5 a day revision B5 – Plant development Describe how to take a cutting. What are auxins and what do they do? What is phototropism? 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. @aegilopoides

5 a day revision B5 – Plant development A plants response to the direction of light. 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. @aegilopoides

5 a day revision B5 – DNA to protein Where in the cell are proteins made? How does the order of bases in a gene determine which protein is made? Which DNA bases always pair together? Why is a RNA copy of the DNA made before proteins are produced? 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!! @aegilopoides

In the cytoplasm – by ribosomes. B5 – DNA to protein 5 a day revision In the cytoplasm – by ribosomes. A and T G and C 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% @aegilopoides

5 a day revision B5 - Development What name is given to the parts of plants where mitotically active cells are found? 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. @aegilopoides

5 a day revision B5 - Development Meristems They have the potential to become any type of cell. 8 cell stage The cell produced when an egg and sperm fuse together. 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. @aegilopoides

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

5 a day revision B5 – gene switching and stem cells Differentiation In other cells the gene for making myosin is switched off. All of the genes are switched on. Differentiation 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 @aegilopoides

5 a day revision B5 – cell division Why are gametes produced by meiosis and not by mitosis? The nucleus of a cell contains 2 pairs of chromosomes. Draw a diagram to show the daughter cells produced after mitosis. What are the main processes in the cell cycle? 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. @aegilopoides

5 a day revision B5 – cell division 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