Genetics: The Science of Heredity

What does a Punnett square show?

• only the recessive alleles in a genetic cross

• all of Mendel's discoveries about genetic crosses

• all the possible outcomes of a genetic cross

• only the dominant alleles in a genetic cross

What is the chromosome theory of inheritance?

• Codominant genes combine to form new hybrids.

• Genes are carried from parents to offspring on chromosomes.

• Hybrid pairs of chromosomes combine to form offspring.

• Chromosomes are carried from parents to offspring on hybrids.

An organism's ________________ is its allele combinations.

• phenotype

• genotype

• heterozygous

• homozygous

A pea plant that is ______________________ for tall stems has alleles Tt.

• homozygous

• hybrid

• heterozygous

• dominant

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

• mitosis

• purebred

• meiosis

• dominant

What does the notation TT mean to geneticists?

• heterozygous alleles

• at lest one dominant allele

• two dominant alleles

• one dominant and one recessive allele

An organism's genotype is its

• genetic makeup

• physical appearance

• feather color

• stem height

What did Gregor Mendel do to study different characteristics in his genetics experiments?

• He studied only asexual plants.

• He studied only tall and short pea plants.

• He cross-pollinated both plants and animals.

• He cross-pollinated plants.

What happens during meiosis?

• Chromosome pairs separate and are distributed into new sex cells.

• Each sex cell copies itself to form four new chromosomes.

• Two sex cells combine.

• Chromosome pairs remain together when new sex cells are formed.

A hybrid is the offspring of parents that have _______________ alleles for a trait.

• the same

• different

• opposite

• many