Chapter 10: Mendel, Genes and Inheritance

Question 1

Character

Answer 1

Any observable feature, or trait, of an organism, whether acquired or inherited.

Question 2

Traits (2)

Answer 2

1. A descriptive trait: phenotype

2. A trait characterized by the genetic makeup: genotype

Question 3

Self-pollination

Answer 3

The pollination of a flower by pollen from the same flower or from another flower on the exact same plant.

Question 4

Cross-pollination

Answer 4

The transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female productive organ (a stigma or a female cone) of another plant. Insects and wind are the main agents of cross-pollination.

Question 5

True-breeding

Answer 5

Sometimes also called a pure-bred, it is an organism that always passes down a certain phenotypic trait to its offspring. An organism is referred to as true breeding for each tart to which this applies, and the term ‘try breeding’ is also used to describe individual genetic traits.

Question 6

Parental generation

Answer 6

The first set of parents crosses i which their genotype is the basis for predicting the genotype of their offspring, which in turn, may be crossed.

Question 7

F1 generation

Answer 7

The first filial generation of offspring of distinctively different parental types. F1 hybrids are used in genetics and selective breeding.

Question 8

F2 generation

Answer 8

The second filial generation produced by interbreeding individuals of an F1 generation and consisting of individuals that exhibit the result of recombination and segregation of genes controlling traits for which stocks of the P1 generation differ.

Question 9

Testcross

Answer 9

When doing genetics research, there are times when we much know for sure if the organism is homozygous or heterozygous. By crossing the unknown dominant with a recessive we can determine the genotype of the unknown. If the unknown is homozygous there is a 100% chance of it passing on a specific trait. If it is heterozygous there is a 50% chance of it passing on that trait.

Question 10

Monohybrid

Answer 10

A hybrid that is heterozygous with respect to a specified gene.

Question 11

Dihybrid

Answer 11

A hybrid that is heterozygous for alleles of two different genes.

Question 12

Dominance

Answer 12

The allele that produces the phenotype in a heterozygous organism.

Question 13

Recessive

Answer 13

The ‘invisible allele’ in a heterozygous organism (Medel’s principal of segregation)

Question 14

Homozygous

Answer 14

Both alleles are the same.

Question 15

Heterozygous

Answer 15

Both alleles are different

Question 16

Independent assortment (Mendel’s)

Answer 16

Alleles of different genes will assort independently of each other during meiosis (unless the genes are near each other on the same chromosome).

Question 17

Incomplete Dominance

Answer 17

Sometimes a heterozygous offspring will be intermediate in a phenotype. e.g. red flower + white flower = pink flower

Question 18

Codominance

Answer 18

A condition in which both allele for a gene are expressed when present (red cattle + white cattle = roan or spotted cattle)

Question 19

Multiple alleles

Answer 19

The state of having more than two alternative contrasting characters controlled by multiple alleles at a single genetic locus

Question 20

Epistasis

Answer 20

When more than one gene is required for expression of a phenotype. (being bald makes having a brown hair a mute point)

Question 21

Polygenic Inheritance

Answer 21

Polygenic inheritance refers to a single characteristic that is controlled by more than two genes (also called multifactorial inheritance)

Question 22

Pleiotrophy

Answer 22

The single gene controlling or influencing multiple (and possibly unrelated) phenotypic traits. An example being phenylketonuria, which is a human disease that affects multiple systems but is causes by one gene defect.