AQA GCSE B1b module

These cards are for the AQA GCSE syllabus, biology module 1b. Topics included are:

  • Adaptation and Survival
  • Populations and Competition
  • Variation in Plants and Animals
  • Genes, Chromosomes and DNA
  • Reproduction
  • Cloning
  • Genetic Engineering
  • Evolution
  • Human Impact on the Environment
  • The Greenhouse Effect
  • Climate Change
  • Sustainable Development
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Adaptiation and Survival

  • animals and plants have adapted to survive in different environments
  • desert animals have adapted to save water
  • large surface area compared to volume, small amounts of concentrated urine, very little sweat, thin body fat, large feet spread weight, sandy colour for campoflage
  • arctic animals have adapted to reduce heat loss
  • small surface area compared to volume, thick blubber, thick hairy coats, white fur for camoflage, big feet spread weight
  • some plants have adapted to living in a desert
  • spines instead of leaves, small surface area compared to size, stores water in thick stem, shallow but extensive roots, others have deep roots for underground water
  • some plants and animals are adapted to deter predators
  • armor (thorns, sharp spines, hard shell), produce poisons, warning colours
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Populations and Competition

  • organisms living in the same area compete for resources and survival
  • size of any population depends on 3 factors: competition, disease and predation
  • plants compete for light, water and nutrients
  • animals compete for space, food, water and mates
  • infectious disease can kill of members of a population-fit and healthy have a better chance of survival
  • organism eaten=population decrease
  • competition affects location, size and distribution of populations in the wild
  • organisms live where they can find resources for survival
  • competition means a habitat can only support a certain number of organisms (resources decrease=population decrease)
  • competition affects how far apart members of a poulation are (few resources=organism needs more space to find resources, lots of resources=lots of organisms in one place)
  • red and grey squirrels: 1876-grey squirrel introduced, native red squirrels unable to compete, red squirrel population decrease, grey squirrel adapted to deciduous woodland, red squirrel adapted best to coniferous woodland
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Variation in Plants and Animals

  • organisms of the same species have differences-called variation
  • two types: genetic variation and environmental variation
  • different genes cause genetic variation
  • plants and animals all have characteristics that are similar to their "parents"
  • characteristics are determined by genes inherited from parents
  • some genes from mother and some from father
  • combination of genes causes genetic variation: eye colour, blood group, inherited disorders
  • characteristics also influenced by the environment
  • environment organisms live and grow in causes differences between members of the same species-environmental variation
  • wide range of differences: losing your toes to suntan to yellow leaves
  • any difference caused by conditions something lives in is an environmental variation
  • most characteristics are due to genes AND the environment
  • body weight, height, skin colour, condition of teeth, academic or athletic
  • genes could determin maximum height but environment determins whether it grows that tall or not (how much food it gets, for example)
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Genes, Chromosomes and DNA

  • most cells in your body have a nucleus-contains your genetic material
  • human cell nucleus contains 23 pairs of chromosomes-all numbered (two no. 19's, two no. 12's etc.-one half of each pair from each parent)
  • pairs of chromosomes are held together in the centre
  • chromosomes carry genes-different genes control different characteristics
  • gene=short length of the chromosome-long length of DNA
  • DNA is coiled up to form arms of the chromosome
  • genes can exist in different versions-each version gives a different characteristic (blue or brown eyes)
  • different versions of the same gene are called alleles
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Reproduction

  • asexual reproduction produces genetically identical cells
  • cell divides in two-new cell has the exact same genetic information
  • only one parent-no variation-clones
  • chromosomes have 2 identical halves-----each chromosome splits down the middle to form 2 identical sets of half chromosomes-----DNA replicates itself in each cell to complete chromosomes producing 2 identical cells
  • how all plants and animals grow and produce replacement cells
  • some organisms reproduce asexually like bacteria and certain plants
  • sexual reproduction produces genetically different cells
  • genetic information from 2 organisms is combined-produced offspring which is genetically different to both mother and father
  • gametes: sexual reproduction cells
  • ech gamete contain 23 chromosomes (half of what's needed)-one of each chromosome-not 2
  • gamete from mother and gamete from father fuse together (fertalisation)-form cell with full chromosomes
  • offspring inherits features from both parents
  • sexual reproduction produces more variation than asexual reproduction
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Cloning

  • plants can be cloned from cuttings and by tissue culture
  • cuttings: take cuttings from parent plant and plant them-genetically identical, cheap and quick,however, reduced gene pool
  • tissue culture: a few plant cells put into a growth medium with hormones-grow into genetically identical new plants, quick, little space needed, grow all year, however, reduced gene pool
  • make animal clones using embryo transplants or adult cell cloning
  • embryo transplants: sperm from prize bull and egg from prize cow---artificially fertilized---developing embryo split lots to form clones before cells specialise---clones implanted into lots of other cows (surrogate mothers): can produce hundreds of "ideal" offspring every year from best bull and best cow, however, reduced gene pool (open to disease)
  • adult cell cloning: used to create Dolly, remove genetic material from egg cell---nucleas from adult body cell inserted into empty egg cell---grows into embryo---placed into surrogate mother or stem cells harvested: human adult cell cloning could help treat diseases-unethical?
  • fusion cloning: adult cell fused to embrionic stem cell---properties of stem cell but identical to adult
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Genetic Engineering

  • gengetic engineering uses enzymes to cut and paste genes: useful gene is cut from one organism's chromosome using enzymes---enzymes cut into other organisms chromosome and insert useful gene (called gene splicing): method can be used for lots of things like inserting human insulin gene into bacteria to produces human insulin
  • genes can be transferred into animals and plants: same method used at a very early age-GM plants that are resistant to viruses and herbicides-genes inserted into animal embryos (sheep GM to produce drugs for treating diseases in their milk)-genetic disorders are caused by faulty genes-attempting to cure by inserting working genes into sufferers (gene therapy)
  • wrong to change genes? create unplanned problems which get passed on?
  • GM crops, +'ve's: increase yield, produce extra nutrients, currently used with no problems
  • GM crops, -'ve's: affect no. of weed, flowers and wildlife (reduce biodiversity), may not be safe, transplanted genes may get into the natural environment (create things like super weeds that are resistant to herbicides)
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Evolution

  • no one knows how life began-know that living things come from other living things-don't know where first living things came from-various theories
  • fossil record shows that organisms have evolved-form in rocks as minerals replace slowly decaying tissue-show us what was on Earth millions of years ago, habitat and what they ate-also show timeline due to soil depth/type (show how long a species lived)-very few fossils actually form-creates gaps in fossil record-could put all species on a family tree structure
  • theory of evolution: life on Earth began as simple organisms from which all the more complex organisms evolved
  • extinction happens if you can't evolve quick enough: fossil record contains many species that dont exist anymore (eg. dinosaurs and mammoths)-only fossils tell us they existed
  • species become extinct for 3 main reasons: environment changes too quickly, new predator or disease kills them all, can't compete with another species for food
  • dodo's are extinct-humans hunted them and introduced other animals which ate their eggs and destroyed their habitat
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Evolution

  • mutations are when DNA changes: change through everyday wear and tear-mostly have no effect
  • if mutation happens in a gene and is passed on: can cause new characteristics: sometimes gives the organism a better chance of survival-over a long period of time, can help a species adapt to it's environment: may lead to a completely new species through evolution
  • natural selection explains how evolution can occur-Charles Darwin
  • not everyone agreed: against religion, different scientific theories, darwin couldn't give a good explanation
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Human Impact on the Environment

  • 6 billion people in the world-rising quickly
  • increasing demands on the environment
  • produce more waste-water, land and air
  • more people means less land for other animals and plants
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The Greenhouse Effect

  • carbon dioxide and methane trap heat from the sun
  • heats up the earth
  • human activity produces a lot of carbon dioxide
  • methane also causes problems
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Climate Change

  • consequences of global warming
  • rising sea levels
  • hurricanes
  • melting ice
  • food affected
  • weigh the evidence before making judgements
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Sustainable Development

  • needs careful planning
  • meets the needs of todays population without harming the ability of future generations to meet their own needs
  • reduction in biodiversity could be a big problem
  • human impact can be measured using indicator species
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Comments

Uzma

ThankYouuu Soo Muchh .. ***

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