5. Which of the following is not a source of genetic variation in sexual reproduction? a. Crossing over of chromosomes b. Random fertilisation c. DNA replication d. Independent Assortment 6. What is the cardiac cycle? a. The amount of blood pumped out in one minute b. The contraction and relaxation of the heart muscle c. The rate at which the heart beats d. The amount of oxygen which is picked up by red blood cells 7. Which of the following statements are not true for alleles a. They are different forms of the same gene b. They will be found in the same place on a chromosome c. They are always dominant d. You have two alleles for each feature one from each parent. 8. What is variation? a) The differences that we see between animals of the same species b) The differences that we see between different species c) The differences that we see between species and within species d) The changes that occur as a result of geographical isolation 9. Sickle cell anaemia is an inherited diseases. The allele responsible for it is a recessive. What would be the chance of the offspring having the disease if 2 carriers (Ss) have children? a. 50% b. 25% c. 20% d. 0%