Chapter 4

Question 1

Homogametic

Answer 1

1 type of gamete

Question 1

Heterogametic

Answer 1

2 types of gametes

Question 2

In the XX-XY sex determining system, which is the heterogametic and homogametic.

Answer 2

XX: homogametic
XY: heterogametic

Question 3

In the ZZ-ZW sex determining system, which is the heterogametic and homogametic and what sexes are each?

Answer 3

ZZ: homogametic, male
ZW: heterogametic, female

Question 4

In turtles and alligators how is sex determined?

Answer 4

determined by environmental factors like egg incubation temperature

Question 4

In the XX-XY sex-determining system, which regions are the Y chromosome are homologous to the X chromosomes?

Answer 4

the pseudoautosomal regions

Question 5

What is sequential hermaphroditism and give an example of it.

Answer 5

each individual can be male or female just not at the same time; example is stack position in limpets

Question 6

Sex determining in Drosophila.

Answer 6

X: A ratio

Question 7

X:A ratio

Answer 7

X chromosomes / # haploid sets

Question 8

Intersex

Answer 8

X: A ratio between 0.5-1, both female and male characteristics

Question 9

metamale

Answer 9

<0.5

Question 10

metafemale

Answer 10

> 1

Question 11

How does the presence of the Y chromosome determine maleness in humans?

Answer 11

The Y chromosome possesses a SRY gene which is expressed and turns on a testis determining factor (TDF) in which gonads turn into testies. In female they lack the Y chromosome and therefore lack TDF

Question 12

nondisjunction

Answer 12

failure to properly separate homologous chromosomes or chromatids in meiosis

Question 13

Nullisomy

Answer 13

loss of homologous pair (2n-2) lethal to humans

Question 14

Aneuploid

Answer 14

abnormal # of chromosomes

Question 15

Monosomy

Answer 15

loss of single chromosome (2n-1)

Question 16

Trisomy

Answer 16

gain of a single chromosome (2n+1)

Question 17

Tetrasomy

Answer 17

gain of homologous pair (2n+2)

Question 18

Example of monosomy

Answer 18

Turners Syndrome (XO)

Question 19

Example of Tetrasomy

Answer 19

Kleinfelters Syndrome (XXXY)

Question 19

Example of trisomy

Answer 19

Down syndrome; Trisomy 21

Question 20

Turners Syndrome

Answer 20

monosomy (XO)
females

Question 21

Kleinfelter Syndrome

Answer 21

XXY, 47
males
less maleness; sometimes testies do not descend

Question 22

Triple X Syndrome

Answer 22

XXX, 47
female
so underdiagnosed because not many signs

Question 23

Androgen Insensitivity Syndrome (AIS)

Answer 23

47, XY
genetically male, but physically female
have Y chromosome so has SRY gene, however testies remain in abdominal cavity; develop breasts and vagina
however has a mutation on the Y chromosomes androgen receptor which can not read that this is a male