Transcript 3.2.3: Mitosis & Meiosis

State Assessment
Life Sciences
S.HS. 3.2.3
All questions taken from California
Dept. of Ed. Released Test Questions
2007
Mitosis & Meiosis
• Mitosis produces 2 body cells that are diploid
(containing a complete set of chromosomes)
body cells; these cells are made for the purpose
of growth and repair
• Meiosis produces gametes (sex cells) and is
responsible for 4 haploid cells; when the four
haploid cells are produced
A. Prophase I of Meiosis is responsible for
genetic recombination due to crossing over of
homologous chromosomes.
Genetics Question #1
•
Which of the following best describes
meiosis?
A It occurs only in cells in the reproductive
structures of the organism.
B It is carried out in tissues that require cell
replacement.
C It happens in tissues except the brain and
spinal cord.
D It is the first stage of mitosis.
Genetics Question #2
• The diagram to the left shows
homologous chromosomes
during prophase I of meiosis.
Which of the following correctly
describes the process being
illustrated?
A mutation in which the DNA
content of the gene is altered
B segregation of sister
chromatids
C condensation and
segregation of alleles
D crossing-over in which alleles
are exchanged
Genetics Question #3
• Mendel hypothesized that reproductive
cells have only one factor for each
inherited trait. This hypothesis is
supported by the observation that
A haploid cells are produced by mitosis.
B diploid cells are produced by mitosis.
C haploid cells are produced by meiosis.
D diploid cells are produced by meiosis.
Genetics Background Info.
•
•
Chromosomes contain DNA; segments of DNA are called genes
Watson and Crick- determined that DNA was a structure that appeared to be a double
helix.
• When looking at genetics several vocabulary terms are important:
A. alleles-forms of a gene
1.)homozygous-two of the same forms of a trait (e.g.TT or tt)
2.)heterozygous(hybrid)-two different forms of the trait (e.g. use hybrid cars and Tt)
B. genotype-genetic makeup of an organism (alleles Gg)
C. phenotype-physical appearance of an organism (green)
D. carrier- individual who carries the trait and can pass the trait to offspring, but they do
not show signs of the trait being demonstrated
E. autosomes- in humans the first twenty-two pairs of chromosomes
F. sex chromosomes- in humans the twenty-third pair of chromosomes
1.)Males sex chromosomes are XY
2.)Females sex chromosomes are XX
*males can only receive sex linked traits (X linked traits) from their mothers because they
receive their Y chromosome from their father and are more frequently colorblind and
hemophiliacs because these two disorders are X linked and recessive; females must
receive two recessive alleles from both parents to be colorblind or a hemophiliac
Monohybrid Cross
•
•
Trait examining one trait of an
organism
The two alleles each parent can
give to offspring must separate as
gametes can do this. If one
parent has a genotype of Ww and
the other parent has a genotype of
ww, each of the w’s will separate.
A cross can be demonstrated to
show probability for offspring
genotypes.
W
w
w
w
Ww
ww
Ww
ww
Genetics Question # 4
• In mice, the gene for red eyes R is dominant and
the gene for sepia eyes r is recessive. What are
the possible combinations of genes in the
offspring of two red-eyed heterozygous mice
(Rr)?
A
B
C
D
RR only
rr only
Rr and rr only
RR, Rr, and rr only
Genetics Question #5
• In certain breeds of dogs, deafness is due to a
recessive allele (d) of a particular gene, and
normal hearing is due to its dominant allele (D).
What percentage of the offspring of a normal
heterozygous (Dd) dog and a deaf dog (dd)
would be expected to have normal hearing?
A
B
C
D
0%
25%
50%
100%
Dihybrid Crosses
• Dihybrid crosses are done when a person is looking at
two traits that an organism has and the chances of
offspring receiving a particular genotype or phenotype
• Because two traits are involved, each parent has four
alleles that sort independently of one another
A. For instance, if a parent has alleles
RrYy, the gene combinations can be
RY, Ry, rY, and ry
B. For roundness, “R” can combine with “Y” and “y”.
C. For wrinkledness, “r” can combine with “Y” and “y”.
Genetics Question #6
• If a corn plant has a genotype of Ttyy,
what are the possible genetic
combinations?
A
B
C
D
Ty, ty
TY, ty
TY, Ty, ty
Ty, ty, tY, TY
Dihybrid Cross Implementation
•
In order to complete a dihybrid
cross you must first have two traits
from each parent in order to find
offspring using this method.
• If the male’s genotype is RrYy and
the female’s genotype is RrYy,
then what are the possible
phenotypes of their offspring?
• Cross- RrYyX RrYy
• Use the FOIL method: first, outer,
inner, last
A for the first parent, RY: Ry: rY: ry
B for the second parent, RY: Ry:
rY: ry
Because you have four combinations
for each parent,
sixteen boxes will be needed
RY
RY
Ry
rY
ry
Ry
rY
ry
Genetics Question #7
•
Fur color in cats is controlled by
an autosomal gene that can occur
in the dominant form, (B), or the
recessive form, (b). The length of
the cat’s fur is controlled by
another autosomal gene that
occurs in the dominant form, (S),
or the recessive form, (s). The
table shows the traits for these
allele codes.
BbSs (male) bbSS (female)
The following genotypes were found
in a male and a female cat.
BbSs (male)
bbSS (female)
Which one of the following choices is
true of the phenotype of offspring
from these parents?
A All offspring will have black fur.
B All offspring will have white fur.
C All offspring will have long-haired
fur.
D All offspring will have short-haired
fur.
Genetics Question #8
• The chart to the left shows four
alleles at the same locus that
affect rabbits’ coat color. Each
allele is dominant to the ones
below it. Rabbits with an
albino or Himalayan coat are
more susceptible to predators.
Which of the following
genotypes will produce a rabbit
that is least likely to survive?
A cchc
B Cc
C c hc
D Cch
Genetics Question #9
• In pigeons there is a rare inherited condition that
causes the death of chicks before hatching. In
order for this disease to be passed from
generation to generation there must be parent
birds that
A
B
C
D
are heterozygous for the disease.
have the disease themselves.
produce new mutations for this disease.
are closely interbred.
Genetics Question #10
• A healthy individual is a carrier of a lethal allele
but is unaffected by it. What is the probable
genotype of this individual?
A two dominant normal alleles
B one recessive lethal allele and one dominant
lethal allele
C one recessive lethal allele and one dominant
normal allele
D one dominant lethal allele and one recessive
normal allele
Genetics Question #11
•
The diagram below shows Rosalind Franklin’s x-ray diffraction image of
DNA.
How did this evidence affect the work of
Watson and Crick?
A It was used to determine the physical structure of DNA.
B It was used to identify the four bases that make up DNA.
C It was used to develop the theory of independent assortment.
D It was used to show that DNA was the molecule of inheritance.
Genetics Question #12
• If a human baby boy inherits a recessive allele
from his mother, in which circumstance would he
most likely show the trait?
A The baby inherits the dominant allele from his
father.
B The allele is on an autosomal chromosome
and the baby is a twin.
C The allele is on the X chromosome.
D The allele is on the Y chromosome.
Slide Answers
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#1
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A
D
C
D
C
A
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#7 D
#8 C
#9 A
#10 C
#11 A
#12 C