Download Genetics/Genetic Disorders, Evolution

Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
Date ________
Period _______
Genetics/Genetic Disorders, Evolution, & Classification Review Sheet Test 2012-13
Aside from these genetics questions, you can use Review sheets & Genetics Problem Sets from the
Unit 8/9 webpage (answer keys are also on the same page).
Genetics
1. What is a gamete? A sex cell used for reproduction with ½ the regular # of
chromosomes as an organism’s regular body (somatic) cells
2. How many chromosomes are found in a human gamete? 23
3. How does the number of chromosomes in a human gamete compare to the number
of chromosomes in a human body (somatic) cell? Why is this important? a gamete
has ½ the regular # of chromosomes as an organism’s regular body (somatic)
cells so that when fertilization occurs, the offspring has the correct # of
chromosomes (& not too many)
4. What is an allele? different forms of a gene for the same trait (ex.
brown/blonde hair)
5. Compare/contrast dominant & recessive alleles.
Dominant alleles: “block” the expression of the recessive allele, can be
expressed (in the phenotype) when part of a homozygous dominant genotype
or a heterozygous genotype, are represented by a capital letter
Recessive alleles: are “blocked” by the dominant allele, can be expressed (in
the phenotype) ONLY when part of a homozygous recessive genotype, are
represented by a lower-case letter
6. How many alleles for a single trait do we get from each parent? 1 from each
parent (So, we have a total of 2 alleles for each trait.)
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
Date ________
Period _______
7. What is genotype? The allele combination an organism has for a trait. Written
as a combination of 2 letters, ex. TT, Tt, tt.
8. What is phenotype? How the genotype is expressed/”seen” (physically,
physiologically, behaviorally). Usually given as an adjective (ex. purple, tall,
color-blind)
9. What does it mean when an organism’s genotype is homozygous? How is this
represented? Homozygous means that the organism has 2 of the SAME alleles
for a trait. This is represented by using 2 of the same case letters, ex. TT
or tt.
10.
What does it mean when an organism’s genotype is heterozygous? How is this
represented? Heterozygous means that the organism has 2 of DIFFERENT
alleles for a trait. Represented by using 1 letter of each case, ex. Tt.
11. Why must an organism that shows the recessive trait be homozygous for that
trait?
B/c if it had even one dominant allele, that dominant allele would “block” the
recessive allele from being expressed/”seen”
12.
The trait we see (ex. flower color, hair color, etc.) is due to the
__protein__________ that is made as a result of transcription and translation.
13.
In a Punnett Square, the letters along top & side represent _the alleles in
each parent’s gametes (sperm or eggs)___________.
14.
In a Punnett Square, the boxes represent __the possible genotypes of the
offspring resulting from the cross__________.
15.
A female has which 2 sex chromosomes? ____XX____ A male? ____XY____
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
16.
Date ________
Period _______
Which parent’s chromosomes determine the sex of the offspring? Explain your
reasoning. Dad’s (male) b/c mom always gives an X to the offspring. If dad
gives an X, the offspring is a girl. If dad gives a Y, the offspring is a boy.
17.
What is codominance? When 2 alleles are equally dominant and both traits
show up in the heterozygous offspring. Represented by 2 capital letters. Ex.
AB blood type in humans
18.
What is meant by multiple alleles? Give an example of a trait that is controlled
by multiple alleles. Even if a gene has multiple alleles, a person can only have how
many of those alleles? Multiple alleles are when there are more than 2
different genes (alleles) for a trait. Human blood types are controlled by
multiple alleles (There are 3 alleles: A, B, & o). A person can ONLY have 2
alleles even if a gene has more than 2 versions b/c a person gets 1 allele
from mom & 1 from dad. Ex. A human can have an AB genotype for blood
type, but not ABo.
19.
__(Males/Females)_ will have only 1 allele for traits carried on the X
chromosome.
b/c a male only has 1 X chromosome... the Y doesn't carry an allele.
20.
When making a Punnett Square for ___sex-linked__________ traits (such as
hemophilia), you must consider the sex chromosome (X or Y) & gene it carries
(shown as superscript/exponent) together as a unit… ex. XG.
21.
What does it mean that a female is a carrier for a (recessive) X-linked trait?
If a female is a carrier for an X-linked trait, she has a heterozygous
genotype, ex. XGXg. She, herself, does not have the trait/disorder b/c she
has the dominant "normal" allele, but she does carry the recessive "affected"
allele that can be passed on to her offspring.
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
22.
Date ________
Period _______
Sex-linked traits that are controlled by recessive alleles on the X-chromosome
are more likely to show up in _____(males/females)_____. Why? b/c a male
only has 1 X chromosome... the Y doesn't carry an allele. So, while a female
can have 3 genotypes: XGXG, XGXg, XgXg (2 of which do not cause her to be
affected b/c they contain at least 1 dominant allele), a male can only have 2
genotypes: XGY & XgY (only 1 of which does not cause him to be affected
b/c it contains the dominant allele).
23.
What category (autosomal recessive, autosomal dominant, sex-linked, or
chromosomal abnormality) do most genetic disorders fall into? autosomal recess.
24.
What category (autosomal recessive, autosomal dominant, sex-linked, or
chromosomal abnormality) do the following genetic disorders fall into?
a. Cystic Fibrosis, Sickle-cell, Tay-Sachs Disease autosomal recessive (most
genetic disorders)
b. Huntington’s Disease autosomal dominant
c. Hemophilia & Color Blindness seX-linked (recessive)
d. Down Syndrome (trisomy 21) & Klinefelter’s Syndrome (XXY) chromosomal
abnormality
25.
KNOW how to make and interpret Punnett Squares for dominant/recessive, X-
linked and human blood types (codominant and multiple alleles).
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
26.
Date ________
Period _______
In pea plants, purple flowers are dominant to white flowers. Is it possible for
two purple flowers to have a white-flowered offspring? Explain your
reasoning/use a Punnett Square to show your thinking.
If both plants are heterozygous, they would be purple, but carry the recessive
white allele. If both pass on the recessive allele, the offspring would be white.
P
P
p
27.
p
PP
Pp
Pp
pp
A woman is colorblind (XcXc). She marries a normal man (XCY). Can they have a
son that is normal? Explain your reasoning/use a Punnett Square to show your
thinking.
Since colorblindness is X linked & recessive and the mother has the disorder (is
XcXc), she can only give a Xc allele… the dad gives the son the Y allele… So, all sons
would be colorblind (is XcY)
XC
Y
Xc
Xc
XC Xc
X H Xc
Xc Y
Xc Y
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
Date ________
Period _______
Evolution
28.
Which gas was not part of Earth’s early atmosphere? oxygen
29.
Define evolution. theory that species have changed gradually over time (as
a result of the changes in allele frequency due to natural selection)
30.
What are the 4 mechanisms (causes) of evolution? Give a brief description of
each.
1. migration: gene frequencies change as individuals move in or out of the
population
2. genetic drift: change in gene pool of small population that takes place
by CHANCE
3. mutation: random change in DNA sequence of a gene (can change amino
acid sequence & protein coded for… can change the way the trait is
expressed)… not all mutations matter in evolution, to matter they must
be heritable (in gametes)
4. natural selection: organisms with variation best suited for environment
tend to survive, & reproduce (“survival of the fittest”)… more offspring
will have favorable adaptation than before. …acts on individuals, but
causes evolution of a population (by changing the allele frequencies in
gene pool).
31.
Describe Jean-Baptiste Lamarck’s explanation for how evolution occurs. What
was his theory called? Give an example. “Theory of Acquired Characteristics” 
acquired traits are passed on… Ex giraffe acquired longer neck by reaching
for leaves on higher branches & passed on to offspring; Ex. Tattoo passed to
offspring… Experimentation did not support Lamarck’s theory.
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
32.
Date ________
Period _______
What are Darwin’s 4 main points related to his “Theory of Natural Selection”?
Give an example of each.
1. Overproduction of offspring: more offspring are produced than generally
survive to ensure that at least some will survive long enough to
reproduce & pass on genes
2. Struggle to survive (competition): more organisms than resources to go
around leads to competition (for food, water, shelter, mates, light,
nutrients, etc.).
3. Variation within population: there are differences in traits in a
population… Individuals w/ variations for traits adaptive for their
environment have a better chance of survival, & thus, leave more
offspring… What causes variety?  sexual reproduction, crossing over
during meiosis, arrangement of chromosomes during meiosis, mutations…
Variations can be adaptations & are NOT a response to the
environment, they just happen to be “useful” when environment changes.
4. Successful reproduction (“natural selection”): Those organisms best
suited for environment tend to survive, reproduce, & pass on genes
(“survival of fittest”) leading to more offspring that have the favorable
adaptation than before.
33.
What are the 4 things that can cause variations amongst the individuals of a
population? Give a brief description of how each causes variation.
1. sexual reproduction: combining alleles from 2 genetically different
parents (instead of just copying DNA, like in asexual reproduction)
2. crossing over during meiosis: pieces of chromosomes are swapped during
crossing over during prophase 1 of meiosis
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
Date ________
Period _______
3. arrangement of chromosomes during meiosis: how chromosomes align
during metaphase 1 or 2 of meiosis determines which chromosomes go
into which gametes (& in which combinations)
4. mutations: random change in DNA sequence of a gene (can change amino
acid sequence & protein coded for during translation) which can change
way trait is expressed
34.
Darwin did not have knowledge of ___genetics_______.
35.
Who came up with a similar explanation for evolution as Darwin? Wallace
36.
What is a homologous structure? Give an example. Homologous structures are
structures that are similar in structure (and sometimes function) but with
some modifications. They are evidence of a common ancestor and of
divergent evolution (in which the organisms are becoming more different). Ex.
human arm/hand, whale flipper, dog’s front leg, bat wing, bird wing,
crocodile’s front leg  all have similar bone structures & patterns (w/ some
modifications)
37.
What is an analogous structure? Give an example. Analogous structures have
similar functions, but not structures due to similar environment/use.
Organisms do NOT have common ancestor, but have structures that are
becoming more similar (convergent evolution) due to similar usage. Ex. insect
wing & bird wing  both are used to fly, but insect wings don’t have bones
while bird wings do
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
38.
Date ________
Period _______
What is a vestigial structure? Give an example. Vestigial structures are
structures with decreased size or function. They often have no apparent use
in the present organism. Vestigial structures are evidence that an organism
has changed. Ex. hip bones in whales (evidence of the fact that whales had
ancestors that had legs & walked) & appendix in humans (apparently used
when our diets were more plant-based & less animal-based).
39.
How do embryos, provide evidence for evolution? When looking at embryos of
organisms… the early stages are very similar, which is evidence that they
inherited same basic body plan from a common ancestor. In the later stages
there is more distinction… the greater the # of similar stages, the more
closely related the organisms are (& the more recently they split from their
common ancestor).
40.
How does biochemistry (DNA, amino acids, proteins, etc.) provide evidence for
evolution? Similar organic compounds are coded for by similar DNA (ex.
proteins). DNA is the most reliable form of evidence. If 2 very different
species share (large amounts of the same) DNA it is evidence of common
ancestry. The higher %, more closely related (ex. human & chimpanzees 98%
similar; humans & other mammals 80% similar)
41.
Are adaptations a response to the environment (a choice) or do they just
happen to be “useful” when the environment changes? Explain your reasoning.
Adaptations are NOT a response to environment! They just happen to be
“useful” when environment changes. Certain features are not developed “in
order to” adapt to change in env…. Variation already exists in population &
certain variations become useful when env changes… The organisms w/ the
best-suited variations survive & produce offspring while others die before
they can reproduce… in this way a population/species becomes adapted to its
environment…
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
42.
Date ________
Period _______
___Indirect evidence___________ for evolution includes the fossil record,
comparative anatomy, comparative embryology, & comparative biochemistry.
43.
___Direct evidence___________ for evolution is evolution we can “see”, such
as antibiotic-resistant bacteria and pesticide-resistant insects.
Classification
44.
What “nickname” was Carolus Linnaeus given? Discuss Linnaeus’ classification
system.

“The Father of Modern Taxonomy”

Classification system in which the 2 main groups, plants & animals,
were known as kingdoms…

Also used smaller, more specific groups like genus (a group of similar
species) and species (organisms that can mate w/ each other &
produce fertile offspring)

Gave organisms names that described their traits
o Naming system is known as “binomial nomenclature”
 Names have 2 parts
 1st part is the organism’s genus (similar to a person’s last
name)
 2nd part is the organism’s species (similar to a person’s 1st
name)
45.
What are the rules for writing scientific names? Give examples.

Genus is 1st & always capitalized

Species is 2nd, written in all lowercase letters, & descriptive

When written/typed italicized or underlined when hand-written
o Examples Homo sapiens; Homo sapiens
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
46.
Date ________
Period _______
In the current classification system, organisms are classified by ____?
Evolutionary relationships
47.
When we classify organisms, we start with __ very broad/general________
characteristics down to ____very narrow/specific__________ characteristics.
48.
Show the relationship between the 3 domain, 5 kingdom, & 6 kingdom systems
of classification.
3 Domain system
Archaea
(Eu)bacteria
6 Kingdom
Archaea
(Archaebacteria)
(Eu)bacteria
system
5 Kingdom
system
49.
Monera
Eukaryota (Eukarya)
Protista fungi plantae animalia
List the 8 taxa (classification groups) used to classify organisms from
broadest/most general to narrowest/most specific. What saying can you use to
help you remember? Relate each group to continents, countries, etc.

Domain
Did
Continent (North America)

Kingdom
King
Country (USA)

Phylum
Phillip

Class
come
County (Fairfield)

Order
over
Town (Darien)

Family
for
Neighborhood (Noroton Heights)

Genus
good
Street (High School Lane)

Species
spaghetti?
House # (80)
State (CT)
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
50.
Date ________
Period _______
What is the relationship between taxonomic levels (classification groups)?

From domain down, each level has a new set of criteria
(characteristics) that must be shared

As go down levels, exclude organisms that don’t share the next trait.

The more closely related 2 organisms are, the more levels of
classification (taxa) they share

Once an organism shares a more specific taxon (lower group) it MUST
share the more unifying taxa (higher groups)
o Ex. organisms in the same species (lower taxa) MUST belong
to the same class (higher taxa)
o Ex. organisms in the same class (high taxa) do NOT
NECESSARILY belong to the same species (lower taxa)
51.
Characteristics of each domain/kingdom? Use the chart.
3 Domain
system
6 kingdom
system
5 kingdom
system
Archaea
(Eu)bacteria
Eukaryota (Eukarya)
Archaea
(Eu)bacteria
(Archaebacteria)
Monera
Protista
Fungi
Plantae
Animalia
Prokaryotic/
eukaryotic
Unicellular/
multicellular
feeding

prokaryotic

Prokaryotic

eukaryotic

eukaryotic

eukaryotic

eukaryotic

unicellular

unicellular

Mostly
unicellular

Mostly
multicellular

multicellular

multicellular

Heterotrophic
or autotrophic


Heterotrophic
autotrophic


Heterotrophic
autotrophic


autotrophic
(photosynthesis
)

heterotrophic
other
characterist
ics

Older, less
complex
bacteria
live in extreme
environments
(very hot, very
cold, acidic,
salty, etc.)


can be plantlike, animallike, fungus-like


cell walls
(made of
cellulose)
produce oxygen

no cell wall
bacteria that
live in salt
lakes
bacteria that
live at
hydrothermal
vents



modern, more
complex
bacteria
evolved from
Archaea
most common
bacteria
very diverse
free-living or
pathogenic
Staphylococcus
E. coli
cyanobacteria
Heterotrophic
(digest food
outside &
absorb
nutrients)
Cell walls
(made of
chitin)
decomposers &
parasites
mushrooms
mold
yeast
(unicellular)






mosses
ferns
trees
grasses
shrubs
land-based
plants

examples












Amoeba
Paramecium
Euglena
algae




invertebrates
insects
worms
sponges
corals
vertebrates
o
fish
o
birds
o
amphibians
o
reptiles
o
mammals
o
o
o
o

Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
52.
Date ________
Period _______
What is a dichotomous key?

A tool used to help classify/identify objects by using pairs of
opposing statements or asking a question with 2 possibilities.
53.
What are the 2 formats/methods for making a dichotomous key?
a. List
i. How many pairs of characteristics/statements will you have compared
to objects?
1. One less pair of characteristics than objects… ex. 5 objects
 4 pairs or characteristics/statements
b. Branching/tree diagram
i. How many objects should be in each of the final boxes?
1. (in final box MUST have only 1 object)
54.
When making a dichotomous key always use __paired, opposing__
statements/questions. Give an example. green?/not green?
55.
What type of characteristics/traits do we usually use when making a
dichotomous key? PHYSICAL characteristics/traits Give an example. color,
shape, # of toes
56.
When making a dichotomous key what shouldn’t you do?
a. Usually DON’T use job/function
b. DON'T use a characteristic that changes
c. Ideally, DON'T repeat a trait…
Name _______ANSWER KEY____________________
Mrs. Geithner-Marron (Bio 200)
57.
Make a dichotomous key for the sporting equipment below:
EXAMPLE (LIST FORMAT)
Sporting Equipment
1a worn on feet……………
go to 2
1b not worn on feet…….go to 4
2a laces……………………….go to 3
2b no laces………………….M
3a wheels……………………N
3b no wheels……………….J
4a handle……………
………go to 5
4b no handle………………H
5a oval head……………….L
5b no oval head………….go to 6
6a L-shaped…………………I
6b not L-shaped……………
K
Date ________
Period _______