Biology Year End Review

KEY Science 10 - Year End Review Instructions – proper review for previously covered material is always best undertaken by FIRST reading through the units notes to reactivate memories and remind you of information covered. The following questions should be completed on a separate sheet of paper. Biology 1.) What does DNA stand for? Deoxyribonucleic acid 2.) What purpose does DNA exist for? That is, what is DNA for? DNA is a unique language (or code) used by living organisms to copy or repair their parts. 3.) What are the three main components of DNA? DNA is composed of sugar and phosphate as the backbone, nitrogen bases as the "rungs", and a double helix twist to decrease the space used up by the DNA. 4.) List the 4 bases and which attaches to which? Adenine and Thymine, Cytosine, and Guanine 5.) Draw and label a DNA molecule. Be detailed. 6.) What is the relationship between a trait, a gene, and a chromosome? Genes code for traits, and are found in DNA which is stored as Chromosomes in the nucleus of cells. 7.) Circle the choices that are examples of each of those words. a.) Homozygous dominant AA Gg KK mm uu Rr TT b.) Homozygous recessive ee Ff HH Oo qq Uu ww 8.) a.) What is a mutation? A mutation is a change in the nitrogen bases of DNA that may or may not cause a change to the protein that gene codes for. KEY b.) List the 3 types of mutations. Deletion = one or more bases are deleted causing a change in the codon (three nitrogen bases sequence). Insertion = one or more bases is inserted causing a change in the codon. Substitution = one or more different bases are put into place of other bases causing codon changes. c.) Describe the 3 potential outcomes of mutations. See above. 9.) In corn plants, normal height, N, is dominant to short height, n. Complete these four Punnett squares showing different crosses. Then, circle all of the homozygous dominant offspring. Put an X through all the heterozygous offspring. Leave all the homozygous recessive offspring unshaded. Nn Nn NN Nn NN Nn Nn nn Nn Nn NN Nn Nn nn Nn nn 10.) In humans, being a tongue roller (R) is dominant over non-roller (r). A man who is a non-roller marries a woman who is heterozygous for tongue rolling. r r Father’s phenotype __non-roller__ Mother’s phenotype __roller__ R Rr Rr Father’s genotype __rr__ Mother’s genotype __Rr__ r rr rr What is the probability of this couple having a child who is a tongue roller? ___50%___ 11.) Sickle Cell Anemia is condition that shows codominance. The genotype for normal blood cells is NN. Sickle cell trait is the heterozygous condition (NS) and contains both normal and sickle shaped blood cells. Sickle cell disease (SS) is when all of the blood cells are sickle-shaped and has lifelong medical implications. A man with sickle cell trait has a child with a woman with sickle cell trait. i. Complete the Punnett Square. ii. What is the probability of having a child with sickle cell trait? N S NN NS NS SS N 50% iii. What is the probability of having a normal offspring? 25% S iv. What is the probability of having a child with sickle cell disease? 25% KEY 12.) The Johnsons are married and their first child has just been born. Erin had a perfectly normal pregnancy and continued working until one week before the child's birth. Joseph and Erin's son appears perfectly normal at birth. It is quite a shock when the doctor calls them a few days after they take him home to come back in for a few more tests of their son. The doctor asks that both attend, as he would like to talk to both of them. In his office, the doctor lets them know that a blood test was done on their son, as required by law. The blood test revealed their son may have a rare disease called Phenylketonurea (PKU). However, more tests are needed to confirm the diagnosis. The Johnsons are told not to worry as a treatment exists for the condition. But neither Joseph or Erin have ever heard of the condition nor has anyone in their family. a.) If all newborns are going to be screened, should parents have the chance to refuse? Why or why not? b.) Why might someone not want their child screened? c.) Should screening for diseases or defects be allowed, if no treatment or cure exists? Why or why not.