Download Chapter 8

B
b
NAME ___________________
PERIOD ___________________
B
b
Grades Nine Through Twelve
Biology/Life Sciences
Science Content Standards
Standards that all students are expected to achieve in the course of their studies.
Genetics
2. Mutation and sexual reproduction lead to genetic variation in a population. As a basis for
understanding this concept:
c. Students know how random chromosome segregation explains the probability that a particular
allele will be in a gamete.
d. Students know new combinations of alleles may be generated in a zygote through the fusion of
male and female gametes (fertilization).
e. Students know why approximately half of an individual's DNA sequence comes from each
parent.
f. Students know the role of chromosomes in determining an individual's sex.
g. Students know how to predict possible combinations of alleles in a zygote from the genetic
makeup of the parents.
3. A multicellular organism develops from a single zygote, and its phenotype depends on its genotype,
which is established at fertilization. As a basis for understanding this concept:
a. Students know how to predict the probable outcome of phenotypes in a genetic cross from the
genotypes of the parents and mode of inheritance (autosomal or X-linked, dominant or
recessive).
b. Students know the genetic basis for Mendel's laws of segregation and independent assortment.
Directions: Before answering questions in this packet, you should read the sections in the textbook that
cover the material.
1. heredity:
2. genetics:
3. Briefly describe Mendel’s Experiment with peas:
4. self-fertilization (self-pollination):
5. cross-fertilization (cross-pollination):
6. Name an important aspect of Mendel’s experimental design:
7. Explain what is meant by a plant that is “true-breeding”.
8. By allowing the plants to self-pollinate, Mendel obtained 14 strains, one for each of the 14
traits. Each strain is called a __________________________, or P1 generation.
9. After cross-pollinating two strains and allowing the seeds to grow, Mendel counted the number of
each type of offspring. He called the offspring of the P1 generation the
______________________________________ or F1 generation.
10. He then self-pollinated flowers from the F1 generation and collected the seeds. The
offspring of this cross are called _________________________________ or
________________________________.
11. monohybrid cross:
12. gene:
13. allele:
14. dominant allele:
15. recessive allele:
16. How do scientists represent dominant and recessive alleles?
17. homozygous:
How would geneticists represent the genotype of a homozygous tall pea plant?
18. heterozygous:
How would geneticists represent the genotype of a heterozygous tall pea plant?
19. genotype:
20. phenotype:
21. In one of Mendel’s experiments, a true-breeding plant for green pods was crossed with a true-breeding
plant for yellow pods. What were the results in the following generations?
F1 generation:
F2 generation:
22. After studying thousands of pollinations, what pattern emerged in the F1 and F2 generations?
Geneticists rely on the use of Mendel’s principles to predict the likely outcome of genetic crosses.
23.After many years of research and counting traits, Mendel concluded that patterns of inheritance were
governed by 2 principles:
Principle
Description of Principle
1)
2)
24. Monohybrid cross:
25. Use a Punnett square to predict the results of a monohybrid cross between a pea plant homozygous for
yellow seed color and a pea plant homozygous for green seed color.
Gametes
G = yellow seed color
g = green seed color
Gametes
a. Genotypes of offspring: ____________________________________
b. Phenotypes of offspring: ___________________________________
26. A brown (recessive trait) mouse is crossed with a heterozygous black (dominant trait) mouse. If the
mother has a litter of four, what are the chances (probability) that all of them will be brown? Use the
Punnett square.
Gametes
a. Genotype of brown mouse ________
b. Genotype of black mouse ________
c. Probability of a brown mouse ______
Gametes
d. Probability that all 4 are brown _______
27. Predict the results of crossing two pea plants that are both heterozygous (Ii) for inflated pod
appearance.
Gametes
a. ratio of plants with inflated pod =________
b. ratio of plants with constricted pod = ________
c. Genotypic ratio: ________________
Gametes
d. Phenotypic ratio: _______________
28. In tomatoes, red (R) fruit color is dominant to yellow (r). Suppose you cross a true-breeding (pure)
plant bearing red fruit with a true-breeding plant bearing yellow fruit. Predict the offspring of both the
F1 and F2 generations.
29. Albinism is a condition where an organism has no pigmentation. In humans, it is controlled by a
recessive gene (c). From a marriage between a normally pigmented person known to be a carrier (Cc)
and an albino (cc), what proportion of the children would be expected to be albinos? Set up a Punnett
square.
30. testcross:
31. A testcross can determine the genotype of any individual whose phenotype is
__________________.
32. In guinea pigs, both RR and Rr result in a rough coat. How might you determine whether a rough
coated guinea pig was homozygous (RR) or heterozygous (Rr)? TESTCROSS
a. If the guinea pig were homozygous, what type of offspring would a testcross produce?
b. If the guinea pig were heterozygous, what type of offspring would a testcross produce?
c.
If about half of the offspring in the testcross are smooth, what must be the genotype of the guinea
pig?
33. Dihybrid cross:
34. In tomatoes, red (R) fruit color is dominant
to yellow (r). Round-shaped (P) fruit is
dominant to pear-shaped (p) fruit.
Suppose you cross a true-breeding
plant bearing red round-shaped
fruit with a heterozygous plant
Gamete
bearing yellow pear-shaped
s
fruit. Predict the appearance of
the F1 generation.
Gametes
35. probability:
formula:
36. When determining probabilities, in what situation would you use each of the following?
a. rule of multiplication:
b. rule of addition:
Variations on Mendel’s Principles
37.
polygenic trait:
example:
38. Incomplete dominance:
39. Incomplete dominance is seen in the inheritance of hypercholesterolemia. Mack and Toni are both
heterozygous for this characteristic, and both have elevated levels of cholesterol. Their daughter Zoe
has a cholesterol level six times normal; she is apparently homozygous, hh. What fraction of Mack
and Toni’s children are likely to have elevated but not extreme levels of cholesterol, like parents? If
Mack and Toni have one more child, what is he probability that the child will suffer from the more
serious form of hypercholesterolemia seen in Zoe?
40. Codominance:
41. One of the most firmly established series of multiple alleles in humans involves the genetic locus
controlling the blood types: A, B, AB, and O. The ABO locus has three common alleles: IA, IB, and
IO. IA and IB are codominant (IA IB heterozygotes have both A and B antigens on their red blood
cells) and IO is recessive (IO IO homozygotes have no ABO antigens on their red blood cells; IA IO
and IB IO heterozygotes have A and B antigens, respectively, on their red blood cells.)
What are the possible blood types of children in the following families:
a) Type A mother, type A father
b) Type A mother, type O father
c) Type B mother, type AB father
d) Type AB mother, type AB father
42. In paternity lawsuits, blood typing often is used to provide genetic evidence that the alleged father
could not be related to the child. For the following mother-child combinations, indicate which blood
types could NOT have been the father’s.
Mother
Child
O
B
B
A
AB
B
Impossible Blood types for father
43.
linked genes:
44.
sex-linked genes:
45.
A white-eyed female Drosophila (fly) is mated with a red-eyed (wild-type) male. What result do
you predict for the numerous offspring? (Red is dominant to white)
46.
hemophilia: