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WorksheetsBiology #4
Total questions: 88
Worksheet time: 45mins
What are gametes?
eggs and sperm, haploid (1n); a reproductive cell that contains 2 chromosomes
What are somatic cells?
all non reproductive cells, diploid (2n); they have 4 chromosomes
What is the definition of a zygote?
The diploid (2n) cell resulting from the fusion of male and
female gametes, with two copies of each chromosome, produced through fertilization
What occurs during fertilization?
The fusion of gametes to form a new cell
Gametes are formed with half the number of chromosomes so
that when they combine with another gamete, that new cell will
have the __ of chromosomes.
correct number
The combination of meiosis and fertilization make up the cycle that is known as _
photosynthesis
reproduction
What is sexual reproduction?
The process of producing offspring through an
alternation of fertilization
(producing diploid cells) and meiotic reduction in chromosome number
(producing haploid cells).
True or False: In sexual reproduction, each offspring will contain half of
their chromosomes that came
from the mother, and half that
came from the father.
True
False
In early in development, specific cells
are set aside to undergo meiosis to form the gametes that can be used
later in life to reproduce. These specific cells are called __
germ-line cells
despite both somatic cells and germ-line cells both being diploid, how are they different?
Somatic cells undergo mitosis to form genetically identical diploid daughter cells , while Germ-line cells undergo meiosis (do divide the number of chromosomes to produce haploids
What happens during meiosis 1?
Homologous chromosomes replicate their DNA.
Homologous chromosomes separate and move to opposite poles of the cell.
Homologous chromosomes fuse together to form a single chromosome.
Homologous chromosomes
separate, and the daughter cells have only the haploid number of chromosomes.
What is synapsis and when does it occur?
The process of crossing over between non-homologous chromosomes during prophase II of meiosis.
The pairing of sister chromatids during prophase I of meiosis.
When homologous chromosomes find each other and
become closely associated or paired.
The separation of homologous chromosomes during prophase I of meiosis.
What is the Synaptonemal complex?
A protein lattice that forms between two homologous chromosomes in prophase I of meiosis, holding the replicated chromosomes in contact with each other
The synaptonemal complex is done so that that base-pairs can form between nonsister
chromatids (opposite chromosome chromatids) for the crossing
over process. What dies this process result in?
Paired homologues
What is recombination in biology?
The exchange of
corresponding chromatid segments between homologous chromosomes; responsible for genetic recombination between homologous chromosomes
The sites of recombination or crossing over are called _
What is the chiasmata, and what does it indicate?
The chiasmata is an X-shaped figure that can be seen in the light
microscope during meiosis; evidence of crossing over, where two chromatids have exchanged parts
What is the difference between meiosis and mitosis?
Meiosis involves two divisions with no replication of genetic material
back to back.
In prophase I, DNA coils tighter and chromosomes become
visible under a microscope. What occurs later in prophase 1?
homologous chromosomes become closely associated in synapsis, and exchange segments by
crossing over.
The ends of the chromatids, of germ-line cells, are attached to the
nuclear envelope at _ sites
specific
True or false: During synapsis, homologous chromosomes are joined along
their entire length
True
False
Recombination is the exchange of corresponding chromatid
segments between homologous chromosomes and is also sometimes
called crossing over. What occurs during recombination?
During recombination (prophase I), the synaptonemal complex
forms but another structure appears called recombination nodules.
During recombination (prophase I), the synaptonemal complex
forms but another structure appears called recombination
nodules. What is the purpose of recombination nodules?
Recombination nodules promote the separation of homologous chromosomes
Recombination nodules prevent the formation of the synaptonemal complex
Recombination nodules inhibit the exchange of genetic material between homologous chromosomes
Recombination nodules contain the enzymes needed to
break and rejoin chromatids of homologous chromosomes
What is crossing over?
A series of events in which the DNA segments of the chromatids are broken, switched with their sister chromatid, and then re-joined at the same site.
The four chromatids are held together in which two ways?
Homologous chromatid cohesion and telomere cohesion
Cohesion proteins and exchange of material by crossing over between homologous
Centrosome cohesion and spindle fiber cohesion
Nucleosome cohesion and kinetochore cohesion
While recombination is occurring, what also needs to happen to have prophase 1?
The nuclear envelope must be dispersed
The centrioles must move to opposite poles
The nuclear envelope must reform
Homologous chromosomes must pair up
By the end of prophase I, each homologous pair is locked together as
a bivalent. What is the purpose of a bivalent?
To capture spindle fibers and move to the center of the cell to align on the metaphase plate
The kinetochores of the sister chromatids for each homologue act
as a unit to capture the polar microtubules. What is this process called?
monopolar attachment
microtubule adhesion
What is monopolar attachment?
Each homologous chromosome is
attached to one pole instead of having its sister chromatids attached to the opposite pole in the bipolar fashion of mitosis.
The stage of mitosis in which spindle fibers line up at the center
Electrode placement used in electroconvulsive therapy (ECT) where one electrode is placed on the patient's forehead and the other is placed on the back of the head.
True or false: Relaxation on the paired homologous chromosomes pulls them to the
equator of the cell so that they can line up on the metaphase plate
True
False
The spindle axis orientation is _?
Random
Chromosomes begin to condense, Spindle of microtubules begin to form, DNA has already been replicated during the S phase of interphase, each chromosome consists of two sister
chromatids attached at the centromere, each cell has 4 chromosomes or two pairs of
paired chromosomes, and crossing over occurs, forming chiasmata.
What phase of meiosis 1 does this process describe?
Paired chromosomes line up at the equator, chiasmata keeps the paired chromosomes
together Microtubules from opposite poles attach to sister kinetochores of each homologous chromosome (not the pair).
One microtubule attaches to one of the aired homologous chromosomes and a
different microtubules connects to the other chromosome creating tension.
Which phase of meiosis 1 does this process describe?
True or false: During anaphase I, the microtubules of the
spindle fibers begin to shorten, breaking the
chiasmata and pulling each sister chromatid to opposite poles.
True
False
What occurs at the beginning of telophase 1?
Chromosomes are
clustered together at opposite ends of the cell, while the nuclear membrane reforms around them.
Spindle fibers attach to the centromeres of the homologous chromosomes
Chromosomes condense and become visible
During telophase 1, why are the sister chromatids no longer identical?
Formation of new combinations of alleles
Separation of homologous chromosomes
Crossing over
Independent assortment
Why is there no S phase after meiosis 1?
The chromosomes are already paired
What occurs at the beginning of the prophase II stage?
During metaphase II the newly formed spindle fibers from opposite poles
bind to the kinetochores of each sister chromatid.
What does this process cause?
Tension to align the chromosomes
along the equator of the cell
Chromatids to condense and become less visible.
Cells to separate and move towards opposite poles.
True or false: during Anaphase II, the spindle fibers contract, breaking the cohesion
protein bond between the sister chromatids and
pulling them towards opposite poles.
True
False
What is the difference between meiosis and mitosis? (select all that apply)
The nuclear envelope re-forms around the four sets of daughter chromosomes
Cytokinesis follows, leaving 4 new cells, all with different genetic information
Each of these cells contains a complete haploid set of chromosomes
These cells may develop directly into
gametes or divide
True or false: Any error in meiosis can produce gametes with too many or too
few chromosomes
True
False
What are aneuploid gametes?
Gametes that have an improper number of chromosomes
What FOUR distinct features is meiosis characterized by?
1. Homologous separation
2. Sister chromatids
3. Kinetochores
4. DNA extraction
1. Homologous pairing
2. homologous chromosomes
3. Protein synthesis
4. DNA replication
1. Homologous pairing
2. Sister chromatids
3. Kinetochores
4. DNA replication
1. Homologous pairing
2. Sister chromatids
3. Binary fusion
4. DNA replication
During prophase I of meiosis, the __ __are
paired together, connected together.
After mitosis occurs, DNA must again be replicated in order for the
next division to occur, If meiosis is going to half the number of chromosomes this replication has to be __ between meiosis I and meiosis II.
Suppressed
Replicated
True or false: During mitosis, the daughter cells that are produced are identical
to the parent cell in terms of their chromosome make up
During meiosis, it is rare that a new cell that is produced is identical
to the parent cell.
True
False
What is the first filial generation?
F1 generation, the offspring resulting from a cross between a parental generation (P)
What is a dominant trait?
An allele that is expressed when present in either the heterozygous or the homozygous condition.
An allele that is expressed or observed when an individual has four copies of the gene associated with the trait.
What is a recessive trait?
An allele that is expressed regardless of the number of copies of the recessive allele.
An allele that is expressed only when present in the homozygous condition, but is “hidden” by the expression of a dominant allele in the heterozygous condition.
What is the second filial generation?
The F2 generation is the offspring produced by crossing two individuals from the second filial generation (F2 generation)
The F2 generation is the offspring produced by crossing two individuals from the parent generation
The F2 generation is the offspring produced by crossing two individuals from the grandparent generation
The F2 generation is the offspring resulting
from a cross between members of the first filial (F1) generation.
When Mendel did this experiment, he observed among 929 F2
plants, 705 were purple and 224 were white.
What was the dominant to recessive ratio that resulted from this experiment?
During Mendel's experiment the observed F2
ratio was 3:1, dominant to recessive, but in reality it was actually _:_?
What is an allele?
One of two or more alternative states of a gene, dominant or recessive
A type of disease that is accumulated through the growth of cells during mitosis
Cells that lack the needed amount of chromosomes
Two types of proteins that are bonded to cells through protein adhesion
True or false: In a hybrid, only two form of a gene, or an allele, is going to be
apparent
True
False
What is genotype?
The total set of alleles that an individual contains, the genetic constitution underlying a single trait or set of traits.
The physical appearance or other observable
characteristics of that individual that result from an allele’s expression, the realized expression of the genotype
What is phenotype?
The total set of alleles that an individual contains, the genetic constitution underlying a single trait or set of traits.
The physical appearance or other observable
characteristics of that individual that result from an allele’s expression, the realized expression of the genotype.
The 3:1 ratio of dominant to recessive is the monohybrid __ ratio
Phenotypic
Genotypic
The 1:2:1 ratio of homozygous dominant to heterozygous to
homozygous recessive is the monohybrid __ ratio
Phenotypic
Genotypic
What is the Principle of Segregation?
When two alleles join, and prepare the cells for DNA replication and the protein synthesis process
The two alleles for a gene segregate during gamete formation and are rejoined at random, one from each parent, during fertilization
The process of combining two alleles for a trait. It results in the identical two daughter cells
During fertilization, How many from chromatids from each parent join
together to form a new homologous pair?
In a Punnett square __ represents the dominant genes, while __ represents the recessive genes.
Uppercase letters , lowercase letters
What is a dihybrid cross?
An experiment between two individuals that differ in one trait.
A single genetic cross involving two different traits, such as flower color and plant height.
An experiment between two individuals that have the same traits.
What is The Principle of Independent Assortment in a dihybrid cross?
The principle of independent assortment describes the random assortment of alleles for each of the genes.
A mating between a phenotypically dominant individual
of unknown genotype and a homozygous “tester,” done to
determine whether the phenotypically dominant individual is
homozygous or heterozygous for the relevant gene is typically known as which of the following?
When do mutually exclusive events occur?
When two events cannot both
happen at the same time
The rule stating that for two independent
events, the probability of either event occurring is the sum of the
individual probabilities is known as _
The rule of addition
The rule of division
The subtraction Rule
The multiplication Rule
For a cross of a heterozygous purple F1
, the possible outcomes are PP, Pp, pP, and pp.
What is the probability of being heterozygous?
1/2
1
1/3
1/4
What is the rule of multiplication?
The rule of multiplication is a rule that states and explains the process of adding two numbers, then dividing them by the total variables
The rule of multiplication is the process of dividing a number by another number.
A rule stating that for two independent events, the probability of both events occurring is the product of the individual probabilities.
If the probability of an F2
individual being pp (homozygous recessive) is
the probability of receiving a p gamete from the male (1⁄2) times the
probability of receiving a p gamete from the female (1⁄2).
What is the probability of a pp homozygote?
When crossing two heterozygous organisms RrYy,
The probability of getting wrinkled seeds (rr) 1⁄2 (male parent) X 1⁄2 (female parent) = 1⁄4
The probability of getting green seeds (yy) 1⁄2 (male parent) X 1⁄2 (female parent) = 1⁄4
What is the probability of getting wrinkled green seeds?
Mendel made a lot of assumptions that do not always hold
true, which of the following are the false assumptions Mendel made? (select all that apply)
There are no environmental effects
Each trait is specified by a single gene with two alternative alleles
Genes only affect one trait
Gene products act independently
In a hybrid, only one form of a gene, or an allele, is going to be apparent
The ability of
environmental effects to produce a range of
phenotypes for the same genotype is known as which of the following?
What is continuous variation?
Variation in a trait that occurs along a
continuum, often occurs when a trait is determined by more
than one gene.
A trait that is determined by the effects of
more than one gene; such a trait usually exhibits continuous
variation rather than discrete either–or values is called a __
quantitative trait
What is pleiotropy?
A condition in genetics where a single gene can only affect the physical appearance of an organism.
A condition in genetics where a single gene can only affect one trait or phenotype.
A condition in which an individual allele has more than one effect on production of the phenotype.
A condition in genetics where multiple genes can affect a single trait or phenotype.
What kind of effects occur when a single gene affects more than one trait?
Typically, the effect is codominance between two dominant traits, resulting in an abnormality
No effects occur
Usually one effect is a normal phenotypic code, and the other is a lethal developmental defect
Polygenic inheritance is altered causing a increase in bodily hormone production
Pleiotropic effects are characteristic of many inherited disorders in
humans, which of the following are the most common? (select all that apply)
Cystic fibrosis
Type 1 diabetes
Hemophilia
Sickle cell anemia
What can the multiple symptoms (phenotype) be traced back to which of the following?
A single
gene defect
True or false: A diploid individual can carry only two alleles for a gene, but
there many be more than two alleles in a population
True
False
Incomplete dominance describes a case in which two or more
alleles of a gene do not display clear dominance, the phenotype
of a heterozygote is intermediate between the homozygous
forms.
Which of the following is an example of incomplete dominance?
Crossing red flowers with white flowers yields pink
heterozygotes.
Describe codominant alleles.
A case in which two or more
alleles of a gene are each dominant to other alleles but not to each other.
Explain the difference in appearance of a heterozygote for codominance and incomplete dominance.
The heterozygote for codominance has some aspects of both traits, while the heterozygote for incomplete dominance will have an intermediate phenotype.
The gene that determines ABO blood types encodes an enzyme
that adds sugar molecules to proteins on the surface of red
blood cells that act as ___ ___ for the immune system.
recognition markers
What are the three common alleles for the gene that
encodes the enzyme involving ABO blood types?
IA
IB
i
IC
A set of four phenotypes produced by different
combinations of three alleles at a single locus; blood types are A, B,
AB, and O, depending on which antigens are on the red blood cell
surface is known as which of the following groups?
ABO blood group
What are the four phenotypes of the ABO blood system?
Type A individuals add only galactosamine,
Type B individuals add only galactose, Type AB individuals add neither galactosamine and galactose, Type O individuals add both sugar
Type A individuals don't add galactosamine,
Type B individuals add only galactose, Type AB individuals add both galactosamine and galactose, Type O individuals add both sugar
Type A individuals add only galactosamine,
Type B individuals add only galactose, Type AB individuals add both galactosamine and galactose, Type O individuals add neither sugar
Type A individuals add only galactosamine,
Type B individuals don't add galactose, Type AB individuals add neither galactosamine or galactose, Type O individuals add neither sugar
Why is O blood considered the "universal" donor?
There are is both galactose and galactosamine present in O blood
There is the perfect amount of B antigen on the red blood cells.
There are no galactose or galactosamine antigens, causing no immune reactions
