Page 10 16. Triticale is a hybrid cereal species which was produced by crossing Triticum durum (a species of wheat) with Secale cereale (a species of rye) as shown in the diagram. F1 hybrid (sterile) Triticale 2n = 42 Chromosome number artificially induced to double Secale cereale Triticum durum 2n = 28 × What was the diploid (2n) number of chromosomes in Secale cereale? A 7 B 14 C 21 D 28 17. The following statements describe symbiotic relationships between organisms. 1 Mistletoe plants absorb nutrients from apple trees on which they grow. 2 Egyptian Plover birds clean the teeth of Nile crocodiles and feed on the debris they remove. 3 Tapeworms live in the small intestine of pigs and absorb some of their nutrients. Which of these relationships can be described as parasitic? A 2 only B 3 only C 1 and 2 only D 1 and 3 only