Download 10 Biology Exam Review 2015

10 Biology Exam Review 2015
1. Describe the purpose of meiosis.
Meiosis is the type of cell division used to produce gametes for sexual reproduction. As a result of meiosis, the
number of chromosomes is halved (one of each of the parent’s homologous chromosomes passed to each gamete)
and sorted into unique sets.
2. Label the phases of meiosis. Refer to page 324 of your book.
Interphase With DNA synthesisprophase/metaphaseanaphase/telophasecytokinesisinterphase
Without DNA synthesis(not shown, PMAT)cytokinesis
3. Circle and identify the two stages of meiosis which cause the gametes to be genetically different from the parent cells.
Step two/three are steps during which crossover of homologous chromosomes and independent assortment of
chromosomes occur.
4. How does genetic diversity and sexual reproduction benefit a species?
Genetic diversity results from sexual reproduction because of: combination of DNA from two different
parents; independent assortment of a person’s pairs of chromosomes into different gametes; crossing over,
mutation. Genetic diversity allows some members of populations to have more fit traits than others in the face
of natural selection during evolution.
5. What are homologous chromosomes? Matching chromosomes that each individual receives from two different
parents; they have the same set of genes on them, as well as the same size and shape.
6. What are sister chromatids?
Sister chromatids are the paired copies of a chromosome. These are joined at the centromere and are
synthesized during S phase of mitosis and meiosis.
7. What is the difference between haploid (n) and diploid (2n)? Body cells are diploid, meaning they have pairs of
homologous chromosomes & are diploid. The gametes have only one of each pair of chromosomes & are haploid.
8. What is the haploid number of an organism if a normal body cell has 32 chromosomes?
Body cells are diploid, meaning that if the cell has 32 chromosomes, it has 16 pairs of homologous
chromosomes. The gametes of this individual would have only one of each pair for a total of 16
chromosomes.
9. What is a gamete? Is it haploid or diploid? A gamete is a sex cell—sperm or egg. Gametes have only one copy of
the parent’s two copies for each homologuos chromosomes, so they are haploid (e.g., in humans, gametes
contain 23 chromosomes, whereas somatic cells—body cells—have 23 pairs of chromosomes.
10 Biology Exam Review 2015
10. Define the term “allele.” The variable forms of the same gene—some dominant, some recessive—the DNA
sequence is slightly different in the different alleles of the same gene.
11. Describe the difference between homozygous and heterozygous. Is “HH” homologous or heterozygous?
Homozygous means both alleles in the genotype are the same—like HH or hh
Heterozygous means the organism contains one dominant and one recessive allele—like Hh
12. Describe the differences between phenotype and genotype. What is an example of a phenotype if “HH” is a genotype?
Phenotype—the description of an organism’s traits; the result of expression of its genes
Genotype—the two alleles for a gene in the nucleus on an individual’s cells
13. Mendel’s peas showed a pattern of simple dominance inheritance. This means that a homozygous dominant genotype
(TT) produced a dominant phenotype (tall). What are the other options for genotypes and phenotypes?
TT homozygous dominant tall
Tt
heterozygous dominant tall
tt
homozygous dominant short
14. What genetic inheritance pattern is shown in the pedigree below? Fill in the missing genotypes. Label the generations
and individuals using the proper format.
Autosomal recesive (similar numbers affected male and females)
Aa
Aa
Aa
aa
aa
Aa
Aa
aa
AA or Aa
aa
15. A. What is unusual about sex linked conditions? B. Create a set of possible genotypes and phenotypes for an
imaginary, recessive, sex-linked condition. A. sex linked genes are located on the X chromosome OR the Y
chromosome. B. For an X linked gene that is not on the Y chromosome. Assume the sex linked disorder is
caused by the recessive genotype.
XAX A
healthy female
XAXa
healthy carrier female
XaXa unhealthy female
XAY
healthy male
XaY unhealthy male
16. Brown hair is co-dominant to purple hair. Draw a Punnett square showing the cross of two parents with brown and
purple spotted hair. Include the genotypic and phenotypic ratios.
Allele
I B codes brown hair
IP
codes purple spots in hair
i codes albino hair
B P
B P
Parent genotypes I I
X I I
genotype ratios of the offspring ¼ I B IB
2/4 I B IP
¼ I P IP
Phenotypic ratio of the offspring ¼ brown
2/4 brown w/ purple spots
¼ purple
10 Biology Exam Review 2015
17. Long claws are incompletely dominant to short claws. Draw a Punnett square showing the cross of a long clawed
parent and a short clawed parent. Include the genotypic and phenotypic ratios.
L long, l short: LL long claws, Ll medium claws, ll short claws
LL x ll  4/4 offspring (100%) have genotype Ll and 4/4 offspring (100%) have a medium clawed phenotype
18. Describe the various types of stem cells.
1) The 1 celled embryo(fertilized egg) is a TOTIPOTENT STEM CELL—it can form every cell in the
embryo, including the placenta.
2) The ball of cells (blastocyst) formed after the fertilized embryo begins to divide and up to the first 10 days
contains embryonic stem cells that can form the cells of the body BUT NOT the placenta. These are called
embryonic stem cells and are PLEURIPOTENT STEM CELLS. Problem: Embryo must be destroyed to
obtain them.
3) In the embryo that has begun to fold into the 3 layers of the body, stem cells are MULTIPOTENT. They
can differentiate into a subset of cells, but not all cells of the body and not the placenta.
4) Pleuripotent stem cells are either adult stem cells or fully differentiated cells (from a person after birth)
that have had genes reactivated to return them to the pleuripotent cells. Advantage: no embryo has to be
destroyed to obtain them.
19. What are restriction enzymes? B. What are their two main uses?
A. The enzymes cut DNA at a certain sequence, leaving “sticky ends” that will stick to any other complementary
piece of single stranded DNA.
e.g. AAGGCCTT
TT CCGGAA
GCC TT
TT C CG
B. Restriction enzymes are made by bacteria as a defense against viruses. Restriction enzymes are used in
biotechnology to cut plasmid vectors and allow genes to be inserted at matching sticky ends.
20. Create examples or stories for the terms below:
a. artificial Selection
Plant and animal breeders can create new strains or breeds of plants and animals by breeding together,
generation after generation, individuals having the phenotype desired. For example, to get larger ears of corn,
farmers keep and plant only the seeds from the largest ears of the harvest. For example, to get a bassett hound
with longer ears, males with exceptionally long ears are bred with females with exceptionally long ears.
b. natural Selection
When members of a population of a species vary in their phenotype for a heritable trait in a way that gives
some members a survival or reproductive advantage over others, then the alleles that code these more fit
phenotypes will be passed to the following generation more often than those alleles for less fit phenotypes.
Each generation, the % of the population with the fit phenotype will increase, resulting in adaptation of the
population to the natural selective pressure.
c. genetic drift
In small populations, loss or gain of only a few individuals can result in a very large shift in the % of
particular alleles and therefore in % of individuals having the related phenotype. These small populations
10 Biology Exam Review 2015
show a shift in their predominant traits, not due to natural selection, but rather due to random chance.
For example, if population of 10 beetles having 50% A allele and 50% a allele loses only one individual with
genotype aa, then its % A increases to 60% and its %a drops to 40%.
d. sexual selection
Some traits that either do not increase chances of survival or may even decrease chances of survival
increase changes of reproduction in a process called sexual selection because males that have these traits
(like a longer peacock tail) are allowed to breed more often than those without.
e. Adaptation
Over many generations of similar natural selective pressure (e.g., like being preyed upon by a visual
predator) results in an increased % of a population inheriting more fit alleles for a trait so that more
individuals are well suited to survive and reproduce in their habitat (e.g., mice whose color allows them to
blend in with their surroundings to be less visible to a visual predator).
f.
founder’s effect
This is the genetic effect of having a very small % of a population split off into a new gene pool that is
reproductively isolated (no longer breeds with) from its old larger population; as a result, the small
population may have a very different % of phenotypes and alleles for traits than its original group, not as a
result of natural population, but just as the result of the random grouping of their alleles according to
which individuals became parts of the smaller group. For example, if a population having 70% brown and
30% yellow individuals has a small group split off, then it that new group is comprised of mostly yellow
individuals, the next generation, the new group may be nearly 100% yellow—not because of natural
selection, but just because most of its founding members carried alleles for yellow fur.
g. Speciation
If a subpopulation remains genetically isolated (reproductively isolated) from its old population long
enough for mutations in genes affecting reproduction to accumulate, then it may become unable to mate
with the population that it arose from. In that case, it has undergone speciation. For example, if a
subpopulation develops mating behaviors that result in breeding at a different time of year, then it will
have become a new species.
h. bottle neck
A catastrophic event that results in the death of most individuals in a population, not depending upon their
phenotype but just by random chance—like being in front of a lava flow or not, then the % of alleles in the
population can change quickly. Bottlenecks result in genetic drift.
21. What is a plasmid? How do they help in industrial protein production?
Small circle of DNA that exists in the cytoplasm of prokaryotes that is copied when the cell replicates its
chromosome before binary fission; often these carry genes allowing the bacteria to survive in presence of toxins
like antibiotics; scientists add new genes to these plasmids, then use the bacteria to make many copies of the
gene for research OR to make the proteins coded by the recombinant plasmids. For example, the protein
insulin is made by bacteria having recombinant plasmids that contain the insulin gene.
22. List the 6 kingdoms and include at least three distinguishing characteristics for each kingdom.
Bacteria—one celled, most less than 5 micrometers at greatest dimension, DNA w/o introns, no nucleus, no
membrane bound organelles
10 Biology Exam Review 2015
Archaebacteria-- one celled, most less than 5 micrometers at greatest dimension, DNA HAS some introns, no
nucleus, no membrane bound organelles, many are extremophiles that live in very harsh conditions
Protista—most are one-celled, eukaryotes, have nuclei AND membrane bound organelles, some are autotrophic
like plants, some are saprotrophic (absorptive) heterotrophs like fungi, and others are animal like (ingestive)
heterotrophs
Plant—multicellular, eukaryotic, use chloroplasts to carry out photosynthesis, cell walls of cellulose, adapted to life
on land with presence of a waxy cuticle coating outside
Fungi—all but yeasts are multicellular, cell walls of chitin, eukaryotes, saprotrophic heterotrophs, reproduce with
spores, body called a mycelium looks like tangled strings and has high surface area for rapid absorption of nutrient
solutions
Animals-multicellular eukaryote with specialized cells, no cell walls, and ingestive heterotrophs
23. Which species is most closely related to frogs according to the
cladogram below? What do they have in common?
Salamander—both are amphibia