Download Genetics Unit Test Review

Name: _______________________________________
Date: _____________
Science 7
Genetics Unit Test Review
1.
a. What is the function of DNA?
Stores genetic information, blueprint for life, makes up genes
b. What is the structure of DNA? (What is its shape? What makes it up?)
DeoxyriboNucleic Acid
Double helix, twisted ladder, made up of nucleic acids:
1.Phosphate, 2.Sugar, 3.Nitrogen base
c. There are __4__ bases:
___A (adenine)______ pairs with __T (thymine)______.
___G (guanine)________ pairs with C (cytosine)__.
d. If one side of DNA has the bases, A-T-C-G-C-A, what is the other side of the
molecule?
T-A-G-C-G-T
2. Put the following terms in order from smallest to biggest: chromosomes, genes,
DNA, nucleus, cell.
DNA – genes – chromosomes – nucleus - cell
3
a. What is an allele?
Different forms of genes
b. Give two examples of alleles.
Gene is eye color (blue and brown would be alleles) - Bb
Gene is for height (Tall and short would be alleles) - Tt
4.
a. What is a dominant trait?
Trait that always shows when present (ex. Brown eyes “B”)
1
b. What are the genotypes that represent a dominant trait?
BB Capital letters
c. Give 3 examples of dominant traits.
B = Brown
T = Tall
C = Curly hair
5.
a. What is a recessive trait?
Trait that is hidden when the dominant is present.
Need 2 recessive alleles for organism to show recessive trait.
b. What are the genotypes that represent a recessive trait?
bb lower case letters
c. Give 3 examples of recessive traits.
b = blue
t = short
c = straight
6. Compare and contrast genotype and phenotype
Genotype
Phenotype
What the “Genes”
Say
Letters (Bb)
“Physical” appearance
Words (Brown eyes)
Both
Describe
Traits
Influenced
By environment
2
7. In humans, brown eye color (B), is dominant over blue eye color (b). What are the
phenotypes of the following genotypes? In other words, what color eyes will they have?
A. BB _____Brown__
B. bb _____blue________
C. Bb _____Brown_________
8.
a. What does it mean to be purebred?
You have the same alleles for a gene
b. What are the genotypes that represent a purebred trait?
Needs to be the same letter
BB (purebred dominant) or bb (purebred recessive)
c. What is another term that means the same thing as purebred?
Homozygous
9.
a. What does it mean to be hybrid?
Have two different alleles for a gene/trait
b. What are the genotypes that represent a hybrid trait?
Bb
c. What is another term that means the same thing as hybrid?
Heterozygous
10. Describe the genotypes given. The first two are already done.
A. DD homozygous, dominant
D. ss __homozygous recessive
B. Dd _heterozygous
E. Yy __heterozygous__
C. dd _homozygous recessive_
F. WW _homozygous dominant__
Punnett squares
11. A heterozygous, smooth pea pod, plant is crossed with a wrinkled pea pod plant.
There are two alleles for pea pod, smooth (S) and wrinkled (s).
a. What are the genotypes of the parents? ___Ss______ and ___ss____
b. Draw the Punnett Square
3
c. What percent of the plants will be:
Homozygous dominant ___0%__ Smooth ______50%_______
Heterozygous (hybrid) ____50%_______
Wrinkled _____50%________
Homozygous recessive ___50%______
12.
a. What is incomplete dominance?
Neither allele is dominant, and there is “blend” or traits.
(red (rr) and white (ww) flowers will make pink (rw), black (bb) and white (ww) fur
will make gray (bw)
Co-dominance – neither one is dominant but BOTH traits show. Black (BB) and
white (WW) will give Black and White spots (BW) or
(ROAN cows RR x WW = RW)
b. Four o’clock flowers the alleles for flower color are both equal therefore
neither dominates over the other.
1) What is the genotype for red flowers? ___rr__
2) What is the genotype for white flowers? __ww_
3) What is the genotype for pink flowers? ___rw___
c. Draw a Punnett Square to predict the offspring of two pink Four o’clock
flowers:
rw x rw
d.
What percent of the offspring will be:
Red______rr - 25%________________
White ____ww - 25%________________
Pink ____rw -_50%__________________
13. You have blood type AB, you marry a person with type BO blood.
a. Complete a Punnett Square for this cross.
AB x BO
4
b. What is the probability of having offspring with type A blood? ___25%__
Type B blood? ____50%__
(AB is Codominance)
Type AB blood? ___25%____
Type O blood? ____0%__
14. What is selective breeding? Explain how it is used in dogs.
Choose desirable traits between two of the same species and cross breed them
(pollinate)
Labrador retriever and standard poodle will give you a labradoodle
15. What is genetic engineering? How can it be used?
Gene from one organism and put into another organism.
Cut a gene or you additionally add genes
Flounder – gene for cold water placed into a tomato cell
Tomato – receives gene and can last through cold temps.
Human Insulin (insulin gene in bacteria)
16. What is cloning? Compare the offspring to the parent. Explain, briefly, how cloning
works.
Exact copy of an organism. Identical to parent because you take the body cell (somatic)
nucleus and place it into an egg. (asexual reproduction)
1.
2.
3.
4.
Take donor nucleus from a somatic (body cell) with full amount of chromosomes
Take an egg cell and remove the nucleus (half the DNA)
Place the donor nucleus into the empty egg and place it into a mother
Baby will be born as a clone to the donor nucleus.
Dolly the sheep
7. What is a mutation? Explain how it impacts DNA. Give an example of a genetic
mutation.
Mutation is a change in the DNA. It can change so much that there is an actual physical
change in the organism, or it is minor and your body fixes it.
5
*If the genetic mutation occurs in the egg or sperm and changes the genetic code you
will have a GENETIC DISORDER
Example is Down Syndrome
Example – sickle cell anemia (changes the shape of your blood cells and it results
in clots and pain)
18. What is a karyotype? How can it be used by doctors? Give two examples.
Photo or a map of your chromosomes. It shows all 23 pairs including the sex of the
child.
XX – Girl
XY – Boy
19. What are two examples of genetic disorders? Briefly describe each.
It will also show genetic disorders such as Downs Syndrome (3 – on the 21st pair).
Slower mental capabilities and physical features are similar
Sex Linked Traits
We went over this in class today
6
7