SBI4U Terms PDF

SBI4U FINAL EXAM PREP UNIT 1: BIOCHEMISTRY Terms Active site (enzyme) - A depression in the surface of the globular protein where the substrate binds. Active transport - Movement of materials against the concentration gradient, requiring energy; requires specific...

SBI4U FINAL EXAM PREP UNIT 1: BIOCHEMISTRY Terms Active site (enzyme) - A depression in the surface of the globular protein where the substrate binds. Active transport - Movement of materials against the concentration gradient, requiring energy; requires specificity in molecules ATP - Energy required for cellular function Benedict’s solution - Can be used to identify reducing sugars Coenzyme - Function similar to cofactors but are organic, non-protein molecules Cofactor - Inorganic ions located in the active site to increase binding ability of enzyme and substrate Condensation (dehydration) - Water is released to form one thing from two Coupled channel - Utilizes concentration created by active transport to move other molecules in via passive transport Diffusion - The random movement of molecules down the concentration gradient Electronegativity - The measure of the ability of an atom to attract electrons to itself when forming a bond Endocytosis - Movement of large molecules into the cell, requiring energy Enzyme - Made of globular proteins, held together by hydrogen bonds and other IMFs. Reduces activation energy of a reaction. Enzyme saturation - The point where increasing enzyme concentration has no effect on reaction rate. Can be overcome by increasing substrate concentration. Essential Amino Acids - 8 amino acids that cannot be produced by the body Exocytosis - The movement of large molecules out of the cell, requiring energy Facilitated diffusion - Diffusion through the use of integral proteins; requires specificity in molecules Feedback inhibition - A product formed later which inhibits the original production of the product Glycolipids - Carbohydrates on the layer of the cell membrane connected to a phospholipid. Acts as a cell to cell marker/antigen identification Glycoproteins - Chains of carbohydrates attached to transmembrane proteins. Allows for cell to cell recognition, communication, and tissue formations, serves as receptors for chemical signals Hydrogenation - A food preservation process where hydrogen is chemically added to unsaturated fatty acids, producing trans fats Hydrolysis - Water is consumed to break one thing to two Isomer - Same chemical formula, different arrangement of atoms Lateral diffusion (phospholipid bilayer) - Phospholipids and proteins drifting sideways Osmosis - Movement of water molecules across a selectively permeable membrane Oxidation - Loss of electrons Peripheral proteins - Proteins that exist only at the surface of the lipid bilayer Phagocytosis - Cell eating; particles, bacteria, viruses are engulfed in a vesicle Phospholipid - The unit that makes up the phospholipid bilayer and is made up of a polar, hydrophilic head, and a non-polar, hydrophobic tail. Pinocytosis - Cell drinking; water containing solutes is take into the cell in a vesicle Protein Denaturation - Proteins unfolding completely due to bonds breaking from temperature, ionic concentration, exposure to chemicals, change in pH, change in pressure Proton pump - Pumps hydrogen ions out by active transport, forming an electrochemical gradient Receptor-Mediated Endocytosis - Endocytosis that needs a receptor to enter (clathrin) Reducing sugar - Sugars with a free -OH group at the anomeric carbon. Reduction - Gain of electrons Saturated Fats - Contain only single bonds Secretory vesicles - Vesicles that travel from golgi bodies to the plasma membrane (and fuse to it) Sodium-potassium pump - Pumps 3 sodium ions out and 2 potassium ions in Stereoisomers - Atoms are bonded the same, but atoms are arranged differently Structural isomers - Atoms are bonded differently Substrate saturation - The point where increasing substrate concentration has no effect on reaction rate. Can be overcome by increasing enzyme concentration. Trans fats - Unsaturated fats with trans double bonds Transmembrane protein (integral proteins) - Protein that spans the entire lipid bilayer. Used in both facilitated diffusion and active transport Transport vesicles - Vesicles that travel from endoplasmic reticulum to the golgi bodies Unsaturated fats - Contain one or more double bonds (cis bonds) Processes​ Electronegativity Pure Covalent ​ ​ 0​ ​ ​ 0.5​ ​ ​ 1.6​ ​ ​ 2.0​ ​ 4.0 ​ Nonpolar covalent Polar Covalent ​ Polar Covalent or Ionic​ Ionic Identifying Oxidation/Reduction Reactions Naming functional groups Name enantiomers (R vs. S) Label hemi-acetal vs. hemi-ketal and α vs. β Label linkages in carbohydrates Label isomers of amino acids using CORN rule (L vs. D) Identify hypotonic, isotonic, and hypertonic solutions Label exergonic and endergonic graphs Label the different types of enzyme regulation Classify enzyme regulation -​ Competitive inhibition -​ Non-competitive inhibition -​ Non-competitive activation -​ Substrate activation Classify amino acids  -​ Non-polar (Benzene) -​ Polar (Alcohol, Sulfhydryl, Amide) -​ Acidic (Negatively charged, carboxylic acid) -​ Basic (Positively charged, Amine) Classify Proteins -​ Primary: Linear sequence of amino acids connected by peptide bonds -​ Secondary: Hydrogen bonded α-helix and β-pleated sheets -​ Tertiary: 3D structure -​ Quaternary: Multiple Tertiary structures Brute Force Memorization Organic molecules POLYMER MONOMER(S) FUNCTION OF POLYMER glycogen α-glucose Storage of excess glucose in animals amylose α-glucose Storage of excess glucose in plants amylopectin α-glucose Storage of excess glucose in plants cellulose β-glucose Used in cell walls chitin N-acetylglucosamine Exoskeleton of insects, cell walls of fungi protein/enzyme amino acids Cell enzymes, structure, transport, defense triglycerides glycerol + 3 fatty acids Long-term energy storage phospholipid polar hydrophilic head, Makes up cell membrane non-polar hydrophobic tail cholesterol four fused carbon rings Part of cell membrane, (steroid rings) hormones nucleic acids nucleotides Genetic information Cell organelles STRUCTURE LOCATION DESCRIPTION AND FUNCTION Plasma membrane ​ Animal Contains the cell’s components and allows ​ Plant transport of material in and out of cell Cytoplasm (cytosol) ​ Animal Gel-like fluid that holds the internal components of ​ Plant cells in place  Nucleus ​ Animal Protects and controls access to DNA; makes ​ Plant ribosome subunits Nuclear envelope ​ Animal Separates the contents of the nucleus from the ​ Plant cytoplasm and provides the structural framework of the nucleus Nucleolus ​ Animal Produces and assembles the cell’s ribosomes ​ Plant Ribosomes ​ Animal Responsible for making proteins ​ Plant Endoplasmic ​ Animal The location where proteins are made, produces Reticulum ​ Plant lipids, etc. Golgi apparatus ​ Animal Modifies, sorts, and packages proteins and lipids ​ Plant for transport Vesicles ​ Animal Move molecules, secrete substances, digest ​ Plant materials Lysosomes ​ Animal Break down excess/worn-out cell parts ​ Plant Peroxisomes ​ Animal Detoxifies substances, breaks down fatty acids ​ Plant Mitochondria ​ Animal Produces ATP ​ Plant Chloroplasts ​ Animal Performs photosynthesis, converts light to ​ Plant chemical energy Cell wall ​ Animal Provides cell with structural support, shape, and ​ Plant protection Vacuole ​ Animal Store substances and waste ​ Plant Cytoskeleton ​ Animal Helps maintain the cell’s shape and internal ​ Plant organization UNIT 2: MOLECULAR GENETICS Terms Antiparallel - Describes DNA as strands are parallel but run in opposite directions Blunt ends - Fragments of DNA that have no overhangs and must be joined together with T4 ligase Conservative model - DNA replication forms a completely new helix Dispersive - DNA parental strand is broken in fragments DNA gyrase - Relaxes the tension of the double helix ahead of the helicase DNA Helicase - Continually unwinds DNA ahead of replication by breaking hydrogen bonds DNA ligase - Splices together Okazaki fragments which were produced form discontinuous synthesis by reforming phosphodiester bonds DNA polymerase I - Replaces primers with DNA base pairs. Proofreads and replaces incorrect bases as it replaces RNA primers DNA polymerase III - Synthesizes DNA starting front the primer, building complementary base pairs from 5’ to 3’. Can notice when hydrogen bonding is incorrect and swap it with the correct nucleotide, acting as an exonuclease Exons - Coding regions of DNA Frameshift mutation - Insertion.Deletion of base(s) Gel electrophoresis - A DNA separation technique that separates DNA by size and charge (smaller the fragment, faster it travels) Hydrogen bond - Bond between complementary base pairs. Forms the double helix shape. Strong enough to hold DNA together, weak enough to break open for DNA replication. Are broken during PCR at 94-96 degrees Celsius Initiator proteins - Recognises the replication origins and opens a replication bubble Introns - Non-coding regions dispersed with exons Methylases - Enzymes that add a methyl group to DNA to prevent restriction endonucleases from cutting it away Mis-sense mutation - Altered codon produces different amino acid N-glycosidic bond - Bond between a sugar and base Non-sense mutation - Altered codon becomes a stop codon Nucleotide - The unit that builds DNA and RNA. Made up of a phosphate, pentose sugar, and nitrogenous base Okazaki fragments - Fragments newly produced DNA produced by discontinuous synthesis as a result of the 3’ to 5’ synthesis PCR - Used to amplify the quantity of DNA using a thermal cycler Phosphodiester bond - Bond between a phosphate group and sugar Purines - Double ring nitrogenous base (Adenine, Guanine) Pyrimidines - Single ring nitrogenous base (Thymine, Cytosine, Uracil) Recombinant DNA - DNA that is artificially formed by combining pieces of DNA. Sticky ends are the best for this. Replication fork - The shape that is formed when DNA is opened by initiator proteins Replication origin - The sequence of nucleotides where DNA replication begins Restriction endonuclease - Enzymes found in bacteria that act as molecular scissors, cutting double stranded DNA. Can break both hydrogen bonds and phosphodiester bonds RNA primase - Adds a primer where DNA polymerase III will begin Semi-Conservative model - DNA daughter strand is made up of one parent strand. This is the correct model and is proved by Meselson & Stahl by using nitrogen isotopes and centrifuge, forming 2 bands. Silent mutation - Altered codon still codes the same amino acid SSBs - Holds strands apart during replication by preventing hydrogen bonds from reforming Sticky Ends - Fragments of DNA that can be joined by another complementary sticky end Substitution mutation - One base is substituted for another Taq polymerase - Used in PCR, acts as a DNA polymerase III, and is resistant to extreme temperatures Telomeres - Sections at the end of DNA that are repeated gibberish and acts a buffer People Chargaff - Discovered that the amount of purines = pyrimidines in DNA Franklin and Wilkins - Produced an x-ray diffraction pattern of DNA Griffith - Experimented with virulent and non-virulent bacteria on mice Hammerling - Experimented with the foot, stalk and cap of unicellular green algae Hershey and Chase - Experimented with radioactively labeled viruses and bacteria Kary Mullis - Developed PCR Meselson and Stahl - Used heavy and light nitrogen to prove semi-conservative replication Miescher - Isolated “nuclein” from pus Oswald Avery - The Canadian who experimented further with the “transforming principle” Watson and Crick - Made a model of the double helix structure of DNA Processes​ DNA packaging -​ 2nm: Double helix from hydrogen bonding -​ 11nm: Nucleosome, due to wrapping around 8 histone proteins -​ 30nm: Solenoidal Fiber (chromatin) from H1 histone proteins -​ 300nm: Chromatin forms loops that attach to a protein scaffold (NHC proteins) -​ 700nm: Continues to condense -​ 1400nm: Chromosome Types of RNA in protein synthesis -​ mRNA -​ snRNA -​ tRNA -​ rRNA Describe transcription -​ Describe initiation phase of DNA replication -​ Describe elongation phase of DNA replication (continuous and discontinuous synthesis) Describe translation Label transcription Label translation Perform transcription and translation on paper Perform a restriction endonuclease cut on a DNA sequence Perform Sanger sequencing UNIT 3: METABOLIC PROCESSES Terms Anaerobic respiration - Similar to aerobic respiration but in the ETC, the final electron acceptor is an inorganic molecule ATP Synthase - Takes the proton gradient to pass hydrogen ions through it, making ATP from ADP and inorganic phosphate Chlorophyll - The pigment found in chloroplasts. Made up of a porphyrin ring and hydrocarbon tail. Magnesium is found in the centre. Chlorophyll a has a methyl group while chlorophyll b has an aldehyde Electrochemical gradient - A concentration gradient of ions formed between the matrix and intermembrane space Facultative anaerobe - Organisms that can live with or without oxygen Glycerol-Phosphate Shuttle - Moves NADH created in glycolysis to the matrix in incomplete cellular respiration Malate-Aspartate Shuttle - Moves NADH created in glycolysis to the matrix in complete cellular respiration Obligate anaerobe - Organisms that cannot lie in the presence of oxygen Oxidative phosphorylation - ATP production through energy from the ETC/proton gradient. Occurs in the ETC and chemiosmosis Photorespiration - Consumes O2, releases Co2, doesn’t produce ATP or sugar. Occurs in hot weather or when O2 is more plentiful than CO2 Rubisco - the catalyst protein that helps combine CO2 and RuBP. Binds easier to O2 than CO2 Substrate-level phosphorylation - Directly forming ATP by transferring a phosphate to ADP using an enzyme. Occurs in glycolysis and citric acid cycle. Processes Describe the general equation for cellular respiration Describe Cellular Respiration and numbers involved -​ Glycolysis -​ Transition Reaction -​ Citric Acid/Krebs Cycle -​ Electron transport chain (ETC) Describe the Electron Transport Chain (in increasing electronegativity) -​ Complex I -​ Complex II -​ Complex III -​ Complex IV -​ Ubiquinone and Cytochrome Label the mitochondria Describe alcohol and lactic acid fermentation Describe the general equation for photosynthesis Label the chloroplast Describe photoexcitation Label cyclic and non-cyclic photosynthesis Describe the stages of the light-independent reactions -​ Carbon fixation -​ Reduction -​ Regeneration of of RuBP Describe C3, C4, and CAM plants Describe and label the C4 and Cam pathways UNIT 4: HOMEOSTASIS Terms Acetylcholine - The neurotransmitter released at a neuromuscular junction Acetylcholinesterase - Breaks down acetylcholine to acetic acid and choline ADH - Controls the permeability of water in the distal convoluted tubule and collecting duct. Higher levels of ADH = high water reabsorption Antagonistic hormones - Hormones that have opposite effects Astrocytes - Provides physical support to neurons in the central nervous system Autonomic nervous system - Controls smooth muscle and automatic body functions Broca’s Area - The area of the cerebral cortex associated with speaking ability Central Nervous System - Contains the brain and spinal cord Cerebellum - The part of the brain that controls posture and balance Cerebral cortex - The layer covering both cerebral hemispheres Cerebrospinal fluid - Produced by ependymal cells, cushioning and protecting the spinal cord Cerebrum - The most developed part of the brain in humans Control Centre/Integrator - Relays message from receptor to appropriate location for a response Corpus callosum - The connection between the two hemispheres of the brain Diuretic - Inhibits ADH production Effector - Responds to the message, leads to a change in the body that restores balance Frontal lobe - The lobe of the cerebrum associated with intellectual activity Glial cells - the cells that provide nutritional and structural support to neurons Homeostasis - The state of the body in which the internal physical and chemical conditions are maintained within a tolerable range Hypersecretion - Over secretion of hormones Hyposecretion - Under secretion of hormones Limbic system - Contains pleasure and punishment centre. Controls deep-seated unconscious drives, emotions, memory, and motivation. Made up of Olfactory bulb, Thalamus, Hypothalamus, Amygdala, Hippocampus Medulla Oblongata - The site of autonomic nerve control Microglia - Located in the CNS, are specialized immune cells Midbrain - The relay centre for eye and ear reflex Negative feedback - Maintains a normal body constant Nephron - The functional unit of the kidney Neuromuscular junction - The synapse between a neuron and a muscle Occipital lobe - The lobe of the cerebrum associated with vision Olfactory lobe - The forebrain lobe that receives sensory information about and detects smell Oligodendrocytes - Cells that form the myelin sheath in the central nervous system Parietal lobe - The lobe of the cerebrum associated with touch Peripheral Nervous System - Contains the rest of the nervous system other than the brain and spinal cord Pons - The relay station passing information between the cerebellum and cerebrum Positive feedback - Does not maintain homeostasis, when there is a definite end goal Prefrontal cortex - The part of the cerebral cortex associated with higher mental activities Receptor - Receives stimulus from the environment and sends message Refractory period - A small period of time where the neuron is unable to fire Reticular formation - Allows background information to be inhibited Satellite cells - Provides physical support to the neurons in the peripheral nervous system Schwann cells - Cells that form myelin sheath in the peripheral nervous system Synaptic cleft - The space between two neurons Temporal lobe - The lobe of the cerebrum associated with hearing Thalamus - The sensory relay centre that receives stimuli involving pain Wernickie’s Area - The area of the cerebral cortex associated with speaking syntax Processes Describe and label each part of the nephron Describe the types of neurons -​ Sensory receptors (uni/bi-polar) -​ Brain/Spinal cord (multipolar) -​ Effector (multipolar) Label the neuron Describe each part of the neuron -​ Dendrite -​ Cell body -​ Axon -​ End brush Describe action potential and how myelin sheath speeds up nerve impulses Describe the components of the reflex arc -​ Sensory receptor -​ Sensory neuron -​ Interneuron (absent in monosynaptic) -​ Motor neuron -​ Effector Describe and label how neurotransmitters move across the synapse Brute Force Memorization The endocrine hormones  Endocrine Gland Location Hormone Produced Target Tissue Function Triggered by Hormone Posterior Pituitary Base of ADH Kidney Tubules Increases permeability of kidney to Brain water, increases water retention Posterior Pituitary Base of Oxytocin Uterus, Stimulates contractions, milk release Brain Mammary glands Anterior Pituitary Base of Growth Hormone General Stimulates growth of bones and tissue Brain (GH) Anterior Pituitary Base of Prolactin Mammary Stimulates milk production Brain Glands Anterior Pituitary Base of Thyroid Stimulating Thyroid Gland Stimulates the release of thyroid Brain Hormone (TSH) hormones Anterior Pituitary Base of ACTH Adrenal Cortex Stimulates release of glucocorticoids, Brain raising bloods sugar, anti-inflammatory response Anterior Pituitary Base of Follicle-stimulating Sex organs Males: Stimulates sperm production Brain Hormone (FSH) Females: Stimulates follicle development Anterior Pituitary Base of Luteinizing Hormone Sex organs Males: Stimulates male sex hormones​ Brain (LH) Females: Regulates follicle development, triggers ovulation Anterior Pituitary Base of Melanocyte-stimulati Melanocytes in Promotes darkening skin Brain ng Hormone (MSH) skin Thyroid Gland Throat T4 & T3 Body cells Increases metabolic rate, necessary for normal body growth Thyroid Gland Throat Calcitonin Bones Lowers calcium levels, adds calcium to bone Parathyroid Gland Throat Parathyroid Bones Raises calcium levels, removes calcium Hormone (PTH) from bone Pineal Gland Centre of Melatonin Brain, Anterior Synchronize biological clock with day Brain pituitary gland, reproductive organs Adrenal Cortex Above Cortisol General Releases glucose, suppresses immune Kidneys system Adrenal Cortex Above Aldosterone Kidney Tubules Promotes Na+ reabsorption in kidney Kidneys Adrenal Medulla Above Adrenaline/noradren Muscle, heart, Fight or flight response Kidneys aline blood vessels Pancreas (beta cells in Behind Insulin Body cells, Decrease blood sugar islets of Langerhans) Stomach liver Pancreas (alpha cells Behind Glucagon Liver, fat tissue Increase blood sugar in islets of Langerhans) Stomach Hypothalamus Centre of GnRH Anterior Controls secretion of LH and FSH Brain pituitary gland Ovaries (female) Pelvic Estrogen Female Thickens endometrium Region reproductive structures  Ovaries (female) Pelvic Progesterone Female Thickens uterine lining Region reproductive structures Testes (male) Pelvic Testosterone Male Stimulates spermatogenesis Region reproductive structures Sympathetic vs. parasympathetic effects Organ Sympathetic Parasympathetic Heart Increases heart rate Decreases heart rate Eyes Dilate eyes Constrict eyes Liver Increase release of glucose Stores glucose Adrenal Gland Releases adrenaline No effect UNIT 5: POPULATION DYNAMICS Terms Allee effect - A density-dependent phenomenon that occurs when a population cannot survive or fails to reproduce enough to offset mortality once the population density is too low Carnivory - Act of eating meat. Some animals have fast mobility to catch prey or sharp teeth to bite into meat Closed population - There is no movement of individuals in and out of a population Coevolution - When two or more species evolve in response to each other’s selective pressures. Ex: Sickle shaped bills in hummingbirds and conical, curved flowers Emigration - Movement of individuals out of a population Exploitative competition - Two or more populations exploit a limiting factor, reducing food availability Exponential model - Population growth rate increases at a faster rate forever Fecundity - Biological potential/capcity to produce offspring in ideal conditions Fertility - Actual reproductive performance/# of offspring produced Herbivory - Act of eating plants. Some animals have chemical sensors to locate/process plants or specialized teeth to grind tough vegetation Immigration - Movement of individuals into a population Interference competition - Presence of one species harms the other species for food Interspecific competition - Competition between members of different species Intraspecific competition - Competition between members of the same population for resources Logistic model - Population growth rate increases until it starts slowly slowing down until hitting a maximum Mark-Recapture method - Capturing and marking, releasing, and recapturing animals to estimate population density. Works well on mobile, stable population size, and tolerant of being marked species Mortality - The rate individuals die Natality - The rate new individuals are added through births Open population - There is movement of individuals in and out of a population Quadrat method - Drawing quadrats and counting to estimate population density. Works well on stationary/slow moving, uniformly distributed, and easily countable species Resource partitioning - Many species live in the same place but use resources differently Formulas 𝑁 Density: 𝐷 = 𝑆 # 𝑜𝑓 𝑖𝑛𝑑𝑖𝑣𝑖𝑑𝑢𝑎𝑙𝑠 Population Density (and estimated quadrat): 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑆𝑎𝑚𝑝𝑙𝑖𝑛𝑔 𝑎𝑟𝑒𝑎 𝑀𝑛 Population Size (estimated mark-recapture): 𝑁 = 𝑚 Population Size: 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 𝑆𝑖𝑧𝑒 = 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 × 𝐴𝑟𝑒𝑎 (𝑏𝑖𝑟𝑡ℎ𝑠+𝑖𝑚𝑚𝑖𝑔𝑟𝑎𝑛𝑡𝑠)−(𝑑𝑒𝑎𝑡ℎ+𝑒𝑚𝑖𝑔𝑟𝑎𝑡𝑖𝑜𝑛) Population Growth Rate: 𝑃𝐺𝑅 = 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 × 100 𝑑𝑁 Instantaneous Growth Rate: 𝑑𝑡 = 𝑟𝑁 0.69 Doubling time: 𝑡𝑑 = 𝑟 𝑑𝑁 𝐾−𝑁 Logistic Growth Rate: 𝑑𝑡 = 𝑟𝑚𝑎𝑥𝑁( 𝐾 ) Brute Force Memorization Dispersion Patterns Clumped Random Uniform Image Description Individuals are closely Individuals are dispersed Individuals are more grouped together independent of one widely dispersed than another random Benefits Easy to find mates Less competition for Enough resources for resources each individual Enhanced protection in numbers Flexible resource usage Territorial benefits Efficient resource Adaptable to Efficient resource utilisation environmental conditions distribution Assumptions of mark-recapture method -​ Chance for capture for each individual is equal and uniform for both initial and final captures -​ Proportion of marked to unmarked individuals remain same between captures  -​ Sufficient time was allowed for marked individuals to disperse -​ Captured animals aren’t affected by marks -​ Captured animals don’t lose their marks Survivorship Curves Type I Type II Type III Image Description Flat at start, drops Steadily declining Drops rapidly at the steeply towards the survivorship start, flattens out near end the end Examples Dall mountain sheep Five-lined skink Black crappie fish Traits Large animals Face constant mortality Large number of producing few young probability offspring Provide young with Relatively short Babies are preyed on extended care gestation period Can survive in old age Able to fend for Feed on Type III but are themselves prey to Type I Density-Dependent vs. Density Independent factors Density Dependent Density Independent -​ Predation -​ Habitat lost -​ Disease -​ Weather/climate change -​ Allee effect -​ Natural disasters -​ Competition -​ Human destruction (usually)  -​ Crowding Why are smaller populations more likely to become extinct than larger populations? -​ Reduced genetic diversity -​ Greater impact of loss of individuals -​ More vulnerable to environmental changes Why is it harder for large animals to bounce back from negative habitat changes? -​ Increased competition -​ Limited dispersal options -​ Migratory challenges Types of defense -​ Active (fleeing or displays) -​ Passive camouflage -​ Passive hiding -​ Behavioural alarm calls -​ Chemical defence -​ Mimicry Biotic interactions -​ Competition -​ Predation -​ Mutualism -​ Commensalism -​ Parasitism -​ Herbivory