5.1 - Patterns of Inheritance

Question 1

True-breeding

Answer 1

An organism that produces offspring that are genetically identical for 1 or more traits when self-pollinated or when crossed with another true-breeding organism for the same traits.

Example: True-breeding purple flowers that are self-pollinated or crossed with another true-breeding with purple flowers will produce all offspring with purple flowers.

Question 2

P-generation

Answer 2

Parent plants used in a cross

Cross is a breeding of 2 organisms with different traits

Question 3

F1-generation

Answer 3

Offspring of a P-generation cross.

Also called the filial generation. They are monohybrids (differs in 1 characteristic only), so only studies inheritance in 1 trait

Question 4

F2-generation

Answer 4

Offspring of an F1-generation cross

Studies inheritance of both traits.

Question 5

Monohybrid cross

Answer 5

Cross designed to study inheritance of only 1 trait

Question 6

Law of segregation

Answer 6

Scientific law, where:
1. Organisms inherit 2 copies of genes; one from each parent
2. Parent organisms donate only one copy of each gene in their gametes (sex cells) because the genes separate during meiosis

Question 7

Allele

Answer 7

A form of a gene. There are at least 2 alleles for each gene (genes come in pairs on the chromosome), where some are dominant and some are recessive. They’re inherited from your parents.

Note: A gene is a piece of DNA that codes for a particular trait.

Question 8

Homozygous

Answer 8

An individual that carries 2 of the same alleles for a characteristic.

Example: Both flower colour alleles coded for purple

Question 9

Heterozygous

Answer 9

An individual that carries 2 different alleles for a gene

Example: One flower colour coded for purple, while the other one coded for white

Question 10

Genotype

Answer 10

Genetic makeup/set of alleles of an individual. All forms of genes, including hidden ones.

Question 11

Phenotype

Answer 11

Traits of an individual (appearance). Only expressed alleles (no hidden ones).

Question 12

Dominant allele

Answer 12

Allele that is always expressed, if present.

Question 13

Recessive allele

Answer 13

Allele expressed only if not in presence of dominant allele

Basically… If the indivual is homozygous for the recessive allele

Question 14

Test cross

Answer 14

Cross used to see if an individual exhibiting a dominant trait is homozygous or heterozygous for that trait. Done with unknown genotype and homozygous recessive genotype.

If all offspring show dominant phenotype: Homozyous dominant
Both dominant and recessive phenotypes: Heterozygous

Question 15

Punnett square

Answer 15

Diagram showing all possible combinations for each allele