| A | B |
|---|
| A DNA molecule looks like | twisted ladder |
| the passing on of traits from an organism to its offspring is known as | heredity |
| the visible characteristics of an organism are called | phenotypes |
| the units of heredity are called | genes |
| the main function of chromosomes and genes is to control the production of | proteins |
| Genes that Mask other genes are said to be | dominant |
| the genetic makeup of an organism is called its | genotype |
| an organism that has different genes for a particular trait is called a | hybrid |
| In the cross Bb X Bb, approximately what percentage of the offspring have the same phenotype as the parents? | 75 percent |
| an organism that has genes which are alike for a particular trait is called a | purebred |
| the symbol for a recessive trait is | a lower case letter |
| a characteristic of an organism can also be called a | trait |
| Which are formed by meiosis? | sex cells |
| A sudden change in a characteristic caused by a change in a gene or a chromosome is called a | mutation |
| A human male carries the sex chromosomes | XX |
| The rungs of a DNA molecule are composed of | nitrogen bases |
| How many chromosomes do human sex cells contain? | 23 |
| How many chromosomes are there in a person's body cells? | 46 |
| A trait that is the “weaker” of two traits is called | recessive |
| The pairing of bases in a DNA molecule | adenine-thymine |
| The number of chromosomes in a sex cell is | double the number of chromosomes in body cells |
| DNA molecules form exact duplicates of themse1ves in the process of | mitosis |
| Substances that cause mutations are called | mutagens |
| Chromosomes are made of long strands of | DNA |
| The substance that carries the genetic code of DNA from the nucleus to the cytoplasm is | RNA |
