1. In pea plants, the tall-stem allele and the short-stem allele are different forms of the same ____________________. gene

2. During reproduction by mitosis, a parent cell divides into two new cells, each identical to its parent. _________________ asexual

3. The order of the bases along a gene determines the order in which amino acids are put together to form a protein.

4. An organism that is the offspring of many generations that have the same form of a trait is called ___________________. purebred

5. If D represents the dominant allele of a gene, then ____________ represents the recessive allele. d

6. The genetic code is found in the order of nitrogen _______________ along a gene. bases

7. A chart used to predict results of genetic crosses is known as a(n) ____________________. Punnett square

8. In a cross between two hybrid Pp pea plants, ____________________ percent of the offspring will be Pp. 50

9. In which form of reproduction do the offspring look exactly like the parent? What is an advantage of this reproductive strategy for the species? asexual reproduction; The parent organism can produce many identical offspring in a short period of time without having to find a mate. With many offspring, there is more chance that some will survive to reproduce and continue the species.

10. The process in which a parent cell divides twice to produce sex cells is called ____________________. meiosis

11. Which form of reproduction combines the genetic material from two different parents? What is one advantage of this form of reproduction? sexual reproduction; The offspring may have new characteristics that help them survive changes in their environment.

12. A DNA molecule is shaped like a twisted ladder or double helix.

13. What forms a genetic code? the order of nitrogen bases along a gene

14. Explain how DNA replicates or copies itself. DNA replication is the process by which an identical copy of the DNA strand forms for a new cell. During DNA replication, the two sides of the DNA unwind and separate like a zipper. The nitrogen bases in the nucleus pair up (adenine pairs with thymine and cytosine pairs with guanine) so that the new DNA strand exactly matches the order of the original strand.

15. During DNA replication, adenine (A) always pairs with thymine (T).

16. What does the notation BB mean to geneticists? two dominant alleles

17. What does the notation Tt mean to geneticists? one dominant allele and one recessive allele

18. Factors that control traits are called genes.

19. What does a Punnett square show? all the possible outcomes of a genetic cross

20. Scientists call an organism that has two different alleles for a trait a hybrid.

21. The different forms of a gene are called alleles.

22. What is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea plants? three in four

23. An organism’s genotype is its genetic makeup.

24. An organism’s physical appearance is its phenotype.

25. 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

26. What happens during meiosis? Chromosome pairs separate and are distributed into new sex cells.

27. What is the chromosome theory of inheritance? Genes are carried from parents to offspring on chromosomes.

28. Each skunk body cell has 50 chromosomes. How many chromosomes will each skunk sex cell (sperm and egg) have? 25

29. Chromosomes are made up of many genes joined together.

30. The sex cells produced by meiosis have ______the number of chromosomes as the parent cells. ____________________ half

31. When Mendel crossed purebred short plants with purebred tall plants, all of the offspring were tall

32. When sex cells combine to produce offspring, each sex cell will contribute half the number of chromosomes in body cells.

33. The process by which a new organism forms from the joining of an egg cell and a sperm cell is called sexual reproduction.