Study Guide – Answer Key
Chapter 5 (Section 3) and Chapter 6
1. There are two types of reproduction, what are they? Asexual & Sexual
2. There are two major differences between asexual and sexual reproduction. What are
the differences? Asexual has one parent and identical traits as the parents. Sexual has
two parents and a combination of traits from the two parents.
3. Most of the cells in your body reproduce by a process called Mitosis.
4. What are the parent cells in sexual reproduction called? Sex cells – sperm & egg
5. Two chromosomes that carry the exact same gene sequence and have the same
structure are called Homologous Chromosomes
6. What process produces sex cells? Meiosis
7. How many cells are produced at the end of meiosis? Four Each of the cells produced
have half the number of chromosomes.
8. What term describes the half-number of chromosomes in the four sex cells produced
through meiosis. Haploid cells
9. What term describes the full set of chromosomes in body cells produced by mitosis?
Diploid cells
10. If a parent cell has 36 chromosomes, what will the process of meiosis produce?
A: A total of 4 sex cells will be produced. If the organism is male, the cells will be
sperm. If the organism is female, the cells will be eggs. Each of the sex cells produced
will contain 18 chromosomes.
11. A parent cell has 16 pair of chromosomes. How many chromosomes will his sperm have?
16
12. Where are genes found/located? On the chromosome
13. Who determines the sex of a child? And how is the sex of a child determined? The
father determines the sex of a child because he carries both an X and a Y chromosome. The
mother only carries X chromosomes. If the sperm that fertilizes an egg contains an X allele, it
will be a girl (XX). If the sperm that fertilizes an egg contains a Y allele, it will be a boy (XY).
14. Which 2 chromosomes do females carry that determine their gender? XX
15. Which 2 chromosomes do males carry that determine their gender? XY
16. Some diseases attach to the X chromosome of the female. What are these diseases
called? Sex linked genetic disorders
17. Why does colorblindness (a sex-linked disorder) occur more often in males? It is a
recessive trait so it usually is only passed on to a male child because they only have one X
chromosome, but females have a “backup” X chromosome.
18. Draw the symbol(s) for the following parts of a pedigree (assume you are tracking a
recessive trait):
 Male

Female

Male and Female: Has no signs of the trait because it carries two dominant alleles

Male and Female: Carries the trait but does not have it

Male and Female: Has the trait because it carries two recessive alleles

Couples

Children - (brothers and sisters)

Different generations – numbers to the left of the pedigree
19. What is the purpose of a pedigree? A tool used to detect traits that are passed down
through generations
20. Read the following scenario:
A dairy farmer collects data on his herd of cows for how much milk each produces.
Two cows in particular produce large quantities of milk. The farmer breeds these two
cows with his bull in order to have offspring that will produce large amounts of milk.
What is this an example of? Selective Breeding
21. Put these words in order of size (small to large): nucleus, chromosome, cell, and gene.
Gene, Chromosome, Nucleus, Cell
22. How are sex cells different from body cells? Sex cells have ½ the # of chromosomes
23. If a scientist is looking to choose a specific mate for an organism to produce a
desirable trait, what is this process called? Selective breeding
24. If you were the carrier of a genetic disease, how could genetic counseling help you
prepare for the future? Genetic counseling could help to prepare the family for problems
associated with the disease, allow parents to make decisions in regards to having children
(have children naturally or adopt), seek proper medical attention to prevent early onset of the
disease, learn how to best live with the disease.
25. If a mouse’s tail is cut off as it escapes from a cat (causing the mouse to be shorttailed), would the offspring’s tail be short also? Explain your answer. The offspring would
have a normal tail because having a tail cut off does not change the genetic makeup of the
rat, and the tail length is determined by genes.
26. Where are chromosomes located in the cell? In the nucleus.
27. What are chromosomes made of? Microscopic threadlike strands of DNA
28. What does DNA stand for? Deoxyribonucleic Acid
29. What is the basic function of the DNA? To control the production of proteins within the
cell
30. What is the relationship of a gene and DNA? A gene is a segment of DNA that codes for
a particular protein & trait.
31. What scientist(s) found the structure for DNA? James Watson & Francis Crick
32. Name the two (2) scientists who paved the way for Watson and Cricks’s
model.Chargaff (Chargaff’s rule – A = T, C = G) and Franklin (used x-ray diffraction to take
a picture of DNA)
33. What does DNA look like? Long twisted ladder/Double Helix
34. What is a nucleotide made up of? A sugar, a phosphate, one of four bases (A, C, G, or T)
35. Each part of the ladder of DNA is made up of a different chemical. Tell the chemical
for each of the parts of the ladder:
 The sides of the ladder – sugar (deoxyribose) & phosphates
 Rungs of the ladder – adenine, thymine, guanine, cytosine
 Connectors – hydrogen bonds
36. What is the “Base-Pair Rule?” A only pairs with T; C only pairs with G
37. What holds together the two sides of the DNA ladder? Hydrogen Bonds
38. Where are proteins made? In Ribosomes
39. What chemical is needed to read the code of the DNA and tell the ribosomes what
proteins to make? Messenger RNA (mRNA)
40. Why is messenger RNA needed in a cell? mRNA is needed to carry messages through the
nuclear membrane pores to the ribosomes about what proteins to make from the DNA
because DNA is too big to fit through the pores of the nucleus.
41. DNA is referred to as the “blueprint” of the cell? Why is it referred to in this way?
DNA is referred to as the “blueprint” of the cell because it tells the cell how to build an
organism
42. What is a mutation a change in? And what are the 3 possible consequences to
mutations?
Mutations are changes in the number, type or order of the nucleotide base sequence of a
gene or DNA molecule. The 3 possible consequences are: improved trait, no change, or
harmful trait.
43. List the 3 kinds of mutations, and explain each one. See pictures on page 152
1. Deletion – bases are left out
2. Insertion – extra base(s) added
3. Substitution – wrong bases used (most common) – this can be harmful because it may
cause a gene to produce the wrong protein. One example of this is sickle cell disease.
44. Any physical or chemical agent that can cause a mutation in DNA is called a mutagen.
Give two (2) examples of this.
Examples: radiation, UV radiation (from the sun), asbestos, chemicals in cigarette smoke
45. Manipulating individual genes within organisms is called genetic engineering. Why do
scientists do this?To create new products (ex: bacteria may be used to make proteins
found in a spider’s silk)
46. Crime detection has improved because of DNA fingerprinting, which identifies the
unique patterns of an individual’s DNA.
47. When a new organism that has the exact copy of another organism’s genes is created,
it is called cloning.