Download Genetics study guide answers

Genetics Study Guide
Name ____________________
1. What factors can affect a person’s height? Genes & the environment
2. Which combination of sex chromosomes results in a male human being? XY
3. Sex-linked genes are genes on _XY____.
4. A carrier is a person who has _one recessive trait and one dominate trait____.
5. Which form of genetic engineering crosses genetically different individuals in an attempt
to keep the best traits of both parents? hybridization
6. How are copies of DNA made? DNA strands unwind and complementary nucleotides are
added
7. A scientist conducts research on a sample of DNA that contains 200 nucleotides. Her
results show that adenine makes up 30% of the sample and cytosine makes up 20% of
the sample. The remaining 50% of the sample is made up of thymine and guanine. What
percent of the nucleotides are thymine? 30%
8. What did Gregor Mendel do to make his experiments accurate? He repeated them
9. Which term refers to physical characteristics that are studied in genetics? traits
10. Factors that control traits are called genes_____.
11. The different forms of a gene are called _alleles____.
12. Which of the following best describes the chromosomes of eukaryotic cells?
a. More-complex eukaryotes have more chromosomes than simpler eukaryotes do
b. Different kinds of eukaryotes have different numbers of chromosomes.
c. The chromosomes in a pair contain very different genetic information.
d. Each of the chromosomes contains one copy of circular DNA.
13. DNA and RNA are _nucleic acids____.
14. DNA is organized in structures. What are these structures called? chromosomes
15. Scientists call an organism that has two different alleles for a trait a _hybrid____.
16. What does the notation TT mean to geneticists? Two dominate alleles
Use the Punnett square below to answer the next question.
R
r
RR
Rr
Rr
??
R
r
17. In some plants, the allele for round seeds (R) is dominant over wrinkled seeds (r). What
genotype will accurately complete the Punnett square above? rr
18. The allele for freckles, F, is dominant among humans. If a woman with freckles (FF) and a
man without freckles (ff) have children, what are the possible genotypes of the children?
Ff
19. Traits such as an individual’s skin, hair, and eye color result from
a. one gene acting alone.
b. one allele from each parent acting together.
c. several genes acting together.
d. one dominant allele.
20. Part of a mouse’s tail is cut off as the mouse escapes from a cat. The mouse later
reproduces. Describe why the mouse’s offspring have long tails? Cutting his tail off
doesn’t change his genes
Use the table below to answer the next question.
Characteristic
Dominant traits
Recessive traits
Ratio
Flower Color
Seed Color
Seed Shape
705 purple
6,002 yellow
5,474 round
224 white
2,001 green
1,850 wrinkled
3.51:1
?
?
21. The table above shows the results of crosses of pea plants. Based on the information in
the table, what is the approximate ratio of yellow seeds to green seeds? 3:1
22. Which pattern shows how bases pair in complementary strands of DNA?
a. A–A and C–C
b. A–G and T–C
c. A–T and C–G
d. A–C and T–G
23. What does the notation tt mean to geneticists? Two recessive alleles
24. What does the notation Tt mean to geneticists? One dominate allele and one recessive
allele
25. What is probability? The likelihood that a particular event will occur
26. What did Mendel predict was the probability of producing a tall plant from a genetic cross
of two hybrid tall plants?
a. 1:4
b. 2:4
c. 3:4
d. 4:4
27. What does a Punnett square show? All the possible outcomes of a genetic cross
28. 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? 100%
29. An organism's physical appearance is its __phenotype___.
30. An organism's genotype is its genetic make-up.
31. What does co-dominance mean in genetics?
a. Both alleles are dominant.
b. Both alleles are recessive.
c. The alleles are neither dominant nor recessive.
d. Each allele is both dominant and recessive.
32. 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
33. Multiple alleles are _____.
a. more than two genes that control a trait
b. three or more forms of a gene that code for a single trait
c. three or more chromosomes that determine a trait
d. more than two co-dominant genes in a chromosome