B1.7.2 Reproduction

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  1. What are the 2 basic ways that organisms can reproduce?
    Sexual reproduction and asexual reproduction
  2. What is sexual reproduction?
    It's where genetic information from 2 organisms (a father and a mother) is combined to produce offspring which are genetically different to either parent
  3. In sexual reproduction, the mother and father produce...
    Gametes (e.g. egg/sperm)
  4. Gamete+gamete=?
  5. How many chromosomes do gametes contain?
    23 chromosomes - half the number of chromosomes in a normal cell
  6. Do gametes have pairs of chromosomes?
    No, instead of having 2 of each pair of chromosome, they have just 1 each
  7. How do gametes produce the full number of chromosomes?
    By fusing together (fertilisation) to form a cell with the full number of chromosomes (50% from each parent)
  8. What does sexual reproduction involve in terms of gametes?
    It involves the fusion of male and female gamete. As there are 2 parents, the offspring contain a mixture of their parents' genes
  9. The mixture of genetic material produces......in the offspring
  10. What does asexual reproduction produce?
    Genetically identical cells
  11. What is asexual reproduction?
    When an ordinary cell makes a new cell by dividing in 2. The new cell has exactly the same genetic information (genes) at the parent cell
  12. In asexual reproduction, there is......parent
  13. Is there fusion of gametes in asexual reproduction
  14. Is there any genetic variation in asexual reproduction?
  15. The offspring are genetically identical to their parents in asexual reproduction. They could also be called...
  16. X shaped chromosomes have...
    2 identical halves
  17. How does asexual reproduction work?
    The X-shaped chromosomes have 2 halves. Each chromosome splits down the middle to form 2 identical sets of chromosomes of 'half chromosomes' (2 sets of DNA strands) A membrane forms around each set and the DNA replicates itself to form 2 identical cells with complete sets of X-shaped chromosomes. This is how all plants and animals grow and produce replacement cellsĀ 
  18. A similar way to how asexual reproduction works, all animals and plants...
    Grow and produce replacement cells
  19. Name 2 organisms that reproduce by asexual reproduction
  20. What can an amateur gardener do, to produce genetically identical copies of another plant?
    They can take cuttings from the parent plant, then put the cuttings in moist conditions until they are ready to plant
  21. What is good about gardeners taking cutting off plants to clone them?
    It's cheap and the plants can be produced quickly
  22. How do you clone a plant through tissue culture?
    A few plant cells are put in a growth medium with hormones, and they grow into new plants - clones of the parent plantĀ 
  23. What is good about cloning a plant through tissue culture?
    The plants can be made very quickly, in very little space and be grown all year
  24. What does the process of embryo transplanting involve and why would a farmer want to do it?
    A farmer would want to do it to produce cloned offspring from their best bull/cow. They can do this bt taking the sperm cells from their prize bull and egg cells from their prize cow, which are then used to artifically fertilise an egg cell. The embryo that develops is then split many times (to form clones) before any cells are specialised. These cloned embryos are then implanted into lots of other cows where they grow baby calves (which are genetically identical to each other)
  25. What is good about embryo transplanting?
    Hundreds of 'ideal' offspring can be produced every year from the best bull/cow
  26. What does adult cell cloning involve?
    It involves taking an unfertilised egg cell and removing its genetic material (the nucleus) and then inserting a complete set of chromosomes from an adult body cell (e.g. skin cell) into the 'empty' egg cell. The egg cell is then stimulated by electric shock - this makes it divide, just like a normal embryo. When the embryo is a ball of cells, it's implanted into an adult female to grow into a genetically identical copy of the original adult body cell (clone)
  27. What technique was used to create Dolly?
    Adult cell cloning
  28. What does a reduced gene pool mean?
    It means that there are fewer different alleles in a population
  29. What are the 4 main disadvantages of adult cell animal cloning?
    • Reduced gene pool
    • If a population is closely related, a new disease could wipe them all out - they may be no allele in population resistant to that disease
    • It's possible that cloned animals might not be as healthy as normal
    • Human may be cloned in the future - if this was allowed, any success may follow many unsuccessful attempts (e.g. children being born disabled)
  30. What are the 3 main advantages of adult cell cloning?
    • Cloning could be used to preserve endangered species
    • Cloning gets you lots of 'ideal' offspring
    • The study of animal clones could lead to greater understanding of the development of the embryo, and of ageing and age-related disorder
  31. What is the basic idea behind genetic engineering?
    The basic idea is to copy a useful gene from 1 organism's chromosomes into the cells of another
  32. What does genetic engineering involve?
    It involves a useful gene being 'cut' from 1 organism's chromosomes using enzymes. Enzymes are then used to cut another organism's chromosome and then to insert the useful gene
  33. What can scientists use genetic engineering for?
    They can use for many things such as - the human insulin gene can be inserted into bacteria to produce human insulin which can be used by people with diabetes
  34. What does GM crops stand for?
    Genetically modified crops
  35. When can genetic engineering be used to transfer useful genes into animals anf plants?
    At the early stages of their development (shortly after fertilisation)
  36. What are GM crops?
    They are crops that have had their genes modified (e.g. to make them resistant to viruses, insects or herbicides)
  37. How have sheep been genetically engineered?
    They have been genetically engineered to produce substances, like drugs, in their milk that can be used to treat human diseases
  38. What are scientists trying to do, to fix genetic disorders such as cystic fibrosis?
    They are trying to treat these disorders by inserting working genes into sufferers - this is called gene therapy
  39. What is an advantage of GE?
    GE is an exciting new area of science which has the potential to solve many problems such as treating disease, more efficent food production etc
  40. What is a disadvantage of GE?
    GE could result in long term health effects as it could change someones genes accidently creating unplanned problems, which could get passed on to future generations
  41. What are the 3 pros of GM crops?
    • GM crops increase the yield of a crop, making more food
    • People who live in developing nations often lack nutrients in their diets and so GM crops could be engineered to contrain the nutrient that's missing
    • GM crops are already grown elsewhere in the world, often without any problems
  42. What are the 3 cons of GM crops?
    • Some say that growing them will affect the number of weeds and flowers (and so population of insects) that live in and around crops - reducing farmland biodiversity
    • Not everyone is convinced that GM crops are safe. People are worried they may develop allergies to food
    • Transplanted genes may get out into the environment. (E.g. the herbicide resistance gene may be picked up by weeds, creating a new 'superweed' variety
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B1.7.2 Reproduction
2012-11-19 20:32:09
GCSE Biology B1 Reproduction

Covers reproduction topic in Biology GCSE
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