Topic 11-1

Question 1

refers to sexual phenotypes (anatomical or physiological traits)

Answer 1

biological sex

Question 2

category assigned by the individual (identity) or others based on behavioural and cultural practices

Answer 2

gender

Question 3

many organisms are hermaphrodites; this means that:

Answer 3

the organism has both male and female sex organs

Question 4

biological mechanisms that regulate sexual phenotypes (chr, genetics, environment)

Answer 4

sex determination

Question 5

in chromosomal sex-determining systems, teh genome consists of:

Answer 5

• autosomes: non-sex chromosomes
• sex chromosomes: distinct in males and females

Question 6

XX-XY species:

Answer 6

most common system, generates 1:1 ratios of sex phenotypes
female: XX
male: XY

Question 7

Y chr is not actually Y-shaped, but is:

Answer 7

acrocentric - one chr arm is much shorter than the other

Question 8

the sex chr pair during metaphase (meiosis I) bc they are homologous in small regions called:

Answer 8

pseudoautosomal regions

Question 9

what is the heterogametic sex?

Answer 9

the sex that makes two types of gametes (ex: X or Y)

Question 10

what is the homogametic sex?

Answer 10

the sex that makes all the same gametes (ex: all X)

Question 11

XX-XO system

Answer 11

simplest sex determination, generates 1:1 ratios of sex phenotypes
females: XX
males: XO

Question 12

ZZ-ZW system

Answer 12

females: ZW
males: ZZ

Question 13

for chromosomal sex-determining systems, sex is determined by:

Answer 13

individual genes locates on these sex chr working in conjunction w/ genes on autosomes

Question 14

genotypes at one or more loci determine the sex of an individual w/out specific sex chr

Answer 14

genic sex determination

Question 15

what are two examples of organisms that determine sex based fully or in part on environmental factors

Answer 15

mollusks and reptiles

Question 16

true or false: male mollusks can change sex after mating

Answer 16

true

Question 17

each individual can be both male and female, but not at the same time

Answer 17

sequential hermaphroditism

Question 18

in many turtles, crocodiles, alligators, and a few birds, sexual phenotypes are affected by _________ during embryonic development

Answer 18

temperature

Question 19

Calvin Bridges proposed that in fruit flies sex was determined not by the amount of X and Y chr, but a balance b/w:

Answer 19

• female-determining genes on X
• male-determining genes on the autosomes
• X:A ratio

Question 20

human males contain a gene known as the _____ gene, which is the located on the Y chromosome

Answer 20

sex-determining region Y gene (SRY gene)

Question 21

what are the five main roles of sex chr in humans?

Answer 21

1) X chr contains genes essential for both sexes
2) male-determining gene on the Y
3) abscence of Y leads to female sex
4) fertility genes located on both X and Y
5) additional X chr can upset normal development of males and females

Question 22

describe Turner’s syndrome:

Answer 22

• genotype: XO
• 1:3000 births
• female w/ underdeveloped secondary sex characteristics
• normal intelligence

Question 23

describe Klinefelter syndrome:

Answer 23

• genotype: XXY or XXXY
• 1:1000 male births
• men w/ small testis, reduced facial and pubic hair, sterile, tall
• normal intelligence

Question 24

describe androgen-insensitivity syndrome

Answer 24

have normal male chr (XY) but have female external sexual characteristics (vagina but no uterus, oviducts, or ovaries). inside abdominal cavity have pair of testis that have defective androgen receptors, so while testosterone is made, the tissues do not receive the signal and female characteristics develop

Question 25

what are sex-linked genes?

Answer 25

genes found on the sex chr

Question 26

does recombination happen in females w/ XX?

Answer 26

yes

Question 27

does recombination occur in males w/ XY?

Answer 27

yes

Question 28

true or false: in males, most of the genes on the X chr have only one allele/copy

Answer 28

true

Question 29

what does it mean to be hemizygous?

Answer 29

possessing only one copy of a gene

Question 30

swapping the sex of the parental phenotypes is called making a:

Answer 30

reciprocal cross

Question 31

for autosomal linked genes, reciprocal crosses give:

Answer 31

same proportions of genotypes/phenotypes

Question 32

for sex-linked genes, reciprocal crosses give:

Answer 32

very different progeny

Question 33

Bridges hyptohesized that the exceptional white-eyed female flies had ______. this could occur through a process called ______.

Answer 33

two X chr and one Y, nondisjunction

Question 34

failure of homologous chr or ssiter chromatids to separate in meiosis or mitosis

Answer 34

nondisjunction

Question 35

red-green colour perception is a ________ trait in humans

Answer 35

recessive, X-linked

Question 36

in order for human females to develop colour blindness, they have to:

Answer 36

inherit mutant X alleles from both parents

Question 37

in order for human males to develop colour-blindess, they have to:

Answer 37

inherit the mutant X allele from their mother

Question 38

sex-linked traits can have multi-generational effects;

Answer 38

1) trait can alternate which sex has the phenotype 2) trait can skip a generation