| A | B |
|---|
| What did Gregor Mendel do to study different characteristics in his genetics experiments? | He cross-pollinated plants. |
| In Mendel’s experiments, what proportion of the plants in the F2 generation had a trait that had been absent in the F1 generation? | one fourth, 25% |
| Which term refers to physical characteristics that are studied in genetics? | traits |
| Factors that control traits are called | genes. |
| Scientists call an organism that has two different alleles for a trait a | hybrid. |
| What does the notation AA mean to geneticists? | two dominant alleles |
| What does the notation Aa mean to geneticists? | one dominant allele and one recessive allele |
| The different forms of a gene are called | alleles. |
| What is probability? | a number that describes how likely it is that an event will occur |
| What is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea plants? | three in four |
| What does a Punnett square show? | What does a Punnett square show? |
| If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that an offspring will have black fur? | 100 percent |
| An organism’s physical appearance is its | phenotype. |
| An organism’s genotype is its | genetic makeup. |
| An organism that has two identical alleles for a trait is | homozygous. |
| A heterozygous organism has | two different alleles for a trait. |
| A purebred chicken with white feathers is crossed with a purebred chicken that has black feathers. Each of their offspring has both black and white feathers. Why does this happen? | The alleles for feather color are neither dominant nor recessive. |
| What is the chromosome theory of inheritance? | Genes are carried from parents to offspring on chromosomes. |
| Walter Sutton discovered that the sex cells of grasshoppers have | half the number of chromosomes found in the body cells. |
| What happens during meiosis? | Chromosome pairs separate and are distributed into new sex cells. |
| When sex cells combine to produce offspring, each sex cell will contribute | half the number of chromosomes in body cells. |
| Chromosomes are made up of | many genes joined together. |
| What determines the genetic code? | the order of nitrogen bases along a gene |
| The order of the bases along a gene determines the order in which | amino acids are put together to form a protein. |
| What does messenger RNA do during protein synthesis? | carries amino acids and adds them to the growing protein |
| What do transfer RNA molecules do during protein synthesis? | carry amino acids and add them to the growing protein |
| Where does protein synthesis take place? | on the ribosomes in the cytoplasm of the cell |
| Which nitrogen base in RNA is NOT part of DNA? | uracil |
| What is a mutation? | any change in a gene or chromosome |
| A mutation is harmful to an organism if it | reduces the organism’s chances for survival and reproduction. |
| A(n) ____________________ organism is the offspring of many generations of organisms that have the same trait. | purebred |
| If a(n) ____________________ allele is present, its trait will appear in the organism. | dominant |
| In pea plants, the tall-stem allele and the short-stem allele are different forms of the same ____________________. | gene |
| If D represents the dominant allele of a gene, then ____________________ represents the recessive allele. | d |
| Mendel used the principles of ____________________ to predict what percent of offspring would show a particular trait. | probability |
| A chart used to predict results of genetic crosses is known as a(n) ____________________. | Punnett square |
| In a cross between two hybrid Tt pea plants, ____________________ percent of the offspring will be Tt. | 50 |
| An organism that has two dominant or two recessive alleles is said to be ____________________ for that trait. | homozygous |
| Alleles that are neither dominant nor recessive produce an inheritance pattern known as ____________________. | codominance |
| The process in which a parent cell divides twice to produce sex cells is called ____________________. | meiosis |
