Question

19. If an organism's DNA contains 20% adenine nucleotides, what percentage of its DNA is composed of thymine nucleotides?

20. Explain how two gene loci on the same chromosome affect gene linkage.

21. What is inaccurate or misleading about the following statement: individuals adapt to their environment and pass the adaptation to their offspring?

22. Your nerve cells and skin cells contain the same genes. Explain why these cells are different.

23. Explain why sex-linked disorders on the X chromosome are more common in males than females.

Answer 1

Question 19

Answer: In DNA molecules, adenine always pairs with thymine. The number of adenine nucleotides in the DNA molecule is equal to the number of thymine nucleotides (A =T). So, if an organism's DNA contains 20% adenine nucleotides, it will 20 % thymine nucleotides.

Question 20

Answer: Genetic linkage is defined as the tendency of genes sequence to be inherited together during meiosis, when they are present close to each other on the same chromosome. If two gene loci are closely located on the same chromosome, they are inherited together during meiosis and the genes are called as linked genes. If two gene loci are present far from each other on the same chromosomes, they are not inherited together during meiosis due to crossing over between homologous chromosomes. These genes are called as unlinked genes.