Unit 3 External Revision PDF

[Unit 3: Biodiversity and the interconnectedness of life: ] ======================================================================= [Topic 1: Describing biodiversity ] =============================================== Ecosystem: Self-sustaining units consisting of all interactions between communitie...

[Unit 3: Biodiversity and the interconnectedness of life: ] ======================================================================= [Topic 1: Describing biodiversity ] =============================================== Ecosystem: Self-sustaining units consisting of all interactions between communities of organisms, their physical surroundings and each other Levels: Habitat, ecosystem, biome, biosphere Abiotic: Temp, rainfall, pH, salinity levels, wind speeds Biotic: Ways in which organisms directly influence their environment such as: Food source, disease, human interference, births, deaths, migration Photosynthetic organisms capture light to make organic compounds Organic compounds: Monomer Polymer Cellular structure -------------------------- ---------------- -------------------- ------------------------ Carbohydrates Monosaccharide Starch Chloroplast Lipids (fats) Fatty acids Triglyceride Adipose Cells Proteins Amino acids Polypeptide Intermediate filaments Nucleic acids (DNA, RNA) Nucleotide Double helix (DNA) Chromosome Photosynthesis is the process of carbon fixing. Meaning it incorporates inorganic carbon into organic molecules Autotrophs: self-feeding, produces and main source of biomass in a food chain Biomass= total mass of living matter in an ecosystem Heterotrophs: consumers because they consume other organisms. (All animals and fungi). Majority of all energy originates from the sun, and it's converted into chemical potential energy by producers. Animals then turn it into ATP. Once the conversion of light energy into chemical energy takes place through the autotrophs, it allows other organisms to access it (sun-plant-grasshopper-frog-eagle) Transformation means changing form, transfer means same form but different organism Energy flows via photosynthesis, cellular respiration, and consumption. Matter available is finite so must be recycled. Essential elements: carbon, hydrogen, oxygen, and nitrogen. These can be recycling through the biotic and abiotic parts of an ecosystem through organic and inorganic molecules. Ecological niche: Role and space that an organism fills an ecosystem, including all its interactions with the biotic and abiotic factors of its environment - If two separate species occupy the same niche they will compete until only one remains. (Competitive exclusion) Organisms can have overlapping niches but not identical ones. Fundamental niche: ideal (no competitors or predators) Realised niche: reality. Competition: comp for resources, inter vs intraspecies, competitive exclusion Predation: Predator organisms kills prey to consume. Populations fluctuate as numbers rely on interactions. Natural vs introduced predators (Cane toads being brought in to kill cane beetles.) Symbiosis: general term for a close and long-term interaction between 2 species. - Parasitism: Organism lives on or in another to cause it harm (Malaria or tics) - Commensalism: Organisms live together where one benefits, the other is unaffected. (Lycans live in trees, but doesn't affect it) - Mutualism: both organisms' benefit (bees and pollen, pollen dropping) - Amensalism: One is harmed, other is unaffected - Disease: One organism is benefited, other harmed Abundance: Number of individuals. Distribution: The way organism are arranged in physical and geographical space in ecosystem Density: clumped, uniform, random Limiting factors: Density dependant (Biotic) and density independent (Abiotic) Keystone species: Organism that plays unique and critical role in the way an ecosystem functions (middle part of arch) Population: total number of one species in a certain space - They're dynamic as they change sizes over years and etc Carrying capacity: Max population size that ecosystem can support and sustain Asexual reproduction: - Binary fission: 1 cell becomes 2 - Fission: 1 becomes more - Fragmentation: cutting up organism that can multiply and become identical versions of previous - Budding: bud shoots off body Sexual reproduction: - Spawning: eggs and sperms are realised - Shelled eggs - Live young Pathogenesis: Virgin young of live young K and r selection: Sexually reproducing organisms are classified in terms of energy being spent. - K= carrying capacity of environment: If K selected, organism often lives in dense environments (chimp) - Stable environments, longer lives, fewer offspring - r= High potential to exploit niche and reproduce (tuna- RRRRRapid) - Short lives, strong sex drive, very little care of offspring after birth Population growth rate = (Births + immigration) -- (deaths + emigration) - Positive number indicates an incline. Lincoln index: [\$N = \\ \\frac{M\\ \\times \\ n}{m}\$]{.math.inline} N= size of population M= \# in 1^st^ sample n= Total caught in 2^nd^ sample m= Number of marked animals in second sample (recaptured. Exponential "J curves" Logistic curve "S curve" Biodiversity= Range of organisms in 1 area Sampling techniques: quadrats and transects Species richness: tally of unique species present [\$\\text{Richness} = \\ \\frac{s}{\\sqrt{}N}\$]{.math.inline} s= How many diff species N= total of every species Relative abundance: number of individuals of a special in relation to the total number of species in the area Simpson's diversity index: n= total of 1 species N= total overall - A number of 0= low diversity Succession: progressive change of community's overtime 1. Primary succession: initial colonisation (bare land) 2. Recolonisation of previously established community Sere: A community that forms during process of succession 1. Pioneer 2. Intermediate 3. Climax community Taxonomies: classifying and sorting living things based on similarities Kingdom, Phylum, Class, order, family, genus, species - Katy perry cracks open five gummy snacks Hybrid that doesn't produce fertile offspring: mules, Zorse, liger A-T, C-G (ACGT- code for amino acid sequence of protein) (Adenine, thymine, cytosine, guanine) 1. DNA= Transcription 2. mRNA= translation 3. Polypeptide chain Clade: group of organisms that consists of common ancestors and all its descendants. [Unit 4: ] ====================== Macromolecules: Carbos, lipids, proteins and nucleic acids - All formed by smaller monomers, join to make polymers Nucleic acids: carry hereditary info from 1 gen to next DNA= deoxyribonucleic acid - In eukaryotic cells (like animal and plant cells), DNA is mostly located in the nucleus. Where it is bound to proteins called histones to form structures called chromosomes. - Prokaryotic cells (like bacteria) have DNA that exists as a single, circular strand of unbound DNA in the cytosol (the liquid part of the cell). Nucleotide consists of 1. Phosphate 2. Deoxyribose sugar 3. Nitrogenous base Cell cycle: Interphase, Mitosis, Cytokinesis DNA replication: process by which DNA makes a copy of itself, which is essential for cell division. Key enzymes involved include helicase and DNA polymerase. 1. Helicase: unwinds DNA double helix and separates the two strands by breaking the hydrogen bonds between bases. This creates a replication fork, where each separated strand is a template for formation of new strand. 2. DNA Polymerase: synthesizes new DNA strands by adding nucleotides that are complementary to the template strand. DNA polymerase synthesizes each fragment separately, and another enzyme (DNA ligase), joins these together. Meiosis I and II: Meiosis= process of cell division that reduces chromosome number by half, producing four gametes from an original diploid cell. 1. Meiosis I: Homologous chromosomes separate, results in two haploid cells with duplicated chromosomes. 2. Meiosis II: Sister chromatids separate, producing four genetically unique haploid cells. Role of Homologous Chromosomes in Meiosis: - Homologous chromosomes are pairs of chromosomes that have the same structure and carry the same genes, but they may have different alleles. Crossing Over and Recombination 1. Crossing Over: During Prophase 1 of Meiosis I. Homologous chromosomes exchange segments of DNA at points called chiasmata. Creats new combinations of alleles on each chromosome. 2. Recombination: result of crossing over, leads to chromosomes with new allele combinations. Comparing Spermatogenesis and Oogenesis 1. Spermatogenesis: Located in testes, sperm producer. Begins with a diploid cell, ends with four haploid sperm cells 2. Oogenesis: Ovaries, Fertilisation. Begins with a diploid cell, ends with one haploid egg cell and polar bodies Independent assortment- random distribution of chromosomes to gametes Random fertilization- random pairing of gametes from each parent Gene: regions of DNA made up of nucleotides. Genome: entire set of genetic material in organism, includes all genes as well as noncoding regions of DNA. - Coding DNA (Exons): These are the portions of a gene that are transcribed into mRNA and then translated into proteins. - Noncoding DNA: Sections of DNA that do not code for proteins. These regions include: Functional RNA: Transcribed RNA molecules that have roles other than coding for proteins, such as tRNA (transfer RNA) and rRNA (ribosomal RNA). Centromeres: Regions of chromosome that help in cell division Telomeres: Repetitive sequences at ends of chromosomes that protect them Introns: Noncoding sequences within genes that are removed during RNA processing. Transcription: Genes DNA sequence is used to create mRNA. Translation: mRNA is used to synthesis protein (tRNA= transfer rna) Errors in mutations in Genes and Chromosomes can occur due to: - DNA Replication: Point Mutation, Frameshift Mutation: - Cell Division (Non-Disjunction): Improper separation of chromosomes during meiosis - Damage by Mutagens: Physical Mutagens (UV radiation, ionizing radiation, heat) Inherited Mutations: Mutations passed through generations introduce new genotypic variations in offspring. Biotechnology - Recombinant DNA Creation: 1. Isolation of DNA: DNA is extracted from cells. 2. Cutting DNA with Restriction Enzymes 3. Inserting DNA Fragment 4. Joining DNA with DNA Ligase 5. Amplification through Bacterial Transformation Applications of DNA Technology: 1. Polymerase Chain Reaction (PCR): technique to amplify small DNA samples 2. Gel Electrophoresis: method for separating DNA fragments by size, useful for DNA profiling and analysing genetic material. Polygenic inheritance: 1 characteristic being controlled by 2 or more genes Evolution: change in genetic composition of population during successive generations. May result in new species Microevolution: Small scale variation of allele frequencies within species where decedents are of same taxonomic group Macroevolution: arises from processes that influence evolution above the species level, typically occurring over longer time scales.