Ch 8: Genetics

Question 1

What term refers to an organism’s observable traits?

Answer 1

Phenotype

Question 2

What term refers to an organism’s genes responsible for observable traits?

Answer 2

Genotype

Question 3

What are versions of a gene called?

Answer 3

allele

Question 4

What term refers to the fact that the gene responsible for a particular observable trait might exist in more than one version?

Answer 4

allele

Question 5

If one allele in a member of a homologous chromosome pair codes for blue eye color and a corresponding allele on the other codes for brown eye color, the organism is said to be _________ for eye color.

Answer 5

heterozygous

Question 6

What does it mean if an organism is homozygous for a trait?

Answer 6

Its two alleles are in agreement

Question 7

What does it mean if an organism is heterozygous for a trait?

Answer 7

Their two alleles don’t agree

Question 8

What is codominance?

Answer 8

In the case of multiple alleles, a heterozygote expresses a mixture of the traits of both alleles

Question 9

What are all chromosomes besides sex chromosomes called?

Answer 9

autosomes

Question 10

What is a monohybrid cross?

Answer 10

Crossing 2 true breeds for 1 trait to study 1 trait

Question 11

What is the Law of Dominance?

Answer 11

One trait masks the effects of another trait

Question 12

What is the Law of Segregation?

Answer 12

Alleles can segregate and recombine

Question 13

What is the Law of Independent Assortment?

Answer 13

Traits can segregate and recombine independently of other traits

Question 14

What is a test cross?

Answer 14

Using a recessive organism to determine the genotype of an organism of unknown genotype

Question 15

What is a sex-linked trait?

Answer 15

A trait whose allele is carried on one of the sex chromosomes- X CHROMOSOME for test

Question 16

What are the 3 X-linked traits to know for the test?

Answer 16

hemophilia
color blindness
male pattern baldness

Question 17

What does it mean if a trait is an X-linked recessive trait?

Answer 17

A female can only get it if she’s homozygous for the X chromosome that carries the allele for the trait

Question 18

What is a female who is heterozygous for an X-linked recessive trait?

Answer 18

Carrier- don’t express the trait but carry the allele for it

Question 19

If a male is carrying the allele for hemophilia on his X chromosome, is his phenotype hemophilia?

Answer 19

Yes- there is no normal X chromosome to dominate it

Question 20

X-linked recessive diseases are much more common in males than females because:

Answer 20

Females have to be homozygous for it and males only have to carry it on the X chromosome

Question 21

An X-linked recessive trait cannot go from ______.

Answer 21

father to son

Question 22

In pedigrees, males are represented by _____ and females by ______

Answer 22

squares, circles