DNA: The Code of Life

Transcription

1 DNA: The Code of Life Chapter Test A Multiple Choice Write the letter of the correct answer on the line at the left. 1. Cancer is a disease in which cells a. grow and divide uncontrollably. b. die before they can mature. c. stop producing DNA. d. die during mitosis. 2. Which of these traits is controlled by a gene with multiple alleles? a. straight hairline b. smile dimples c. widow s peak d. blood type 3. Which branch of science includes the study of plants, animals, and the human body? a. earth and space science b. life science c. physical science d. scientific literacy 4. Which of these is an example of the benefits of genetic engineering? a. cross-breeding to create disease-resistant crops b. creating human insulin to treat people with diabetes c. analyzing karyotypes and pedigree charts d. growing a new plant from a cutting 5. The order of the bases along a gene determines the order in which a. sugars are put together to form a carbohydrate. b. phosphates are arranged in DNA. c. amino acids are put together to form a protein. d. chromosomes are arranged in the nucleus. 6. A carrier is a person who has a. one recessive and one dominant allele for a trait. b. two recessive alleles for a trait. c. two dominant alleles for a trait. d. more than two alleles for a trait. 7. During DNA replication, adenine (A) always pairs with a. guanine (G). b. cytosine (C). c. thymine (T). d. adenine (A). 8. Sex-linked genes are genes on a. the X chromosome only. b. the Y chromosome only. c. the X and Y chromosomes. d. all 23 pairs of chromosomes. 1

2 9. What does messenger RNA do during protein synthesis? a. copies the coded message from the DNA and carries it into the cytoplasm b. copies the coded message from the DNA and carries it into the nucleus c. carries amino acids and adds them to the growing protein d. copies the coded message from the protein and carries it into the nucleus 10. How can a mutation affecting skin be harmful to an animal? a. It can make the animal more visible to its prey or predators. b. It can cause disease in the animal. c. It can make the animal resistant to certain diseases. d. It can make the animal resistant to drugs. Completion Fill in the line to complete each statement. 11. Cancer can spread when cells break off a tumor and are carried through the body by the. 12. When many genes control a trait, the trait will show a large number of. 13. A carrier of a trait controlled by a allele does not express the trait. 14. The genetic code is found in the order of nitrogen along a gene. 15. Breeders use a technique called to cross genetically different individuals. True or False If the statement is true, write true. If it is false, change the underlined word or words to make the statement true. 16. A mutation in a sex cell can be passed to offspring. 17. Even if a gene has multiple alleles, a person cannot have more than three of those alleles. 18. Transfer RNA carries coded messages from the nucleus to the cytoplasm. 19. Cancerous cells grow in an abnormal way. 20. Inbreeding decreases the chance of an organism receiving two recessive genes for a genetic disorder. 2

3 Using Science Skills Use the diagram to answer each question. 21. Identify structures B and C. 22. Identify structure D and state where it is made. 23. If one of the nitrogen bases on structure D were replaced by a different base, what effect might that have on protein synthesis? Essay Write an answer for each of the following questions on a separate sheet of paper. 24. Contrast the effects of harmful and helpful mutations. 3

4 25. A person visits a hospital because of a sore arm. Tests show that cancer is present in the arm bone, but that the cancer began in the stomach. Explain why the cancer is called stomach cancer and not bone cancer. Using Science Skills Use the diagram to answer each question. 26. Explain what is happening in Step Explain what is happening in Step 2. 4

5 28. Explain what is happening in Step 3. Essay Write an answer for each of the following questions on a separate sheet of paper. 29. Using the nitrogen bases (adenine, thymine, guanine, and cytosine) in your answer, explain how DNA copies itself. 30. Is it possible for a son to inherit an allele on an X chromosome from his father? Explain why or why not. 5