Chapter 11

Question 1

two processes create new combinations of genetic info in populations during sexual reproduction

Answer 1

1. indepenedent assortment of chromosomes

2. crossing over

Question 2

independant assortment of chromosomes

Answer 2

produces gametes with different maternal and paternal chromosomes
the more chromosomes present, the greater the number of different gametes

Question 3

crossing over

Answer 3

exchange of sections of chromosomes on homologous pairs
occurs during prophase 1 of meiosis
mixes maternal and paternal homologous chromosomes

Question 4

mutations

Answer 4

change in the genetics of an organisms

Question 5

point mutations

Answer 5

change in the nucleotide sequence or a small section of a nucleic acid. caused by:
-copying errors during DNA replication
-changes in the structure of nucleotides by:
high energy photons (radiation)
chemicals in the environment

Question 6

types of point mutations

Answer 6

1. base substitutions

2. base deletions

Question 7

base substitutions

Answer 7

change in nucleotide sequence

Question 8

base deletions

Answer 8

loss of nucleotide

results in a change in the amino acid sequences downstream from the deletion

Question 9

chromosomal mutations

Answer 9

1. extra or missing copies of chromosomes
   results from nodisjunction (failure of chromosomes to seperate) during meiosis
   missing chromsoems are lethal
   extra chromosomes are usually lethal in animals

Question 10

nondisjunction in meiosis 1

Answer 10

all abnormal gametes

results in extra chromosomes and missing chromosomes

Question 11

nondisjunction in meiosis 2

Answer 11

normal and abnormal gametes

results in normal, extra, and missing chromosome

Question 12

exceptions to lethal effects of extra chromosomes in animal

Answer 12

1. extra copies of sex chromosomes:
extra X chromosomes are silenced 
Y chromosomes carry few geens
XXX- normal female
XYY- normal male
XXY- sterile male
2. extra copy of chromosome 21
causes down syndrome

Question 13

nondisjunction events

Answer 13

increase with age

Question 14

chromosomal abnormalities: result from

Answer 14

from improper crossing over and seperation of chromosomes
a) deletions
b) duplications
c) inversions
d) translocation:
exchange of chromosomal material between non homologous chromosome
cane result in extra or missing regions of chromosome in gamates