CH 16 Mendelian Inheritance Reading Guide Flashcards Preview

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Flashcards in CH 16 Mendelian Inheritance Reading Guide Deck (36):
1

What are some examples that lend support to the hypothesis of blending inheritance?

Offspring with resemble the average traits of their parents. Example a flower being purple would have parents that had blue and red flowers.

2

What are some examples that would reject the hypothesis of blending inheritance hypothesis?

It cannot explain the reappearance of a trait several generations after it has apparently disappeared.

3

What were some reasons why the garden pea was a good model organism in which to
study heredity? Why not use oak trees or elephants instead?

Relatively faster reproduction rate than other organisms like elephants and he could also produce 1000's of test subjects

4

What does it mean for a strain to be true breeding for a particular character, e.g. flower
colour, seed pod colour?

The physical appearance of the offspring in each successive generation is identical to the previous one

5

What does hybridization mean?

Interbreeding between two different varieties or species of an organism

6

When crossing plants from different types of true breeding strains, what did Mendel
have to do in order to prevent the ‘mother’ plant from self-fertilizing? (Fig 16.4)

Removed the anthers of the male plant so that it could not self fertilize

7

What is the relationship between the P1 (often just called P) generation and F1
generation?

P1 is the parental generation
F1 is the First offspring generation

8

What does it mean that one trait was ‘dominant’? What does it mean that one trait was
‘recessive’?

A trait that appears in the F1 generation is considered dominant and the trait that does not appear is recessive

9

What does it mean to perform ‘reciprocal’ crosses? Why bother?

Expression of the trait in the female and male parents are interchanges
To show that they yield the same results. Acts as a control

10

Recall that the recessive trait (e.g. white flower colour) receded/disappeared in the F1
generation. But what actually happened to that trait? Was it destroyed somehow, or just
hidden?

It was not destroyed, but it only has a 1 in 4 chance of being expressed.

11

How many types of gametes can a true breeding P1 individual make? How many types
of gametes can a heterozygous (for a single gene, e.g. Aa) F1 individual make?

P1 can produce 2 gametes that can contain either A or a but not both
F1 can produce 3 types of zygote AA, Aa or aa

12

Staying with Figure 16.7, notice that phenotypic and genotypic ratios differ from each
other in the F2. Why is that?

Because there are only 3 types of genotypes AA, Aa and aa with a 1/4 chance of AA, 1/4 chance of aa but a 1/2 chance of Aa
Phenotypes are AA, Aa and aa. With only aa being able to show the recessive trait. Therefore 3/4 chance of dominant trait being expressed

13

Are all F2 individuals that show the recessive phenotype going to be true breeding?
What does the Punnett square predict?

Yes

14

Are all F2 individuals that show the dominant phenotype going to be true breeding?
What does the Punnett square predict?

No

15

How can you find out the actual genotype of an individual that displays a dominant
phenotype, given that such an individual could be either homozygous (AA), or
heterozygous (Aa)?

If left to self fertilize the AA should only produce A (yellow seeds) phenotype. While the Aa will produce a (green seeds) in a 3:1 ratio. 3 yellow to 1 green

16

Why does the ratio of non-true breeding to true breeding F2s break down into a 2:1
ratio, rather than a 3:1 ratio as we encountered in a different context earlier in our
discussion?

Because you've removed the true breeding (recessive genotype) from the group

17

How does a testcross work?

Crossing an unknown genotype with a homozygous recessive genotype

18

A parent with a dominant phenotype; what can you say for sure about their genotype?
what can you not know?

Genotype is not aa but you cannot know if its not Aa or AA.

19

What kind of kitten ratios would you expect if you crossed a heterozygous short-haired
cat (Ss) to a homozygous recessive long-haired cat (ss)? What if you crossed a
homozygous short-haired cat (SS) to a homozygous recessive long-haired cat (ss)?
Relate this to Figure 16.8.

2/4 would be Ss and 2/4 would be ss

20

What happens in meiosis (and when during
meiosis) to separate alleles that are carried on homologous chromosomes from each
other? Relate to Fig 16.9.

Segregation of the homologous chromosomes separate in Anaphase 1.

21

Practice the meiosis finger dance.

OK

22

What is incomplete dominance?

The phenotype of the heterozygous genotypes is intermediate between those of the homozygous genotypes.

23

Consider an individual of genotype Aa, what is the probability that an egg made by this
individual carries the A allele of the gene? what is the probability (p) that an egg made
by this individual carries the a allele of the gene?

1/2 chance of A and 1/2 chance of a

24

If two Aa individuals have offspring together, what is the probability that they have an
AA baby?

Use Punnet Square
1/4 chance of AA

25

If two Aa individuals have offspring together, what is the probability that they have an
Aa baby?

Use Punnet Square
1/2 chance of Aa

26

Do alleles change other when they co-exist in a heterozygous individual.

No, there is no blending or averaging

27

Define particulate in terms of alleles.

Enter an individual during fertilization and leave an individual via meiosis and gamete formation, intact and unchanged

28

What determines characters( seed shape) and what determines traits (seed colour).

Characters are determined by genes
Traits are determined by alleles

29

Define monohybrid

Cross when only one gene under study is heterozygous in the cross Aa

30

Define dihybrid

Cross between two AaBb individuals, cross between two genes under study are heterozygous in the cross

31

How many copies of a dominant allele does one need in order to show a dominant
phenotype?

1

32

If a person displays a dominant phenotype, can you be perfectly sure of their genotype?

No. Becasue they only require 1 dominant genotype to express a certain phenotype therefore they could be AA or Aa.

33

Can an individual display a dominant phenotype (e.g. purple flower colour) but still
carry a recessive allele (e.g. for white flower colour)?

Yes

34

If a person displays a recessive phenotype such as red hair, what can you say for sure
about the genotypes of the mom and dad of that person?
Can you be perfectly sure of those parents’ hair colour (red vs. non-red)?

They both carried a recessive genotype both are Aa. Cannot be AA

35

What do we mean by ‘carrier’ in the context of recessive character traits?

When individuals carry recessive traits in their genes that are not expressed

36

For
the genetic variants that cause OCA2-related albinism, what type of genetic changes can
you envision that might render the OCA2 protein non-functional?

A mutation of the nucleotides in the gene