BIOLOGY TEST |50 QUESTIONS AND ANSWERS

The letters "DNA" stand for... deoxyribose nucleic acid DNA is composed of smaller subunits known as... nucleotides The three parts of a nucleotide are... pentose group, phosphate group, and nitrogen base The four nitrogen bases that are found in DNA are... adenine, guanine, cytosine, and thymine Two of the nitrogen bases are double ring structures known as ____. These two bases are ___ & ____. purines, adenine, guanine The other two bases are single ring structures known as ____. These two bases are ____ & ____. pyrimidines, thymine, cytosine Who are the two scientists that discovered the structure of the DNA molecule? Watson and Crick DNA looks like a ladder twisted into a shape known as a... double helix The two molecules that make up the sides of the ladder or the side portion of a DNA molecule are... phosphate and sugar The molecules that meet across the middle, forming the steps of the "ladder" are known as... nitrogen bases Which nitrogen bases always pair with one another? A&T C&G According to Chargaff's rules, the percentages of ____ are equal to those of thymine and the percentages of ___ are equal to those of guanine in the DNA molecule. adenine and cytosine The nitrogen bases are held together in the center of the molecule by... hydrogen bonds True or False? According to the principle of base pairing, hydrogen bonds could form only between adenine and cytosine. false The type of sugar found in DNA is... deoxyribose If the sequence on the right hand side of the DNA molecule was TAGGCTA, the complimentary side would have a sequence of... ATCCGAG The process in which DNA builds an exact duplicate of itself is known as... replication What is the primary function of DNA? To hold all genetic material that determines which proteins are made. Why is it so important that the DNA molecule be able to make copies of itself? Every cell needs a copy of DNA. During replication, the two nucleotide chains ___ and each chain serves as a ____ for a new nucleotide chain. The sites where DNA replication and separation occur are called ____. separate, template, replication forks During replication, enzymes called ____ untwist the double helix, separating the two parental strands. The point at which the two chains separate is known as the ___. helicase, replication fork Enzymes called ____ move along the separated strands assembling the new chains of DNA. DNA polymerase True or False? The replication of DNA begins at one end of the molecule and proceeds to the other end. False True or False? DNA replication occurs simultaneously at many sites along the molecule speeding up the process of replication. True When replication is complete, two ___ copies of the DNA molecule have been produced and the cell is ready to begin ____. exact, cell division True or False? Each DNA molecule resulting from replication has one original strand and one new strand. True The process of replication is very accurate. There is about ___ error in every _____ bases. A change in the nucleotide sequence is known as a ______. These errors may be caused when enzymes fail to "proofread" properly, or they may be caused by outside sources such as ______. 1, 10,000, mutation, x-rays, UV radiation, chemicals The letters "RNA" stand for... ribonucleic acid