1.
Twin colts were born from a black mare
and a black stallion. One colt was black,
and one was brown. The colts have
different traits because their DNA contains
Correct Answer
B. Different arrangements of nucleotides
Explanation
The colts have different traits because their DNA contains different arrangements of nucleotides. Nucleotides are the building blocks of DNA, and the order in which they are arranged determines the genetic information and characteristics of an organism. The different arrangements of nucleotides in the colts' DNA would result in variations in the genes and proteins produced, leading to differences in their traits such as coat color.
2.
In guinea pigs, the allele for a rough coat (R)
is dominant over the allele for a smooth coat
(r). A heterozygous guinea pig and a
homozygous recessive guinea pig is
mated.
Which of the following would be the
phenotypes of the offspring?
Correct Answer
C. 2 rough coat and 2 smooth coat
Explanation
When a heterozygous guinea pig (Rr) is mated with a homozygous recessive guinea pig (rr), the offspring will inherit one allele from each parent. Since the allele for a rough coat (R) is dominant over the allele for a smooth coat (r), the offspring will have a 50% chance of inheriting the rough coat allele from the heterozygous parent and a 50% chance of inheriting the smooth coat allele from the homozygous recessive parent. Therefore, the phenotypes of the offspring will be 2 rough coat and 2 smooth coat.
3.
Which choice represents a dihybrid cross?
Correct Answer
B. RRYy x RrYY
Explanation
A dihybrid cross is a cross between two individuals that are heterozygous for two different traits. In the given answer, RRYy x RrYY, both parents are heterozygous for two traits (Rr and Yy), making it a dihybrid cross.
4.
A particular variety of corn can produce
yellow or white seeds. Yellow is dominant.
White is recessive.
If a particular ear of corn contains ONLY
white corn, it must be —
Correct Answer
A. Homozygous for white color
Explanation
If a particular ear of corn contains ONLY white corn, it must be homozygous for white color. This means that both alleles for color in the corn are the recessive white alleles. If it were heterozygous for white color, it would have both dominant yellow alleles and recessive white alleles, resulting in a yellow color. Similarly, if it were heterozygous for yellow color, it would have both recessive white alleles and dominant yellow alleles, resulting in a yellow color. Therefore, the only possibility for a corn ear containing only white corn is that it is homozygous for white color.
5.
The Punnett square above shows a cross between a homozygous dominant genotype for haircolor and a heterozygous genotype for hair color. Which conclusion can be drawn from thePunnet square above?
Correct Answer
D. All of the offspring will have the same hair color.
Explanation
The Punnett square shows that both parents have at least one dominant allele for hair color. Since dominant alleles always express their trait, all of the offspring will inherit the dominant allele for hair color from at least one parent. Therefore, all of the offspring will have the same hair color.
6.
In a particular population of bees, longwings are dominant over short wings.Which of the following must be TRUE aboutthe genetic material that produced a beewith long wings?
Correct Answer
D. Heterozygous for long wings OR
homozygous for long wings
Explanation
If long wings are dominant over short wings in a population of bees, then a bee with long wings can either be heterozygous for long wings (meaning it has one dominant allele for long wings and one recessive allele for short wings) or homozygous for long wings (meaning it has two dominant alleles for long wings). Both of these possibilities would result in the bee having long wings.
7.
Having freckles is a dominant trait inhumans. Kimberly has freckles, but herbrother, Hugo, does not. What must herparents’ genotypes be for this to bepossible?
Correct Answer
C. Ff and Ff
Explanation
If having freckles is a dominant trait in humans, then it means that only one copy of the gene is needed to express the trait. Since Kimberly has freckles and her brother Hugo does not, this suggests that their parents must both be carriers of the freckles gene. The genotype Ff indicates that they each have one copy of the freckles gene and one copy of the non-freckles gene.
8.
Edwards Syndrome is a serious condition
causing 10% of those born with it to die
within their first year. The cause is trisomy
18, the presence of three chromosome
18s. All children with this condition are
mentally retarded and suffer with breathing
problems and possible seizures. The
technique for diagnosing Edwards
Syndrome involves a series of steps:
obtaining cells from the individual, staining
chromosomes from the cells; identifying
chromosomes by their size and staining
patterns, and rearranging, grouping, and
sequencing the autosomes in order of
decreasing length. This method of
diagnosis is a form of —
Correct Answer
B. Karyotyping
Explanation
The technique described in the passage involves obtaining cells from the individual, staining chromosomes, and identifying them based on their size and staining patterns. This process is known as karyotyping, which is a method used to analyze the chromosomes in a sample. It allows for the detection of abnormalities, such as trisomy 18 in Edwards Syndrome, by examining the number, size, and structure of the chromosomes. Genetic modification, DNA fingerprinting, and genetic transformation are not mentioned or relevant to the process described in the passage.
9.
In cattle, the allele for short horns (S) isdominant over the allele for long horns(s). Two shorthorn cows are bred andproduce four offspring. Three have shorthorns and one has long horns.Which of the following is the MOST likelycombination of genotypes in theseoffspring?
Correct Answer
B. 1 SS, 2 Ss, and 1 ss
Explanation
In this scenario, the allele for short horns (S) is dominant over the allele for long horns (s). When two short-horn cows (SS) are bred, they can pass on either the S allele or the s allele to their offspring. The combination of genotypes that is most likely to occur in the offspring is 1 SS (both parents pass on the S allele), 2 Ss (one parent passes on the S allele and the other passes on the s allele), and 1 ss (both parents pass on the s allele). This combination accounts for the three offspring with short horns and one offspring with long horns.
10.
What determines the traits of an
organism?
Correct Answer
D. Sequence of nitrogen bases in DNA
Explanation
The traits of an organism are determined by the sequence of nitrogen bases in DNA. DNA contains the genetic information that codes for the production of proteins, which ultimately determine an organism's traits. The sequence of nitrogen bases in DNA forms the genetic code, which is translated into specific proteins through the process of transcription and translation. Different sequences of nitrogen bases result in different proteins being produced, leading to variations in traits among organisms.
11.
The DNA regions that code for proteinsare —
Correct Answer
B. Exons
Explanation
Exons are the DNA regions that code for proteins. They are the segments of DNA that are transcribed into mRNA and eventually translated into proteins. Introns, on the other hand, are non-coding regions of DNA that are removed during RNA processing. Promoters are DNA sequences that signal the start of transcription. Polymerase refers to the enzyme responsible for catalyzing the synthesis of RNA from a DNA template.
12.
Compared with mitosis, the process ofmeiosis results in —
Correct Answer
C. Greater number of daughter cells
Explanation
The process of meiosis results in a greater number of daughter cells compared to mitosis. During meiosis, a single cell divides twice, resulting in the formation of four daughter cells. In contrast, mitosis only produces two daughter cells. Therefore, meiosis leads to a greater number of daughter cells.
13.
In cellular reproduction, which of thefollowing processes occurs thesame number of times in meiosis as itdoes in mitosis?
Correct Answer
B. The DNA in the chromosomes is
duplicated.
Explanation
In both meiosis and mitosis, the DNA in the chromosomes is duplicated. This process is known as DNA replication. During DNA replication, the double-stranded DNA molecule unwinds and each strand serves as a template for the synthesis of a new complementary strand. This results in two identical copies of the DNA molecule. In both meiosis and mitosis, this duplication of DNA is essential for the proper distribution of genetic material to the daughter cells.
14.
Meiosis plays a more significant role inreproduction than mitosis in which of thefollowing?
Correct Answer
A. Increasing the variability of genetic
information
Explanation
Meiosis plays a more significant role in increasing the variability of genetic information compared to mitosis. During meiosis, genetic material is shuffled and recombined through processes such as crossing over and independent assortment, leading to the creation of genetically diverse gametes. This genetic diversity is crucial for sexual reproduction, as it allows for the combination of different alleles and the creation of offspring with unique genetic traits. In contrast, mitosis is a process of cell division that produces genetically identical daughter cells, which is important for growth, repair, and asexual reproduction.
15.
When one or more nucleotides are lostduring chromosomal crossover in meiosis,this is called —
Correct Answer
A. Deletion mutation
Explanation
During chromosomal crossover in meiosis, if one or more nucleotides are lost, this is referred to as a deletion mutation. This type of mutation involves the removal of nucleotides from the DNA sequence, which can result in a shift or loss of genetic information. Deletion mutations can have significant effects on the resulting protein or gene function, leading to various genetic disorders or diseases.
16.
This diagram illustrates ______ which occurs during _____.
Correct Answer
C. Crossing over, meiosis
Explanation
This diagram illustrates crossing over which occurs during meiosis. During meiosis, homologous chromosomes exchange genetic material through a process called crossing over. This results in genetic recombination and increases genetic diversity in the offspring.
17.
Refer to the diagram. What processoccurs at Y?
Correct Answer
D. Meiosis II
Explanation
At location Y, the process that occurs is Meiosis II. Meiosis is a type of cell division that results in the formation of gametes (sex cells) with half the number of chromosomes as the parent cell. Meiosis consists of two rounds of cell division, known as Meiosis I and Meiosis II. Meiosis II is the second round of division, where the sister chromatids are separated, resulting in the production of four haploid cells. This process is essential for sexual reproduction and the production of genetically diverse offspring.
18.
How many daughter cells result from aparent cell in meiosis?
Correct Answer
B. 4
Explanation
During meiosis, a parent cell undergoes two rounds of cell division resulting in the formation of four daughter cells. Each daughter cell contains half the number of chromosomes as the parent cell, allowing for genetic diversity. Therefore, the correct answer is 4.
19.
Which of the following BEST describesmeiosis?
Correct Answer
A. Cell division that occurs only in the
reproductive structures of an organism
Explanation
Meiosis is a type of cell division that occurs only in the reproductive structures of an organism. It is responsible for the formation of gametes (sperm and egg cells) in sexually reproducing organisms. During meiosis, the number of chromosomes is halved, resulting in the production of genetically diverse offspring. This process is essential for sexual reproduction and ensures genetic variation in a population.
20.
How does a stem cell become a nervecell, bone cell, or muscle cell?
Correct Answer
C. By expressing certain combinations of
genes and repressing others
Explanation
Stem cells have the ability to differentiate into various types of cells, such as nerve cells, bone cells, or muscle cells. This differentiation process is regulated by the expression and repression of specific combinations of genes. By activating certain genes and repressing others, stem cells can undergo the necessary changes to become specialized cells of different tissues. This gene regulation allows stem cells to develop into specific cell types with unique functions and characteristics.
21.
What technique is BEST for matchingevidence left at a crime scene with asuspect’s nasal swab?
Correct Answer
A. Gel electropHoresis
Explanation
Gel electrophoresis is the best technique for matching evidence left at a crime scene with a suspect's nasal swab because it allows for the separation and analysis of DNA fragments based on their size and charge. By comparing the DNA profiles obtained from the crime scene evidence and the suspect's nasal swab, gel electrophoresis can determine whether there is a match or not. This technique is commonly used in forensic science to provide valuable evidence in criminal investigations.
22.
Which of the following represents thegenotype of offspring Ttrr?
Correct Answer
A. Heterozygous tall, homozygous
wrinkled
Explanation
The genotype of offspring Ttrr represents a combination of two alleles for two different traits. The first allele, T, represents the gene for tall height, and the second allele, r, represents the gene for wrinkled seeds. The lowercase letters indicate recessive traits, while the uppercase letters indicate dominant traits. Therefore, the genotype Ttrr means that the offspring is heterozygous for the tall trait (one dominant allele and one recessive allele) and homozygous for the wrinkled trait (two recessive alleles).
23.
What is the appearance of offspring X?
Correct Answer
D. Tall, wrinkled
Explanation
Offspring X is tall and wrinkled. This can be inferred from the given options where the appearance of offspring X is described as "tall, wrinkled".
24.
What is the correct genetic combinationof offspring X?
Correct Answer
B. Tr x Tr
Explanation
The correct genetic combination of offspring X is Tr x Tr. This means that both parents have the genotype Tr, and the offspring will inherit one copy of the Tr allele from each parent.
25.
What, if anything, is wrong with the patient below?
Correct Answer
B. Abnormal; missing a sex chromosome; has Turner's syndrome
Explanation
The patient is described as "abnormal" and "missing a sex chromosome," which indicates that there is a genetic abnormality present. This condition is specifically identified as Turner's syndrome, which is characterized by the absence of one of the sex chromosomes (typically an X chromosome in females). Turner's syndrome can result in various physical and developmental abnormalities, such as short stature, infertility, and certain heart and kidney problems.
26.
In snap peas, yellow flowers (Y) are dominant to white flowers (y). If a homozygous dominant yellow flower is crossed with a heterozygous yellow flower, what would be the genotypic ratio of the F1 generation?
Correct Answer
A. 1:1
Explanation
When a homozygous dominant yellow flower (YY) is crossed with a heterozygous yellow flower (Yy), the possible genotypes of the F1 generation are YY and Yy. Therefore, the genotypic ratio of the F1 generation would be 1:1.
27.
Analyze the pedigree below.What are the genotypes of the grandparents?
Correct Answer
B. Both heterozygous
Explanation
Based on the information provided, the grandparents have both heterozygous genotypes. This means that they have one dominant allele and one recessive allele for the specific trait being analyzed.
28.
Analyze the pedigree below.How many offspring did the second generation have and what were the genders of the offspring?
Correct Answer
C. 4 total; 3 male, 1 female
Explanation
In the given pedigree, the second generation had a total of 4 offspring. Out of these, 3 were male and 1 was female.