🧬 AP Biology Unit 5 (copy) (copy)

AP Biology Unit 5

What is the total number of chromosomes in humans?

Humans have 46 total chromosomes, which are arranged in 23 homologous pairs.

What are gametic cells in humans?

Egg or sperm cells that contain half the number of chromosomes of normal somatic cells.

Define haploid cell.

A cell with half the normal amount of chromosomes, represented as 'n', containing a single of each type of chromosome.

What is the definition of diploid cell?

A cell that contains two chromosomes of each type, represented as '2n', and has homologous pairs.

What is syngamy?

The fusion of two gametes during fertilization.

What is a zygote?

A fertilized egg that is diploid.

What are alleles?

Variants of genes that determine specific traits, such as flower color.

What is the significance of loci/locus?

The specific position where a gene or allele is found on a chromosome.

Explain monosomy.

A condition resulting from nondisjunction where a cell has only one chromosome of a pair, often not viable, except in some cases like Turner syndrome.

What is a tetrad?

A pair of homologous chromosomes that come together during meiosis.

Why do humans remain diploid throughout their lives?

Humans remain diploid after fertilization because all cells, except gametes, have two copies of each chromosome.

Describe the process of crossing over.

The exchange of genetic material between homologous chromosomes during prophase I of meiosis, leading to genetic variation.

What is the Law of Segregation?

The principle stating that during the formation of gametes, the alleles for each gene segregate from each other so that each gamete carries one allele for each gene.

Differentiate between dominant and recessive alleles.

Dominant alleles express their phenotype with one copy, while recessive alleles require two copies to express their phenotype.

What is a monohybrid cross?

A genetic cross involving one trait, typically between two heterozygous organisms, which results in a 1:2:1 genotypic ratio.

Define incomplete dominance.

A form of inheritance in which the phenotype of heterozygotes is intermediate between those of the two homozygotes.

Explain codominance.

A genetic situation in which both alleles in a heterozygous organism are fully expressed in their phenotype.

What is pleiotropy?

A genetic phenomenon where one allele controls multiple traits or phenotypes.

What does epistasis refer to?

A situation in genetics where one gene affects the expression of another gene.

What is phenotypic plasticity?

The ability of one genotype to produce different phenotypes in response to environmental changes.

Describe mitochondrial inheritance.

A type of genetic inheritance that occurs through mitochondria passed from the mother to her offspring.

What is the significance of a Punnett square?

A diagram used to predict the outcome of a genetic cross by showing possible combinations of alleles from the parents.

What does the multiplication rule state in probability calculations?

The rule stating that the probability of two independent events occurring together is the product of their individual probabilities.

List the phenotypic ratio for a typical dihybrid cross.

The expected phenotypic ratio for a dihybrid cross is 9:3:3:1.