Biology Grade 11 Exam Notes PDF

Biology grade 11 exam notes Simran Randhawa Terms: Somatic cells: body cells Alleles: Different forms of the same gene Cellular respiration: allows organisms to use all the energy stored in food to form ATP molecules Unit 1: Genetics -​ Meiosis and mitosis are covered in the notebook notes...

Biology grade 11 exam notes Simran Randhawa Terms: Somatic cells: body cells Alleles: Different forms of the same gene Cellular respiration: allows organisms to use all the energy stored in food to form ATP molecules Unit 1: Genetics -​ Meiosis and mitosis are covered in the notebook notes -​ DNA structure -​ DNA is a long molecule that is a double helix (twisted ladder) -​ Each unit along the stand is called a nucleotide -​ Each nucleotide is composed of a) a phosphate group b) a sugar group c) a base -​ Base pairings: A-T, G-C -​ Complimentary base pairs allow each strand of DNA to serve as a template for DNA replication -​ DNA replication consists of two identical strands, called sister chromatids in mitosis -​ Homologous chromosomes: humans have 46, two chromosomes in a pair. Having similar genes but not identical. -​ Autosomes: Not similar to each other, sex chromosomes (x and y) -​ Males have XY and females have XX -​ Gametogenesis is the process of producing SEX CELLS -​ Oogenesis occurs in the ovaries and results in ONE egg cell being produced each month -​ Meiosis produces a few hundred eggs over a lifetime -​ The cell with the most cytoplasm becomes the egg -​ The other 3 become polar bodies -​ Spermatogenesis occurs in the testes and results in sperm cells being produced all the time -​ Meiosis produces about 200 million sperm per day -​ Multiple births: 2 possibilities -​ More than one egg is released, both fertilized by different sperm (fraternal) -​ 1 egg is fertilized, and 1 zygote, divides into two bodies in a span of a couple of days (identical) -​ Independent assortment: Chromosome pairs assort themselves randomly in metaphase I on either side of the plane. Gametes produced have a random mixture of maternal and paternal chromosomes -​ Crossing over: During prophase I, an exchange of genetic material between homologous chromosome pairs occurs. Produces recombinant chromosomes that now have a mixture of traits, enhances genetic diversity -​ Nondisjunction: Occurs during anaphase I when two homologous chromosomes move to the same pole during meiosis. It can also happen during Anaphase II when two sister chromatids move to the same pole.  -​ Results in daughter cells missing a chromosome or having an extra chromosome. CELLS WON’T FUNCTION PROPERLY. -​ Monosomy: 23 + 22= 45 -​ Trisomy: 23 + 24= 47 -​ Mutations: changes in genetic sequence. The main cause of diversity among organisms -​ Errors during crossing over: Deletions; parts of the chromosome is deleted -​ Duplications; section is repeated (2x,3x..) -​ Inversions; The section is in reversed order -​ Translocation: A section of one chromosome goes to a non-homologous chromosome - CROSSES/PUNNETT SQUARES, TEST CROSS, PATTERNS OF INHERITANCE (AUTOSOMAL DOMINATE, AUTOSOMAL RECESSIVE, X-LINKED, INCOMPLETE AND CODOMINANCE), MULTIPLE ALLELES, PEDIGREES ARE ALL IN NOTEBOOK Unit 2: Evolution -​ Evolution is the process in which significant changes in the genetic makeup of a species or population occur over time Sources of evidence: 1.​ Fossils- Footprints, petrified remains, casts, imprints, amber, ice preservation -​ The fossil record is often incomplete, some fossils of intermediate forms have been found -​ Eg. Archaeopterix had characteristics of both reptiles and birds (jaw with teeth, long pointy tail, claws, wings, and feathers) -​ Another Eg. is Tiktaalik possibly the evolutionary transition from fish to amphibian -​ Cambrian explosion; 500 mill years ago, there was a sudden appearance of many soft-bodied imprints in the rock. Diverse animal life appeared -​ Limitations of the fossil record -​ Gaps: Many organisms do not fossilize easily or live in areas where conditions are not suitable for fossilization so they decompose first -​ Evidence destruction: Erosion and transportation by water, landslides or elevated earthquake activity results in the loss of valuable information 2.​ Geographical distribution of organisms- Closely related species to be found in areas geographically close to each other. -​ Colonizing species from the nearest mainland may evolve in different ways from their mainland relatives -​ Island species will remain more closely related to the mainland species than to the species in more distant areas of the world. -​ Eg. Madagascar 184 bird species, 46 were not found anywhere else in the world 3.​ Anatomy -​ Homologous structures: parts of the body where species have the same physical structure but have different functions. Eg. Forelimbs, whales, birds, and humans all have it but are used for a different purpose.  -​ Analogous structures: Species have similar functions but are structured differently. Eg wings in birds vs insects -​ Vestigial structure: body stricture that has no function the present-day organisms but once once useful to ancestors (wisdom teeth, appendix, tonsils) 4.​ Comparative embryology -​ Similarities in the development of embryos suggest a distant, common ancestor. The more closely related forms share nearly identical developmental sequences until very late in development. -​ Eg humans and chimpanzees 5.​ Biochemical similarities -​ Molecular uniformity among organisms -​ Universal genetic code and common cell components (nucleotides, proteins, lipids, carbohydrates) -​ Enzymes control organic reactions -​ Proteins are synthesized from about 20 known amino acids - Natural selection: a process that results when characteristics of a population of organisms change over many generations. This change occurs because individuals with certain inherited characteristics survive and reproduce, passing the alleles to their offspring. For this to happen, there must be genetic diversity in the population - Selective advantage: Any characteristic or trait that gives an organism or a genotype greater chances of surviving and reproducing than the available alternatives. - Mutations and sexual reproduction increase genetic variation in a population. - Fitness: An organism that exhibits fitness to its environment is one that is able to survive and pass its advantageous genes on to the population gene pool. The more viable offspring that an individual produces, the higher that individual's level of fitness. - Bottleneck effect: Occurs when a population’s size is reduced for at least one generation. Because genetic drift acts more quickly to reduce genetic variation in small populations, undergoing a bottleneck can reduce a population’s genetic variation by a lot, even if it doesn't last for many generations. - Founder effects: Occurs when a colony is started by a few members of the original population. This small population means the colony may have reduced genetic variation from the original population or a non-representative sample of the genes in the original population. -​ Prezygotic and postzygotic isolating mechanisms are mechanisms that prevent interbreeding between different species, contributing to reproductive isolation and ultimately speciation. -​ Prezygotic isolating mechanisms: -​ Temporal isolation: Species reproduce at different times, eg frog species may breed in different seasons -​ Behavioural isolation: Differences in courtship behaviours or mating signals prevent interbreeding. Eg diff species of birds may have distinct songs or mating dances -​ Mechanical isolation: Physical differences in reproductive structures prevent successful mating. Eg. flowering plants may have structures that allow only specific pollinators to transfer pollen -​ Postzygotic isolation mechanisms:  -​ Hybrid inviability: A hybrid zygote fails to develop properly and dies at an early stage. Eg. crosses between different species of frogs often result in embryos that do not develop -​ Hybrid sterility: A hybrid organism is sterile and cannot produce offspring. Eg. mules, a hybrid of a horse and a donkey are sterile -​ Hybrid breakdown: Hybrids are fertile, but their offspring are weak, sterile, or inviable in subsequent generations. Eg. some hybrid plants can produce seeds, but the next generation is often less robust or sterile Unit 3: Diversity of all living things -​ Taxonomy: Domain, kingdom, phylum, class, order, family, genus, species -​ Dichotomous key: -​ Prokaryote vs. Eukaryotic cells: Prokaryotic cells Eukaryotic cells Ancient cell type means “before the nucleus” This means “true nucleus” Do not have a membrane-bound nucleus Has a membrane-bound nucleus Internal membranes mostly in photosynthetic Internal membranes around organelles (ER, bacteria only vacuoles, mitochondria) Single pieces of Circular DNA Usually many linear chromosomes Asexual reproduction (binary fission) Sexual and asexual reproduction (mitosis) Many are anaerobic (don’t require oxygen for Most are aerobic (require oxygen for cellular cellular respiration) respiration) 3 species concept MORPHOLOGICAL SPECIES Relies on comparing measurements and ADVANTAGE: The relative simplicity CONCEPT: Based on body size, shape, descriptions of similar organisms, of this species concept makes it the and structural features taking into account that species change most widely used, particularly for plants over time and that they have variation. DISADVANTAGE: Deciding how After comparisons are completed, much difference between individuals is scientists decide whether similar too much variation. Almost all pop is organisms represent different species made up of non-identical individuals BIOLOGICAL SPECIES CONCEPT: This means that if two individual ADVANTAGE: widely used by The ability of two organisms to mate organisms can mate under natural scientists and produce fertile offspring (Offspring circumstances and produce offspring DISADVANTAGE: This cannot be that can successfully live and produce, applied in all cases. Eg, when two pops can have offspring by producing viable then those are the same species are physically separated, they don't gametes) have the opportunity to interbreed in nature. This means that the viable fertile offspring requirements cannot be tested. Also cannot be applied to organisms that reproduce asexually, nor can it be applied to fossil species, which are no longer reproducing PHYLOGENETIC SPECIES Eg. When a prehistoric species branches ADVANTAGE: This can be applied to CONCEPT: How close the evolutionary into two species over time, it becomes extinct species. Also considers history is of the organism. The closer in two different phylogenetic species. This information about relationships among concept has become increasingly organisms learned from DNA analysis, evolutionary time, the more closely popular as biologists have obtained a method scientists use a lot. related. This is determined by DNA and more evidence through DNA analysis protein similarities and how species are related. DISADVANTAGE: Evolutionary histories are not known for all species -​ Kingdom differences: -​ Bacteria: Prokaryotic, unicellular, heterotrophs or autotrophs, asexual reproduction, Eg. cyanobacteria (photosynthetic) - lives in the ocean and produces much of the world's O2 -​ Archaea: Prokaryotic, unicellular, cell wall present, asexual reproduction, live in extreme environments where others can't survive eg. methanogens (generate methane) -​ Protista: Eukaryotic, both uni and multicellular, asexual and sexual reproduction, water environments (slime moulds, single-celled algae) -​ Plantae: Eukaryotic, multicellular, asexual and sexual reproduction, cell wall present, (mosses, ferns, flowering plants) -​ Animalia: Eukaryotic, multicellular, most produce sexually, aquatic and terrestrial environments (worms, lobster, starfish, humans) -​ Fungi: Eukaryotic, multicellular, sexual and asexual reproduction, cell wall present, (mushrooms, bread mould) -​ Viruses: Small, infectious, non-living, noncellular particles, contain no cytoplasm, cannot grow or reproduce on its own, do not produce or use energy, do not create waste, genetic material takes control of other cells. -​ 2 methods of viral replication; the Lytic cycle and the lysogenic cycle -​ Lytic (= breaking open): Virus enters the cell, replicates itself hundreds of times, and then bursts out of the cell destroying it. 1. Attachment 2. Injection/entry 3. Replication 4. Assembly 5. Release  -​ Lysogenic: Virus enters the cell, viral DNA integrates with the host DNA and becomes inactive,and the host functions normally. Then an environmental change may then cause the virus to enter the lytic cycle. 1. Attachment 2. Injection/entry 3. Integration into host’s DNA 4. Dormancy/Normal cell functions 5. Triggering of viral DNA to be released and then lytic cycle begins -​ Difference between the two: Lytic Lysogenic Viral DNA destroys cell DNA, takes over cell Viral DNA merges with cell DNA and does functions and destroys the cell not destroy the cell Virus replicates and produces progeny phages The virus does not produce progeny Symptoms of the viral infection No symptoms of viral infection Bacterial reproduction Binary fission Asexual division Produces two Population growth identical cells Conjunction Horizontal gene Exchange of genetic Genetic diversity transfer material Transformation Uptake of Incorporation of Adaption and environmental DNA foreign DNA diversity Transduction Virus-mediated gene DNA transfer via Horizontal gene transfer bacteriophages transfer Cladograms: Endosymbiotic theory: The endosymbiotic theory states that some of the organelles in eukaryotic cells were once prokaryotic microbes. Mitochondria and chloroplasts are the same size as  prokaryotic cells and divide by binary fission. Mitochondria and chloroplasts have their own DNA which is circular, not linear. Protista and Fungi importance to society, basic structures and examples Protists Importance to Society 1.​ Ecological Roles: ○​ Producers in aquatic ecosystems (e.g., algae perform photosynthesis). ○​ Decomposers recycle nutrients. 2.​ Medical Applications: ○​ Some cause diseases (e.g., Plasmodium causes malaria). ○​ Others produce compounds used in research and medicine. 3.​ Industrial Uses: ○​ Algae provide biofuels, and food additives (e.g., carrageenan, agar). Examples ​ Photosynthetic Protists: Algae (Chlorella, kelp). ​ Pathogenic Protists: Plasmodium (malaria), Trypanosoma (sleeping sickness). ​ Symbiotic Protists: Zooxanthellae in corals. Basic Structures ​ Cell Type: Eukaryotic. ​ Key Features: ○​ Unicellular or multicellular. ○​ Organelles like nuclei, mitochondria, and sometimes chloroplasts. ○​ Diverse locomotion: flagella, cilia, or pseudopodia. Fungi Importance to Society 1.​ Decomposers: Break down organic material, recycling nutrients. 2.​ Food Production: ○​ Yeast in bread, beer, and wine production (Saccharomyces cerevisiae). ○​ Edible fungi (e.g., mushrooms like Agaricus). 3.​ Medicine: ○​ Antibiotics like penicillin (Penicillium). ○​ Immunosuppressants (e.g., cyclosporine). 4.​ Agriculture:  ○​ Mycorrhizal fungi aid plant growth. ○​ Some cause crop diseases (Puccinia in wheat rust). Examples ​ Beneficial Fungi: Penicillium (antibiotics), Aspergillus (fermentation). ​ Pathogenic Fungi: Candida (yeast infections), Aspergillus (lung infections). ​ Edible Fungi: Agaricus bisporus (button mushrooms). Basic Structures ​ Cell Type: Eukaryotic. ​ Key Features: ○​ Hyphae: Thread-like filaments forming the mycelium. ○​ Cell Wall: Made of chitin. ○​ Reproduction: Asexual (spores) or sexual (fusion of hyphae). Unit 4: Animal systems Structures and function of the three organ systems -​ Digestive system: A set of organs that change what we eat into substances that can be used in the body. These substances can be used for energy, growth, and repair -​ Alimentary canal is a tube that runs from the mouth to the anus -​ Structure: -​ Mouth, Breaks food down with teeth and salvia -​ esophagus, food passes down into the pharynx and then the esophagus. The epiglottis is a small flap of cartilage that blocks the entrance to the larynx stops food from going down the wrong way and prevents choking. Carries chewed food to stomach. Mucus lubricates the passage of food -​ stomach, Digests proteins through the action of enzymes, churns food with gastric juices, and lubricates food by producing mucus. -​ small intestine, Pancreatic juice is secreted into the duodenum and contains Trypsin (converts proteins to shorter chains), lipase (converts fats into fatty acids and glycerol), amylase (converts starch into disaccharides). Stores Bile. Intestinal juices have the following enzymes; Maltase, sucrase, and lactase (changes disaccharides into monosaccharides) -​ large intestine, Whatever remains get passed to large intestine. Resabsorbs water and vitamins left in digestive waste. The remaining waste is stored in the rectum before getting removed by defection. -​ Accessory organs: teeth, tongue, and glandular organs such as salivary glands, liver, gallbladder, and pancreas -​ Enzymes: Speeds up biological reactions. All chemical reactions that take place in living systems require the action of enzymes. Eg. Amylase is present in saliva and chemically breaks down starch, and converts starch into a sugar called MALTOSE -​ Macromolecules: Nutrients consumed in large quantities by us to provide energy and raw materials for growth and repair (Carbohydrates, lipids, proteins) -​ Carbohydrates: Structurally C,H, and O. Body cannot make these important chemicals by itself (relies on plants as the source of carbohydrates) -​ Monosaccharides: Simple sugars made of a single sugar molecule (C:H:O 1:2:1 ratio) -​ Eg. glucose is found in all cells of our bodies and primary source of energy -​ Fructose is a simple sugar found in fruits -​ Glactose one of the sugars found in milk -​ Disaccharides: Made of two monosaccharides. Formed in condensation reactions. Has to be chemically broken down by an enzyme into simple monosachharides in order to be absorbed out of the digestive system into the bloodstream -​ Eg. Maltose is made of two glucose molecules (sugarcane, sugarbeets) -​ Sucrose is 1 glucose and 1 fructose molecule (table sugar) -​ Lactose made of 1 glucose and 1 galatose molecule (milk and dairy products) -​ Polysaccharides: Large molecules -​ Eg. Starch- energy store molecules in plants and a good source of energy for human cells -​ Glycogen: short term energy storage molecule in human liver and muscle cells -​ Cellulose: made of plant cell walls, humans cant digest -​ Lipids: very calorie dense nutrient- excellent energy source and storage, harder to break down. Helps absorb some vitamins. Key component of cell membranes -​ Fats and oils: 1 glycerol molecule and 3 fatty acid molecules -​ Saturated fats vs unsaturated: Saturated: no doouble bonds between carbons so have as many hydrogen atoms as possible. Unsaturated: At least one double bond and produces a bend in the molecule -​ Proteins: made of amino acids (carboxyl and amino groups attached side chain to a central carbon atom) -​ Large and complex biological molecules that; control chemical reactions, defense, transport oxygen, chemical messengers, energy -​ Respiratory system: move fresh air into your body while removing waste gases. -​ Air enters the nose/mouth: nasal hairs and mucus filter out foreign particles, warm and moisten air -​ Pharynx: Air travels to pharynx, air flows through glottis and down the trachea. -​ Trachea: Lined by mucus producing goblet cells, mucus traps any debris that has not been filtered. Some cells have cilia, sweep debris back into pharynx to be disposed of coughing, sneezing, swallowing… -​ Larynx: Air from pharynx enters larynx (vocal cords) which vibrates when air is forced from the lungs to the pharynx -​ Lungs: Air from trachea travels into two bronchis, carries air to the right and left lungs and have cartilage rings. -​ TRACHEA STRUCTURES: -​ Cilia: Tiny hairs found on some cells that sweep debris drom the respiratory tract -​ Epiglottis: Covers the glottis (opening of the trachea) during swallowing -​ Cartilage rings: Supprits the trachea but allows it to move and flex when breathing. -​ Circulatory system: Transports gases to and from respiratory system, nutrient/ waste materials. Also regulates internal body temp and transports chemical substances from one part of the body to another. Protects against blood loss and injury against disease causing microbes -​ Heart: Organ pumps blood throughout the body. Only circulatory organ -​ Arteries: Carry oxygeneated blood away from you heart and to every part of your body -​ Veins: return oxygen depleted blood to the heart. Start small and get larger as they approch the heart. Two central veins (superior vena cava and inferior vena cava) deliver blood to the heart. -​ Capillaries: connect small artoes and veins. Have thin walls that allow oxygen, carbon dioxide, nutrients, and waste products to pass into and out of cells -​ Flow of blood within and in/out of the heart -​ Deoxygenated Blood (Right Side): ​ Enters the right atrium via the superior and inferior vena cava. ​ Flows to the right ventricle through the tricuspid valve. ​ Pumped to the lungs via the pulmonary artery through the pulmonary valve for oxygenation. -​ Oxygenated Blood (Left Side): ​ Returns from the lungs to the left atrium via the pulmonary veins. ​ Flows to the left ventricle through the mitral valve. ​ Pumped to the body via the aorta through the aortic valve -​ Blood components: erythrocytes, leukocytes, platelets -​ Red blood cells (erythrocytes) -​ 44% of blood volume -​ Transports oxygen from lungs to tisues and carbon dixoide back to lungs -​ Contain hemoglobin and lacks a nucleus in mature cells -​ White blood cells (leukocytes) -​ Part of the bodys line of defence to fight infection and cancer. Can double in numbers when fighting an infection -​ Have nuclei and appear colourless -​ Platelets -​ Cell fragments that clots the blood -​ No nucleus and produced in bone marrow -​ Short life span -​ When blood vessels ruptures, platelets are actibated and fibrinogen is converted to long fibrin strands -​ Blood pressure: measure of the force of blood pushing aginst artery walls -​ Systolic: left ventricle contracts.NUMERATOR -​ Diastolic: left ventricle relaxes DENOMINATOR -​ Arteries vs veins:  -​ Arties: walls are very elastic (expands as blood moves throigh during contrcation of the ventricles and then snap back during relaxation of the ventricles) -​ Veins: Thinner walls but larger circumference. Not as elastic. Contraction of skeletal muscles keeps the blood flowing towards the heart -​ Control of heart contractions: -​ - Sinoatrial (SA) Node ​ Location: Wall of the right atrium. ​ Function: ○​ Acts as the heart's natural pacemaker. ○​ Generates electrical impulses that initiate each heartbeat (~60–100 beats per minute). ​ Effect: Triggers contraction of the atria. 2. Atrioventricular (AV) Node ​ Location: Between the atria and ventricles (interatrial septum). ​ Function: ○​ Delays the electrical signal slightly, allowing the atria to fully contract and empty blood into the ventricles. 3. Bundle of His ​ Location: In the interventricular septum. ​ Function: ○​ Transmits impulses from the AV node to the ventricles. 4. Purkinje Fibers ​ Location: Spread throughout the walls of the ventricles. ​ Function: ○​ Conduct impulses rapidly, causing the ventricles to contract and pump blood. -​ Alveoil: Sacs of the lung in which the exchange of gases between the atmosphere and the blood occurs. Air moves from the bronchioles into tiny sacs called the alveoli. Gases move from high concentration to low concentration. Thus, oxygen moves from the air within the lung to the alveoli and carbon dioxide moves from the alveoli into the air inside the lung and is excreted  when you exhale. Composed of a single layer of cells allows for faster diffusion of gases. Contains 150 million alveoli. -​ Lung capacity -​ Tidal volume: normal volume of breath -​ Inspiratory reserve volume: Volume of aur that can be forcibly inhaled after a normal breath -​ Expiratory reserve volume: Volume of air that can be forcibly exhaled after a normal exhalation -​ Vital capacity: Max volume of air that can be forcibly inhaled or exhaled (= TV+ IRV +ERV) -​ Homeostasis is the maintenance of a stable internal environment essential for optimal functioning. Blood glucose levels are regulated by insulin and glucagon from the pancreas to balance energy supply. Core temperature is controlled by thermoregulation, where mechanisms like sweating, shivering, and blood vessel dilation or constriction adjust heat loss or retention. Blood CO₂ levels are regulated through breathing; high CO₂ triggers chemoreceptors, increasing respiratory rate to expel CO₂ and restore pH balance. These systems work via feedback loops to ensure physiological stability.