. most populations consist of or fossil species. Disadvantage: Evolutionary diverse individuals. histories are not known for all species. -​ how are species organized – hierarchy; p. 15 know ranks; how does a dichotomous key work (KP COFGS) ​ Taxonomic Categories (RANKS) Domain (general) Kingdom Phylum Class Order Family Genus Species (specific) -​ A system for narrowing down the identification of an unknown species, one step at a time -​ Uses many 2 part choices to narrow down the solution  -​ Ex. how are species related? look at anatomy, physiology and DNA Look at anatomy - what does this word mean? -​ the branch of biology that deals with structure and form, including internal systems Look at physiology - what does this mean -​ the branch of biology dealing with the physical and chemical functions of organisms, including internal processes Look at DNA - what impact has this had; what are DNA barcodes (see page 36) -​ Closely related species will have similar DNA sequences Ex. Fungi and plants are similar in many ways, but DNA evidence shows that fungi are in fact more closely related to animals than to plants. Characteristics of the kingdoms…..see p. 29 Chapter 2: Simple to Complex prokaryotes vs. eukaryotes – see table on page 53; know differences lytic vs. lysogenic cycles for viruses Viruses undergo replication inside a host cell. Some viruses replicate by means of a lytic cycle, where they quickly attach, enter, replicate, assemble, and release from a cell, killing the cell in the process. Lytic viruses burst from host cells and infect neighboring cells. Other viruses replicate by means of a lysogenic cycle, where they enter and then attach their DNA to the host’s chromosomes. Now referred to as a provirus, they can lie dormant within the host chromosome until it re-activates and continues with the lytic cycle. Lysogenic viruses may not cause any immediate effects on the host organism. Their main difference is that in the lysogenic cycle, viruses sneak into the host's DNA, stay hidden, and wait. Later, they become active, make copies, and infect other cells. Example) HIV - A lysogenic virus and a retrovirus where the composed RNA can integrate in the DNA of a cell. bacteria vs. archaea – shapes to identify – prefixes and shape; differences in habitats  -​ mesophiles—organisms that occupy environments with moderate (less extreme) conditions. -​ extremophile—organism that lives in habitats with extreme conditions binary fission vs. conjugation In binary fission, as a cell grows, -​ it makes a copy of its original, single chromosome. -​ When the cell reaches a certain size, it elongates, separating the original chromosome and its copy. -​ The cell then builds a partition between them, called a septum -​ eventually the original cell splits into two smaller, genetically identical cells. During conjugation -​ one cell links to another cell through a bridging structure and transfers all or part of its chromosomes to the other cell, through plasmids -​ Unlike asexual reproduction, conjugation results in cells with new genetic content. -​ The receiving cell then undergoes binary fission to produce more cells with the same genetic make-up. protists – amoeba vs. paramecium only Chapter 3: Multicellular Diversity Animal – characteristics to identify – explain each; what is an invertebrate vs. vertebrate Animals Characteristics They are eukaryotic, multicellular organisms. Their cells do not have cell walls. They are heterotrophs that usually ingest (take in) and then digest their food. They are usually mobile, or have the ability to move, in at least one stage of their lives. They reproduce sexually and produce an embryo that undergoes stages of development. -​ Vertebrate - Backbone -​ Invertebrate - No Backbone Invertebrate Characteristic Symmetry Bilateral Segmentation Segmented Body  Movement Complex Reproduction Sexual (Mostly Internal) Vertebrate Characteristic Reproduction Sexual Internal Fertilization Symmetry Bilateral Segmentation Not distinctly segmented Movement (complex) B) Genetics (chapters 4, 5 and 6) Chapter 4: Cell Division and Reproduction Mitosis – steps of Prophase Metaphase Anaphase Telophase -​ centrosomes -​ centrosomes -​ Chromosome split -​ Nuclear membrane migrate toward now at poles at centromere reappears poles -​ sister chromatids -​ Chromosomes -​ Two identical -​ spindle forms lineup pulled by spindle daughter cells -​ disappearing to centrosome formed nuclear membrane -​ chromosome replicated (Label) karyotype – can you identify Downs, Edwards and Pataus syndromes Karyotype - A photograph of pairs of homologous chromosomes in a cell Gender Disorder Evidence of Diagnosis N/A Downs Trisomy 21 N/A Edwards Trisomy 18 N/A Patau Trisomy 13 MEIOSIS – steps of Law of independent assortment -​ Independent Assortment - The process of the creation of gametes that carry different combinations of maternal and paternal chromosomes. (TEXTBOOK) -​ Different allele combinations depending on how they sort themselves Chapter 5: Patterns of Inheritance Genetic crosses: -​ Ex. White Haired Poodle x Black Haired Labrador monohybrid, dihybrid crosses, autosomal dominant vs. recessive, remember sickle cell, use of pedigrees -​ monohybrid cross - A cross of two individuals that differ by one trait. -​ dihybrid cross - A cross of two individuals that differ in two traits due to two different genes. -​ Autosomal Dominant - If offspring are affected, one parent must be as well. -​ Autosomal Recessive - Phenomenon when kid is affected yet neither parent is. **for each pattern, practise doing sample problems so you remember how to identify them and set up answer (Legend, Parent Cross, Punnett Square, genotype and phenotype percentages) -​ 1 - phenotype cross, 2 - legend, 3 - cross, 4 - gametes, 5 - Punnett Square, 6 - Genotype, 7 - Phenotype; (repeat and show ratio if dihybrid). Chapter 6: Complex Patterns of Inheritance Genetic crosses: -​ Ex. White Haired Poodle x Black Haired Labrador Incomplete dominance (red and white gives pink) , Codominance – (roan cow see red and white hairs) , blood types, Sex Linked – visit pedigrees and analyze and show crosses Incomplete dominance (red and white gives pink) -​ incomplete dominance - A condition in which neither allele for a gene completely conceals the presence of the other; it results in intermediate expression of a trait. ​ Codominance – (roan cow see red and white hairs) -​ codominance - The condition in which both alleles for a trait are equally expressed in a heterozygote; both alleles are dominant. -​ Type A IA IA (homozygote) or IA i (heterozygote)  {A glycoprotein is present on RBCs} -​ Type B ​ IB IB (homozygote) or IB i (heterozygote) {B glycoprotein is present on RBCs} -​ Type AB IA IB (heterozygote) {A and B glycoproteins are on RBCs} -​ Type O ​ ii (homozygote) {no A and B glycoproteins on RBCs} X-Linked Recessive. **for each pattern, practise doing sample problems so you remember how to identify them and set up answer (Legend, Parent Cross, Punnett Square, genotype and phenotype percentages) -​ 1 - phenotype cross, 2 - legend, 3 - cross, 4 - gametes, 5 - Punnett Square, 6 - Genotype, 7 - Phenotype; (repeat and show ratio if dihybrid). C) Evolution Unit (chapters 7, 8, and 9) Chapter 7: Introducing Evolution Adaptation - importance to survival; mimicry – Batesian vs. Mullerian -​ An adaptation is a structure, behaviour, or physiological process that helps an organism survive and reproduce in a particular environment. -​ Mimicry - A structural adaptation in which a harmless species resembles a harmful species in coloration or structure -​ Batesian - Shares signals similar to models with anti-predation attributes.  -​ Malarian - Two species share similar warning symbols and anti-predation attributes. Importance of variation; English peppered moth as a case study to understand variation to adaptation -​ Differences in individuals; can be structural, physiological or behavioural. -​ Caused by offspring receiving different alleles from two parents. Making different combinations. 1.​ Before the Industrial Revolution: -​ Trees were covered with light-colored lichen. -​ Flecked moths were camouflaged and avoided predators. -​ Black moths were easily spotted and preyed upon, keeping their numbers low. 2.​ During the Industrial Revolution: -​ Soot from factories darkened the trees. -​ Black moths became better camouflaged and survived more. -​ Flecked moths were eaten more often, reversing their population ratio. 3.​ After the Clean-Air Legislation (1950s): -​ Lichens grew back on trees. -​ Flecked moths gained an advantage again, increasing in number. 4.​ Takeaway: -​ Revealing to us how specific variations of a species are better adapted to their environment. Mutations vs. mutagens -​ Mutation - A permanent change in the genetic material of an organism; the only source of new genetic variation. -​ Mutagens, such as ultraviolet radiation, are environmental agents that can also cause mutations in DNA. artificial selection vs. natural selection Natural selection -​ Natural Selection - The process by which characteristics of a population change over many generations as organisms with heritable traits survive and reproduce, passing their traits to offspring. -​ Happens through a change in allele frequencies. -​ Natural selection is situational. -​ For natural selection to occur there must be: Variation, competition, adaptations and selections (evolution). Artificial selection -​ Artificial Selection - Selective pressure exerted by humans on populations in order to improve or modify particular desirable traits. Chapter 8: Developing a Theory of Evolution scientific contributions of Lamarck and the inheritance of acquired characteristics, use and disuse and finally Darwin (his discoveries, role of the finches on Galapagos islands, his theory of evolution) -​ Lamark - Suggested use and disuse, noted adaptations could be passed onto offspring, and observed a line of descent as species increased in complexity over time. -​ Inheritance of Acquired Characteristics - The idea that characteristics acquired during an organism’s lifetime can be passed on to its offspring.  -​ Use and Disuse - Body parts not used would eventually disappear. -​ Darwin - Darwin contributed survival of the fittest had 4 main ideas ➔​ Organisms produce more offspring than can survive. Therefore, organisms compete for limited resources. ➔​ Individuals of a population vary extensively, and much of this variation is heritable. ➔​ Individuals that are better suited to local conditions survive to produce more offspring. ➔​ Processes for change are slow and gradual. -​ Descent with modification - Darwin’s theory that natural selection does not demonstrate progress, but merely results from a species’ ability to survive local conditions at a specific time. Galapagos islands species and finches taught him this. -​ 5 Observations ➔​ Darwin observed that organisms in different regions were structurally similar to each other but distinct from those on other continents, leading him to question why organisms were not randomly distributed worldwide. ➔​ He found fossils, resembling living animals in the same region, prompting him to ask why extinct and living organisms were regionally clustered. ➔​ Galapagos and Mainland Similarities: Darwin noted that Galapagos species closely resembled those on the South American mainland, raising questions about their shared origins. ➔​ Variations Among Galapagos Species: He observed slight variations among species, like finches with different beaks adapted to specific foods, suggesting they could have evolved from a common ancestor. ➔​ Artificial Selection Insights: Through breeding experiments, Darwin saw that traits could be passed to offspring, inspiring his idea that natural processes might similarly shape species over time. evidence: fossils – look at transitional fossils and vestigial structures, biogeography, anatomy (homologous vs. analogous structures), DNA and embryology What are transitional fossils? -​ A transitional fossil is one that shows intermediary links between groups of organisms and shares characteristics in common to 2 now separate groups. What is the relevance of Vestigial structures -​ A structure that is a reduced version of a structure that was functional in the organism’s ancestors BIOGEOGRAPHY What does this tell us? -​ Biogeography is the study of the past and present geographical distribution of species populations ANATOMY What does this reveal? -​ Revealing common ancestry between species and how habitat impacts structural traits. What are the differences between Homologous vs. analogous structures -​ Homologous structure are those that have similar structural elements and origin but may have different function -​ Analogous structures are structures of organisms that do not have a common evolutionary origin but perform similar functions EMBRYOLOGY What does this reveal? -​ It is used to determine the evolutionary relationship between animals. DNA How has DNA changed things in terms of evolutionary understanding? -​ If 2 species have similar patterns in their DNA, this indicated that these DNA sequences must have been inherited from a common ancestor Chapter 9: Evolution and Speciation five factors that change allele frequencies in populations – explain each one In terms of natural selection, the diff between stabilizing/directional vs. disruptive selection (remember the bell curve) -​ Stabilizing - Favours common/intermediate phenotype. -​ Directional - Favours one extreme over another, making all phenotypes shift in that direction. -​ Disruptive - Favours extremes of range of phenotypes. reproductive isolating mechanisms found on p. 360 ; prezygotic and post zygotic mechanisms Know the difference between pre-zygotic and post-zygotic reproductive isolating mechanisms -​ Pre-zygotic (pre fertilization barriers) -​ Post-zygotic (post fertilization barriers) Prezygotic - isolation due to behaviour differences, temperature, different ecological locations, the mechanics/body parts can’t connect, gametes don’t recognize each other Prevention of Mating  -​ Behavioural Isolation - Different species use different courtship and other mating clues to find and attract a mate. Ex. Frogs have unique calls that only attract females of their species -​ Temporal Isolation - Species breed at different times of the year. Ex. Pussy willows produce flowers in early spring and are isolated from species that flower at a different time. -​ Ecological/Habitat Isolation - Occupation of different areas. Ex. Mountain bluebird prefers high elevations while eastern bluebird prefers lower elevations, they will not encounter. Prevention of Fertilization -​ Mechanical Isolation - Different morphological features, genitals don't work together. Ex. Flower structure may make pollinators and flowers incompatible. -​ Gametic Isolation - Sperm and egg do not recognize each other. Ex. Many marine animals release sperm into open water. The sperm recognize eggs of their own species through chemical markings on the surface. Post-zygotic - hybrid dies, hybrid lives but is infertile, hybrid lives but cannot survive for very long Prevention of Hybrids -​ Zygotic Mortality - Sperm and Egg only fertilize, the zygote dies. Ex. Goat and Sheep zygote die. -​ Hybrid Inviability - Hybrid develops but dies before birth or before they can mature. Ex. Tiger and Leopard's offspring. -​ Hybrid Infertility - Hybrid is healthy and viable but sterile. Ex. Mule. allopatric speciation - Darwin’s finches an example of allopatric speciation -​ Allopatric Speciation - Speciation in which a population is split into two or more isolated groups by a geographical barrier; -​ Stops gene flow between populations= reproductive incompatibility -​ EX. On Galapagos Islands, Finches on islands were separated from finches on mainland South America D) Animal Unit Review (chapters 10, 11 and 12) Chapter 10: Digestive System Parts of – each part and its role in digestion different macromolecules and what do they break down into; what enzymes are involved -​ Proteins - Amino Acids. -​ Carbohydrates- Simple Sugars. -​ Lipid - Glycerol and Fatty Acids. Monosaccharide vs disaccharide vs. polysaccharide, protein vs. amino acids, lipids into glycerol and fatty acids Carbs Monosaccharide -​ Monosaccharides (simple sugars; 1 sugar molecules) -​ 3 to 7 carbon atoms -​ Ex, glucose (sugar found in blood), fructose (found in fruit) Disaccharides -​ Disaccharides are sugars made up of 2 monosaccharide molecules {di - means 2} -​ Ex, sucrose (table sugar) lactose (found in dairy) Polysaccharides -​ Made up of many linked monosaccharide molecules. -​ Ex, starch, cellulose, glycogen (made up of glucose). -​ Starch stores energy in plants; glycogen stores energy in humans. Protein -​ Amino Acid - A building block of protein  -​ -​ Polypeptide - A linear chain of several amino acids linked by peptide bonds. -​ Peptide Bond - A bond that holds together the amino acids in a protein. Lipids -​ -​ what happens to each macromolecule as it makes its way through the digestive tract; example - a food that contains protein – where is it digested and which enzymes are involved Enzymes - apply lock and key model; substrate vs. active site; how enzyme works to assist chemical reaction Disorders: lactose intolerance, ulcers -​ peptic ulcer - A sore in the lining of the stomach or duodenum, most commonly caused by infection with the bacterium -​ Unable to breakdown Lactose - Lack enzyme Lactase Chapter 11: Respiratory System mechanics of breathing – what happens during inhalation vs. exhalation; role of diaphragm and impact on differences in air pressure During inhalation -​ The intercostal muscles contract lifting the rib cage upward and outward. -​ At the same time, the diaphragm contracts and pulls downward. -​ As the lungs expand, air moves in. During exhalation -​ The intercostal muscles relax, allowing the rib cage to return to its normal position.  -​ The diaphragm also moves upward, resuming its domed shape. -​ As the lungs contract, air moves out. The diaphragm is a dome-shaped layer of muscle that separates the thoracic cavity from the abdominal cavity -​ Textbook 446 -​ P1V1=P2V2 -​ Since air moves from regions of higher pressure to regions of lower pressure, air rushes into the lungs from the external environment. -​ A change in air pressure causes air to move from an area of high pressure (the lungs) to an area of lower pressure (outside the body). -​ A volume of air always moves from a volume of high pressure to low pressure -​ Inverse Relationship - as volume increases pressure decreases and vice versa path of air into the lungs; gas exchange occur between alveoli and capillaries 1.​ Air enters the respiratory system through the nose and mouth 2.​ Behind the nose is a hollow space called the nasal cavity 3.​ The nasal cavity is lined with cells that secrete sticky mucus 4.​ The mucus traps dust, bacteria, and other particles that are inhaled with the air 5.​ In the nasal cavity, incoming air is warmed and moistened which helps keep respiratory surfaces deep inside the lungs from drying out 6.​ Both inhaled air and swallowed food pass through the pharynx 7.​ From the pharynx, air passes into the larynx 8.​ A flap of tissue called the epiglottis covers the entrance to the larynx to keep food and drink from passing into it 9.​ The larynx contains two bands of tissue called the vocal cords 10.​From the larynx, air flows into a tube called the trachea (windpipe) 11.​Some cells that line the trachea have hair-like cilia; other secrete mucus 12.​This combination of sticky mucus and cilia traps pollutants and other particles and sweeps them up to the mouth 13.​Once in the mouth, the particles are swallowed or expelled by coughing Gas Exchange 1.​ The smallest bronchioles end at a cluster of tiny pockets called alveoli 2.​ Alveoli occupy most of the volume of tissue that makes up the lungs 3.​ The wall of each alveolus is one-cell thick and is surrounded by a mesh of capillaries 4.​ Gas exchange occurs where the capillaries and the alveoli come in close contact 5.​ Oxygen from inhaled air enters the alveoli and diffuses into the capillaries 6.​ At the same time, carbon dioxide in the blood diffuses into the air in the alveoli 7.​ The carbon dioxide leaves the lungs and goes out your mouth when you breathe disorders: asthma and COPD -​ asthma - a lung disease that causes chronic inflammation of the lungs and overproduction of mucus in the lungs. -​ Inhaled irritants such as pollen, dust, and smoke can often trigger an inflammation of the bronchi and bronchioles (asthma)  -​ It cannot be cured, it can be managed. Many people who have asthma use a hand-held inhaler, a device that delivers medication deep into the lungs. -​ Bronchitis - inflammation of the mucous membranes of the bronchi; it is classified as either acute (due to infection) or chronic (due to an irritant). -​ Signs and symptoms include: -​ Runny, stuffy nose. -​ Low-grade fever. -​ Chest congestion. -​ Wheezing or a whistling sound while breathing. -​ A cough that may produce yellow or green mucus (sputum) -​ Feeling run-down or tired. -​ Chronic bronchitis is referred to as a chronic obstructive pulmonary disease (COPD), and is one of a few lung diseases that is usually caused by smoking. -​ COPD cannot be cured, but it can be treated by quitting smoking, taking medications, and participating in specialized exercise programs. Chapter 12: Circulatory System structure of the heart – parts (from gr.10); valves and components of electrical conduction system of the heart differences in blood vessels; systemic vs. cardiac vs. pulmonary circulation -​ 3 main blood vessels - artery, vein, capillary -​ Arteries carry blood away from the heart -​ Arteriole - smaller-diameter arteries -​ A network of capillaries joins the arteries and arterioles with venules and veins -​ The 1-cell-thick capillaries are the site where gases, nutrients, and other materials are transferred from blood to tissue cells and from tissue cells to blood -​ Veins carry blood toward the heart and have valves -​ Venules - smaller diameter veins systemic vs. cardiac vs. pulmonary circulation -​ pulmonary circulation - The path that blood follows from the heart to the lungs and back to the heart. -​ systemic circulation - The path that blood follows from the heart to the body and back to the heart. -​ cardiac circulation - The movement of blood through the heart tissues. disorders: high blood pressure, arteriosclerosis -​ arteriosclerosis - General term for several conditions in which the walls of arteries thicken and lose their elasticity. -​ The most common type of arteriosclerosis is called atherosclerosis. This is a condition in which plaque builds up on the inside of artery walls. -​ Once arteriosclerosis sets in, several treatment options are available. Medicines such as Aspirin prevents platelets from sticking together, thus reducing the formation of clots. Special “clot-busting” medicines such as urokinase and t-PA can be used to break down existing clots and improve blood flow. -​ Surgical treatment is also possible. Angioplasty is a procedure in which a surgeon inserts a tube into a clogged artery. When the tube reaches the site where the artery is clogged, a tiny balloon is inflated to force the artery open.  -​ Surgeons may choose to re-route the flow of blood rather than try to unblock blood vessels. To do this, they take a section of the healthy artery or vein from another part of the body and use it to create a new pathway for blood around the blockage. This type of surgery is called a coronary bypass. -​ Blood pressure is affected by genetics, activity, stress, body temperature, diet, and medications. -​ It is normal for your blood pressure to increase when you are exercising and to decrease when you are sleeping. However, continuous high blood pressure, also called hypertension, causes the heart to work harder for extended periods of time. -​ This can cause damage to arteries and increases the risk of heart attack, stroke, and kidney failure. E) Plant Unit (Chapters 13 and 14); can also reference back to section in the Diversity Unit differences between monocots and dicots monocots tend to have flowers and fruits divided into threes or multiples of three, and their leaves usually have parallel veins. Dicots usually have flowers and fruit parts in fours or fives, and their leaf veins tend to be in a netted pattern. parts of the flower meristematic vs. vascular tissue (xylem vs. phloem) -​ meristematic tissue - undifferentiated embryonic plant tissue from which all other plant tissues develop. -​ Vascular tissue - an internal system of tubes that run lengthwise throughout the stem of a plant, connecting the roots and the leaves. -​ xylem - vascular tissue that transports water and minerals from the roots to the leaves -​ phloem - vascular tissue that transports organic nutrients, often from the leaves to the roots, but also from roots and mature leaves to new leaves parts of the leaf -​ cuticle - a waxy layer on the epidermis that is secreted by epidermal cells -​ mesophyll the layer between the upper and lower epidermis of a leaf that contains numerous chloroplasts -​ palisade mesophyll the layer of cells where most photosynthesis takes place, immediately below the epidermis -​ spongy mesophyll the layer of irregularly shaped, loosely packed cells below the palisade mesophyll layer tropisms – what are they and the main types -​ Tropism - Growth in response to a stimulus -​ Positive tropism is when a plant grows towards the stimulus -​ Negative tropism is when a plant grows away from the stimulus EXAM DATE: ​ ​ this is your first period exam of the exam period therefore on Jan. 24, 2025 TIME:​ ​ ​ 8:30 am LOCATION:​ ​ 319 LENGTH:​ ​ 2 hours WORTH: ​ ​ 30% of final mark Bring: need to RETURN YOUR TEXTBOOK, pencil(s), eraser, pen, calculator Breakdown of the Exam: EVALUATION: Marks PART A: Multiple Choice – Knowledge​ ​ 35 marks​ ​ PART B: Diagrams – Knowledge​ ​ ​ 10 marks PART C: Short Answer - Communication​ ​ 15 marks PART C: Short Answer - Thinking/Inquiry ​ ​ 19 marks​ PART D: Short Answer - Application​ ​ 21 marks​ ​ ​ TOTAL Marks:​ ​ ​ ​ ​ 100 marks​ MARK ALLOCATION PER UNIT Diversity Unit, Genetics Unit and Animal Unit are the three units we spent the most time on and therefore, this will be reflected as well on the exam followed by the Evolution Unit. The Plant Unit was the shortest and so this will be reflected on the exam.