Exploring Genetics: Key Concepts and Definitions Quiz

Dominant alleles are always fully expressed whenever they are present. In the case of freckles, even if an individual carries one dominant freckles allele and one recessive non-freckles allele, they will still have freckles because the dominant allele is fully expressed.

A genotype refers to the genetic makeup of an organism, encompassing the combination of alleles present in an individual. It does not refer to the physical characteristics, environmental factors, or gene locations.

A heterozygote refers to an individual who has two different alleles for one gene, usually represented as a capital letter and a lowercase letter (e.g. Bb). This allows for variations in genetic traits.

Homozygous refers to having two identical alleles for a specific trait. In genetics, an individual can be homozygous dominant (two dominant alleles) or homozygous recessive (two recessive alleles).

Polygenic inheritance refers to the situation where multiple genes contribute to the expression of a single trait, leading to a wide range of phenotypic possibilities.

Pleiotropy refers to a single gene having multiple effects on the body, which can manifest in various ways. An example of pleiotropy is sickle-cell anemia, where one gene mutation leads to multiple symptoms and complications.

A phenotype refers to observable characteristics such as blue eyes, height, or physical features, which are the result of an individual's genetic makeup and interactions with the environment.

A recessive allele is one whose effects are only seen when an individual has two copies of that allele (homozygous recessive). In a heterozygote (one dominant and one recessive allele), the effects of the recessive allele are masked.

A sex-influenced trait is a trait in which the expression of certain genes on autosomal chromosomes is influenced by sex hormones, leading to different phenotypic outcomes in males and females. An example of a sex-influenced trait is male pattern baldness, which is influenced by sex hormones and is more commonly seen in males.

X-linked genes are genes that are located on the X chromosome and have no corresponding gene on the Y chromosome. This leads to unique patterns of inheritance, especially in males who have only one X chromosome. Colorblindness is an example of a trait that is often associated with X-linked genes.

Linked genes refer to genes that are located on the same chromosome and tend to be inherited together during meiosis. Unlinked genes, unassociated genes, and distant genes do not have the same close physical proximity on a chromosome as linked genes.

Amniocentesis is a procedure performed during pregnancy to collect cells from the amniotic fluid surrounding the fetus. It is typically done around 14-18 weeks gestation to examine the fetal cells for chromosomal abnormalities and determine the sex of the baby.

Amniocentesis is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections. It does not determine the sex of the baby accurately. Developing a skin infection at the needle insertion site is not a common risk associated with amniocentesis. While amniocentesis is generally considered safe, there are risks involved, such as the needle puncturing the fetus or umbilical cord, and the possibility of miscarriage from removing amniotic fluid.

The correct answer explains what CVS is in the context of pregnancy and medical procedures. The incorrect answers provide other potential interpretations of CVS in different fields.

Chorionic villus sampling (CVS) is a prenatal test that can be performed earlier in pregnancy than amniocentesis, but it is associated with a higher risk of miscarriage. The incorrect answers provide other aspects that are not necessarily true for CVS.

An allele is a variant form of a gene that is located at a specific position on a specific chromosome. Inheritance of alleles from parents determines an individual's traits.

A heterozygous genotype consists of two different alleles for a particular gene, one dominant and one recessive. In this case, the correct answer 'Bb' represents a heterozygous genotype with one dominant allele (B) and one recessive allele (b). The incorrect answers 'BBb', 'bbc', and 'bbd' do not represent a heterozygous genotype as they either have duplicate dominant alleles or different combinations that are not characteristic of heterozygosity.

A phenotype refers to the observable characteristics or traits of an organism, such as its physical appearance. In this case, 'light blue' describes a specific phenotype that can be observed.

The correct way to determine the phenotype of someone's eye color is by visually looking at them.

When crossing a homozygous recessive with a heterozygous individual, the Punnett square shows that half of the offspring will be heterozygous and half will be homozygous recessive. This is due to the fact that one parent carries two copies of the recessive allele, while the other parent carries one copy of the recessive allele and one copy of the dominant allele.

Chromosomes that are not X or Y are known as autosomal chromosomes, which contain genes responsible for most of an individual's inherited traits.

The parents must both be carriers of the Tay-Sachs allele (Tt) in order to have a child with Tay-Sachs disease.

Rh incompatibility occurs when the mother is Rh- and the father is Rh+. In this case, if the father is heterozygous (possesses one Rh+ and one Rh- allele), there is a chance that the second child may also be Rh+. Therefore, problems are possible in this scenario.

When two individuals who are heterozygous for tongue rolling ability have a child, there is a 50% chance that the child will inherit one dominant allele for tongue rolling, resulting in them being able to roll their tongue.

The offspring will inherit one blood type allele from each parent, resulting in a type A or B blood type.

When both parents have unattached earlobes and had a child with attached earlobes, it means they both carry the recessive allele. Therefore, there is a 25% chance that their next child will have attached earlobes.

Codominance is the expression of both alleles in a heterozygote, resulting in a unique phenotype that shows the traits of both alleles. In the case of the AB blood type, individuals have both A and B antigens on their red blood cells, demonstrating codominance.

Height is a complex trait influenced by multiple genes, making it more likely to be polygenic rather than controlled by a single gene or hormone. Sex-linked inheritance and taking growth hormones do not necessarily relate to the variation in height among Alicia's classmates. Additionally, the statement that tallness is dominant to shortness oversimplifies the inheritance of height, which is typically influenced by multiple genetic and environmental factors.

Crossing over is a process during meiosis where homologous chromosomes exchange genetic material, leading to new combinations of alleles. This can disrupt the normal linking pattern of genes by breaking apart linked genes and creating new linkages.