Exam 3 Content (pt 2)

Question 1

what is being segregated in the Principle of Segregation by Mendel?

Answer 1

maternal & paternal chromosomes

Question 2

definition

incomplete dominance

Answer 2

phenotype of an offspring from homozygotes is an intermediate

Question 3

how does a pink snapdragon flower show incomplete dominance?

Answer 3

both its parents are homozygotes for red & white color

Question 4

definition

codominance

Answer 4

each allele involved produces its respective phenotype on the heterozygous organism without blending

Question 5

what is an example of codominance?

Answer 5

blood types

Question 6

what does a probability of 0 indicate?

Answer 6

a genotype of phenotype will never occur

Question 7

a probability of 1 indicates that a genotype or phenotype will always occur

Answer 7

true

Question 8

what is being assorted in Mendel’s Independent Assortment?

Answer 8

different alleles of various traits such as color and shape

Question 9

definition

Independent Assortment

Answer 9

each set of alleles for one trait will assort independently of the ones for other traits on the chromosome

Question 10

punnet squares between F1 & F2 generations are helpful for visualizing Independent Assortment

Answer 10

true

Question 11

what is the phenotypic ratio of offspring between F1 & F2?

Answer 11

9:3:3:1

Question 12

probabilities of genotype or phenotype apply to each offspring only, it does not account for all offspring

Answer 12

true

Question 13

what type of allele would indicate that a parent is a carrier for a certain trait?

Answer 13

heterozygous

Question 14

definition

pedigree

Answer 14

visual tools that are useful in assessing patterns of inheritance among a group of individuals

Question 15

dominant traits appear in every generation

Answer 15

true

Question 16

which type of trait skips generation/s?

Answer 16

recessive trait

Question 17

what is a random union of gametes?

Question 18

how do Mendelian segregation & random union of gametes contribute to the ratio of zygotes?

Question 19

what are complex traits?

Answer 19

these are traits controlled by multiple genes, environment, & lifestyle

Question 20

what are quantitative traits?

Answer 20

type of a phenotype that is assessed by measurement

Question 21

what are single traits?

Question 22

how does genotype affect complex traits?

Question 23

how does environment affect complex traits?

Question 24

what is the resemblance among relatives influenced by?

Answer 24

heritability of traits

Question 25

where are the **x & y chromosomes** located on a _chromatid_?

Answer 25

on either ends (tips)

Question 26

**y chromosomes** are _much smaller_ than *x chromosomes*

Answer 26

**true**

Question 27

how can **sex chromosomes** pair during _Meiosis_ when they differ in size?

Answer 27

they share a small **region of homology** that allows them to _line up and segregate_

Question 28

in which *phase* do **sex chromosomes** _line up and segregate_?

Answer 28

**Anaphase I**

Question 29

which phenomenon leads to the **1:1** ratio of _sex determination_ among progeny?

Answer 29

**random fertilization**

Question 30

why are **x-linked** **_recessive traits_** only expressed in _males_?

Answer 30

they only have **one x chromosome**

Question 31

what causes **recessive traits** to be expressed only in _males_?

Answer 31

most genes on the **x chromosome** have no counterpart in the _y chromosome_ due to differences in length

Question 32

why are **daughters** more likely to inherit _x-linked_ traits from fathers and become ***carriers***?

Answer 32

they have **two x-chromosomes**

Question 33

why are **y-linked** genes only passed from *fathers* to their *sons*?

Answer 33

both have the **y-chromosome**

Question 34

why is it necessary to compare ***genetically identical organisms*** to determine _environmental effects_?

Answer 34

it serves as a control to isolate the environmental effects

Question 35

why is it difficult to measure the _contribution_ of a **specific allele** on a trait?

Answer 35

most traits are controlled by a large number of genes

Question 36

_most_ **environmental effects** on *traits* are minor

Answer 36

true

Question 37

# definition **norm of reaction**

Answer 37

the relationship between trait value & environment for a genotype

Question 38

# definition **inbred**

Answer 38

mating of _genetically identical_ organisms

Question 39

# definition **heritability of a trait**

Answer 39

the proportion of the total _variation_ in a trait that is due to genetic differences

Question 40

why are the **environmental effects** on parental phenotypes not inheritable?

Answer 40

these effects affect only **somatic cells** and not _gametes_

Question 41

what determines **resemblance** among relatives?

Answer 41

**heritability of a trait**

Question 42

# definition **dizygotic twins**

Answer 42

offspring that are fertilized at the same time | ovulation of mother released two eggs

Question 43

# definition **monozygotic twins**

Answer 43

offspring that come from the same _fertilized_ egg | the fertilized egg split in two

Question 44

# definition **concordance**

Answer 44

the percentage of cases in which both members of twins show a trait when it is known that there _should_ only be one that shows it