U1L6

Question 1

Meiosis reduces

Answer 1

the number of
chromosome sets from diploid to haploid

Question 2

What produced in sexual life
cycles contributes to evolution

Answer 2

Genetic Variation

Question 3

Hereditary

Answer 3

Is the transmission of traits from
one generation to the next

Question 4

Variation

Answer 4

Is demonstrated by differences in appearance that offspring show from parents and siblings

Question 5

locus

Answer 5

Each gene has a specific chromosomal location

Question 6

Genes are passed to the next generation via reproductive
cells called

Answer 6

Gametes

Question 7

Asexual reproduction

Answer 7

a single individual passes genes to its offspring without the fusion of gametes

Question 8

Clones

Answer 8

Is a group of genetically identical
individuals from the same parent

Question 9

Sexual reproduction

Answer 9

Two parents give rise to offspring having unique combinations of genes inherited from both

Question 10

Each replicated chromosome

Answer 10

consists of 2 identical sister chromatids

Question 11

Gametes (sperm or egg) contain a single set of chromosomes, and are

Answer 11

Haploid

Question 12

what exhibit an
alternation of generations

Answer 12

Plants and some algae

Question 13

only diploid cells

Answer 13

can undergo meiosis

Question 14

Meiosis takes place in two sets of cell
divisions called

Answer 14

Meiosis I and II

Question 15

The two cell divisions result in

Answer 15

4 daughter cells

Question 16

Each daughter cell in meiosis has only

Answer 16

half as many chromosomes as the parent cell

Question 17

After interphase the sister chromatids are held together by

Answer 17

Cohesions

Question 18

Describe the process of crossing over

Answer 18

The non sister chromatids are broken at precisely corresponding positions
A zipper-like structure called the synaptonemal complex holds the homologs together
DNA breaks are repaired, joining DNA from one non sister chromatid to the corresponding segment of another

Question 19

Comparison between mitosis and meiosis

Answer 19

Mitosis conserves the number of chromosome sets, producing cells that are genetically identical to parent cell

Meiosis reduces the number of chromosome sets from two
(diploid) to one (haploid), producing cells that differ genetically from each other and from parent cell

Question 20

Mutations (changes in an organism’s DNA) are the

Answer 20

original source of genetic diversity

Question 21

Mutations

Answer 21

create different versions of
genes called alleles

Question 22

Three mechanisms contribute to genetic variation

Answer 22

Independent assortment of chromosomes
Crossing over
Random fertilization

Question 23

How many different combinations of
maternal and paternal chromosomes
can be packaged in gametes in an
organism whose diploid number is
16?

Answer 23

2n = 16
n = 6
2^6 = 256

Question 24

The number of combinations possible when chromosomes assort independently into gametes is

Answer 24

2^n n = haploid number

Question 25

Crossing over produces

Answer 25

Recombinant
chromosomes, which combine DNA from each parent

Question 26

Crossing over begins very early in

Answer 26

prophase I, as homologous chromosomes pair up gene by gene

Question 27

In crossing over

Answer 27

homologous portions of two
non sister chromatids trade places

Question 28

Crossing over contributes to genetic variation by

Answer 28

combining DNA from two
parents into a single
chromosome

Question 29

Random fertilization adds to genetic variation

Answer 29

Because any sperm can fuse with any ovum(unfertilized egg)

Question 30

In nondisjunction

Answer 30

pairs of homologous chromosomes do not separate normally during meiosis

Question 31

What happens in prophase I

Answer 31

Nuclear envelope breakdown, spindle formation, crossing over: DNA molecules of nonsister chromatids are broken and rejoined

Question 32

What happens in metaphase I

Answer 32

Pairs of homologuous chromosmes are arranged at the metaphase plate

Question 33

What happens at Anaphase I

Answer 33

Breakdown of proteins responsible for sister chromatid cohesion
Move toward opposite poles

Question 34

What happens in Telophase I and cytokinesis

Answer 34

Each half of cell has become a haploid set of chromosomes
Two haploid cells form consisting of two sister chromatids
Cleavage furrow formation

Question 35

What happens in prophase 2

Answer 35

Spindle apparatus forms, move toward metaphase II plate

Question 36

Metaphase II

Answer 36

Chromosomes are positioned at the metaphase plate
Kinetochores of sister chromatids are attached to microtubules extending from opposite poles

Question 37

Anaphase II

Answer 37

Breakdown of proteins holding sister chromatids together
Move toward opposite poles as individual chromosomes

Question 38

Telophase II and cytokinesis

Answer 38

Chromosomes begin de-condensing
Meitoic division of one parent cell produces 4 daughter cells each with a haploid set of chromosomes
Daughter cells are genetically distinct from one another and from the parent cell

Question 39

Independent assortment

Answer 39

refers to the random distribution of different chromosome pairs into gametes. In other words, the inheritance of one gene is independent of the inheritance of another gene located on a different chromosome.

Question 40

Segregation

Answer 40

alleles of a gene pair separate or “segregate” during the formation of gametes (eggs and sperm) in a sexually reproducing organism