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Edexcel Snab Topic 4
How did organisms become so well adapted?
| Question | Answer |
|---|---|
| How many different species are there? | 30 million different species |
| What is a species? | A species is a group of organisms with similar morphology, physiology and behaviour which can interbreed to produce fertile offspring and which are reproductively isolated from other species. |
| How can DNA analysis help? | To help identify species. |
| What is a habitat? | A habitat is a place where an organism lives. |
| What is a population? | A population is a group of interbreeding individuals of the same species found in an area. |
| What is an ecological niche? | The way an organism exploits it's environment. |
| What will happen if they have the same niche? | They will compete against each other and the better-adapted organism will out compete the other and exclude it from the habitat. |
| How are orchids specialised? | They produce the same scent of female wasps and are only pollinated by one species of insect. They mimic female insects and trick pollinators and by doing so they out-compete other flowering plants. |
| What are the three different types of woodpeckers? | The lesser spotted, great spotted and the green woodpecker. They have a powerful beak which use to probe into rotting wood. They pick up woodlice, bettle larvae and ants using their long tongue. |
| What do each woodpecker prefer? | Lesser spotted woodpecker prefers fine branches. Great spotted feeds on broader branches and the green woodpecker feeds on the ground, co-exist in same habitat as they have a different niche. |
| Why are woodpeckers, aye-aye's and orchids adapted? | So they are able to exploit they're own niche. |
| What are the 3 different types of Adaptations? | Behavioural, Physiological and Anatomical. |
| Give three examples of each? | Behavioural - When Agoutis bury Brazil nuts, which will aid survival producing a future food source. Physiological-Some plants are able to tolerate high salt concentrations. Anatomical - Bodies of bumblebees show adaptations to collect nectar and pollen. |
| What else do bumblebees have? [Extra] | Pollen basket on hind legs; which is a fringe of hairs to hold pollen combed from the body; allowing pollen to be carried back to the nest. |
| What is it when organisms become dependent on each other? | Co-adaptation. |
| What is Natural Selection? | Mechanism proposed by Darwin and Wallace, by which an organisms change over time as they adapt to their changing environments. |
| What is it called when some organisms possess some characteristic which gives them an advantage over others? | Survival of the fittest |
| What is a Evolution? | A change in allele frequency in a population over time (generation) |
| What are stages of Natural Selection? | 1. Population ( Genetic Variation) - New alleles' mutation 2. Change in Environment - Selection pressures 3. Allele no particular adv- favourable 4. Organisms with allele- more likely to survive, reproduce- offspring 5. Offspring likely to have allele |
| What do the ability of a population to adapt to new conditions depend on? | 1. Strength of the selection pressure 2. Size of the gene pool 3. Reproductive rate of the organism |
| What is a gene pool? | Consists of all the alleles of all the genes present in a population. |
| How does becoming adapted help? | Helps avoid competition with other species living in the same area. |
| Why are organisms given a scientific name? | To avoid confusion and precise/ |
| What did Carolus Linnaeus come up with and why? | The binomial system [Genus species] (WHICH IS UNIQUE and HIGHLY DESCRIPTIVE) to catalogue living things. |
| What does the dichotomous key do? | A traditional way of identifying organisms |
| What is taxonomy? | Placing organisms into groups on shared features; results in a manageable number of categories. |
| What are the hierarchy of the groups? | Kingdom, Phylum, Class,Order, Family, Genius and Species |
| What are the 5 main kingdoms Whittaker proposed? | 1. Animalia 2. Plantae 3. Fungi 4. Protocista 5. Prokaryotae |
| How did Woese discover the new system, Archaea (which are found in hot springs and salty lakes)? | By pioneering RNA sequencing bacteria to construct phylogenies of groups bacteria. He realised that one group of bacteria lacked the sequence characteristic. Also the methanogenes had no peptidoglycan and had different membrane lipids. |
| How do scientists publish their data? | They report their findings by publishing their work in scientific journals, conference papers and Internet. This allows scientists to see and comment on data,methods and interpretations.Peer review to detect invalid claims and add weight to valid ones. |
| Explain Woese process? | Woese work suggested life was microbial ; many scientists were sceptical, ignored and dismissed his ideas. He hated large meetings so had few oppurtunites to argue and barely attended meetings. |
| Explain Woese process? [ part 2] | However Kandler accepted it and held the first conference to influence scientists. Eventually theory became accepted by publishing international journals. |
| What do Phylogenic trees represent? | The Evolutionary relationships based on the best existing evidence - constantly revised as new data comes along. |
| Why may DNA Analysis not support Linnaean classification? | As in the traditional classification Vertebrates, birds and reptiles are placed in separate classes however DNA Anaylysis places birds in the same taxon as Turtles, lizards, snakes and Crocodiles. New evidence - fossil evidence. |
| What are Phenotypic traits? | Are observable characteristics; flower structure or bone structure. Organisms often look similar as they are adapted to similar conditions. |
| Dolphins and sharks look similar But they are not related. What is this an example of. | Convergent Evolution- Unrelated organisms evolve similar appearances as they adapt to the same habitat. |
| How does Classification help? | It enables us to look at evolutionary relationships. |
| What is Genetic Diversity? | When each organism has a unique combination of alleles( the greater the variety of genotypes the more genetically diverse the population)- Allows population to adapt to changing conditions |
| How does Meiosis result in Genetic Variation? | Through Random assortment- (random aligning of chromosomes and new combinations of parental chromosomes / alleles and crossing over( breaking and rejoining of {chromatids / DNA / on same chromosome pair recombines genes/alleles} / produces recombinants. |
| How else can genetic variation take place? | Through mutations (random)- Changing DNA Sequence- creating new alleles, and increasing gene pools |
| How can you test molecular differences? | Using techniques; gel electrophoresis of 2 proteins |
| What is Biodiversity? | Variety of Species that belong to every different group of organisms, animals, plants, fungi, bacteria and other MO's living in all the habitats on the planets.- Diversity within species. |
| How to measure Biodiversity? | Through species richness. - No of species present in a habitat(Doesn't take account of population) |
| What is a dominant organism? | A very common species in a habitat. |
| What is a Biodiversity hotspot? | Is a place containing the largest proportion of plant species. It must have at least 1250 different plant species.[endemic] E.g. Mediterranean Basin, Ocean Sea beds |
| Where did the term Biodiversity hotspot come from ? | From Norman Myers to describe areas of particularly high biodiversity in order to to focus on conservation. |
| How to measure Genetic Diversity? | Through DNA Sequencing to determine bases in a segment of DNA- which alleles are present. Where it is cut into fragments through Gel Electrophoresis. Therefore different fragments can be identified- different lengths. |
| Why may Conservation biologists use genetic diversity? | To compare different populations when deciding which population may need to be conserved. |
| What do plants do to produce tall structures? | - Strong Cell Walls out of Cellulose - Build columns and tubes from specialised cells. - Stiffen special cells with another polymer; Lignin |
| Why may trees add a ring of Lignified tissue each year? | To grow taller,stronger and flexible. |
| What is a Parenchyma? | Type of plant tissue found through out plant, where cells fill spaces between more specialised tissues and may have specialised functions. |
| Draw a Plant Cell. | [Planet Cell Diagram] |
| What are the properties of Cellulose? | - Polymer of Glucose - 1,4 GB between 2 B - Glucose - Form H bonds with adjacent molecules. - Polysaccaride - Long Unbranched molecule - Contains 1000-10000 Units - Remain as straight chains - Hydrogen bonds between -OH groups bundles Of microfibri |
| What are the properties of Cellulose? [2] | -Weak Hydrogen bond, strong Glycosidic bond -Large no of Hydrogen bonds; strong structure -MF [60-70] Cellulose molecules; helical arrangement stuck with a Polysaccaride glue -Glue; short branched PS; Hemicellulose & Pectin; bind to surface |
| What does Pectin do? | Holds cells together important component of middle lamella; makes it strong but pliable. |
| Why do the Microfibrils make it strong and flexible? | As they are laid down in different angles. |
| What are Plasmodesmata's? | Narrow fluid-filled channels; located in pits. |
| Name the 2 specialised types of cells? | - Xylem vessels; tubes for transport and stiffened walls help support plant. - Schlerenchyma fibres - Columns of these cells with stiffened walls allow transport |
| What are the 3 basic types of tissue found in plant? | Dermal (Epidermis), Vascular and Ground |
| What do the Xylem carry? | Water and Inorganic ions, upwards |
| What do the Phloem carry? | Sugars made by photosynthesis in the leaves; up and down |
| What are the properties of Xylem? | - Hollow tubes/ broken end walls; allow movement of water. - Waterproof - Lignified Walls - Lignin impregnates cellulose cell wall - End walls - Elongated -Dead - Stiffened, thick walls |
| How is water transported through Xylem vessels? | Water evaporates at the surface of the cell that line the substomatal cavities. [Transpiration] Water diffusing out through stomoate down diffusion gradient; replaced by roots. By Capillary action; capillaries draw up water; surface tension. |
| How is water transported through Xylem vessels? [2] | Draws up more water to cell surface; where capillaries draw up water in a continuous stream. From cohesive forces between water molecules which are a result of hydrogen bonding. |
| What are the properties of water? | - Cohesion -Surface Tension - Solvent Properties - Thermal Properties - Density and freezing Properties |
| What are the 4 different ions needed for Plants? | - Nitrogen; For Cell Growth - Calcium; Calium Pectate; Middle lamella - Magnesium; Chlorophyll - Phosphorus; DNA and RNA |
| What do the Sclerenchyma fibres have? | - Lignified walls - Dead - Chisel end - Elongated thick walls - Support |
| What does Lignin do? | - Waterproofs cell walls - Stiffer - Stronger - Greater Tensile strength |
| What do human's use Plant fibres for? | Rope, Clothing, floor coverings, paper |
| Why are they used? | - Long and thing - Flexible - Strong |
| How can we extract fibres? | - Take plant apart mechanically by pulling out fibres or digesting surrounding tissue. - Cellulose/Ligning resistant to chemical and enzymic degradation; whilst the Polysaccarides can be dissolved |
| What is the term used for extracting fibre processes? | Retting |
| What other uses do Fibres have? | To absorb heavy metal and Hydrocarbons from polluted water. |
| What are advantages of using Bicomposites ( fibre added to other materials)? | Stronger, Renewable, Biodegradable, Easier and Locally grown, safer, cheaper, Less use of fossil fuel |
| Why may plants have chemical defences? | To repel and kill animals that feed on them |
| What are the uses of Pyrethrum? | - Insecticides; contains chemicals which are toxic. Active Ingredient: Various Pyrethrins. Sprays, Flea treatments and reduction of tick infestation. Useage of companion plant, natural insect repellant. |
| What chemicals do mint contain? | Menthone and Carvone |
| How can you calculate Biodiversity? | Simpson's Index |
| What is the Active Ingredient in Garlic? | Allicin; produced when cut or damaged. Inactive precursor, alliin is converted into active form by the enzyme alliinase. |
| Which parts of the plant may have greater antibacterial properties? | Seed coat, Fruit coat, Bulb and roots |
| Name 3 plant derived medicines | Aspirin (Salycylic Acid from Willow bark) , Morphine and Codeine ( Opium poppies) |
| What are the symptoms of Foxglove[Digitalis] and what can it treat? | Dizziness, Hallucinations, Heart Failure, from irregular heartbeat and Oedema [Dropsy]; fluid accumulates in body tissues and as BP is raised tissue fluid fails to return |
| Draw a Flow diagram of Withering's process | 1. Identified active ingredient 2. Individual cases 3. Studied side effects of digitalis using small number of patients 4.Tested to find dose on small number of patients. |
| Stages of Drug testing today | 1.pre-clinical testing; Animal and Lab studies on isolated cells and tissue culture; where effective 2. Small Group of Volunteers- Different doses; healthy. Whether compound is absorbed, distributed, metabolised and excreted. |
| Stages of Drug testing today [2] | 3. Small group of volunteers patients drug effectiveness 4. Large group of patients selected and divided into 2 groups. Compound and placebo; Double blind. Now open to be licensed and marketed. Trials continue to collect data on effective ness and safet |
| How do plants try and survive? | - Being a seed; protect embryo, aid dispersal, provide nutrition for the new plant. |
| What happens when the ovule is fertilised? | - Outer layers of the ovule become lignified forming a tough seed coat; protects embryo. Surrounding ovary develops into a fruit. |
| What is it called when stored food is outside the embryo in storage? | Endosperm[ common in monocotyledons; cereals] |
| What happens in dicotyledons? | Embryo absorbs stored nutrients from endosperm and food is stored in seed leaves [ cotyledons] which swell up to fill seeds. |
| How do Brazil Nuts store food? | In the Hypocotyls ( developing stalk) |
| How does Seed dispersal help? | Offspring to avoid competing with parent or each other and allows plant to colonize new habitats. |
| What are the 4 different types of seed dispersal? | Wind, Animal, Water and Self-dispersal |
| What happens when conditions are suitable and dormancy has been broken? | Seed takes in water through a small pore in seed coat., absorbing it triggers metabolic changes in seed. Production of plant growth substances is switched on; secretion of enzyme, mobilise stored food reserves. |
| What breaks down starch which is converted to sucrose for transport to the radicle and plumule. | Maltase and Amylase |
| What breaks down proteins in the food store to give amino acids? | Proteases |
| What breaks down Stored lipids to give Glycerol and Fatty acid? | Lipases |
| Why is starch easy to extract? | As they don't dissolve in water, but can be washed out. In wheat protein remaining is Gluten [bread making] |
| What are the the common uses of starch? | Adhesives, Paints, textiles, plaster, insulatin material and toiletries; conditioners, mousse, sun screens and anti-perspirant |
| What are the main uses for Starch? | - Thickening; Granules heated in water; swell, absorb water and thicken liquid. 'gelatinisation' - custard, wallpaper paste - Stiffening fabrics - ' Sizing' - Paper coatings, cloth treatment. Starch mixture applied to surface is gelatinised. |
| What are the main uses for Starch? [2] | Then cooled- bonds to form between molecules. Addition of water - reverses stiffening; called plasticisation.(flexible) and the water is a plasticiser. - useful as it can change shape. |
| What are the main uses for Starch? [3] | - Super Absorbents Starch is chemically cross-linked before gelatinsed then particles are formed then dried. When rehyrdated; take large amount of water e.g. nappies. - Starch foam Temp at which it gelatinise depends on amount of water. |
| What are the main uses for Starch? [4] | If pressure is suddenly released; seed coat ruptures and starch puff is formed. Cereal and Foam packaging made in an extruder. As hot starch leaves small exit hole; pressure is released, causing it to expand as water turns to steam. |
| What are plant based plastics made of? | Sugars from wheat, sugar beet, potatoes or agriculture waste. |
| Use of Vegetable Oils | - Fuels; Castrol(Castor bean), Peanut Oil, Biodiesel; less SO2, CO2. (Rapeseed). Can be used 100% or in a blend with Fossil fuel. |
| Why is the use of oil-based plastics not sustainable? | - Burning Fossil Fuels; produces CO2 in atmosphere; contributing to global warming - Oil is unrenewable; running out; finite resource - Generate non-biodegradable waste |
| What are the advantages of a plant-based fuel? | That it can be removed from the atmosphere recently when the crop that had produce the oil was grown. |
| What are the problems with moving to plant products? | Less room growing biofuels & plant materials by replacing rainforests and food crops Unsuitable agriculture & essential for wildlife/water conservation, Agriculture energy demanding e.g. ploughing,harvesting and fertilising Human population increasing |
| What are the problems with moving to plant products? [2] | May Not have desirable qualities High Energy consumption; production and transport |
| What is an ecological footprint? | The area of land you would require to support you're lifestyle. |
| Give an example of a primary threat towards species. | Human activity for e.g. Habitat destruction, fragmentation and Degradation, Pollution, Intro of alien species, Over-exploitation |
| What should be done to help conserve these organisms? | Conservation management on site (in situ), protecting ecosystems and maintaining fragile habitats. Also ZOOS AND SEEDBANKS. |
| How can scientists, conservationists and educators protect species? | - Habitat management - Captive breeding - Reintroduction to the wild - Education - Research |
| What does the Zoo Licensing Act 1981 aim to do? | - Promote minimum standards of welfare - Meaningful Education - Effective conservation - Valuable research - Essential public safety |
| What do Captive breeding programmes do? | - To increase the number of individuals of the species if numbers are low - To maintain genetic diversity within captive population - To reintroduce animals in the wild |
| How do they know which species should/should not be breed? | Studbook holders and Appointed co-ordinator |
| What is a genetic drift? | Change in an allele frequency over time; which leads to reduction of genetic variation therefore genetic variation can be lost; as by chance alleles may not be passed on. |
| What is genetic uniformity? | Where individuals within a population have similar genotypes and can be an advantage however of the environment changes, new disease occurs, a more genetic diverse population will be at advantage. |
| Why do scientists want to ensure genetic diversity? | So individuals can cope with new conditions; allowing them to survive. Which is known as natural selection which results in adaptation, accumulation of genotypes favoured by environment. |
| What is essential for long term survival for populations? | That they should be able to evolve as a result of natural selection. |
| How can evolution be likely? | If there is genetic variation or the mutation rate is very high. |
| What is Inbreeding? | As is causes the frequency of homozygous genotypes to increase with the loss of heterozygotes. It then results in individual inheriting recessive alleles from both the parents. Also the accumulation of Homozygous recessive genotypes in offspring. |
| How is Inbreeding depression harmful? | As many recessive alleles are harmful and the offspring may me less fit( survive or reproduce). They may be smaller, may not live as long and produce fewer eggs. I t can occur in the wild or in captivity where mating increases. |
| How does Conserving genetic diversity help? | To maintain the size of the wild population to prevent genetic drift and inbreeding depression. |
| Why is important to keep a studbook? | As it shows for an individual species the history and location of all the captive animals of that species in the places co-operating in an overall breeding plan. It provides raw data about breeding these animals. |
| What must conservation scientists ensure? | Genes from all members of population or all remainging breeding adults are retained and equally represented in subsequent generations. Requires individuals which are poorly captivated to be encouraged to breed ,those who are good breeders must be limited. |
| What techniques are used for studbooks? | Cytogenetics and Molecular biology;whether some individuals are more closely related than is desirable for breeding purposes. |
| How is Reintroduction to the wild complicated? | As they have to learn new skills to survive in the wild. |
| What does the term hacking out mean? | Being taken out the forest and given more freedom and less food to encourage them to feed themselves. |
| How can plants become threatened? | Habitat destruction, Climate change and Over harvesting, Man-made and Natural disasters |
| How can plants be conserved in situ? | By protecting and managing habitats |
| How can plants be conserved ex situ? | By Seedbanks and Botanic gardens |
| What is the aim of Millenium Seed Projects? | To conserve samples from threatened species of plants; already 10,000 species banked. Focuses on plants living in dryland, most threatened. |
| How do seed banks work? | Seeds stored in cool, dry conditions Can be stored for long time Viability tests carried out at regular intervals More economic, less costly, less labour involved than conserving living plants |
| How do seed banks work? [2] | Less space needed Large numbers of plants can be stored Seeds do not need be stored in original habitat Less likely to be damaged by vandalism natural disaster Less likely to be damaged by disease or herbivores Value of conserving plant species |
| What is tensile strength? | Ability to resist stretching or being broken when pulled , maximum force which can be applied before breaking |
| Why are seeds in dry and cool conditions and reduced in temperature and moisture content? | As they're life span doubles.[-20C] |
| Why is it easy to obtain seeds? | As plants produce large amount of seeds and collecting them are unlikely to damage a wild population. They are also small and eay to store and can survive in a desiccated state for years. |
| What happens after a month the seeds have been placed in cold storage? | A sample is taken and germinated in Agar plates to make sure the seeds survive in storage conditions. Then tested every 10 years and if it falls below 75% then they will be grown to collect new sample; which is then placed in storage. |
| What can seed collections be used for? | Research, Habitat Restoration and species Re introductions. |
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