Download HW 1 UNIT 4_v02

UNIT 4. HEREDITY
ACTIVITTIES
1. Define: Trait, gene, loci, allele
2. Explain the difference between:
a)
b)
c)
d)
Dominant and recessive allele
Homozygotic and heterozygotic
Genotype and Phenotype
Gene and allele
3. Copy and complete the sentences with the word gene(s) or allele(s).
a) A(n) ______________is the unit of genetic transmission.
b) ___________occur in pairs.
c) ___________are different versions of the same____________.
d) ___________can be classified as dominant or recessive.
e) Sometimes,____________ are co-dominant.
f) When two alleles have an equal capacity to express a trait, they are called_____________ alleles
and produce an intermediate trait.
4. Match the word with the definitions:
1.
Genotype
a) is an individual’s complete hereditary information.
2.
Homozygous
b) when an individual has two different alleles for a trait.
3.
Phenotype
c) is an individual’s observable characteristics, morphology
(shape, size or colour), development or behaviour.
4.
Heterozygous
d) when an individual has identical alleles for a trait.
5. For each genotype below, indicate whether it is heterozygous (He) or homozygous (Ho)
AA _____
Ee ____
Ii _____
Mm _____
Bb _____
ff ____
Jj _____
nn _____
Cc _____
Gg ____
kk _____
oo _____
DD _____
HH ____
LL _____
Pp _____
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6. For each of the genotypes below determine what phenotypes would be possible.
Purple flowers are dominant to white flowers.
Brown eyes are dominant to blue eyes
PP __________________
BB ________________
Pp __________________
Bb ________________
pp __________________
bb ________________
Round seeds are dominant to wrinkled seeds.
Bobtails in cats are recessive.
RR __________________
TT _________________
Rr __________________
Tt _________________
rr __________________
tt __________________
7. For each phenotype below, list the genotypes (remember to use the letter of the dominant trait)
Straight hair is dominant to curly.
Pointed heads are dominant to round heads.
____ straight
_____ pointed
____ straight
_____ pointed
____ curly
_____ round
8. In peas, tall stem (T) is dominant over the dwarf stem (t). This character is governed by a gene that
determines the height of the stem and has two alleles: T and t. What gametes does the parent
produce? How will the phenotype of the offspring (tall or dwarf) of each of the following crosses be?
- Tt-tt
- TT- Tt
- Tt-Tt
9. A brown mouse is mated to a white mouse and all of their offspring are brown.
a) Assign symbols for the possible alleles. Which allele is dominant?
b) What are the genotypes of the mice that were crossed?
c) If two of the F1 brown offspring were mated together, what percentage of the F2 mice would be
brown?
10. In guinea pigs black hair colour (N) is dominant over white hair colour (n). If a white guinea pig is
crossed with another purebred black (Homozygous dominant)
a. How are the children?
b. If the children are crossing each other. How will their descendants be?
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11. In humans, dimples are inherited as a dominant trait. A man heterozygous for dimples marries a
woman without dimples.
a) What are the genotypes of the couple?
b) What proportion of their children will have dimples?
12. In humans the gene for farsightedness is inherited as a dominant (therefore normal vision is
recessive). What fraction of children will have normal vision if a normal man marries a woman who
is farsighted and had a father with normal vision?
13. In tomatoes, red fruit (R) is dominant to yellow fruit (r). A homozygous breeding red-fruited plant is
bred to a homozygous breeding yellow-fruited plant.
a) What phenotypic ratio would you expect to see in the F1 offspring?
b) If two of the F1 plants were bred, what phenotypic ratio would you expect to see in the F2
offspring?
c) What genotypic ratio would you expect to see in the F2 offspring?
14. Describe the result of:
a) a cross between a dominant homozygous individual and a heterozygous individual.
b) a cross between a recessive homozygous individual and a heterozygous individual.
c) a cross between two heterozygous individuals.
15. A clear-eyed man whose parents had dark eyes has offspring with a woman with dark eyes. Have a
child with blue eyes. What are the genotypes of all individuals mentioned above? We assume that
the colour of dark eyes (M) dominates the colour of light eyes (m).
16. The achondroplasia is a form of dwarfism due to an abnormally small growth of long bones, which is
inherited by a single gene. Two dwarfs who worked in a circus got married and had a dwarf child and
later a normal child.
a) Is achondroplasia a dominant or recessive trait? Why?
b) What are the genotypes of the parents?
17. In humans, lack of pigmentation called albinism is the result of the action of one allele. Two normal
parents had 2 albino children and 1 normal child.
a. Is albinism a dominant or recessive trait?
b. What is the genotype of the parents?
18. A farmer has crossed two purebred lines of hens a brown plumage (M) and simple crest (s) and other
white plumage (m) and rosette crest (S). If the brown plumage and rosette crest are dominant
characters, what phenotypic ratios are obtained in the F2?
19. In tomatoes, red fruit is dominant to yellow and tall stem is dominant to the dwarf. A grower has
pure breeds of red and dwarf plants and yellow and tall plants. He wants a race of red and tall
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plants. If you cross two breeds and get the F1 and F2 generations what proportion of the F2 will be
red and tall? How much of this will be homozygous for the two characters?
20. In rabbits, short hair is determined by the dominant allele H and long hair by the recessive allele h.
The black hair is the action of the dominant allele N and brown hair of the action of the recessive
allele n. If we cross a male with short hair and black colour (with double heterozygous genotype)
with a female longhaired and black and whose father was brown. How the F2 will be?
21. In Drosophila, grey body is determined by the dominant allele a +and the black body by the recessive
allele a. Normal wings normal are determined by the dominant allele vg + and vestigial wings by the
recessive allele vg. What are the genotypic and phenotypic ratios resulting from a cross between a
double homozygous grey body and vestigial wings and a double heterozygote?
22. In peas, yellow colour is determined by the dominant allele A and green colour by recessive green
allele a. Tall stem is determined by the dominant allele T and the dwarf stem by the recessive allele
t. If you cross a green and tall stem plant, one of whose parents was tiny, with another yellow and
tall stem double heterozygous. What is the likelihood of a green and dwarf stem plant appear among
offspring?
23. The domestic rat is usually sparse moustache and brown fur (dominant traits). In the laboratory
obtained two pure lines, one white fur and sparse moustache and other brown fur and thick
moustache (white colour and thick moustache are recessive traits). Calculate the genotypic and
phenotypic ratios in the F2. (M - brown fur, m - white fur, R - sparse mustache, r - thick mustache).
24. True or false? Copy these statements if they are correct. If not, correct them.
a) Mendel’s first law: If there is dominance between alleles, the offspring will show an intermediate
trait.
b) Mendel’s principle of segregation explains genetic transmission from the first generation parents
to the second generation offspring.
c) Mendel’s principle of independent assortment explains the transmission of more than one trait.
d) A first generation (F1) of two purebred individuals will produce a second generation (F2) which
will have four phenotypes.
25. The results of a cross can be written with numbers to indicate the different genotypes or
phenotypes. Example: The phenotype result of Mendel’s third law is 9:3:3:1. Use numbers to write:
a) the genotype result of Mendel’s second law
b) the phenotype result of Mendel’s second law
26. In Andalusia’s hens, the colour of feathers is determined by two alleles, (B) determining the black
colour and (b) determining the white colour. Hens that have a heterozygous genotype (Bb) are blue.
A blue hen is crossed with a rooster with the same colour. How will their descendants be?
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27. In four o'clock flower (Mirabilis jalapa), red flower is determined by the W allele, incompletely
dominant over white flower produced by the w allele. The heterozygous plants have rose flowers. If
a plant with red flowers is crossed with another white flowers:
a) How will the phenotype of F1 be?
b) If two F1 flowers are crossed, how will the phenotype of F2 be?
c) How will the phenotype of the offspring obtained from a cross of the F1 with its red and white
progenitor be?
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