Biology Test 3

Front 1

Complete dominance

Back 1

when the phenotypes of the dominant homozygote and the heterozygote are the same

Front 2

Incomplete dominance

Back 2

when the phenotype of the F1 hybrids is somewhere in between the two parental varieties

Front 3

Codominance

Back 3

When two dominant alleles affect the phenotype in separate, distinguishable ways

Front 4

What ratio is indicative of incomplete dominance?

Back 4

1:2:1

Front 5

A dominant trait subdues a recessive trait. T/F

Back 5

False; alleles don't interact, they are simply variations in a gene's nucleotide sequence

Front 6

Whether alleles appear to be completely dominant, codominant, or incompletely dominant depends on what?

Back 6

the level of analysis

Front 7

What is pleiotropy?

Back 7

when a gene has multiple effects

Front 8

Epistasis

Back 8

when the gene on one locus alters the phenotypic expression of a gene at another locus

Front 9

Where are genes located?

Back 9

Genes are located on chromosomes

Front 10

Law of Segregation

Back 10

states that two alleles for each gene separate during gamete formation

Front 11

Law of Independent Assortment

Back 11

states that alleles of genes on nonhomologous chromosomes assort independently during gamete formation

Front 12

What characterisitics make fruit flies convenient for genetic studies?

Back 12

they breed at a high rate; a generation can be bred every two weeks; they only have four pairs of chromosomes

Front 13

In Morgan's experimentats what was he refering to with the phrase, "wild type"?

Back 13

The nomral phenotypes

Front 14

What term did Morgan use to refer to traits alternative to the wild type?

Back 14

mutant phenotype

Front 15

Sex-linked gene

Back 15

a gene located on either sex chromosome

Front 16

In humans, a sex-linked gene usually refers to what?

Back 16

A gene on the larger X chromosome

Front 17

Fathers pass on all their sex-linked alleles to their sons, but none to the their daughters. T/F

Back 17

False; fathers (XY) pass on all their sex-linked alleles to their daughers (XX)but to NONE of their sons (XY)

Front 18

Sex-linked recessive disorders are much more common in women. T/F

Back 18

False; sex-linked recessive disorders are much more common in males (XY)-only one X

Front 19

Genome

Back 19

all the DNA in a cell

Front 20

chromatin

Back 20

a complex of DNA and protein that condenses during cell division

Front 21

Chromatid

Back 21

one of two identical parts of the chromosome after S phase

Front 22

Centromere

Back 22

the point where the two chromatids touch

Front 23

What does meiosis yield?

Back 23

Nonidentical daughter cells that have only one set of chromosomes (1/2 as many as the parent cell)

Front 24

Where do cells spend 90% of their time during cell division?

Back 24

Interphase

Front 25

In what phase does a cell make copies of its chromosomes?

Back 25

S phase of Interphase

Front 26

In what phase do sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell?

Back 26

anaphase

Front 27

In what phase does assembly of spindle microtubules begin in the centrosome?

Back 27

Prophase

Front 28

In what phase does the centrosome replicate?

Back 28

Prophase

Front 29

At what phase do the chromosomes line up at the midway point between the spindle's two poles?

Back 29

Metaphase

Front 30

In what phase do gentically identical daughter nuclei form at opposite ends of the cell?

Back 30

Telophase

Front 31

In plants, during which phase does a cell plate form?

Back 31

cytokinesis

Front 32

Prokaryotes reproduce by what type of cell division?

Back 32

binary fission

Front 33

At what phase does the nucleoli disappear?

Back 33

Prophase

Front 34

In what phase does the mitotic spindle begin to form?

Back 34

Prophase

Front 35

At what phase does the nuclear envelope begin to fragment?

Back 35

metaphase

Front 36

What is the longest stage of mitosis?

Back 36

metaphase

Front 37

At what phase are the centrosomes at opposite poles of the cell?

Back 37

Metaphase

Front 38

What is the shortest stage of mitosis?

Back 38

Anaphase

Front 39

By the end of what phase are there complete collections of chromosomes? (daughter chromosomes)

Back 39

Anaphase

Front 40

When do nucleoli reappear?

Back 40

telophase

Front 41

When do two nuclei appear?

Back 41

telophase

Front 42

When do kinetochores form?

Back 42

Metaphase

Front 43

What are growth factors?

Back 43

proteins released by certain cells that stimulate other cells to divide

Front 44

What happens with density-dependent inhibition?

Back 44

When the cell gets too crowded it stops dividing