| Question | Answer |
| Why does each nucleus of all human cells except gametes contain 23 homologous pairs of chromosomes? | One chromosome of each pair comes from the father, the other comes from the mother. Each pair contains the same genes, just different forms. |
| Tool used to show possible combinations of alleles in offspring of parents whose genotype for a gene is known. | Punnet square. |
| Genetic makeup (combination of alleles for a gene). | Genotype |
| Example of additional chromosomes. | Down syndrome. Trisomy 21. Presence of all or part of an extra 21st chromosome. |
| Where do sex-linked inheritance genes reside? | On the X chromosome. |
| What are the alternative forms of a gene that code for the same trait called? | Allele |
| Inheritance where dominant allele masks the effect of recessive allele. | Simple dominance-recessive. |
| Inheritance where one gene does not control inherited trait. Common? | Polygenic inheritance applies to most inherited traits. |
| What do you call a permanent heritable change in an allele that produces a different variant. | Mutation |
| What percentage of zygotes formed from 2 heterozygous parents would express the recessive allele? | 25% |
| Expression of ones genetic makeup (appearance). | Phenotype |
| The same alleles for a gene. Two types. | Homozygous dominant or homozygous recessive. |
| PKU | PKU or Phenylkeonuria:an inherited disease where the recessive allele fails to produce the functional enzyme phenylalanine hydrozylase. The dominant allele produces the functional enzyme. |
| What type of sex chromosome does a sperm carry? Ova? | Each sprem has either an X or Y. Each ova has an X chromosome. |
| Term for the combined effects of many genes and environmental factors. Examples of such traits. | Complex inheritance. Skin color (sun exposure, nutrition, 3 genes), hair color, height (nutrition), metabolism rate, body build (nutrition), neural tube deficits (inadequate folic acid in mother). |
| What determines a female pattern of development? Male pattern of development? When does this pattern begin? | Female- absence of Y. Male- initiated by Y. Embryos identical until about 7 weeks. |
| What percentage of zygotes formed from 2 heterozygous parents would produce homozygous genotypes? | 50% |
| The number and appearance of chromosomes in the nucleus of a eukaryote cell. Also means the complete set of chromosomes in a species, or an individual organism. | Karyotype |
| Term for genes that have more than 2 alleles. Example. | Multiple-allele inheritance. ABO blood group has 3 alleles, with 4 phenotypes since A and B are co-dominant. |
| What is inheritance? | The passage of hereditary traits from one generation to the next. |
| Chromosomes that are not sex chromosomes. How many in a somatic cell? | Autosomes. 22 pairs. |
| What percentage of gametes produced by a heterozygous parent would contain the recessive allele? | 50% |
| Inheritance where neither allele is dominant over the other. What does the heterozygote have for a phenotype? Example? | Incomplete dominance. Heterozygote has intermediate phenotype. Ex: alleles that produce normal hemoglobin (Hb^A) and hemoglobin that causes sickle-cell disease (Hb^s). Hb^AHb^S phenotype is minor problems, and obviously a carrier. |
| Two different alleles for a gene. | Heterozygous. |
| Why are there more colorblind males than females? | The allele is found on the X chromosome and males only have one X chromosome, thus one allele. It is either for color blindness or not. Females have the option of being carriers, with both the recessive and dominant allele. |
| Example of disease caused by a dominant allele. What genotypes would get the disease? | Huntington disease. Both homozygous dominant and heterozygous individuals would get the disease. |
| What determines an individual's sex? | Whether the male gamete (sperm) that forms the zygote carries an X or a Y chromosome. |
| Abnormal number of chromosomes called what (4 total terms). Cause? | Nondisjunction caused by an error in cell division causes Aneuploid cells. Monosomic cells are missing 1 chromosome (2n-1). Trisomic cell has 1 additional chromosome (2n+1). |
