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What is phototropism?

B5 – Plant development. 5 a day revision. What are auxins and what do they do?. Why might a plant breeder may take many cuttings from a particular plant?. You are provided with several plant shoots and a sample of auxin.

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What is phototropism?

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  1. B5 – Plant development 5 a day revision What are auxins and what do they do? Why might a plant breeder may take many cuttings from a particular plant? You are provided with several plant shoots and a sample of auxin. Describe an experiment that you could carry out to show that auxin causes a shoot to bend. What is phototropism? Describe how to take a cutting. @aegilopoides

  2. B5 – Plant development 5 a day revision Remove part of plant (must contain meristem cells). Dip in rooting powder. Place in water/soil. Auxins are plant hormones that control growth near the tips of shoots and roots. They cause cells to elongate and grow. The plant has desirable characteristics. Paint auxin onto one side of shoot. Place in a dark for a period of time. Until shoot grows/changes direction. Refer to repeats/ control without auxin. A plants response to the direction of light. @aegilopoides

  3. B5 – DNA to protein 5 a day revision Why is a RNA copy of the DNA made before proteins are produced? How does the order of bases in a gene determine which protein is made? DNA is made up of four different bases, A T, C and G. In a DNA sample, 23% of the bases are T. Calculate the percentage of bases that are G. Show your working!! Which DNA bases always pair together? Where in the cell are proteins made? @aegilopoides

  4. B5 – DNA to protein 5 a day revision Each triplet of DNA bases codes for an amino acid. The order of amino acids is different for each protein. DNA is too large to leave the nucleus. A copy of the information is made. If 23% are T then 23% = A A + T = 46% G + C = 54% G = C G = 542 G = 27% A and T G and C In the cytoplasm – by ribosomes. @aegilopoides

  5. B5 - Development 5 a day revision How are embryonic stem cells different to adult cells? In a human embryo, all the cells are unspecialised until what stage? What is a zygote? Explain how animals and plants different in terms of their capacity to grow. What name is given to the parts of plants where mitotically active cells are found? @aegilopoides

  6. B5 - Development 5 a day revision They have the potential to become any type of cell. The cell produced when an egg and sperm fuse together. 8 cell stage At a certain point animals stop growing and only certain cells are capable of dividing to produce new cells. Plants are able to keep growing throughout their entire life. Meristems @aegilopoides

  7. B5 – gene switching and stem cells 5 a day revision Give an example of an application for embryonic stem cells. Why can embryonic stem cells produce any type of cell? Describe how cloning can be used to produce embryonic stem cells. What name is given to the process of stem cells becoming specialised? Myosin is a protein found in muscle cells. Why is it not found in other cell types? @aegilopoides

  8. B5 – gene switching and stem cells 5 a day revision All of the genes are switched on. • Nucleus removed from a human egg cell • Nucleus from a patient's cell put into the egg cell • Egg cell stimulated to develop into an embryo • Stem cells taken from the embryo • Making new brain cells to treat people with Parkinson's disease • Rebuilding bones and cartilage • Repairing damaged immune systems • Making replacement heart valves In other cells the gene for making myosin is switched off. Differentiation @aegilopoides

  9. B5 – cell division 5 a day revision The nucleus of a cell contains 2 pairs of chromosomes. Draw a diagram to show the daughter cells produced after mitosis. Give two differences between mitosis and meiosis. Every nucleus in the body cell of an elephant contains 56 chromosomes. Read the statements about cell division and put a tick in the correct box for each statement. What are the main processes in the cell cycle? Why are gametes produced by meiosis and not by mitosis? @aegilopoides

  10. B5 – cell division 5 a day revision Gametes need to have half the number of chromosomes so that when they combine during fertilisation they have the correct number of chromosomes. • Number of organelles increases. • Chromosomes are copied. • Chromosomes separate. • Cell divides • Mitosis produces 2 daughter cells, meiosis produces 4. • Daughter cells in mitosis are identical, in meiosis they are not. • Meiosis has 2 divisions, mitosis only 1. Every nucleus in the body cell of an elephant contains 56 chromosomes. Read the statements about cell division and put a tick in the correct box for each statement.      @aegilopoides

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