Molecular Basis of Life

Question 0

Define autosome

Answer 0

Any chromosome other than a sex chromosome

Question 1

Define allele

Answer 1

Alternative versions of the same gene (A or a)

Question 2

Define backcross

Answer 2

A test cross in which an individual is crosses with its parental genotype

Question 3

What is blending theory?

Answer 3

An ancient theory of heredity which predicted that progeny should show a mixture of parental genotypes

Question 4

What human trait shows a distinct flaw in the blending theory of heredity

Answer 4

Gender

When humans reproduce, they produce males and females, with an average 50:50 ratio.

They rarely produce hermaphrodites, showing that gender cannot be blended.

Question 5

What is a character?

Answer 5

Any measurable or observable property of an organism

Question 6

Define chiasmata

Answer 6

Cross over structures formed by two chromatids in prophase 1 of meiosis

Question 7

Define codominance

Answer 7

Each of two alleles of a gene are expressed so that each displays it’s own separate phenotype in the heterozygote

Question 8

Define dihybrid cross

Answer 8

A cross in which the inheritance of two characters or genes is studied

Question 9

What is a diploid?

Answer 9

A cell or individual organism with two complete sets of chromosomes

Question 10

Define dominant

Answer 10

The member of a pair of alleles of a gene (A) that is expressed in the heterozygote

Question 11

Define epistasis

Answer 11

An interaction of gene such as one disguises the effects of a second gene in the phenotype

Question 12

What is a gamete?

Answer 12

A reproductive cell (such as sperm in humans or pollen in plants) that fuses with a partner gamete (egg cell) to form a fertilised zygote

Question 13

What is a gene?

Answer 13

A genetic unit of function that determines a hereditary character

Question 14

Define genotype

Answer 14

The genetic information or constitution of an individual organism or cell

Question 15

Define haploid

Answer 15

A cell or individual organism carrying one set of chromosomes

Question 16

Define heterozygote

Answer 16

A cell or organism that carries different alleles of a particular gene (Aa)

Question 17

Define homozygote

Answer 17

A cell or organism that carries the same alleles of a particular gene (AA or aa)

Question 18

Define incomplete dominance

Answer 18

Neither allele of a gene shows dominance to give an intermediate phenotype in the heterozygote

E.g. Pink carnation from White and red

Question 19

What is an intercross?

Answer 19

A cross between two individuals

Question 20

Define lethality of genes

Answer 20

A genotype that leads to the death of the cell or organism

Question 21

Define linkage

Answer 21

Genes carried on the same chromosome tending to be inherited together

Question 22

What is mapping?

Answer 22

The process of locating individual genes in their relative positions on a chromosome

Question 23

Define meiosis

Answer 23

The process of reductive division of a cell leading to the halving of the diploid number of chromosomes

Question 24

What is a monohybrid cross?

Answer 24

A cross in which the inheritance of one character or gene is studied

Question 25

Define mutation

Answer 25

Any permanent heritable change in the genetic material (making the cell or individual a mutant)

Question 26

What is a pedigree?

Answer 26

A diagram of a family tree showing the inheritance of a trait or traits down the generations

Question 27

Define phenotype

Answer 27

The observable or measurable appearance of an organism or cell caused by it's genotype, environment, and interactions of the two

Question 28

Define recessive

Answer 28

The member of a pair of alleles of a gene that is not expressed in the heterozygote (a)

Question 29

Define reciprocal

Answer 29

A pair of crosses, where the trait is carried by one sex in the first cross, and by the other sex in the second cross

Question 30

Define recombination

Answer 30

A new association of alleles in the progeny caused by crossing over during meiosis

Question 31

What is selfing?

Answer 31

When an individual is allowed to self fertilise to produce the next generation

Question 32

Define sex chromosome

Answer 32

The chromosomes that determine the sex of an individual

Question 33

Define sex influenced

Answer 33

An autosomal trait that may be expressed in either sex, but whose pattern of expression depends upon the sex of the individual

Question 34

Define sex limited

Answer 34

An autosomal trait whose expression is limited to one sex

Question 35

Define sex linked

Answer 35

A trait determined by a gene carried on sex chromosome

Question 36

What is a test cross?

Answer 36

A cross test set up to determine the genotype of one parent by mating with a parent of known genotype

Question 37

What is a trait?

Answer 37

One of the observable forms that a character may show

Question 38

Define wild type

Answer 38

The common or reference form normally found in a natural population of an organism