AP Biology Unit 5: Meiosis, Genetics, and Inheritance Patterns

What is meiosis?

Meiosis is the specialized cell division used by sexually reproducing eukaryotes to transmit genes to the next generation.

How does meiosis differ from mitosis?

Meiosis is a reduction division that halves the chromosome number from diploid (2n) to haploid (n), while mitosis produces identical clones.

What are the two main stages of meiosis?

Meiosis I separates homologous pairs, and Meiosis II separates sister chromatids.

What is independent assortment?

During metaphase I, homologous pairs align randomly, creating over 8 million possible chromosomal combinations in humans.

What is crossing over?

During prophase I, homologous chromosomes exchange DNA segments at chiasmata, creating recombinant chromosomes.

What is random fertilization?

The fusion of two unique gametes, leading to a 1 in 70 trillion probability for a specific human sibling pair.

What chromosomal system do mammals use for sex determination?

Mammals use the XY system, where males are XY and females are XX.

How do birds determine sex?

Birds use the ZW system, where the female (ZW) determines the offspring's sex.

What is nondisjunction?

Nondisjunction is the failure of chromosomes to separate properly during meiosis, leading to aneuploidy.

What is the principle of segregation?

Individuals have two alleles for each gene that separate during gamete formation, so each gamete carries only one allele.

What is the principle of independent assortment?

Genes for different traits are passed on independently of one another, provided they are on different chromosomes.

What is the difference between genotype and phenotype?

Genotype is the underlying DNA (e.g., Aa), while phenotype is the observable trait (e.g., dark fur).

What is incomplete dominance?

A heterozygote shows an intermediate phenotype, such as pink flowers from red and white parents.

What is codominance?

Both alleles are fully expressed, as seen in the AB blood type.

What is pleiotropy?

One gene influences multiple, seemingly unrelated traits, such as in Sickle Cell Anemia.

What is epistasis?

One gene masks or alters the expression of a gene at a different locus, affecting traits like coat color in mice.

What is polygenic inheritance?

Traits controlled by multiple genes, resulting in a phenotypic continuum, such as skin color.

What is genomic imprinting?

The expression of an allele depends on which parent it was inherited from.

What is pedigree analysis?

Geneticists use family trees to trace the inheritance of specific traits.

What is the 3:1 phenotypic ratio?

In a monohybrid cross, three-quarters of the offspring display the dominant phenotype, while one-quarter shows the recessive phenotype.

What is the 9:3:3:1 phenotypic ratio?

The classic result of a dihybrid cross between two double-heterozygotes.

What is the rule of multiplication in genetics?

It predicts the probability of independent events occurring together.

What is the rule of addition in genetics?

It calculates the probability of exclusive events occurring.

What is a Punnett square?

A visual grid used to combine parental gametes and predict offspring genotypes.

What is the FOIL method?

A technique to determine the gametes for a multi-trait cross using 'First, Outside, Inside, Last'.

What is a chi-square test used for in genetics?

It evaluates 'goodness of fit' to determine if observed data supports a hypothesis.