Download Heredity Quiz 2017 Self-Testing Guide DUE day of quiz! ANSWERS

Heredity Quiz 2017 Self-Testing Guide DUE day of quiz! ANSWERS
Name: ______________________________
Students should be able to . . .
Traits and Variations - Remember when we first started looking at traits, and you tasted PTC on a strip of paper?
1. Identify 2 observable traits for humans. Traits are general characteristics. We have used the format “All humans have hair texture.” Or “All human
have height.”
2. Using a brace map or other tool, describe 2 variations of each of the traits in question 1. Mark “dominant” next the dominant variation.
Wavy Dominant
Hair Texture
Straight
3. What are the three sources for traits in organisms?
Organisms can acquire their traits through inheritance from their parents, acquired by learning, or affected by the environment.
4. Give an example of a human trait that comes from each of the three sources described in the question above.
Eye color is an example of an inherited trait, the ability to play video games well is a trait that is learned, and hair color lightened by the sun is an
example of a trait that is affected of the environment.
Genes and Dominance-. Remember when we learned about trait inheritance and dominance by putting leaves on a tree and created
adorable baby caterpillars to practice our knowledge of the 4 rules of inheritance,
5. Who are your genes inherited from?
Our genes are inherited from our parents. We receive half from our mother and half from our father.
6. Where is our genetic code stored?
Our genetic code is stored in strands of DNA. There are 23 different strands for humans. You have one copy of each from your mom and one copy
from your dad totally 46 strands. Sometimes a DNA strand wraps into a little package called a chromosome.
7. What is a gene and where would you find it?
Genes are segments of DNA code on a chromosome (wrapped strand of DNA). Genes are passed from parents to offspring, and contain information
needed to create traits.
8. Give 2 examples of traits controlled by genes.
Our genetic code is the instructions to build either attached or detached earlobes. Human genetic code also is the instructions for glands in your outer
ear to make wet or dry ear wax
9. What is a genotype? Genotype describes the gene for a variation of a trait using two letters. For the genotype, capital letters are used for a dominant
gene and lowercase letters are used for a recessive gene.
What is a phenotype? Phenotype is a description of the organism’s specific variation of a trait. The phenotype describes the physical appearance of a
certain variation of a trait. It is a description of a variation.
10. What is a dominant gene and how does it influence the variations seen in offspring?
A dominant gene “overpowers” a recessive gene. Dominance is when certain versions of traits occur more often because only one copy of a dominant
allele is needed for the organism to have the dominant phenotype (like there are more tongue rolling leaf on our tree of traits). Two copies of the
recessive allele are needed for the organism to have the recessive variation, so they are less common (like there are far less non-tongue rolling leaves on
our tree of traits).
11. Who is credited with discovering the science of heredity and what data did he use to make this discovery?
Mendel is credited with discovering the science of heredity based on many, many examples of certain variations of traits on plants that were seen 3
times more often than other variations. This 3:1 ratio shows that dominant variations occur approximately three times more often than recessive
variations. We see this concept on our Tree of Traits.
12. For the traits you described for humans in question 1, select a letter to represent a gene and describe a genotype of a human with a dominant variation.
I chose wavy as the dominant variation for hair texture. Then the genotype for wavy hair texture could be HH or Hh. Remember that there are always 2
possible genotypes for a dominant trait: Homozygous dominant (HH) or Heterozygous (Hh). NOTE: Usually you don’t choose the variation that is
dominant. The dominant variation is the variation that shows up most on the organism.
13. Give the letters of 2 different homozygous genotypes.
For each one, tell whether the genotype is dominant or recessive.
There are 2 homozygous genotypes, homozygous dominant that show as two capital letters (HH) and homozygous recessive shown as 2 lowercase (hh)
letters. Homozygous dominant (HH) creates a dominant variation. Homozygous recessive (hh) creates a recessive variation.
14. Give the letters of a heterozygous genotype.
Tell whether the genotype is dominant or recessive
Since the word cell “hetero-“ means different, a heterozygous genotype will have one dominant allele and one recessive allele (Hh). For our hair texture
example, the heterozygous genotype would be Hh and because there is one dominant allele it will create a dominant variation.
15. What do we mean by the word allele?
An allele is one of two or more versions of a gene. An allele is the gene that is the code for a specific variation. Any trait that has more than one
variation will have an allele that is the DNA that carries the code for each specific variation.
16. What are the four rules that govern how genes are inherited from parents?
1.
2.
3.
4.
You get one allele from each parent.
The specific allele parents give is determined randomly.
Dominant alleles over-power recessive alleles in the offspring.
The order you write the 2 parent alleles DOESN’T matter.
17. Can a Heterozygous parent have a child that is homozygous recessive? How do you know?
Yes, a heterozygous parent can have a homozygous recessive offspring IF the other parent has either a heterozygous or homozygous recessive genotype
to ensure that each parent has 1 recessive allele to pass.
Predicting Offspring Variations - Punnet Square Remember when we practiced Punnet Square with Sponge Bob and Patrick.
18. Use a Punnett Square to determine what the probability (percent chance) for all genotypes and phenotypes for offspring if a Heterozygous
Brown eye (Bb) parent is crossed with a blue eye parent (bb)
b
b
B
b
Bb
bb
Bb
Genotype
Phenotype
0 % BB
50 % Brown eyes
50 % Bb
50 % Blue eyes
bb
50 % bb
Pedigree Charts – remember when we used the example of freckles and dimples to track how variations are passed through multiple
generations
19. For the chart shown, where shaded is recessive, what is the genotype of the II4
individual (mother in generation II)? Explain how you know.
The II4 individual has a heterozygous genotype. The dominate allele is certain because
the person has a dominant phenotype (because the shape is not shaded). The recessive
allele we know because he has a child that is recessive, proving the he also had a
recessive allele.
20. If you want to find the genotype of a person, which people in the chart should you check to
get information?
When you need to reason through the second allele for anyone who is dominant (because the
shape is not shaded) check the parents and/or offspring. If either has a recessive genotype (shape
is shaded) that’s the only way to be sure the second allele is recessive. Otherwise leave a “?”.
I
d __
d
__
D __
?
__
II
D __
d
__
__
D __
d
D __
d
__
D __
d
__
III
d __
d __
__
D __
?