Biology Notes: Cell Structure, Genetics and More (PDF)
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These are biology notes covering topics such as cell structure, genetics, metabolism, and the organization of life. Key concepts include cell theory, characteristics of living things, cell organelles, DNA replication, and evolution. The notes also include diagrams and explanations.
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Biology Chapter 1: How is life organised? State the 3 aspects of the cell theory ○ All organisms are made up ofoneormore cells. ○ All cellscome frompre-existing cells. ○ The cell is thebasic unit of life....
Biology Chapter 1: How is life organised? State the 3 aspects of the cell theory ○ All organisms are made up ofoneormore cells. ○ All cellscome frompre-existing cells. ○ The cell is thebasic unit of life. Outline the 7 characteristics of living things ○ Metabolism:refers to all the chemical reactions an organism uses to take in and transform energy from the environment. ○ Reproduction: transfers hereditary information to offspring. ○ Homeostasis: the maintenance of a stable level of internal conditions. ○ Growth: living organisms increase in size and/or number of cells ○ Response: can be the result of a physical or chemical change in the environment. This change produces a purposeful response. ○ Excretion: the removal of bodily waste, which results from normal life processes. ○ Nutrition: the intake and use of raw materials for growth and repair. Deduce whether or not viruses are living things ○ Virusesaren’t made of cells, theycan’tmaintainhomeostasis, theydon’t growandcannot make their ownenergy. Even though they definitelyreplicate and adapt to their environment,viruses are more likeandroidsthan real living organisms. Describe Pasteur’s experiment ○ Draw and label eukaryotic cells (animal and plant) ○ Eukaryotic cells-They are cells that contain a nucleus and organelles, enclosed by a plasma membrane. Organisms which have this type of cell include protozoa, fungi, plants and animals. Domain: Eukaryota ○ ○ Compare and contrast animal/plant cells ○ Draw and label a prokaryotic (bacterial) cell ○ Prokaryotic cells-Single-celledorganisms thatlackanucleusandmembrane-bound organelles. They are not divided up in the inside, like eukaryotic cells, by membrane walls but consist of asingle open spaceinstead. ○ ○ Describe the functions of cell organelles ○ Nucleus: It holds and protects the cell’s DNA. DNA is the genetic material for the cell. DNA carries the information and instructions that direct the cell. ○ Mitochondria: This produces ATP. ATP is cellular energy & to make ATP, the mitochondria needs to take in glucose and oxygen. The powerhouse of the cell. ○ Vacuole: Cell storage (of water mostly, but also food waste). ○ Chloroplast: Contains chlorophyll to conduct photosynthesis. ○ Cell Wall:Supports and protects the cell. ○ Cell Membrane: The plasma membrane is the boundary that surrounds all cells. It regulates what enters and leaves, ensuring it maintains homeostasis. ○ Cytoplasm: This is the gel-like fluid inside the cell. It is the medium for chemical reactions, providing a platform which other organelles can operate within the cell. ○ Ribosomes: produce protein. ○ Golgi apparatus:site for protein and lipid processes and packaging. ○ Lysosome: membrane bound containing digestive enzymes. ○ Smooth endoplasmic reticulum:synthesis of essential lipids + hormones. ○ Rough ER:protein production, folding and quality control. ○ Cytoskeleton: maintains the cell shape and internal organisation. Define the terms: embryonic stem cells, hierarchy, multicellular, organisation, physical, unicellular, differentiation ○ Stem cell:cells which can adapt and change into a wide range of other cells. ○ Embryonic stem cells: A type of cell found in the embryo, capable of dividing into almost any cell type. Kingdom - Domain, etc. ○ Hierarchy:Taxonomic classification of living organisms in a level by level format. ○ Multicellular: This is an organism that has more than one cell. ○ Unicellular: An organism that only has one cell. ○ Differentiation: when an unspecialised cell becomes a more specialised type. Outline with a flow diagram the life of a cell ○ Explain examples of specialised cells ○ Red blood cells: Containhaemoglobin, which carries oxygen. No nucleuspresent, allowing more space to carry oxygen. These cells are shapedbi-conclave, giving them alarge surface area,and the best chance of absorbing as much oxygen as they can. ○ Nerve Cells Thinand can be more than1 metre long. They can carry messages up and down the body over large distances. Nerve cells havebranched connections at each end.Thesejointo other nerve cells, ensuring messages are transmitted around the body. There arefatty (myelin) sheathsthat surround these cells. The sheath helpsincrease the speedat which the message can travel. ○ Muscle Cells ○ Sperm Cells Flagellum/tail that allows them to navigate the fallopian tubes easily. Lots of mitochondriaforenergyto swim to the egg cell Stream-line shapefor bettermanoeuvrabilityand swimming Lots of digestive enzymesat their tip to bettercrack open and penetratethe egg cell Compare different organ systems ○ Structure: Skeletal, Muscular, Cardiovascular, Nervous ○ Regulation: Endocrine, Urinary, Lymphatic (immune) ○ Energy: Respiratory, Digestive ○ Reproductive: Reproductive Summarise the levels of organisation of life ○ Organelles: nucleus, mitochondria, etc… ○ Cells: animal cell, plant cell ○ Tissue: cardiac muscle tissue, guard cell ○ Organs: heart, leaf ○ Organ Systems: Circulatory system, etc ○ Organisms: HUMAN & PLANT ○ Species:genus, family, order, class, phylum, kingdom, domain ○ Population ○ Community ○ Ecosystems ○ Biome ○ Biosphere Define classification ○ Classification, in biology, is the establishment of ahierarchical system of categorieson the basis of presumed natural relationships among organisms. The science ofbiological classificationis calledtaxonomy. ○ Describe features of each kingdom (protoctista, fungi, animal, plants, monera) FEATURE KINGDOM ANIMALS PLANTS FUNGI PROTOCTISTA BACTERIA Cell Wall NO YES Cellulose YES - Chitin sually no cell wall, U ES - Y although some forms Peptidoglycan may have one True nucleus YES YES YES YES NO Number of cells Multicellular Multicellular Multicellular Most are unicellular Unicellular Chloroplasts NO YES YES SOME MOST DON’T ermanent P NO YES YES SOME YES Vacuole ○ Distinguish between analogous and homologous features ○ Analogous Features:Similarfunctions butoriginandanatomyaredifferent.(e.g. bat wing and insect wing.) ○ Homologous Features:Differentfunctionsbut have acommon originandsimilar anatomy. (e.g. bat wing and human arm.) Outline how organisms are named according to binomial nomenclature ○ FOR SPECIFIC ANIMALS PUT THEIRGENUS + SPECIESNAME List the stages of the hierarchy of life (Kingdom, Phylum etc.) ○ Da intyKo alasPackCandyOm inouslyFo rGamblingSo rcerers. ○ Do main,Kingdom,Phylum,Class,Or der,Family,Ge nus,Sp ecies Discuss the possibility of creating artificial life Suggest ethical issues of creating artificial life Chapter 2: What chemical processes support life? Define the term: metabolic ○ Metabolism: It is the sum of all biological transformations of energy and matter in an organism ○ Metabolic: It is the term that means “related to metabolism.”E.G- A disease can have metabolic causes, or metabolic effects. Distinguish between anabolic and catabolic reactions State examples of anabolic and catabolic reactions ○ Anabolic Reactions: Energy + Smaller molecules → larger molecule Building muscles (making proteins) Photosynthesis ○ Catabolic Reactions:Larger molecule → energy + smaller molecules Digestion Cellular respiration Discuss factors affecting rates of reaction ○ Concentration,surface area,temperature, and thepresence of a catalyst.(check chem too) State the word and balanced chemical equation for aerobic respiration ○ C6H12O6 + 6O2 → 6CO2 + 6H2O ○ Glucose + Oxygen → Carbon Dioxide + Water State the word equation for anaerobic respiration ○ Glucose → ethanol + carbon dioxide + energy (ATP) Label the structure of a mitochondrion and describe the functions of the parts ○ ○ Inner membrane folds→larger surface area→ more places for reaction → more usable energy. Outline the process of respiration ○ Respiration: This is the chemical process of breaking down food particles in the cells in presence of oxygen and releasing energy. There are two stages -inspiration and expiration. ○ Inspiration: taking in air rich in oxygen. During inspiration, the ribs are lifted up and the diaphragm flattens. This increases the volume of the thoracic cavity, helping the inhalation of oxygen. ○ Expiration: giving out carbon dioxide. During expiration, the ribs move downward and back to its original position and the diaphragm moves upward back to its dome shape. This decreases the volume of the thoracic cavity and pumps out carbon dioxide into the atmosphere from the lungs. Compare aerobic and anaerobic respiration Anaerobic Aerobic reactants glucose Glucose and oxygen combustion incomplete complete energy yield Low (2 ATP) High (36-38 ATP) products Animals: Lactic acid CO2 & H2O Yeast: Ethanol + CO2 location cytoplasm Cytoplasm and mitochondria stages lycolysis G lycolysis G Fermentation Link reaction Krebs cycle Electron transport chain Suggest uses of anaerobic respiration in industry Define photosynthesis ○ Photosynthesis: the process is which light energy is converted to chemical energy in the forms of sugars. State the word and balanced chemical equation for photosynthesis ○ 6CO2+6H2O→C6H12O6+6O2 ○ Carbon dioxide + water → glucose + oxygen Discuss the limiting factors that affect the rate of photosynthesis ○ Light intensity ○ Carbon dioxide concentration ○ Temperature Draw and label the structure of a leaf Sketch graphs to show the effect of limiting factors on photosynthesis ○ ○ Light intensity: rapidly increases to a certain point. It stays relatively the same throughout the rest of the graph. Start at the origin. ○ Carbon dioxide concentration:Rapidly increases then stays relatively the same afterwards. Also starts at the origin. ○ Temperature:Rapidly increases, reaching its peak, then rapidly decreases. Start at the origin. Define the terms: catalyst, kinetic, limiting factor, transfer, yield, active site ○ Catalyst: A substance that increases the speed of a reaction without being changed or used in the process. ○ Active site:Region of the enzyme with a specific shape to the substrate molecules. Describe the structure and function of enzymes ○ Structure: They’re basically large proteins/a chain of amino acids ○ Function: They are biological catalysts that speed up the rate of reaction. Explain what is meant by the lock and key theory ○ In thelock and key hypothesis, theshapeof theactive sitematches the shape of its substrate molecules. This makes enzymeshighly specificand that each type of enzyme can usually catalyseonly onetype of reaction. (some may do more though) Distinguish between substrate, enzyme, product and enzyme-substrate complex ○ Substrate: A reactant used in an enzyme ○ Enzyme: Biological catalysts to increase speed in reactions ○ Product: substances after a biological process has occurred. ○ Enzyme-substrate complex: ○ Outline limiting factors of enzyme activity ○ Concentration of the enzyme ○ Concentration of the substrate ○ Temperature ○ The pH List 3 enzymes that function within the human body ○ Amylase break down starches ○ Lipase breaks down fats ○ Lactase- breaks down sugar Lactose Chapter 3: How do organisms sustain themselves? Outline the main nutrients required by an organism with the functions ○ Lipids, Proteins, Carbohydrates List examples of foods containing the major nutrients ○ Carbohydrates: Wheat, Barley ○ Lipidds: Butter, Coconut oil ○ Proteins: Lentils, Fish ○ Nucleic acids: Anything living State the monomers of carbohydrates, lipids and proteins ○ Carbohydrates: Monosaccharides ○ Lipids: Fatty acids and glycerol ○ Proteins: Amino acids Distinguish between saturated and unsaturated fats ○ ○ Label the parts of the digestive system ○ Describe the functions of the parts of the digestive system ○ Ingestion: food is taken into the body ○ Digestion: breakdown of complex food substances into smaller soluble food substances ○ Absorption: digested food is absorbed into body cells. ○ Assimilation: absorbed food is used to provide energy. ○ Egestion: removal of undigested foods. ○ Liver: produces bile. ○ Gallbladder: stores bile. ○ Pancreas: produces juices for digestion, neutralises the acidic stuff in your stomach. Outline the function of bile ○ Bile is the greenish-yellow fluid(consisting of waste products, bile salts and cholesterol)which is produced by the liver. It doestwo functions: Carry away waste Break down fats during digestion State the location and pH requirements of the digestive enzymes???? ○ Pepsinworks in thehighly acidicconditions of the stomach. It has an optimumpHof about 1.5. On the other hand,trypsinworks in thesmall intestine, parts of which have apHof around7.5.Trypsin's optimum pH is about 8. Distinguish between mechanical and chemical digestion ○ Mechanical/physical: muscles in the body break down food. ○ Chemical: food is broken down via a chemical reaction. Draw and label the structure of the breathing system ○ ○ Order: Nose & Mouth →Trachea → Bronchi → Bronchiole → Alveoli→ Red blood cells Explain the mechanism of ventilation ○ Inhalation: Diaphragm contracts + moves down ○ Exhalation: Diaphragm relaxes, curves + muscle relaxes Suggest how the alveoli are adapted for gas exchange ○ One cell thick, thin walls→ decreases diffusion distance ○ Moist walls→ gases dissolve in the moisture and are able to diffuse more quickly ○ High oxygen concentration, large diffusion gradient→ O2 concentration is higher in alveoli so that oxygen will diffuse down the concentration gradient into the bloodstream. ○ Oxygendiffusesdown aconcentration gradient(from high to low).The oxygen gets picked up byred blood cellsin thecapillarywhich takes it to the heart so it can be pumped to the rest of the body. ○ This same thing is done in reverse from capillaries to alveoli with CO2. State that gases are exchanged by diffusion. Define: deoxygenated, oxygenated, vessel ○ Deoxygenated: there is a low concentration of oxygen in the blood. ○ Oxygenated: high concentration of oxygen in the blood. ○ Vessel: Blood vessels arechannelsthatcarry bloodthroughout your body. They form a closed loop, like a circuit, thatbegins and ends at your heart.Together, the heart vessels and blood vessels form your circulatory system. Label the structure of the heart ○ Outline the flow of blood through the heart ○ Lungs, superior/inferior vena cava, right atrium, right ventricle, pulmonary artery, pulmonary veins, left atrium, left ventricle, aorta, other organs. Compare and contrast arteries, veins, capillaries ○ Arteries: Strong, muscular walls, carry oxygenated blood away from the heart to your organs, small lumen. ○ Veins: Thin walls due to less pressure, valves to prevent backflow, carry deoxygenated blood to the heart and lungs, large lumen. ○ Capillaries: Very thin walls, single-cell thick, very small lumen and lets oxygen diffuse into organs. Define: concentration gradient ○ Concentration Gradient:molecules diffuse down a concentration gradient from high concentration to a low concentration. Define: Diffusion ○ Diffusion: Thepassive movementof particles from a region ofhigherconcentration to a region oflowerconcentration (passive transport: no energy)untilequilibriumis reached. ○ Osmosis: Thediffusion of wateracross apermeable membranefrom an area ofhigher waterconcentration to an area oflower waterconcentration.Solutesdissolvein water. More solute, less water and less solute, more water. HYPERTONIC= Higher in solute HYPOTONIC= Lower in solute ISOTONIC= Equal in solute Osmosis is the diffusion of water across a membrane from an area of lower solute concentration to an area of higher solute concentration. ○ Active transport:Requires ATP to occur. This is the movement of a substance against its concentration gradient (from low to high). Outline examples of where the transport types occur ○ Diffusion:alveoli ○ Osmosis:small and large intestines ○ Active transport:gut wall(sugars are transported from low con to high con in the blood, letting it be absorbed. The glucose is used for respiration). Outline the factors that speed up the rate of diffusion ○ Temperature: increased temperature increases diffusion rate. ○ Concentration Gradient change: greater concentration gradient increases diffusion rate. ○ Surface Area:large surface area of the membrane, the higher the rate of diffusion. Chapter 4: What factors affect human health? (not yet completed) Define: Homeostasis, vasodilation, vasoconstriction, piloerection Define: stimulus, reflex, neurons, neurotransmitter Describe what is meant by a reflex arc ○ Stimulus: A change in the environment/internally that triggers a response ○ Reflex (action): an involuntary sequence or action that is a nearly instantaneous response to a stimulus. ○ Neurons: fundamental units of the brain and nervous system. ○ Neurotransmitter: chemical messengers that carry chemical signals (“messages”) from one neuron to the next cell. ○ Reflex arc:pathway for a reflex action. Stimulus → receptor → sensory neuron → relay neuron → motor neuron → effector → response Distinguish between the CNS and PNS ○ CNS (central nervous system): includes only two organs-the brain and spinal cord. ○ PNS (peripheral nervous system): everything else which includesnerves. Draw and label a motor neuron (done in book gr.9) ○ Outline the difference between sensory, relay and motor neurons ○ Sensory neurons: carry electric impulses from sensory organs (receptors) to the CNS. ○ Relay neurons: found in the brain and spinal cord and allow sensory + motor neurons to communicate. ○ Motor neurons:carry electron impulses from the CNS to specific effectors. ○ Effectors: parts of the body- such as muscles and glands- that produce a response to a detected stimulus. Explain how a synapse functions ○ Identify different types of stimuli that cause a response ○ Pain & touch ○ Vision ○ Taste ○ Sounds ○ Smells State the different types of receptors and where they’re located ○ Receptors: groups of specialised cells. They detect change in the environment (stimuli) and trigger electrical impulses in response. Mechanoreceptors: mechanical forces-skin, ear Chemoreceptors: chemicals-tongue, nose Thermoreceptors: temperature-skin Photoreceptors: light-eyes Chapter 5: How do characteristics pass from one generation to another Define: replication, heredity, DNA helix, genome. Identify the components of a nucleotide. Draw simple diagrams of the structure of single nucleotides of DNA and RNA, using circles, pentagons, and rectangles to represent phosphates, pentoses and bases. ○ Phosphate, Pento-sugar, Nitrogen base ○ Identify the four base pairs ○ Adenine, Thymine (In RNA is Uracil), Guanine, Cytosine Outline the process of DNA replication. ○ ○ Helicase -Unzips the DNA strand into two ○ Primase -Adds primer to the ends of the DNA strands ○ Polymerase III -Synthesises the new DNA strand ○ Polymerase I -Removes the primers on the end and replaces them with proper bases ○ Ligase -Repairs any damages and Okazaki fragments, ensuring the DNA is stable Compare and contrast DNA, genes and chromosomes. Explain how a gene codes for the formation of protein (DNA -> RNA -> Protein) (PROTEIN SYNTHESIS) ○ Transcription- The copying of a gene to make mRNA. DNA must unzip for this process to occur. ○ Translation- ThemRNAtravels to theRibosome(site of protein synthesis) and the tRNA then pairs a protein using a codon and anticodon. The protein is made this way (length + order of amino acids will determine the type of protein). ○ Codon: Triplet of bases on mRNA. ○ !!! Amino acid chains all have peptide bonds between amino acids !!! ○ Selective Breeding / Artificial Selection Definition: Selective breeding, also known as artificialselection, is when humans intentionally choose specific organisms with desired traits (like size, color, or resistance to disease) to reproduce, aiming to produce offspring with these traits. Examples in Plants: ○ Crop Improvement: Farmers select plants with desirabletraits (e.g., wheat that resists disease or corn with larger kernels) and breed them over multiple generations. This makes crops more productive and resilient. ○ Flower Breeding: Gardeners breed flowers like rosesor tulips for specific colors or petal shapes, creating unique varieties. Examples in Animals: ○ Livestock: Cattle are often bred for high milk productionor faster growth, creating animals better suited to farming needs. ○ Dogs: Different dog breeds (e.g., Labradors, Poodles)have been selectively bred for traits like size, temperament, or coat type. Methods of Artificial Selection: ○ Crossbreeding: Mating two individuals from differentbreeds or varieties (like a beef cow and a dairy cow) to combine desirable traits. ○ Hybridization: Crossing individuals from different species to create a hybrid (e.g., mule, a horse-donkey hybrid). Advantages: ○ Produces high-yield crops or animals ○ Can improve disease resistance or growth rates ○ Enhances specific, desired traits (e.g., flavor, appearance) Disadvantages: ○ Reduced Genetic Diversity: Less genetic variation, which can make populations more vulnerable to disease or environmental changes. ○ Inbreeding Risks: Breeding similar individuals canlead to health problems (e.g., genetic disorders in dog breeds). Evidence of Evolution Fossil Evidence: ○ Fossils are the preserved remains of ancient organisms found in layers of rock. By studying fossils, scientists can see how organisms have changed over time. ○ Transitional Fossils: Fossils showing intermediatestages between ancient species and modern ones (e.g., Archaeopteryx, showing traits of both dinosaurs and birds). ○ Fossil Record: This is the history of life documentedby fossils, showing a timeline of gradual change and helping to map the evolution of life forms. Comparative Anatomy: ○ Homologous Structures: Similar body parts in differentspecies, like the limb bones in humans, cats, whales, and bats, which all have similar bone structures due to shared ancestry. ○ Vestigial Structures: Parts that have lost their originalfunction over time, like the human appendix or tailbone, indicating evolutionary change. Comparative Embryology: Studies similarities in embryosof different species. For example, human, chicken, and fish embryos look very similar at early stages, suggesting a common ancestor. Molecular Evidence: ○ DNA Sequencing: Comparing DNA sequences of differentorganisms reveals genetic similarities. For example, humans share a high percentage of their DNA with chimpanzees, showing close evolutionary ties. ○ Genetic Similarities: Genes that are highly similarbetween species provide evidence for common ancestry. Biogeography: ○ The study of species distribution across the planet. Isolated islands, like the Galápagos, have unique species (e.g., Galápagos tortoises), demonstrating how location influences evolution. Natural Selection Definition: Natural selection is the process by which individuals with traits that are better suited to their environment survive and reproduce more successfully, passing on those traits to the next generation. Darwin’s Theory: Charles Darwin proposed that naturalselection drives evolution. Key ideas include: ○ Variation: Individuals in a species vary in traits. ○ Competition: Organisms compete for resources. ○ Survival of the Fittest: Traits that improve survivaland reproduction are passed down. Examples: ○ Peppered Moth: During the Industrial Revolution, pollution darkened tree bark, so darker moths blended in and survived better. Over time, the population became mostly dark-colored. ○ Antibiotic Resistance: Bacteria can evolve to resistantibiotics, leading to stronger bacteria that survive and spread. Factors Affecting Natural Selection: ○ Variation: Genetic differences within a population. ○ Competition: Limited resources drive competition. ○ Selection Pressures: Environmental challenges (e.g.,predators, climate) that affect survival. Speciation Definition: Speciation is the process by which onespecies splits into two or more distinct species, usually due to genetic changes and isolation. Mechanisms: ○ Allopatric Speciation: Occurs when a population isgeographically separated, leading each group to evolve differently (e.g., river divides). ○ Sympatric Speciation: New species arise in the samelocation, often due to different ecological niches (e.g., insects adapting to different food sources). Examples: ○ Galápagos Finches: Different species of finches onthe Galápagos Islands evolved unique beaks suited to specific food sources. ○ Cichlid Fishes: In African lakes, different speciesevolved within the same lake by specializing in unique food sources or habitats. Role of Isolation: Physical or reproductive isolation prevents gene flow, allowing populations to evolve independently. Heritable Variation Definition: Heritable variation refers to geneticdifferences that can be passed from parents to offspring. Sources: ○ Mutations: Random changes in DNA can create new traits. ○ Genetic Recombination: During sexual reproduction,gene combinations shuffle, creating unique genetic mixes. Importance: Genetic variation is critical for evolution,as it provides the material for selection to act upon. Types: ○ Single Nucleotide Polymorphisms (SNPs): Variationsin a single DNA base. ○ Gene Duplications: Entire genes can duplicate, sometimesleading to new functions. Antibiotics Definition: Antibiotics are drugs used to kill orinhibit the growth of bacteria, treating bacterial infections. Mechanisms of Action: ○ Cell Wall Targeting: Penicillin stops bacteria frombuilding cell walls. ○ Protein Synthesis Inhibition: Some antibiotics disruptbacterial protein creation. ○ DNA Replication Disruption: Other antibiotics interferewith bacterial DNA replication. Antibiotic Resistance: Overuse of antibiotics canlead to bacteria evolving resistance, making infections harder to treat. Strategies to Combat Resistance: ○ Limiting unnecessary antibiotic use. ○ Developing new antibiotics. ○ Using combination therapies to attack bacteria in multiple ways. Interacting with the Environment Adaptations: Traits that increase an organism’s ability to survive in its environment. Behavioral Adaptations: Actions organisms take tosurvive, like birds migrating seasonally. Physiological Adaptations: Internal processes likeproducing antifreeze proteins in Arctic fish to survive cold temperatures. Impact of Environmental Change: Changes like climateshifts can alter food availability, habitats, and survival rates, forcing organisms to adapt or risk extinction. Specialized Structures Definition: Specialized structures are body partsadapted for specific functions. Examples: ○ Plants: Cacti have spines that reduce water loss. ○ Animals: Birds have wings adapted for flight; giraffeshave long necks for reaching high leaves. Relationship to Adaptation: Specialized structuresevolve to meet specific survival needs, enhancing fitness in their environment. Comparing Adaptations Environmental Adaptations: Species evolve unique traitssuited to their specific environments, like desert animals conserving water. Analogous vs. Homologous Structures: ○ Analogous Structures: Different origins but similarfunctions (e.g., wings of birds and insects). ○ Homologous Structures: Shared origin but may havedifferent functions (e.g., human and whale forelimbs). Extinction Definition: Extinction is the complete loss of a species from the planet. Causes: Habitat destruction, overhunting, climatechange, invasive species, and disease. Mass Extinctions: Events where large numbers of speciesdie out (e.g., dinosaurs 66 million years ago). Current Extinction Rates and Conservation: Human activity is accelerating extinction rates, and conservation efforts aim to protect endangered species through habitat preservation, legal protection, and breeding programs. 30/10/2024, 06:45 Chapter 4: Nervous and Immune system Chapter 4: Nervous and Immune system Define Stimulus A change in the environment/internally that triggers a response Define Reflex (action) An involuntary sequence or action that is a nearly instantaneous response to a stimulus Define Neurons fundamental units (cells) of the brain and nervous system. Define Neurotransmitter chemical messengers that carry chemical signals from one neuron to the next cell CNS (central nervous system): includes only two organs- the brain Distinguish between the CNS and PNS and spinal cord. PNS (peripheral nervous system): everything else which includes nerves and sensory organs pathway for a reflex action. Define Reflex arc Stimulus → receptor → sensory neuron → relay neuron → motor neuron → effector → response Draw and label a motor neuron Outline the difference between sensory, Sensory neurons: carry electric relay and motor neurones impulses from sensory organs (receptors) to the CNS. Relay neurons: found in the brain and spinal cord and allow sensory + motor https://knowt.com/flashcards/4dc8a48c-a260-4fd7-af4f-852053d179ab 1/4 30/10/2024, 06:45 Chapter 4: Nervous and Immune system neurons to communicate. Motor neurons: carry electron impulses from the CNS to specific effectors. Pain & touch Vision Identify different types of stimuli that cause a Taste response Sounds Smells Receptors: groups of specialised cells. They detect change in the environment (stimuli) and trigger electrical impulses in response. Mechanoreceptors: State the different types of receptors and mechanical forces- skin, ear where they’re located Chemoreceptors: chemicals- tongue, nose Thermoreceptors: temperature- skin Photoreceptors: light- eyes Synapse Function reflex action a way for the body to quickly and efficiently respond to a change in stimuli receptors groups of specialised cells that detect changes in the environment parts of the body- such as muscles and effectors glands- that produce a response to a detected stimulus. not all bacteria are harmful like probiotics which colonise your digestive system https://knowt.com/flashcards/4dc8a48c-a260-4fd7-af4f-852053d179ab 2/4 30/10/2024, 06:45 Chapter 4: Nervous and Immune system pathogens microorganisms that can cause disease parasite symbiote that benefits at host’s expense host organism that provides nourishment or shelter to another organism at its own expense budding asexual repro by an outgrowth from the parents body asexual reproduction producing offspring (identical to parents) without gametes types of pathogens bacteria, viruses, protozoa, fungi physical: skin and mucous membrane immune: cells, tissues, organs to neutralise and how the body prevents pathogenic entry eliminate threats chemical: stomach acid (pH of 2) hostile environment: inflammation steps of viral replication attachment→ penetration → replication → assembly → release can cause cell damage and illness by interfering with cellular processes toxins caused by pathogenic bacteria disrupts bodily processes and triggers auto-immune responses that result in inflammation and tissue damage antibody produced by the immune system in response to an antigen (recognises and neutralises it) antibiotics medications used to treat bacterial infections by killing or inhibiting bacterial growth vaccination weakened form of pathogen introduced to immune system to stimulate anti-body creation https://knowt.com/flashcards/4dc8a48c-a260-4fd7-af4f-852053d179ab 3/4 30/10/2024, 06:45 Chapter 4: Nervous and Immune system 1928- penicillin (1st anti-biotic) alexander fleming accidental petri dish left over the summer discovery mould that inhibited microbial growth 1st successful smallpox vaccine edward jenner 1796- milkmaids inoculation through cowpox scabs herd immunity reduced spread of the disease when majority of a population is immune; indirect protection sudden increase in number of cases of a epidemic disease ina. specific community or region (exceeding what’s considered normal) inherited diseases pased from arent to offspring through genetic mutations caused by infectious agents transmitted diseases transmitted by either direct or indirect contact air or vector borne mutation: genetic mutation of resistance, horizontal gene transfer (acquiring resistant how does bacterial resistance occur gene from other bacteria), misuse of antibiotics (exposure to antibiotics creates selection pressure, favours resistant one’s survival) https://knowt.com/flashcards/4dc8a48c-a260-4fd7-af4f-852053d179ab 4/4 30/10/2024, 06:46 Chapter 5 - How do characteristics pass from one generation to another Chapter 5 - How do characteristics pass from one generation to another Define Replication the action or process of reproducing or duplicating. Replication of DNA define Hereditary Passing, or capable of passing, naturally from parent to offspring through genes. The complete set of DNA (genetic material) Define Genome in an organism. The genome contains all of the information needed for a person to develop and grow. DNA structure Double helix Nucleotide comprises of what Nitrogen base, pentose sugar, phosphate Identify the four base pairs Adenine, Thymine (In RNA is Uracil), Guanine, Cytosine Helicase - Unzips the DNA strand into two Primase - Adds primer to the ends of the DNA strands Polymerase III - Synthesises the Outline the enzymes involved in DNA new DNA strand replication. Polymerase I - Removes the primers on the end and replaces them with proper bases Ligase - Repairs any damages and Okazaki fragments, ensuring the DNA is stable Compare & Contrast: DNA, genes and Chromosomes carry DNA in cells chromosomes https://knowt.com/flashcards/b76826d0-272b-4f91-9a30-2595ac4d4fab 1/6 30/10/2024, 06:46 Chapter 5 - How do characteristics pass from one generation to another DNA is responsible for building and maintaining your human structure. Genes are segments of your DNA, giving you physical characteristics that differ between person to person. Transcription - The copying of a gene to make mRNA. DNA must unzip for this process to occur. Translation - The mRNA travels to the Ribosome (site of protein synthesis) Explain how a gene codes for the formation and the tRNA then pairs a protein of protein (DNA -> RNA -> Protein) using a codon and anticodon. The (PROTEIN SYNTHESIS) protein is made this way (length + order of amino acids will determine the type of protein). Codon: Triplet of bases on mRNA. !!! Amino acid chains all have peptide bonds between amino acids !!! What is the role of DNA within the body? DNA contains the instructions needed for an organism to develop, survive and reproduce. gametes, requires fertilization cell division: meiosis sexual reproduction (+ pros & cons) advantages: allows for genetic variation & likely survival in new environments (adaptability) disadvantages: time-consuming + mating seasons. less rapid population growth Asexual Reproduction 1 parent Offspring are a complete clone of the parent (genetically similar) Cell division: Binary fission, Mitosis Advantages: Efficient https://knowt.com/flashcards/b76826d0-272b-4f91-9a30-2595ac4d4fab 2/6 30/10/2024, 06:46 Chapter 5 - How do characteristics pass from one generation to another Disadvantages: Can’t adapt to environmental changes Examples: Budding, fragmentation, parthogenesis Gametes of plants Pollen & Eggs Female Reproduction System Male Reproduction System Meiosis is a type of cell division that results in the formation of four daughter cells each with half the number of chromosomes as the parent cell. Define Mitosis & Meiosis Mitosis is the type of cell division that results in the formation of two daughter cells each with the same number and kind of chromosomes as the parent cell. (IMPORTANT FOR GROWTH AND REPAIR) Mitosis: Interphase DNA replication, growth and normal cell function Mitosis: Prophase Chromosomes condense Mitosis: Metaphase Chromosomes line up in the middle of the cell (equator) Mitosis: Anaphase https://knowt.com/flashcards/b76826d0-272b-4f91-9a30-2595ac4d4fab 3/6 30/10/2024, 06:46 Chapter 5 - How do characteristics pass from one generation to another Mitosis: Telophase Mitosis: Cytokinesis Plasma membrane and cytoplasm separate Chromosomes condense and become visible, while the nucleus disintegrates. Homologous Meiosis 1: Prophase chromosomes pair up (TETRAD). Then the homologous chromosomes exchange genetic information (crossing over) Meiosis 1: Metaphase Line up in the middle of the cell (equator) Meiosis 1: Anaphase They split up and move towards the opposite ends of the cell. Meiosis 1: Telophase Two independent cells begin to form. This happens normally during telophase, where Meiosis 1: Cytokinesis it divides the cytoplasm to form two new cells. THE NEW CELLS ARE HAPLOID as they have half the chromosomes of the parent cell. Meiosis 2: Prophase No pairing of chromosomes, but the nucleus still disintegrates Meiosis 2: Metaphase Chromosomes line up single file down the middle of the cell (NO PAIRING UP) Meiosis 2: Anaphase Sister chromatids separate 4 haploid daughter cells are being formed, Meiosis 2: Telophase these are called gametes. The nucleus reforms. Chromosomes uncoil to become chromatin once again. Meiosis 2: Cytokinesis Cytoplasm and plasma membrane split to form 4 haploid cells Gamete organisms produce sex cells called gametes. Needed for reproduction. chromosome Thread-like structures located inside the nucleus of animal and plants cells that contain https://knowt.com/flashcards/b76826d0-272b-4f91-9a30-2595ac4d4fab 4/6 30/10/2024, 06:46 Chapter 5 - How do characteristics pass from one generation to another genetic information. The basic unit of heredity passed from parent gene to child. Genes are made up of sequences of DNA and are arranged, one after another. Segment of DNA. allele/variant singular trait/make-up A dominant allele produces a dominant dominant phenotype in individuals who have one copy of the allele A recessive allele to produce a recessive recessive phenotype, the individual must have two copies, one from each parent. homozygous two copies of the same allele heterozygous different alleles genonome the entire genetic material of an organism phenotype the appearance of an organism monohybrid crosses Crossing over happens during Prophase I. Homologous chromosomes trade genetic The process of Crossing Over information. Crossing over is a random event, so it doesn’t always happen Explain how meiosis increases genetic Specifically, meiosis creates new variation. combinations of genetic material in each of the four daughter cells. These new combinations result from the exchange of DNA between paired chromosomes. Such exchange means that the gametes produced through https://knowt.com/flashcards/b76826d0-272b-4f91-9a30-2595ac4d4fab 5/6 30/10/2024, 06:46 Chapter 5 - How do characteristics pass from one generation to another meiosis exhibit an amazing range of genetic variation. Missense mutations: The amino acid is changed (protein is changed) Types of Mutations Nonsenses mutations: Results with ‘STOP’ on the codon chart. Silent Mutations: The mRNA code is changed, but the amino acid is the same. Mutations result either from errors in DNA replication or from the damaging effects of mutagens, such as chemicals and radiation, which react with DNA and change the How do mutations occur? structures of individual nucleotides. Another way is NON DISJUNCTION where there is an abnormal number of chromosomes in the 4 haploid gametes during meiosis. https://knowt.com/flashcards/b76826d0-272b-4f91-9a30-2595ac4d4fab 6/6 30/10/2024, 06:38 Chapter 6 - How have different forms of life arisen? Flashcards | Knowt Chapter 6 - How have different forms of life arisen? 1. Variation exists within the population 2. Select organisms with desired traits 3. Only let those selected organisms with desired traits reproduce with one Selective Breeding & Artificial Selection: ideal another answer 4. If the trait is heritable, then the offspring will have the desired trait 5. Over many generations, the proportion of the population of the desirable trait in the population will increase. difference in traits passed down from parent to heritable variation (and causes) offspring through genetic inheritance due to genetic mutations, genetic recombination and gene flow selective breeding process of intentionally rearing organism w desire features; artificial selection pros for selective breeding disease/fire/drought resistant, high yeild crops, ideal pet characteristics cons for selective breeding high risk of genetic disease, reduction of genetic diversity natural selection: ideal answer 1. There is genetic variation within the population 2. More offspring will be produced that can survive. Organisms with the traits best suited to their environment are https://knowt.com/flashcards/72da9395-812f-4e72-8f5b-e48c1ce6b4e8 1/6 30/10/2024, 06:38 Chapter 6 - How have different forms of life arisen? Flashcards | Knowt more likely to survive (SURVIVAL OF THE FITTEST) 3. The organisms that are more likely to survive are more likely to reproduce 4. If the trait is heritable, then the offspring will have the advantageous trait 5. Over many generations, the proportion of the population with the advantageous trait will increase Darwin's three main principles of natural selection state that, in order for the process to occur, Darwin's three main principles of natural most characteristics in the population selection must be inherited more offspring must be produced than can survive the fittest offspring must be more likely to survive and reproduce. Competition —> Two organisms fight for the same resources, such as food or mates Predation —>A consumer (predator) eats Factors affecting natural selection (e.g., another consumer (prey) variation, competition, selection pressures) Availability of resources Climate Selection Pressure: Biotic & Abiotic specialised structures enhance an organism’s fitness by performing specific functions for survival and reproduction How can we determine how old a fossil is? The deeper a fossil in within the ground, the older it is. https://knowt.com/flashcards/72da9395-812f-4e72-8f5b-e48c1ce6b4e8 2/6 30/10/2024, 06:38 Chapter 6 - How have different forms of life arisen? Flashcards | Knowt proof of evolution (list) fossil evidence, comparative anatomy, comparative embryology transitional fossils (showing intermediate characteristics between species) fossil evidence fossil record (chronological sequence of fossils that shows evolutionary change over time homologous structures comparative anatomy vestigial structures (shit we have but do not need) comparative embryology similarities in embryonic development between species which suggests common ancestry the process by which a new species forms from a single ancestral species. when a species splits into two or Speciation more due to isolation and natural barriers. for speciation to occur, there must first be isolation and then natural selection. Allopatric: geographical isolation (islands and mountains prevent gene flow) Mechanisms of Speciation Sympatric: species don’t interbreed due to other reproductive barriers/reproductive isolation. prevents gene flow which allows for genetic role of isolation in speciation diversity and accumulation of reproductive barriers A group of organisms that can interbreed and Species produce fertile offspring. Their offspring must also be able to interbreed. https://knowt.com/flashcards/72da9395-812f-4e72-8f5b-e48c1ce6b4e8 3/6 30/10/2024, 06:38 Chapter 6 - How have different forms of life arisen? Flashcards | Knowt Population members of a particular species living in the same place at the same time. Variation allows some individuals within a population to adapt to the changing Importance of genetic variation in species environment. Because natural selection acts survival directly only on phenotypes, more genetic variation within a population usually enables more phenotypic variation. This could increase the likelihood of a species’ survival. a medicine (such as penicillin or its Antibiotics derivatives) that inhibits the growth of or destroys microorganisms Antibiotic resistance is when bacteria change to resist antibiotics that used to effectively Antibiotic resistance (superbugs) treat them. This makes certain bacterial infections difficult to treat. Overuse and misuse of antibiotics cause antibiotic resistance. Variation Natural selection occurs in a population that Heritability has… some kind of selection pressure (competition, predation, disease, etc) How well they can reproduce Fitness of a population Increase fitness within a population = adaptation Evolution change in the traits of a population over time When some alleles become more common Allele frequency over time, evolution has occurred. This is a change in the frequency. 3 Major ways a population can evolve Gene flow: Allele frequency is changed when individuals move populations https://knowt.com/flashcards/72da9395-812f-4e72-8f5b-e48c1ce6b4e8 4/6 30/10/2024, 06:38 Chapter 6 - How have different forms of life arisen? Flashcards | Knowt Genetic Drift: When disease or natural disaster kills a lot of individuals. Or, when a few leave, they start a new population, thus creating the founder effect. Natural Selection: Population evolves due to selective pressures. extinction When a population of a species cease to exist. A drastic change in the number and variety of Mass extinction organisms at the same time (enormous number) Something an animal does usually in Behavioural adaptations response to some type of external stimulus in order to survive. Hibernating during winter is an example of a behavioral adaptation. Physiological adaptation is an internal body process to regulate and maintain homeostasis for an organism to survive in the environment in which it exists. Physiological adaptations Examples include temperature regulation, release of toxins or poisons, releasing antifreeze proteins to avoid freezing in cold environments Physical features of an organism that enable Structural Adaptations it to survive in its environment (e.g. a penguin has blubber to protect itself from freezing temperatures). Social Advantages: Childcare is easier, protection from predators Solo vs Social Behaviour Solo Advantages: Easier to deal with disease (won’t spread within a group of people), competition for food is less, territory disputes are less too https://knowt.com/flashcards/72da9395-812f-4e72-8f5b-e48c1ce6b4e8 5/6 30/10/2024, 06:38 Chapter 6 - How have different forms of life arisen? Flashcards | Knowt photosynthesis, respiration, decomposition, carbon cycle fossil fuel consumption, decaying organisms, carbon sequestration symbiosis types mutualism, commensalism, parasitism keystone species disproportionate impact on ecosystem as compared to their abundance H- habitat destruction I- invasive species P- pollution how do humans destroy the environment C- climate change O- overconsumption P- population https://knowt.com/flashcards/72da9395-812f-4e72-8f5b-e48c1ce6b4e8 6/6
