Biology Chapter 6 And 7 Test

A carrier is an individual who does not exhibit any symptoms of a disease or condition, but carries a disease-causing allele and can pass it on to their offspring. This means that carriers possess the genetic mutation responsible for the disease, but do not experience any negative effects themselves. However, they can still transmit the allele to their children, who may then develop the disease. Carriers are important in understanding the inheritance patterns of genetic diseases and can play a significant role in the spread of certain conditions within a population.

A testcross is a breeding experiment performed to determine the genotype of an organism with a dominant phenotype. It involves crossing the organism with an individual that is homozygous recessive for the trait of interest. By observing the phenotypes of the offspring, the genotype of the unknown organism can be inferred. In this case, the correct answer, "testcross," accurately describes the process of crossing an organism with an unknown genotype with another organism displaying the recessive phenotype.

On page 168

A pedigree is a type of chart that displays the genetic information of a family, allowing for the tracing of phenotypes and genotypes. It is used to determine whether individuals carry recessive alleles, which are responsible for certain traits or conditions. By analyzing the relationships and patterns within a pedigree, geneticists can identify carriers of recessive alleles and assess the likelihood of passing on these traits to future generations.

When a heterozygous plant (Gg) is crossed with another heterozygous plant (Gg), there is a 25% chance of obtaining offspring with the genotype GG (green), a 50% chance of obtaining offspring with the genotype Gg (green), and a 25% chance of obtaining offspring with the genotype gg (yellow). Therefore, the most common phenotype and genotype among the offspring will likely be green (Gg).

A dihybrid Punnett square is used to determine the possible combinations of alleles for two different traits in offspring. Each trait has two possible alleles, and when crossing two individuals heterozygous for both traits, the Punnett square will have 4 rows and 4 columns. This results in a total of 16 inner squares in the Punnett square, representing all the possible genotypes of the offspring for both traits.

Sex-linked disorders are genetic conditions that are linked to the sex chromosomes, specifically the X chromosome. Males have one X and one Y chromosome, while females have two X chromosomes. Since the genes responsible for sex-linked disorders are located on the X chromosome, males have a higher chance of inheriting these disorders. This is because if a male inherits a defective X chromosome, he does not have a second X chromosome to compensate for the defect. In contrast, females have two X chromosomes, so even if one is defective, the other X chromosome can often compensate for the defect. Therefore, it is true that males have a higher chance of inheriting sex-linked disorders.

Each parent contributes one set of chromosomes to each offspring. This is because during sexual reproduction, each parent donates one set of chromosomes to the offspring. In mice, like in most organisms, the offspring receive half of their DNA from the mother (via the egg) and half from the father (via the sperm). Therefore, in the resulting offspring, half of the DNA comes from type A and half comes from type B.

Epistasis refers to the interaction between different genes where the expression of one gene is dependent on the presence or absence of another gene. It is not the term used to describe traits produced by multiple genes. Therefore, the statement that traits produced by two or more genes are called Epistasis is false.

This statement is true because dominance and recessiveness are relative terms. An allele can be dominant to one allele if it is able to express its traits in the presence of that allele. However, the same allele can be recessive to another allele if it is unable to express its traits in the presence of that allele. Therefore, an allele can exhibit both dominant and recessive characteristics depending on the specific alleles it is being compared to.

The correct answer is that the genes are far enough apart to allow crossing over. Crossing over is a process that occurs during meiosis, where genetic material is exchanged between homologous chromosomes. If the two traits are not always inherited together, it suggests that crossing over has occurred between the genes on the chromosome, leading to a recombination of the traits. This implies that the genes must be far enough apart to allow for this exchange of genetic material to happen.

On page 185

A karyotype refers to a picture of all of the chromosomes in a cell. It provides a visual representation of an individual's chromosomes, arranged in pairs according to size and structure. This allows for the identification of any abnormalities or mutations in the chromosomes, such as deletions or rearrangements. By analyzing a karyotype, geneticists can diagnose genetic disorders and determine the sex of an individual.

Incomplete dominance occurs when neither trait is fully expressed, but instead a blend of the two traits is observed. This means that the correct answer is False, as the statement implies that both traits are fully and separately expressed, which is not the case in incomplete dominance.

This statement is incorrect. Males cannot be carriers of sex-linked disorders because they only have one copy of the X chromosome. In sex-linked disorders, the gene responsible for the disorder is located on the X chromosome. Females have two X chromosomes, so they can be carriers of sex-linked disorders even if they do not show any symptoms. However, males who inherit the faulty gene on their single X chromosome will typically exhibit the symptoms of the disorder.

The correct answer is BB. This is because all of the offspring from Bob and Bobelina were blue eyed. Since blue eye color is a recessive trait, both Bob and Bobelina must have had the genotype BB, as they could only pass on the blue eye allele. If either of them had the genotype Bb or bb, there would have been a chance of producing green eyed offspring. Therefore, the genotype of Bob is BB.

Thomas Hunt Morgan is the correct answer because he is well-known for his work with fruit flies, specifically the study of their inheritance patterns. Morgan's experiments with fruit flies provided important insights into genetics and helped establish the chromosome theory of inheritance. His research on fruit flies laid the foundation for modern genetics and earned him the Nobel Prize in Physiology or Medicine in 1933.

Calico cats have different colors due to X-chromosome inactivation. In female mammals, one of the X chromosomes is randomly inactivated in each cell during early development. This results in patches of cells with either the orange or black color gene expressed, leading to the distinct color patterns seen in calico cats. This process is known as X-chromosome inactivation and is responsible for the variation in coat colors in these cats.

The Law of Segregation states that organisms inherit two copies of a gene, one from each parent. This means that individuals receive two alleles for each gene, and these alleles separate during the formation of gametes. Additionally, the Law of Segregation also states that organisms donate only one gene in their gametes, meaning that only one allele for each gene is passed on to the offspring.