Unit Test #2

Question 1

What is an Alleles?

Answer 1

It is a human somatic cell containing 46 chromosomes = 23 pairs. Each pair codes genetic traits but prove different details. Genes have different forms called Alleles, out of two alleles one is dominant over the other.

Question 2

What does homozygous mean?

Answer 2

It is an individual with two of the same alleles. Ex. Dominant=BB Recessive=bb

Question 3

What does heterozygous mean?

Answer 3

It is an individual with two different alleles. Ex. Bb

Question 4

What is a genotype?

Answer 4

It is the genetic make-up of an individual. Ex. BB,Bb,bb

Question 5

What is a phenotype?

Answer 5

It is the appearance of the individual. Ex. Brown or Not Brown eyes

Question 6

What is the principal of dominance?

Answer 6

It is when someone with different alleles reproduce and the offspring only shows dominant traits.

Question 7

What is the law of segregation?

Answer 7

It is when chromosome pairs split during meiosis with one member per pair going into separate gametes.

Question 8

What is the law of independent assortment?

Answer 8

It is the inheritance of traits that are independent/separate from each other.

Question 9

What is test cross?

Answer 9

It is a homozygous recessive person that is bred to one with an unknown genotype to determine their genotype.

Question 10

What is a pedigree?

Answer 10

It is a diagram that shows the genetic relationship among related individuals.

Question 11

What is incomplete dominance?

Answer 11

It is when neither alleles are responsible for a dominant trait over others. In a heterozygous person it results in blending.

Question 12

What is co-dominance?

Answer 12

It is when both alleles are responsible for the dominant trait. In a heterozygous person it results in the appearance of both alleles.

Question 13

What is multiple alleles?

Answer 13

It is when there are more than two possible alleles for a specific gene.

Question 14

What is sex linkage?

Answer 14

Genetic male=XY
Genetic female=XX
It is when males have a greater risk of X-linked recessive traits than females.

Question 15

What are barr bodies?

Answer 15

It is when one X chromosome in female cells becomes inactivated.
The chromosome coils up and no longer provides instructions to the cell.
It occurs during early embryonic development.
It is random as to which X inactivates in each embryonic cell.

Question 16

What is cytoplasmic inheritance?

Answer 16

It is when organisms are taken by eukaryotic cells to become organelles.
The DNA helps to carry out their processes, Mitochondria= cellular respiration Chloroplast= photosynthesis.
They reproduce separately to make copies of their DNA.

Question 17

What is sexual reproduction?

Answer 17

It is when the gametes contribute to the amount of nuclear DNA.
Equal amounts of cytoplasmic DNA are not contributed.
Male gametes= small and contribute little cytoplasm compared to female egg.

Question 18

What is maternal inheritance?

Answer 18

It is when the female gamete provides the cytoplasm and organelles.
Family lines can be traced using mtDNA.
There are diseases that can be avoided by transferring egg nucleus of impacted female to a normal egg cell.

Question 19

What is polygenic inheritance?

Answer 19

It is controlled by more than one gene.
It results in traits with a wide range of variation.

Question 20

What is modifier genes?

Answer 20

It is when they work together with other gene to control trait expression.
The genes either code for the presence or absence.

Question 21

What is lethal genes?

Answer 21

It is when homozygous organisms with a lethal gene don’t survive.
Heterozygous organisms with a lethal gene will show some effects.