Genetics & Evolution
Name_________________________________________
What is heredity?
Write true if the statement is true. If the statement is false, change the underlined term to make the statement
true.
____________________ 1. Characteristics of an organism are called traits.
____________________ 2. Genetics is the study of heredity.
____________________ 3. The passing of traits from parent to offspring is called sexual reproduction.
____________________ 4. Traits that are passed from parents to their offspring are called acquired traits.
____________________ 5. Eye color is an example of an inherited trait.
____________________ 6. The first person to study heredity was Gregor Monk.
____________________ 7. During heredity, male and female sex cells join together.
____________________ 8. Mendel is often called the father of genetics.
What are chromosomes?
Circle the term that makes each statement true.
9. Heredity is controlled by (chromosomes / traits).
10. Chromosomes are located in the (ribosomes / nucleus) of a cell.
11. The parts of a chromosome that control inherited traits are (genes / daughter cells).
12. Eye color and hair color are determined by (genes / sex cells).
13. Humans have (46 / 23) chromosomes in each body cell.
14. Chromosomes are composed of a material called (DNA / karyotype).
15. (Alleles / Chromosomes) are different versions of the same gene.
Why can offspring differ from their parents?
PART A Match each term in Column B with its description in Column A. Write
the correct letter in the space provided.
Column A
__________ 16. stronger gene whose trait always shows itself
__________ 17. having two unlike genes for the same trait
__________ 18. having two like genes for the same trait
__________ 19. gene of a trait that is hidden when the dominant gene is present
Column B
a. homozygous
b. recessive gene
c. heterozygous
d. dominant gene
PART B Complete the following.
20. In a heterozygous organism, one gene shows itself while the other gene is _______________________ .
21. In pea plants, the gene for tallness is ______________ , while the gene for shortness is ______________.
22. A homozygous pea plant that is short contains two genes that are _______________________________ .
23. A heterozygous pea plant will have one gene for tallness and a second gene for __________________ .
Use the diagrams to answer the following.
24. Which of the diagrams shows a pea plant that you know is homozygous? Explain.
____________________________________________________________________________________________
____________________________________________________________________________________________
25. Is it possible to tell if the tall pea plant is a homozygous plant or a heterozygous plant just by looking at the plant?
Explain.___________________________________________________________________________________________
_________________________________________________________________________________________________
How do genes combine in offspring?
PART A Answer the following.
26. How is a dominant trait represented in a punnett square? _______________________________________
27. How is a recessive trait shown in a punnett square?___________________________________________
28. What is a Punnett square used for? ________________________________________________________
PART B Complete the Punnett square below.
29. What percentage of offspring would have black hair? ________
BbxBb
B = brown hair
b = black hair
Complete the Punnett square. Then, answer the questions below.
Tt xTt
T = tall
t = short
30. Are the parents in this cross homozygous for tallness or are they heterozygous? _____________________
31. Which letters in the diagram represent an offspring that is pure dominant?___________________________
32. Which letters in the diagram represent an organism that is pure recessive? _________________________
33. Which letters in the diagram represent a heterozygous dominant organism?_________________________
34.a. What percentage of the offspring produced by this cross will be homozygous recessive? _____________
b. Homozygous dominant? ________________________________________________________________
c. Heterozygous dominant? _______________________________________________________________
What are incomplete dominance and codominance?
Complete the following.
35. What is incomplete dominance?
________________________________________________________________________________________
________________________________________________________________________________________
36. What is codominance?
________________________________________________________________________________________
________________________________________________________________________________________
37. a. Complete the Punnett square.
BWxBW
B = black feathers
W = white feathers
BW = mix of black and white feathers
b. Are the parents in this cross homozygous or heterozygous? ______________________________________
c. What color are the parents? _______________________________________________________________
d. What are the chances that an offspring will be heterozygous? _____________________________________
e. What percentage of offspring will be white? _________ black?_________ Mix of black and white________?
What are sex-linked traits?
Write the term that best completes each statement in the space provided.
38. Traits that are controlled by the sex chromosomes are called _______________________________ traits.
39. Sex-linked traits are controlled by the X and Y ________________________________________________.
40. A sex-linked disorder that results in improper blood clotting is _________________________________.
41. A sex-linked disorder in which a person cannot see the difference between certain colors is __________________.
42. Sex-linked disorders most often occur in _____________________________________________________.
43. Women who have a normal gene and a gene for a sex-linked disorder are called __________________.
44. If an egg containing the X chromosome that carries a sex-linked disorder is fertilized by a sperm with a Y
chromosome, the son will _____________________________________________ the sex-linked disorder.
How is gender determined?
Write true if the statement is true. If the statement is false, change the underlined term to make the statement
true.
__________________ 45. A child with XX chromosomes will be male.
__________________ 46. The gender of an offspring is controlled by the X and Y chromosomes.
__________________ 45. During mitosis, each gamete(egg or sperm) cell receives only one chromosome from each pair.
__________________ 48. Female egg cells have an XY pair of chromosomes.
__________________49. Only egg cells can contain a Y chromosome.
__________________50. The gender of all children is determined by their fathers.
__________________51. Egg cells can contain an X or a Y chromosome .
__________________52. All human traits are determined by 24 pairs of chromosomes.
__________________53. During mitosis, each egg cell receives one chromosome from each pair of chromosomes.
__________________54. Each new offspring has a 25 percent chance of being a girl.
__________________55. Gender is determined by the twenty-third pair of chromosomes.
__________________56. A fertilized egg cell carrying two X chromosomes will develop into a male.
How is genetics used to improve living things?
PART A Match each term in Column B with its description in Column A. Write the correct letter in the space
provided.
Column A
Column B
_________ 57. mating closely related organisms
a. cloning
_________ 58. mating two different kinds of organisms
b. hybridization
_________ 59. making a new organism with the exact same DNA.
c. inbreeding
_________ 60. process used by plant growers that crosses plants with desirable traits
d. selective breeding
What is evolution?
Write true if the statement is true. If the statement is false, change the underlined
term to make the statement true.
____________________61. Many scientists believe that new species develop from older species as a result of adaptation.
____________________62. A change in a gene is called a mutation.
____________________63. A trait of an organism that helps it survive in its environment is called an evolution.
____________________64. The process by which organisms change throughout time is called evolution.
____________________65. A group of organisms that look alike and can reproduce among themselves are a species.
____________________66. If a mutation is helpful to an organism, it may die out before passing the trait on.
What are fossils?
Write the term that best completes each sentence in the space provided.
67. Species of organisms that are no longer found living are said to be____________________________________ .
68. The remains or traces of once-living organisms are called___________________________________________ .
69. Most fossils are found in layers of ___________________________________________ rock.
70. The deeper a fossil is found in the earth, the ____________________________ it is.
71. Scientists compare the age of one fossil to another in the process of ___________________________ dating.
72. Fossils provide a ______________________ of life on earth .
73. Fossils are evidence that the process of _____________________ has occurred
What evidence supports evolution?
The main ideas of Darwin’s theory of natural selection are listed below.
Explain what is meant by each of these ideas.
Use the peppered moth example in your answers.
74. Overproduction: ________________________________________________________________________________
75. Struggle for Existence: ___________________________________________________________________________
76. Variation: _____________________________________________________________________________________
77. Survival of the Fittest: ___________________________________________________________________________
78. Evolution of New Species: ________________________________________________________________________