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Chapter 16 Test

 

1. 

Which term refers to physical characteristics that are studied in genetics?
a. traits   b. offspring   c. generations   d. hybrids
 

2. 

What did Gregor Mendel do to study different characteristics in his genetics experiments?
a. He studied only asexual animals.   b. He studied only self-pollinating plants.   c. He cross-pollinated plants.   d. He cross-pollinated animals.
 

3. 

In Mendel's experiments, what proportion of the plants in the F2 generation had a trait that had been absent in the F1 generation?
a. none   b. one fourth   c. half   d. three fourths
 

4. 

What do scientists today call the factors that control traits?
a. genes   b. purebreds   c. recessives   d. parents
 

5. 

The different forms of a gene are called
a. alleles.   b. factors   c. masks.   d. traits.
 

6. 

Scientists call an organism that has two different alleles for a trait a
a. hybrid.   b. cross.   c. purebred.   d. factor.
 

7. 

What does the notation TT mean to geneticists?
a. two dominant alleles   b. two recessive alleles   c. at least one dominant allele   d. one dominant and one recessive allele
 

8. 

What does the notation tt mean to geneticists?
a. two dominant alleles   b. two recessive alleles   c. at least one dominant allele   d. one dominant and one recessive allele
 

9. 

What does the notation Tt mean to geneticists?
a. two dominant alleles   b. two recessive alleles   c. at least one recessive allele   d. one dominant allele and one recessive allele
 

10. 

Probability is the
a. actual result from a series of events.   b. likelihood that a particular event will occur.   c. way the results of one event affect the next event.   d. number of times a tossed coin lands heads up.
 

11. 

What was the probability of Mendel producing a tall plant from a genetic cross of two hybrid tall plants?
a. one in four   b. two in four   c. three in four   d. four in four
 

12. 

What does a Punnett square show?
a. all the possible outcomes of a genetic cross   b. only the dominant alleles in a genetic cross   c. only the recessive alleles in a genetic cross   d. all of Mendel's discoveries about genetic crosses
 

13. 

If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that an offspring will have black fur?
a. 25 percent   b. 50 percent   c. 75 percent   d. 100 percent
 

14. 

An organism's physical appearance is its
a. genotype.   b. phenotype.   c. codominance.   d. probability.
 

15. 

An organism's genotype is its
a. genetic makeup.   b. feather color.   c. physical appearance.   d. stem height.
 

16. 

An organism that has two identical alleles for a trait is
a. codominant.   b. hybrid.   c. homozygous.   d. heterozygous.
 

17. 

A heterozygous organism has
a. three different alleles for a trait.   b. two identical alleles for a trait.   c. only one allele for a trait.   d. two different alleles for a trait.
 

18. 

What does codominance mean in genetics?
a. Both alleles for a trait are dominant.   b. Both alleles for a trait are recessive.   c. The alleles for a trait are neither dominant nor recessive.   d. Each allele for a trait is both dominant and recessive.
 

19. 

What is the chromosome theory of inheritance?
a. Chromosomes are carried from parents to offspring on hybrids.   b. Genes are carried from parents to offspring on chromosomes.   c. Hybrid pairs of chromosomes combine to form offspring.   d. Codominant genes combine to form new hybrids.
 

20. 

Walter Sutton discovered that the sex cells of grasshoppers have exactly
a. 12 times the number of chromosomes found in the body cells.   b. twice the number of chromosomes found in the body cells.   c. the same number of chromosomes found in the body cells.   d. half the number of chromosomes found in the body cells.
 

21. 

What happens during meiosis?
a. Each sex cell loses half of its chromosomes.   b. Chromosome pairs separate to form new sex cells.   c. Each sex cell copies itself to form four new chromosomes.   d. Chromosome pairs remain together when new sex cells are formed.
 

22. 

When sex cells combine to produce offspring, each sex cell contributes
a. one fourth of the normal number of chromosomes.   b. half the normal number of chromosomes.   c. the normal number of chromosomes.   d. twice the normal number of chromosomes.
 

23. 

The genetic code is the
a. order of nitrogen bases along a gene.   b. number of nitrogen bases in a DNA molecule.   c. order of amino acids in a protein.   d. number of guanine and cytosine bases in a chromosome.
 

24. 

A mutation is any change
a. that is harmful to an organism.   b. in a gene or chromosome.   c. that is helpful to an organism.   d. in the phenotype of a cell.
 

25. 

A mutation is harmful to an organism if it
a. changes the DNA of the organism.   b. changes the phenotype of the organism.   c. reduces the organism's chances for survival and reproduction.   d. makes the organism better able to avoid predators.
 



 
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