15.4

Question 1

What are the source of all new alleles, which leads to new phenotypic traits?

Answer 1

Random mutations

Question 2

What can affect the phenotype of an organism?

Answer 2

• Small-Scale changes involving individual genes.
• Large-Scale chromosomal changes (physical/chemical disturbances, errors during meiosis).

Question 3

Nondisjunction

Answer 3

• Members of a pair of homologous chromosomes do not move apart property during meiosis 1
• Sister chromatids fail to separate during meiosis 2

Question 4

What happens in nondisjunction?

Answer 4

One gamete receives an extra copy of a chromosome and another gamete receives no copy the chromosome.

Question 5

Aneuploidy

Answer 5

The presence of an abnormal number of chromosomes in a cell.

Question 6

Monosomic

Answer 6

An aneuploid zygote that has a missing chromosome.

Question 7

Trisomy

Answer 7

A person has three copies of a chromosome instead of two.

Question 8

What is the main reason for pregnancy loss?

Answer 8

Monosomy and Trisomy

Question 9

Is Down Syndrome an example of monosomy or trisomy?

Answer 9

Trisomy

Question 10

Polyploidy

Answer 10

More than two complete chromosome sets in all somatic cells.

Question 11

What are the four types of changes in chromosome structure?

Answer 11

• Deletion
• Duplication
• Inversion
• Translocation

Question 12

Down Syndrome/Trisomy 21

Answer 12

The result of an extra chromosome 21, so that each body cell has a total of 47 chromosomes.

Question 13

Aneuploidy of Sex Chromosomes

Answer 13

• XXY in males
• XYY in males
• XXX in females
• XO in females

Question 14

Klinefelter Syndrome

Answer 14

A male has an extra X chromosome (XXY)

Question 15

Turner Syndrome

Answer 15

Femailes have a missing X chromosome (XO).