| Multiple alleles are three or more alternative forms of a gene (alleles) that can occupy the same locus in a chromosome. | Multiple Alleles |
| What controls blood group in humans? | Blood group in humans is controlled by multiple alleles. |
| Codominance occurs when two different alleles of a gene are both expressed in the phenotype, resulting in a phenotype that shows both traits. | Codominance |
| What is codominance? | Codominance is when two different alleles of a gene are both expressed in the phenotype. |
| Alleles are different forms of the same gene, which occupy the same locus or position on a chromosome. | Alleles |
| How many possible alleles control blood group in humans? | There are three possible alleles for blood group in humans: IA, IB, and IO. |
| Codominant alleles are alleles that are both expressed in the phenotype when present together, with neither being dominant over the other. | Codominant Alleles |
| What is the relationship between IA and IB alleles? | IA and IB alleles are codominant, meaning no one allele is dominant over the other, and they are both expressed in the phenotype. |
| Blood group AB is a blood type where both IA and IB alleles are present, resulting in the codominant expression of both alleles. | Blood Group AB |
| What blood group phenotype results from having both IA and IB alleles? | The blood group phenotype AB results from having both IA and IB alleles. |
| Blood group A is a blood type where the IA allele is present, either alone or with an IO allele, resulting in the A antigen being expressed on the surface of red blood cells. | Blood Group A |
| What blood group phenotype results from having an IA allele and an IO allele? | The blood group phenotype A results from having an IA allele and an IO allele. |
| Blood group O is a blood type where both alleles are IO, resulting in the absence of A and B antigens on the surface of red blood cells. | Blood Group O |
| When is the IO allele expressed in the blood group phenotype? | The IO allele is expressed in the blood group phenotype only if two copies of it are inherited (recessive), one from each parent, resulting in blood group O. |
| How many possible blood group phenotypes exist in humans? | There are four possible blood group phenotypes in humans: A, B, AB, and O. |
| Conditions caused by abnormalities in an individual's genetic material. | Genetic Disorders |
| What causes most genetic disorders? | Most genetic disorders are caused by recessive alleles. |
| Alleles that are masked by dominant alleles and only expressed when present in two copies. | Recessive Alleles |
| How many copies of a recessive allele are usually needed to have a genetic disorder? | Usually, a person needs to inherit 2 copies of the recessive allele to have the disorder. |
| Genetic disorders caused by alleles on the sex chromosomes (X and Y). | Sex-Linked Genetic Disorders |
| What chromosomes are involved in sex-linked genetic disorders? | Sex chromosomes (X and Y). |
| One of the two sex chromosomes, responsible for carrying genes that are not related to sex determination. | X Chromosome |
| How many X chromosomes do females have? | Females have 2 X chromosomes (XX). |
| The sex chromosome found in males, responsible for determining male sex characteristics. | Y Chromosome |
| What chromosomes do males have? | Males have an X and a Y chromosome (XY). |
| The number of genes present in a given length of DNA. | Gene Density |
| Why are there fewer genes on the Y chromosome compared to the X chromosome? | The Y chromosome is smaller than the X chromosome. |
| How can males suffer from a sex-linked genetic disorder with only one allele? | Males can inherit just one allele for a sex-linked genetic disorder on the X chromosome. |
| The phenomenon where one allele hides the effect of another allele. | Masking Effect |
| Why are genetic disorders usually more common in males? | Genetic disorders are usually more common in males because there is no corresponding allele on the smaller Y chromosome that could "mask" the recessive allele. |
