1.
The chemicals that produce instructions on each gene are:
Correct Answer
C. Four bases
Explanation
Genes are made up of DNA, which consists of sequences of four different bases: adenine (A), cytosine (C), guanine (G), and thymine (T). These bases act as the chemical instructions that determine the genetic code. Therefore, the correct answer is "four bases."
2.
The full set of genes that is the instructions to make a living organism is called:
Correct Answer
D. Genome
Explanation
The term "genome" refers to the complete set of genes or genetic material present in an organism. It includes all the instructions required for the development, functioning, and reproduction of that organism. DNA, on the other hand, is the molecule that carries the genetic information within the genome. Genotype refers to the specific combination of genes an organism possesses, while gamete refers to the reproductive cells involved in sexual reproduction. Therefore, "genome" is the correct answer as it encompasses the entire set of genetic instructions.
3.
The human genome contains about ______ on _____.
Correct Answer
B. 25,000 genes; 46 chromosomes
Explanation
The human genome contains approximately 25,000 genes, which are segments of DNA that code for proteins and play a role in determining an individual's traits and characteristics. These genes are located on the 46 chromosomes found in human cells, with each chromosome containing numerous genes. The number of genes and chromosomes in the human genome is important for understanding the complexity and diversity of human biology.
4.
What is formed when a sperm cell and an ovum fuse?
Correct Answer
A. Zygote
Explanation
When a sperm cell and an ovum fuse, they form a zygote. The zygote is the initial stage of a new organism's development, resulting from the combination of genetic material from both parents. It is the first cell of a new individual and will undergo cell division to eventually develop into an embryo and then a fetus. The zygote contains all the genetic information necessary for the development of a new organism.
5.
Because of cultural preferences, women have sometimes looked for ways to alter the sex of their embryos. Which of the following is true?
Correct Answer
D. No post-conception diet or action can alter the sex of an embryo
Explanation
The correct answer is that no post-conception diet or action can alter the sex of an embryo. This means that regardless of what a woman eats or how she sleeps, it will not have any impact on the sex of the embryo. The sex of the embryo is determined by the genetic material provided by the parents at the time of conception. Cultural preferences or beliefs may lead some women to seek ways to alter the sex of their embryos, but scientifically, it is not possible.
6.
If a zygote has the genes for "musical genius," which is true?
Correct Answer
C. Additional genes and factors in the environment may result in the development of a trait for musical genius
Explanation
The presence of genes for "musical genius" in a zygote does not guarantee that the individual will become a musical genius. The development of a trait is influenced by both genetic factors and environmental factors. Therefore, additional genes and factors in the environment may contribute to the development of a trait for musical genius. This means that other factors such as upbringing, education, and practice can also play a role in determining whether the individual will actually become a musical genius.
7.
_____ refers to traits that are affected by many genes, and _____refers to traits that are influenced by many factors.
Correct Answer
B. Polygenic; multifactorial
Explanation
Polygenic traits are those that are influenced by multiple genes. This means that the phenotype of the trait is determined by the combined effects of many different genes. On the other hand, multifactorial traits are influenced by a variety of factors, including both genetic and environmental factors. Therefore, the correct answer is "Polygenic; multifactorial".
8.
When a pair of alleles interact, the resulting phenotype reveals the influence of one allele more than that of the other allele. This pattern is called:
Correct Answer
B. A dominant-recessive pattern
Explanation
When a pair of alleles interact, the resulting phenotype reveals the influence of one allele more than that of the other allele. This pattern is called a dominant-recessive pattern. In this pattern, the dominant allele is expressed and determines the phenotype, while the recessive allele is masked and does not have a visible effect on the phenotype. This is a fundamental concept in genetics, where dominant alleles are represented by uppercase letters and recessive alleles by lowercase letters. This pattern helps explain why certain traits are more common in populations, as dominant alleles are more likely to be expressed and passed on to future generations.
9.
Most recessive genes on a male's X chromosome are expressed because:
Correct Answer
D. The X-linked allele is not paired with any allele on the Y chromosome
Explanation
The correct answer is that the X-linked allele is not paired with any allele on the Y chromosome. This is because males have one X chromosome and one Y chromosome, while females have two X chromosomes. Therefore, any allele on the X chromosome in males does not have a corresponding allele on the Y chromosome to pair with, resulting in the expression of most recessive genes on the X chromosome.
10.
Monozygotic twins, Randy and Rowdy, originated from the same zygote and therefore have identical genes. They have many similarities, but what explains the differences in their height, weight, and behavior?
Correct Answer
D. Something in one of the boy's environment affected his genes differently than his brother
Explanation
The differences in height, weight, and behavior between monozygotic twins Randy and Rowdy cannot be solely attributed to their genes since they share identical genes. Therefore, the most plausible explanation is that something in one of the boys' environment affected his genes differently than his brother. This suggests that external factors such as nutrition, lifestyle, or experiences might have influenced the expression of certain genes, leading to the observed differences in height, weight, and behavior.
11.
The process by which ova are surgically removed from a woman, and then mixed with sperm to produce a zygote, which then is inserted into the uterus, is called:
Correct Answer
A. In vitro fertilization
Explanation
In vitro fertilization is the correct answer because it accurately describes the process of surgically removing ova from a woman, combining them with sperm to create a zygote, and then implanting the zygote into the uterus. This method is commonly used to assist couples with fertility issues and help them conceive a child. Amniocentesis is a different medical procedure used to collect amniotic fluid for genetic testing during pregnancy. Cloning and stem cell research are unrelated to the process of fertilization.
12.
Multiple births from the implantation of more than one zygote may cause:
Correct Answer
D. All of the answers are correct
Explanation
Multiple births from the implantation of more than one zygote can cause various complications for both the mother and the babies. The mother may experience high blood pressure and toxemia, which are conditions that can be harmful to her health. The babies born from multiple births are more likely to be underweight and premature, which can increase their risk of health issues and developmental delays. Additionally, multiple births are associated with higher rates of early death, disease, and disabilities in the babies. Therefore, all of the answers provided are correct in highlighting the potential consequences of multiple births.
13.
Schizophrenia is a result of:
Correct Answer
B. Both gene-gene and gene-environment interaction
Explanation
Schizophrenia is believed to be a complex disorder that results from a combination of genetic and environmental factors. The answer "both gene-gene and gene-environment interaction" suggests that the development of schizophrenia involves interactions between multiple genes as well as interactions between genes and the environment. This means that both genetic predisposition and environmental triggers play a role in the manifestation of schizophrenia. It is important to note that poor parenting or environment alone is not considered the sole cause of schizophrenia, but rather factors that contribute to the overall risk.
14.
Which statement is true?
Correct Answer
C. Without genes, no behavior could exist and without environment, no gene could be expressed
Explanation
This statement explains the interplay between genes and the environment in shaping behavior. It suggests that genes are necessary for behavior to exist, but they need an environment to be expressed. This implies that both genetic factors and environmental factors contribute to the development of behavior.
15.
Approximately _____ percent of twins are dizygotic
Correct Answer
B. 66
Explanation
Approximately 66 percent of twins are dizygotic. This means that 66 percent of twins are fraternal twins, resulting from the fertilization of two separate eggs by two separate sperm. Dizygotic twins can be of the same or different sexes and share, on average, 50 percent of their genetic material. This is in contrast to monozygotic twins, who are identical twins that result from the fertilization of a single egg that splits into two embryos.
16.
Based on recent research on twins and siblings, scientists now conclude that:
Correct Answer
A. Children and adults choose environments that are compatible with their genes and that genetic influences increase in adulthood
Explanation
The given answer suggests that based on recent research on twins and siblings, scientists have concluded that children and adults have a tendency to choose environments that are compatible with their genes. Additionally, it states that genetic influences tend to increase in adulthood. This implies that individuals may be more likely to seek out and thrive in environments that align with their genetic predispositions.
17.
If one monozygotic twin is nearsighted, the other twin
Correct Answer
C. Will have a 90% chance of being nearsighted
Explanation
Monozygotic twins, also known as identical twins, originate from a single fertilized egg and therefore share the same genetic makeup. Nearsightedness, or myopia, has been found to have a genetic component. Studies have shown that if one monozygotic twin is nearsighted, the other twin is likely to also be nearsighted. However, the exact probability may vary. The given answer suggests that there is a 90% chance of the other twin being nearsighted, indicating a high likelihood of the trait being inherited.
18.
Mrs. Lara wants to prevent her 5-year old daughter from developing the genetic family trait of type 2 diabetes. What should she do?
Correct Answer
D. All of the answers are correct
Explanation
Mrs. Lara should do all of the mentioned actions to prevent her daughter from developing type 2 diabetes. Monitoring her daughter's weight is important because obesity is a risk factor for diabetes. Providing opportunities for outdoor play activities promotes physical activity, which helps in maintaining a healthy weight and reducing the risk of diabetes. Preparing healthy balanced meals ensures that her daughter consumes a nutritious diet, which is crucial for preventing diabetes. Therefore, all of these actions combined can help in preventing the genetic family trait of type 2 diabetes in her daughter.
19.
The variable that most often correlates with chromosomal abnormalities is:
Correct Answer
A. The age of the mother
Explanation
The age of the mother is the variable that most often correlates with chromosomal abnormalities. As women age, the risk of chromosomal abnormalities in their offspring increases. This is because the eggs a woman is born with age over time, and older eggs are more likely to have abnormalities in the chromosomes. On the other hand, the age of the father does not have as significant an impact on the risk of chromosomal abnormalities.
20.
Down syndrome is a condition in which an individual has 3 copies of:
Correct Answer
B. Chromosome 21
Explanation
Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. Individuals with Down syndrome have a total of 47 chromosomes instead of the usual 46. This extra chromosome affects the development and functioning of the body and brain, leading to characteristic physical features and intellectual disabilities.
21.
Which statement is true?
Correct Answer
C. Everyone is a carrier for genetic abnormalities, but usually these conditions are recessive
Explanation
This statement is true because everyone carries some genetic abnormalities, but most of these conditions are recessive, meaning that they are not expressed unless both parents pass on the abnormal gene. This is why genetic disorders are often seen in families with a history of the disorder. Additionally, it is not accurate to say that only men are carriers for genetic abnormalities or that women over the age of 35 produce abnormal ovum and are at risk of having unhealthy babies.
22.
An embryo cannot develop without
Correct Answer
A. An X chromosome
Explanation
An embryo cannot develop without an X chromosome because it is a crucial component for determining the sex of the individual. The presence of an X chromosome is necessary for the development of female characteristics, while the presence of a Y chromosome is necessary for the development of male characteristics. Without an X chromosome, the embryo would not have the necessary genetic information to develop into a viable individual.
23.
Who is more likely to be a carrier of an X-linked trait?
Correct Answer
A. A woman
Explanation
A woman is more likely to be a carrier of an X-linked trait because she has two X chromosomes. If she carries a recessive allele for the trait on one of her X chromosomes, she can still exhibit the dominant allele and not show any symptoms. However, she can pass on the recessive allele to her offspring, making them carriers or showing the trait if they inherit another recessive allele from the father. Men, on the other hand, only have one X chromosome, so if they carry the recessive allele, they will exhibit the trait. A colorblind man is an example of a man exhibiting an X-linked trait. A dizygotic twin does not have any relevance to being a carrier of an X-linked trait.
24.
In general, genetic counseling is recommended for:
Correct Answer
D. Women older than 34 and men older than 39
Explanation
Genetic counseling is recommended for women older than 34 and men older than 39 because advanced parental age increases the risk of genetic disorders in their offspring. As individuals age, the chances of genetic mutations and chromosomal abnormalities occurring in their reproductive cells also increase. Genetic counseling can help these individuals understand the potential risks and make informed decisions about family planning, including the option of undergoing genetic testing to assess the risk of passing on genetic conditions to their children.
25.
A genetic disorder that causes the inability to metabolize phenylalinine that may lead to brain damage and mental retardation is called
Correct Answer
B. pHenylketonuria
Explanation
Phenylketonuria is a genetic disorder that affects the body's ability to break down phenylalanine, an amino acid found in many foods. If left untreated, the buildup of phenylalanine can lead to brain damage and mental retardation. Hemophilia is a blood disorder that affects the body's ability to clot blood. Pyloric stenosis is a condition that affects the opening between the stomach and small intestine. Thalassemia is a group of blood disorders that affect the production of hemoglobin.