Question

21.       Which of the following terms refers to RNA only?

a.         Double helix

b.         Thymine

c.         Uracil

d.         Cytosine

e.         Guanine

22.       Codons are located on:

a.         Ribosomes                  d.         rRNA

b.         tRNA                           e.         DNA

c.         mRNA

23.       EcoR1 and HindIII are two different restriction enzymes. If the DNAs of different organisms are cut as described below, which DNAs could NOT join together and be permanently sealed?

a.      Human DNA cut with EcoR1/ chimp DNA cut with EcoR1

b.      Prokaryotic DNA cut with HindIII/ eukaryotic DNA cut with HindIII

c.      Mouse liver DNA cut with EcoR1/ mouse kidney DNA cut with EcoR1

d.      Mouse DNA cut with HindIII/ chimp DNA cut with HindIII

e.      Bacterial DNA cut with EcoR1/ mouse DNA cut with HindIII

24.                   Organism                    Diploid Chromosome number

Crab                                        236

Human                                    46

Spider Lily                              46

Pea                                          14

Yeast   (fungus)                       12

The chromosome counts above support the idea that:

a.                     the more chromosomes a species has, the more complex it is.

b.                    the fewer chromosomes a species has, the more ancient its evolutionary history.

c.                     all species have a unique chromosome number common only to them.

d.                     species may differ from each other in chromosome number.

                      

27. Roundup-Ready ™ Soybeans are:

       a.    easier to harvest than other varieties.

       b.    resistant to insect attack.

       c.    higher in nutrition than other varieties.

       d.    resistant to a specific herbicide.

                                   e.         not usable in food products

28        Which of the following organisms has the most chromosomes (DNA?)

            a.         a fruit fly

            b.         a human

            c.         a dog

            d.         a grass plant

            e.         you cannot tell without looking at cells.

                       29.       One species’ DNA differs from others in its _____.

            a          sugars

            b          phosphates

            c          base sequences

            d          all of the above

                       30.       What are the base-pairing rules for DNA?

            a          A-G, T-C

            b          A-C, T-G

            c          A-U, C-G

            d          A-T, G-C

            e          either c or d

Answer 1

21. c. uracil. Uracil is not present in DNA as nitrogenous base while it is present in RNA. Thymine is usually not found in RNA. Double helix is not present in RNA. Although cytosine and guanine are present in RNA, they are also present in DNA.

22. c. mRNA. Codon is a triplet of nucleotides which codes code for a particular amino acid. mRNA has has coding sequence which is translated to synthesize protein on ribosomes with the help of tRNA.

23. e. Bacterial DNA cut with EcoR1/ mouse DNA cut with HindIII. Restriction endonucleases are universal so irrespective of source of DNA they generate same sticky ends after cleavage.If two DNA strands are cleaved with same enzyme and produces sticky ends then both the DNA can be joined. If two different restriction enzymes are used they will not form complementary sticky ends, so hey will not join.

24. d. species may differ from each other in chromosome number.

27. d. resistant to a specific herbicide.

28. d. a grass plant.

29. c base sequences.

30. d A-T, G-C.