20   8 Cells can be classified as either prokaryotic or eukaryotic. (a) Which row identifies the type of DNA found in prokaryotic cells? (1) A B C D Plasmid DNA is Chromosomal DNA is double‑stranded double‑stranded double‑stranded single‑stranded single‑stranded double‑stranded single‑stranded single‑stranded (b) Eukaryotic cells contain a range of membrane‑bound organelles including the Golgi apparatus and the rough endoplasmic reticulum (rER). (i) Name two other organelles that are bound by a single membrane. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... Turn over 21   (ii) The table shows the percentage of cell membranes that make up Golgi apparatus and rER in the cells from two organs. Organ Percentage of cell membranes (%) Golgi apparatus rER Liver 7 35 Pancreas 10 60 Explain the differences in the percentage of membranes that comprise the two organelles in these cells. (5) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 22   (c) In one study, measurements were taken of a single Golgi apparatus. The measurements were: • total number of cisternae = 6 • height of each cisterna = 15 nm • distance between adjacent cisterna = 25 nm Calculate the total height of the stack of cisternae in this Golgi apparatus. Give your answer in micrometres. (2) .............................................................. μm (d) Beetroot cells contain the pigment betalain. When beetroot cells are placed in alcohol, the concentration of betalain in the cells changes. Explain why alcohol affects the concentration of betalain in these cells. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 8 = 12 marks) Turn over 23   9 The inheritance of coat colour in mice has been investigated. Some scientists crossed mice that had yellow coats. The offspring had either yellow coats or non‑yellow coats. (a) (i) Explain how the scientists knew which allele for coat colour was recessive. (2) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (ii) The crosses led to a total of 1599 offspring being produced. Predict the number of yellow and non‑yellow offspring produced. (2) Offspring with a yellow coat Offspring with a non‑yellow coat 24   (iii) The table shows the actual number of offspring with each coat colour. Offspring with a yellow coat Offspring with a non‑yellow coat 1064 535 Explain why there are differences between the predicted and actual numbers of these mice. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... Turn over 25   *(b) There is a gene in humans similar to the mouse coat colour gene. This human gene comprises 74 775 base pairs. The mRNA produced from this gene codes for a protein made up of 132 amino acids. Explain the differences in the gene coding for this protein and the mRNA produced from it. (6) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 9 = 13 marks)