chapter 9

Question 1

gene pool

Answer 1

All the genes and alleles in a population at a particular time

Question 2

Non- disjunction

Answer 2

when chromosomes or chromatids do not split equally during anaphase

Question 3

polyploidy

Answer 3

type of chromosome mutation where there are changes to the whole set of chromosomes occur when organisms have 3 or more sets of chromosomes rather than the usual 2

Question 4

aneuploidy

Answer 4

type of chromosome mutation where there is a change in the number of individual chromosomes

Question 5

what is meiosis

Answer 5

cell division creates genetically different gametes, 4 haploid daughters cells are produced

Question 6

haploid (n)

Answer 6

one copy of each chromosomes

Question 7

diploid (2n)

Answer 7

two copies of each chromosomes

Question 8

genetic diversity

Answer 8

the number of different alleles in a population

Question 9

evolution

Answer 9

changes in allele frequency over many generation

Question 10

gene mutation

Answer 10

change in the base sequence of DNA

Question 11

mutagenic agent

Answer 11

factor the increases rate of mutation

Question 12

chromosome mutation

Answer 12

random changes in the number of chromosomes caused by chromosome non-disjunction during meiosis

Question 13

2 reasons why gene mutations may not cause change to the primary structure of a protein

Answer 13

1- the genetic code is degenerate, so the new triplet of bases may still code for the same amino acid

2- if the mutation occurs in an intron

Question 14

describe crossing over

Answer 14

pair of homologous chromosomes associate with each other, creates a chiasma, this causes tension in the chromatid causing them to break off, broken chromatids recombine with one another

Question 15

independent segregation

Answer 15

homologous pairs of chromosomes line up opposite each other at the equator, the side where they line up is random, pairs separate so one from each pairs ends up in a daughter cell, creates number of combination

Question 16

natural selection

Answer 16

• New alleles that increase genetic diversity created by random mutation
• If the new alleles increase the chances of the individual to survive in that environment, then they are more likely to survive and reproduce
• The reproduction passes on the advantageous allele to the next generation
  -As a result, over many generation the new allele increase in frequency in the population
• Other alleles decrease in frequency

Question 17

stabilizing selection

Answer 17

mean trait has the advantage
there’s no change in the environment
mean trait is not changed
standard deviation decreases as individuals with extreme traits decrease

Question 18

directional selection

Answer 18

one of the extremes has the selective advantage
only occurs when there’s a change to the environment
mean trait changes

Question 19

advantage of natural selection

Answer 19

it results in species becoming better adapted to their environment