1. A group of DNA nucleotides that codes for a single amino acid is a: · promote

Question

1. A group of DNA nucleotides that codes for a single amino acid is a:

·       promoter

·       gene

·       codon

2. Unlike what Mendel observed in his pea plants, which were either tall or short, human height varies gradually over a range. Why is this so?

·       the gene controlling height displays incomplete dominance

·       the gene controlling height is codominant

·       multple genes contribute to human height

3. A testcross is a mating of an individual with an unknown genotype and an individual that

·       is heterozygous

·         is homozygous recessive

·       is homozygous dominant

4. What is meant by a “DNA fingerprint?” How is it useful in forensics?

·       fingerprints contain DNA

·       every individual's DNA is different, analogous to fingerprints

·       every individual's DNA is alike, so forensics resort to fingerprints

5. What is incomplete dominance? What is codominance?

·       the phenotype is a blend of parental traits; both parental traits appear

·       in both cases the phenotype changes during development

·       some offspring show the dominant trait and some show the recessive trait

6. What is a codon?

·       the instructions to begin the cell cycle

·       individual nucleotides

·       the unit of 3 nucleotides that codes for an amino acid

7. How do cells permanently turn off genes they will no longer use as they differentiate?

·       such genes are destroyed

·       such genes are wrapped in histones so that they cannot be transcribed

·       such genes are wrapped in histones so that they not be duplicated

8. An individual’s mother has blond hair and blue eyes. That individual’s father has brown hair and brown eyes. The individual, however, has brown hair and blue eyes. How did that individual inherit a “mixture” of traits rather than either maternal (blonde hair and blue eyes) OR paternal (brown hair and brown eyes) traits?

·       maternal and paternal chromosomes sort independently

·       maternal chromosomes and paternal chromosomes remain together

·       one of the gametes was missing a chromosome

9. What do dominant and recessive refer to with regard to alleles?

·       dominant and recessive blend

·       dominant will mask recessive

·       dominant appears faster than recessive

10. What is the difference between genotype and phenotype?

·       genotype is what is seen; phenotype refers to alleles

·       genotype refers to alleles; phenotype is what is seen

·       genotype is dominant; phenotype is recessive

11. How do hormones signal cells throughout the body?

·       they are carried throughout the body by transfer RNA

·       they are secreted into the blood stream

·       they are secreted into the digestive system

12. Why can translocation of a portion of one chromosome onto another result in mutation even though there is no net loss of DNA?

·       translocation can make a chromosome too long to be utilized

·       each chromosome utilizes a different coding system

·       regulation of the translocated genes is often disrupted

13. What is Preimplantation Genetic Diagnosis? What is the methodology utilized to detect a genetic abnormality?

·       examination of an early stage embryo during IVF; DNA matching all normal human sequences is used

·       examination of an early stage embryo during IVF; DNA matching a human disease sequence is used

·       examination of sperm and eggs before IVF; DNA matching a human disease sequence is used

14. How can a genetic disorder be dominant even if the deleterious sequence is only inherited from one parent, and there is still another normal allele?

·       alleles coding for a dominant disorder stop functioning

·       alleles coding for dominant disorders turn off the other allele

·       alleles coding for dominant disorders provide a gain of function

15. Which occurs in meiosis but not in mitosis?

·       cytokinesis

·       crossing over

·       DNA replication

·       chromosome condensation

16. Exchange of genetic information between homologous chromosomes is:

·       random fertilization

·       crossing over

·       independent assortment

·       All of these are correct

17. When a pedigree is constructed, autosomal recessive disorders typically

·       appear only in males

·       appear only in females

·       seem to disappear in one generation, only to reappear in the next generation

·       appear in every generation

18. Sex of a child is determined by the

·         sex chromosome in the egg

·       autosomes in the sperm

·       sex chromosome in the sperm

·       autosomes in the egg

19. Why does the frequency of children born with Down’s syndrome increase with the age of the mother? Why does it not increase similarly with the age of the father?

·       the gene conferring Down's syndrome is located on the Y chromosome

·       the gene conferring Down's syndrome is located on the X chromosome

·       eggs are set aside before birth and therefore have aged; sperm are made continuously

20. What is a key difference between reproductive and therapeutic cloning?

·       reproductive cloning makes replacement cells and tissues; therapeutic cloning makes a new individual

·       reproductive cloing makes reproducible stem cells; therapeutic cloning repairs damaged stem cells

·       reproductive cloning makes a new individual; therapeutic cloning makes replacement cells and tissues

21. Why are autosomal genetic disorders usually recessive?

·       we carry only one copy of each autosomal allele

·       we carry two copies of each autosomal allele

·       the defective allele is not transcribed

22. Condensed DNA and associated proteins form a

·       ribosome

·       Golgi body

·       chromosome

Explanation / Answer

1.   codon

explanation: Three nucleotides encode an amino acid. Proteins are built from a basic set of 20 amino acids, but there are only four bases. Simple calculations show that a minimum of three bases is required to encode at least 20 amino acids. Genetic experiments showed that an amino acid is in fact encoded by a group of three bases, or codon.

2. multple genes contribute to human height

3.  is homozygous recessive

4. every individual's DNA is different, analogous to fingerprints

5. some offspring show the dominant trait and some show the recessive trait

6. the unit of 3 nucleotides that codes for an amino acid

7. such genes are wrapped in histones so that they cannot be transcribed

8. maternal and paternal chromosomes sort independently

9. dominant appears faster than recessive

10. genotype refers to alleles; phenotype is what is seen

11. they are secreted into the blood stream

12. translocation can make a chromosome too long to be utilized

13. examination of sperm and eggs before IVF; DNA matching a human disease sequence is used

14.   alleles coding for dominant disorders provide a gain of function

15. crossing over

16. crossing over

17. seem to disappear in one generation, only to reappear in the next generation

18. sex chromosome in the egg

19. eggs are set aside before birth and therefore have aged; sperm are made continuously

20. reproductive cloning makes a new individual; therapeutic cloning makes replacement cells and tissues

21. we carry only one copy of each autosomal allele

22. chromosome

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