Topic 4 Three Star LOs 2020 PDF

4.3)Define the following terms, and give a named example for each: 1. species 2. population 3. community 4. habitat 5. niche 6. environment 7. interspecific competition 8. intraspecific competition 4.3) Species 4.3) Species A group of organisms that can interbreed to pr...

4.3)Define the following terms, and give a named example for each: 1. species 2. population 3. community 4. habitat 5. niche 6. environment 7. interspecific competition 8. intraspecific competition 4.3) Species 4.3) Species A group of organisms that can interbreed to produce viable, fertile offspring (e.g. Grey squirrels, Hazel trees etc.). 4.3) Population 4.3) Population All the organisms of one species in a particular place at a particular time (e.g. the Human population of Britain in 2014). 4.3) Community 4.3) Community All the populations of all the species in a particular place at a particular time (i.e. all life in an area including animals, plants, fungi, bacteria…everything living). 4.3) Habitat 4.3) Habitat The place, with a distinctive set of conditions, where an organism lives. 4.3) Niche 4.3) Niche The role an organism plays in its environment or how an organism exploits (uses) its environment. Most importantly it describes what it eats / where it is located in a food chain / its trophic level. But it also includes where it shelters and the times it is active. Only one species can survive in a single niche. If a second species inhabits exactly the same niche they will compete and one species will die out. 4.3) Environment 4.3) Environment The external surroundings including all of the biotic (living) and abiotic (non-living) factors. 4.3) Interspecific competition 4.3) Interspecific competition Competition for resources (e.g. light, space, food, minerals) between individuals of different species. 4.3) Intraspecific competition 4.3) Intraspecific competition Competition for resources (e.g. light, space, food, minerals) between individuals of the same species. 4.4, 4.5, 4.6)Explain what is meant by the terms “behavioural adaptations”, “physiological adaptations”, and “anatomical adaptations”  4.4, 4.5, 4.6) Behavioural adaptations 4.4, 4.5, 4.6) Behavioural adaptations Actions by an organism that help them to survive or reproduce. e.g. hibernation, migration, hunting strategies, herding together for protection, burying acorns to store food for winter.  4.4, 4.5, 4.6) Physiological adaptations 4.4, 4.5, 4.6) Physiological adaptations Features of an organisms body chemistry that help them survive or reproduce. e.g. chemicals acting as pigments for colouration, modified haemoglobin to work at high altitudes, venom, anti-venom, digestive enzymes, bacterial with thermostable (heat stable) enzymes.  4.4, 4.5, 4.6) Anatomical adaptations 4.4, 4.5, 4.6) Anatomical adaptations Structures that an organism has that help them survive or reproduce. e.g. lungs adapted to have a large surface area, muscles in arterioles to adjust rate of blood flow to particular organs, antlers on deer, claws, large ears on an elephant. 4.10)List the 5 general points needed to explain the process of natural selection 1. A population has some naturally-occurring genetic variation with new alleles created through mutations. 2. A change in the environment causes a change in the selection pressures acting on the population 3. An allele which was previously of no particular advantage now becomes favourable. 4. Organisms with the allele are more likely to survive, reproduce and so produce offspring. 5. Their offspring are more likely to have the allele, so it becomes more common in the population. 4.12)Define the term “gene pool”, and state how this relates to the genetic diversity in a population Gene Pool = All the alleles of all the genes in a population at a given time. Genetic Diversity = the variety of alleles in a gene pool (often derived from meiosis – crossing over, independent assortment – or from mutations and random fertilisation So the more different alleles there are in a gene pool the greater the genetic diversity. 4.15) List the 5 main assumptions that are made when working with the Hardy-Weinberg equation (explain why each is required). a. It is a large population – to prevent in-breeding effects b. Mating is random – individuals with a particular genotype must not tend to mate with other individuals of the same genotype c. There is no selection – this would affect the frequency of particular alleles d. There are no mutations – this would affect the frequency of particular alleles e. There is no immigration (movement of organisms into a habitat) or emigration (movement of organisms out of a habitat) – so no gene flow into or out of the population - as this would affect the frequency of particular alleles. 4.16)State the 2 main components of biodiversity Genetic diversity - a measure of the variety of alleles in a gene pool. Tends to increase over time as mutations accumulate. Genetic diversity is largely a result of meiosis and mutations Species diversity – the number of individuals and the number of species in a community. This should increase over time. 4.20)State the 2 main sources of genetic diversity 1. Mutations to DNA – either by a mutagen (e.g. ionising radiation , toxin from cigarette smoke) or randomly by inaccurate copying of DNS during the S phase of the cell cycle. May result in a new allele. 2. Meiosis a) crossing over – when non-sister chromatids exchange alleles b) independent assortment – homologous pairs line up at the equator, but their orientation with respect to maternal and paternal chromosomes is random 4.21) Define the terms biodiversity, species richness and endemism Species richness = The number of different species present in a particular habitat at a particular time - but tells us nothing about their abundance Biodiversity = made up of 2 main components: Genetic diversity – there is genetic variation between members of a species. However, if a population falls below the level of 50 breeding adults, there is likely to be genetic inbreeding, usually resulting in the accumulation of harmful recessive alleles. Species diversity – a measure of both the number of individuals and the number of species in a community. Endemism = Where an organism’s distribution is restricted to specific geographical areas. Islands which have been isolated for a long time often have endemic species. The longer the isolation, the greater the number of endemic species present. E.g. Madagascar 88 m years, Australia 30 m yrs, Galapagos 5 m yrs 4.22)Name a statistical test that can be used to estimate species diversity, and be able to use its formula to calculate an index of diversity This can be quantified by use a statistical test, such as Simpson’s Biodiversity Diversity Index (D), where N = total number of organisms of all species, and n = total number of organisms of a particular species. 4.26)List the 5 kingdoms, and give the main characteristics of each  Animals Plants Fungi Protoctista Prokaryotes Type of cell Eukaryotic Eukaryotic Eukaryotic Eukaryotic Prokaryotic Number of cells multicellular multicellular Some are single Some are single celled Singled celled celled and some and some are are multicellular multicellular Nutrition heterotrophic autotrophic heterotrophic Some are Some are (they have to eat (they produce heterotrophic some heterotrophic their food) their own food) are autotrophic and some are some can do both autotrophic Movement can freely move - can’t freely move can’t freely move some can move freely some can move motile – but some parts and others can’t freely and others can move can’t relatively slowly Reproduction almost always many use both many use both many use both sexual asexual sexual sexual and sexual and asexual and asexual asexual Organisation of complex tissues, complex tissues, Those that are Those that are no tissues due to cells/tissues differentiated cells differentiated cells multicellular form multicellular only being single hyphae and other form simple tissues - celled - Not simple tissues. Not Not differentiated differentiated differentiated Cell wall No Yes - cellulose Yes - chitin Some have a cell wall Yes – and some don’t peptidoglycan DNA Linear DNA with Linear DNA with Linear DNA with Linear DNA with Circular DNA, no histone proteins histone proteins histone proteins histone proteins histone proteins 4.28)Describe the 3 domains theory of Woese Woese grouped all life into 3 domains: Bacteria Archaea Bacteria Archaea Eucarya Eucarya The Bacteria and Archaea are Prokaryotic where as the Eucarya are Eukaryotic. He found that the Archaea are more closely related to the Eucarya than the Bacteria. 4.31) Label a plant cell with its organelles and structures, and describe what the following features are for - cell wall, chloroplasts, amyloplasts, vacuole, tonoplast, plasmodesmata, pits and middle lamella See animal eukaryotic cell for the function of organelles they have in common Vacuole: contains cell sap – minerals, sugars, waste products, toxins. Keeps cell turgid when water enters by osmosis. Tonoplast: Membrane around vacuole. Chloroplast: Site of photosynthesis. Amyloplast: Storage of starch. Pit: Area of very thin cell wall – helps movement of substances between cells. Plasmodesma: Allows movement of dissolved substances directly from one cell to another without having to pass through a cell membrane. 4.36)Describe how the structure of cellulose is related to its properties and function Cellulose has a structural function Cellulose has a high tensile strength because: Cellulose is made of beta-glucose. The beta-glucoses are joined by beta(1-4) glycosidic bonds Cellulose molecules are unbranched Chains of beta-glucose are straight. Many cellulose molecules can lie next to each other. Many Hydrogen bonds form between adjacent cellulose molecules. Many molecules bound together in this way is a microfibril. Also: Cellulose is insoluble in water because it is such a large molecule. 4.37)Draw a table that shows the differences in structure and function between starch and cellulose  Starch Cellulose Monomer Glucose Glucose Specific type of Alpha-glucose Beta-glucose monomer Types of bond Alpha(1-4) glycosidic Beta(1-4) glycosidic bonds present bonds Hydrogen bonds between Alpha(1-6) glycosidic cellulose molecules to form bonds microfibrils Branching Yes (in amylopectin) No Location in plant Amyloplasts Cell wall cell Function in plants Storage of glucose (to be Structural. Supports plant cells used to make new cell wall or to provide energy through respiration) Solubility Insoluble Insoluble 4.39) Identify xylem vessels, phloem sieve tubes and sclerenchyma fibres from diagrams and as viewed with a light microscope http://sci.waikato.ac.nz/farm/images/dicot%20stem_labelled_web.png 4.40) Describe the location of xylem vessels, phloem sieve tubes and sclerenchyma fibres in plant stems 4.43) Describe the detailed structure of xylem vessels and explain how this relates to their function Xylem (cells) vessels – tissue to transport water and mineral ions from the root to the stems and leaves, and also to support the stem 1. Made up of large cells with thick cell walls (resembling drainpipes), with cross walls missing. They form a column of cells acting as tubes for the transport of water and mineral ions up the plant (one direction only). 2. The cells walls need to be waterproof. This is achieved using lignin. This impregnates the cell walls of the xylem vessels (they become lignified). Adding lignin thickens the cell wall more than normal, and is called secondary thickening (adds strength for support role) 3. As they become lignified, the tonoplast (the membrane surrounding the vacuole) also breaks down, and there is autolysis (breakdown) of cell contents (hence they are dead cells, no nucleus). 4.44) Describe the detailed structure of phloem and explain how this relates to their function Phloem is responsible for transporting the products of photosynthesis (sucrose and other organic solutes) away from the leaves to other parts of the plant. It has no role in support of plants. No lignin so is alive. Phloem is made up of two main cell types: (a) sieve tubes, (b) companion cells. See next slides Structure and function of sieve tubes Sieve tubes - individual cells arranged end to end (similar to xylem). The walls between these cells are perforated and form characteristic sieve plates, allowing easy movement of substances between the fluid-filled lumens of adjacent cells. Sieve tubes do not contain nuclei, and have only a little cytoplasm, but they remain alive (unlike xylem vessels).  Structure and function of companion cells The functioning of sieve-tube elements depends on a close association with the companion cells. All of the cellular functions (e.g. chemicals reactions of metabolism) of a sieve-tube element are carried out by the (much smaller) companion cell, a typical plant cell except the companion cell usually has a larger number of ribosomes and mitochondria. 4.45) Describe the detailed structure of sclerenchyma fibres and explain how this relates to their function Sclerenchyma fibres – a type of supporting tissue in plants. They also have very thick cells walls thickened with lignin (small lumen). They do not have living contents (e.g. no cytoplasm present), so are dead cells. How are xylem vessels different in structure to sclerenchyma fibres? Sclerenchyma fibres have cross walls, whereas xylem vessels do not Xylem vessels form tubes, whereas sclerenchyma fibres do not Sclerenchyma fibres have thicker, more lignified walls than xylem vessels Sclerenchyma fibres have a smaller diameter / lumen than xylem vessels Core practical: 4.51) Describe a safe, reliable method for measuring the effect of mineral deficiencies on plants Core practical: 4.51) Describe a safe, reliable method for measuring the effect of mineral deficiencies on plants 1) Put solutions with different mineral concentrations or a different mineral missing into different test tubes. Also set up a test tube with a solution containing all minerals needed for growth. (keep all mineral concentrations constant except for the one being investigated and keep the volume of solution constant) 2) Put a clear film over the top of the test tube and allow the seedling to sit so that its roots are in the solution and its stem comes out through a hole in the clear film (the clear film prevents entry of bacteria or algae that can compete for minerals) 3) Wrap silver foil around the test tube (to prevent entry of light, to prevent algal growth, to prevent competition for minerals) 4) Set up 10 repeats for each solution used 5) Control temperature and light intensity as well as age of seedling and pre- treatment of seeding 6) Leave to grow for 3 weeks 7) Measure change in: length of stem, mass (better as it takes into account growth in all directions), number of leaves, colour of leaves 4.54)List 3 types of inorganic ion required by plants and state what they are required for Nitrate ions – needed to make amino acids, proteins, chlorophyll, nucleic acids – deficiency causes stunted growth and yellow leaves Magnesium ions – needed to make chlorophyll – deficiency causes yellow leaves, but veins remain green Calcium ions – needed to make cell walls, to make pectins, and for correct cell membrane permeability - deficiency results in stunted growth and misshapen leaves Core practical: 4.55) Describe a safe, reliable method for measuring the tensile strength of plant fibres Core practical: 4.55) Describe a safe, reliable method for measuring the tensile strength of plant fibres 1) Extract plant fibres from a suitable plant (in a standardised way – e.g. retting or scraping) 2) Use plants of the same age / leaves collected the same time ago 3) Attach fibre to a hook hanging from a clamp (use fibres that are the same diameter, length, undamaged) 4) Hang a mass holder from the fibre and progressively add mass (10g at a time) to the holder (being careful to place the mass and not drop it) 5) Continue adding mass until the fibre breaks – record this mass (the break point is somewhere between the mass to break and the previous mass that didn’t break it) 6) Repeat 10 times with each type of fibre being tested to calculate an average for each type of fibre 7) Control temperature and humidity Safety: Don’t allow masses to drop very far (set up so masses hang just above table) Keep fingers away from masses that may fall Cut away from yourself when scraping out fibres 4.62)Describe today’s drug testing process (a 5 stage process) Stage Method Purpose Pre-clinical Animal studies and Identify active ingredient if not known testing tissue cultures Test for safety / toxicity Test for effectiveness No harm done to a human May use animal clones as genetically the same Clinical Small group of healthy Check for safety in humans trials – volunteers Identification of side effects / monitor safety phase 1 Identify maximum tolerated dose Clinical Small group of patients Test for effectiveness of treatment in humans trials – with the illness (100- phase 2 300) Clinical Large group of patients To get statistical evidence, unbiased by patient trials – with the illness (1- or researcher, for whether the new drug is phase 3 3,000) better than existing treatments and whether the effect is more than just a placebo effect Double-blind trials After Data still collected on To identify rare or long term side effects and to licensing effectiveness and safety confirm that the clinical trials were correct 4.65) List the conditions required for bacterial growth and explain the importance of each 1. Warm temperature – for efficient enzyme reactions 2. Moisture – for chemical reactions (e.g. respiration) 3. Oxygen – for aerobic respiration 4. pH – for efficient enzyme reactions Core practical: 4.67) Describe a safe, reliable method for investigating the antimicrobial properties of plants Core practical: 4.67) Describe a safe, reliable method for investigating the antimicrobial properties of plants 1) Make a plant extract from the plants being investigated by crushing (with pestle and mortar) 5g of plant material in 10cm3 of ethanol 2) Soak filter paper discs in this extract 3) Leave discs to dry in sterile petri dish (also soak a disc in just ethanol and leave this to dry – this will be the control) 4) Spread agar plates with a bacterial lawn (using aseptic techniques – dip spreader in ethanol and pass through Bunsen flame, work near Bunsen burner, when lifting lid off agar plate hold it directly above the plate, wipe down work surface with ethanol, flame forceps) 5) Place the dried discs onto the agar plate with the bacterial lawn 6) Tape lid of agar plate in 4 sections to prevent lid coming off (ensures bacteria don’t escape and there is no contamination of the plate) – don’t completely seal to allow air to get in (reduces chance of pathogenic bacteria growing) 7) Incubate agar plate at 25°C (below human body temperature so that bacteria in lawn outcompete an pathogenic bacteria) for 24hrs 8) Measure clear zone around each disc (either 4 different diameters for each one or surface area – to account for irregular shaped clear zones) 9) Do 10 repeats for each plant 10) Compare mean size of clear zones (larger = more effective at preventing growth of bacteria) 11) Safety: tie hair back to prevent burning from Bunsen burner / see others above 4.70)Define sustainability and state 3 reasons why the use of oil-based fuels and plastics is not sustainable Sustainability: The principle that the use of resources (or the environment in general) should only be permitted if it can be done without damaging the environment or reducing those resources in the long term. The use of oil-based fuels and plastics is not sustainable because: 1) Oil reserves will eventually run out 2) Burning oil-based fossil fuels releases CO2 into the atmosphere, contributing to global warming (so long term damage to the environment) 3) Plastics generate non-biodegradable waste, creating major waste disposal problems (so space will run out) 4.73)Define “carbon-sink” and explain why fossil fuels are an example of a carbon sink A carbon sink is a (long-term) store of carbon (where carbon is prevented from cycling around the carbon cycle). 1. If a dead plant or animal is deposited in anaerobic conditions (e.g. in a swamp, or at the bottom of the sea) it won’t decay as the decomposers need aerobic conditions to respire. 2. The carbon in the dead organisms turns into a fossil fuel, such as coal, oil or gas. But, the carbon is not naturally released back into the environment (only by human intervention – combustion). Hence the fossil fuel is acting as a carbon sink. 3. The carbon in the fossil fuel stays there for a long time and isn’t cycling around the carbon cycle. 4.74)List the aims of captive breeding programmes Increasing the number of individuals of a species by having a successful breeding programme Maintaining genetic diversity within the captive population by using studbooks to make decisions about which individuals to breed together by collaborating with other zoos around the world to increase the effective captive breeding population (minimum 50 individuals) Reintroducing animals to the wild if possible by training animals to have the skills they need in the wild whilst in captivity prevent over exposure to humans so that they remain fearful of humans 4.80)Draw a flow chart to summarise the processes involved in the storage of seeds in a seed bank 1. Seed collection from the wild, and species identified 2. Seed x-rayed for presence of an embryo to confirm viability 3. Seeds dried, surface-sterilised and packed 4. Seeds stored in large numbers at -20°C, so no germination and no decomposition 5. Periodic germination trials to check on seed viability Less costly than growing and maintaining whole plants Less space needed to store seeds than whole plants