topic 4

• What is natural selection?

  The idea that the fittest survive and pass along their traits to their offspring.
• How do fossils provide evidence for evolution?

  They provide the evidence of the organisms that lived years ago, they can show how much or little organisms have evolved over time.

  Generally, the deeper the fossil is found, the older it is.
• What is the problem with the fossil record?

  There are gaps.
• How do bacteria provide evidence for evolution?

  -develop random mutations

  -less affected by antibiotics

  -advantage to help them survive

  (remember to indicate that the person may not have finished the course of antibiotics in answers to exam question)
• Who was Charles Darwin?

  Charles Darwin promoted natural selection as the method of evolutionary changes.
• How did Charles Darwin think of natural selection?

  - he saw that there was variation in species, and noticed that those with certain characteristics were more likely to survive.

  - he also noticed that characteristics could be passed on to offspring.
• Who was Alfred Wallace?

  - naturalist

  - Same time as Darwin

  he had similar ideas and introduced natural selction

  - they published their ideas together
• What areas of biology has the theory of evolution affected?

  Classification, Antibiotic Resistence, Conservation
• How has the theory of evolution affected classification?

  - if all organsisms descended from a common ancestor, then we all must be related

  - we now classify them based on how closely related they are
• How has the theory of evolution affected antibiotic resistence?

  - we now understand the importance of finishing the course of antibiotics to prevent resistent bacteria spreading

  - we also know that we need to constantly develop new antibiotics as bacteria evolve
• Describe Ardi


  Description : Long arms and long big toes to help her climb trees, brain the same size as a chimpanzee's, walked upright, but also used hands to help

  Discovered : 4.4 million years ago
• Describe Lucy


  Description: arched feet, no ape-like big toe, brain was larger than Ardi, but still similar in sized to a chimpanzee's. Walked upright, but more efficiently than Ardi

  Discovered: 3.2 million years ago
• What did Leakey discover?

  The fossil hominid "Turkana Boy", and it was 1.6 million years old. He was more adapted to walking than Lucy
• How do stone tools provide evidence for human evolution?

  They have developed over time, becoming sharper, with more complex uses

  Newer, sharper tools were used for arrowheads, fish hooks and needles
• How can fossils and stone tools be dated?

  Carbon dating (if it has carbon), stratigraphy (looking at how deep the object was found), looking at structural features and comparing to already discovered fossils
• What is a pentadactyl limb?

  A limb with five digits
• How does the pentadactyl limb provide evidence for evolution?

  - many organisms have the pentadactyl limb, with a similar bone structure, but use it for different things.

  - this suggests they all evolved from a common ancestor, because if all these organisms had a different ancestor, it would be highly unlikely that they would all have the same bone structure.
• What are the five kingdoms?

  Plants, Animals, Prokaryotes, Protists, and Fungi
• What are prokaryotes?


  unicellular organisms that lack a nucleus
• What are protists?


  single celled eukaryotes
• What are the subdivides of kingdoms? (five kingdoms)

  Kingdom, phylum, class, order, family, genus, species
• What are the three domains?

  Bacteria, Archaea, Eukarya
• What is the eukarya domain?

  organisms that have eukaryotic cells (a true nucleus)

  Ex. plants, animals, protists, fungi
• What is the archaea domain?

  it consists of unicellular organisms with no nucleus.
• Why did we switch to the three domain system?

  - we can now compare the genetics of organisms so we know that members of the prokaryote kingdom are not as similar genetically as we believed, so should be split up into 2 domains (archaea and bacteria)

  - we can now organise organisms based on genetics rather than physical characteristics
• What is archaea?


  prokaryotes that often live in Earth's extreme environments
• What is in the domain eukarya?

  -the largest and most morphologically complex organisms on the tree of life

  -includes algae, plants, fungi, and animals
• Describe selective breeding?


  1) from existing stock, select the ones with desirable characteristics

  2) breed them with each other

  3) select the best offspring then breed them together

  4) continue over several generations
• What are the benefits of selective breeding?

  new varieties may be economically important, by producing more or better quality food

  animals can be selected that cannot cause harm, for example cattle without horns

  can also be used in medical research - mice with a strong or weak preference for alcohol can be bred and then scientists can study the differences in their behaviour
• What are the disadvantages of selective breeding?

  -reduces the gene pool

  -health problems as inbreeding means that there is a higher chance of organisms inheriting harmful genes

  -less chance of disease resistance alleles, so the population is less likley to survive a harmful change in environment
• Describe tissue culture


  1) choose plant you want to clone with desirable characteristics

  2) remove small pieces of tissue (from meristems for best results)

  3) place on growth medium (agar) with nurients and growth hormones

  4) use aseptic technique to prevent the growth of harmful or unwanted bacteria

  5) as tissues produce roots and shoots (hormones can be used to induce this), they can be transferred to potting compost to grow further
• How can animal cells be grown using tissue culture?

  1) take sample of the tissue

  2) cells in the sample are separated using enzymes

  3) place in culture vessel with a growth medium

  4) after several rounds of cell division, the cells can be split up again and put into seperate vessels to encourage further growth

  5) once a tissue culture has been grown, it can be stored for further use.
• What are the benefits of tissue culture?

  - animal tissues can be used to test medical drugs

  - clones of plant with desirable features can be quickly produced
• What are the risks of genetic engineering?

  1) Transplanted genes may get out into the environment (a herbicide resistence gene may be transferred to weeds if crossbreeding occurred)

  2) Another concern is that genetically modified crops could affect food chains

  3) Some people are against it altogether as it might cause unforeseen problems

  4) Some people say it will affect the number of weeds and flowers that live around crops which reduces farmland biodiversity
• What are the uses of genetic engineering?

  ~ manufacturing insulin

  ~ higher crop yields (herbicide resistent crops)

  ~ finding out where genes are expressed in the body (glow in the dark gene linked)

  - can be used to add more of a vitamin or nutrient in a crop in order to combat deficiency diseases (eg golden rice is genetically engineered to produce more vitamin A)
• Describe how genetic engineering works

  1) cut out desired gene using a restriction enzyme, then cut vector using the same restriction enzyme

  2) the vector and gene are left with complementary sticky ends

  3) ligase enzymes join the sticky ends to make recombinant DNA

  4) the recombinant DNA is inserted into other cells, like bacteria

  5) the bacteria will quickly reproduce, and will therefore also reproduce this gene, which can then be separated for use
• How can inserting the gene for producing the Bt toxin into crops aid crop yield?

  - the gene makes them resistent to pests, and the tcells in the stems and leaves will produce the toxin

  - this means that areas of the plant which would not be exposed to sprayed pesticides are now pest resistent
• What is biological control?

  The use of a predator or parasite to control a pest species.
• When did Leakey discover "Turkana Boy"?

  1.6 million years ago