LESSON 6

Question 1

in mitosis, Daughter cells are genetically ______ to parent cell – same kind and number of ______

Answer 1

identical ; chromosomes

Question 2

Mitosis occurs in ____ or body cells

Answer 2

somatic

Question 3

This is called its _____ number or the total number of chromosomes in a somatic cell.

Answer 3

diploid

Question 4

Diploid means “_____” and is written as “2N”.

Answer 4

2 sets

Question 5

the process in which the number of chromosomes in the original cell is reduced by HALF through the separation of homologous chromosomes

Answer 5

meiosis

Question 6

meiosis is the process in which the number of chromosomes in the original cell is reduced by ____ through the separation of _____ chromosomes

Answer 6

HALF ; homologous

Question 7

Meiosis occurs in _______ only

Answer 7

sex organs

Question 8

Males (___) – sex organs are the ___ in humans
Females (___) – sex organs are the ___ in humans

Answer 8

XY - testes
XX - ovaries

Question 9

Meiosis produces ___ cells – cells with ___ the number of chromosomes as the original cell

Answer 9

sex ; ½

Question 10

Males – meiosis produces _____
Females – meiosis produces ______

Answer 10

4 sperm ; 1 (viable) egg

Question 11

Females – meiosis produces 1 (viable) egg
The other 3 cells are called ______ – they give up their _____ to nourish the 1 good egg.

Answer 11

polar bodies ; cytoplasm

Question 12

Egg and sperm (sex cells) are also called _____

Answer 12

gametes

Question 13

Gametes have ½ the number of chromosomes as somatic (body) cells. We call this the haploid number. Haploid means “____” and is written as “N”.

Answer 13

1 set

Question 14

If human diploid number is 46, what is its haploid number? ____

Answer 14

23

Question 15

*When does meiosis occur in humans?
1.Males beginning at _____
2.Females ______ – all eggs are produced before birth and at puberty eggs mature

Answer 15

puberty ; before birth

Question 16

Nuclear membrane and nucleolus disappear

Answer 16

prophase 1

Question 17

Each chromosome is composed of two sister chromatids held together by a centromere and is called _____.

Answer 17

dyad

Question 18

Crossing over takes place between two non- sister chromatids

Answer 18

prophase 1

Question 19

Each chromosome is composed of two sister chromatids held together by a centromere and is called dyad.

Answer 19

prophase 1

Question 20

one from the father and one from the mother); along a point called chiasma (plural, chiasmata)

Answer 20

crossing over

Question 21

crossing over takes place between two non-sister chromatids, one from the father and one from the mother); along a point called _____ (plural, chiasmata)

Answer 21

chiasma

Question 22

a pair of homologous chromosomes

Answer 22

tetrad

Question 23

site of synapsis and crossing over

Answer 23

chiasma

Question 24

homologous pairs of chromosomes align along the center of the cell

Answer 24

metaphase 1

Question 25

Spindle fibers increase in number and attach to the kinetochore of each chromatid to facilitate movement.

Answer 25

metaphase 1

Question 26

separation of daughter chromosomes

Answer 26

anaphase 1

Question 27

sister chromatids attached to the centromere

Answer 27

anaphase 1

Question 28

at this stage, there are 46 double stranded chromosomes, which is equivalent to 92 chromatids.

Answer 28

anaphase 1

Question 29

The two daughter cells are completely divided.

Answer 29

telophase 1

Question 30

The number of chromosomes in both cells is the same.

Answer 30

telophase 1

Question 31

This is the short pause between meiosis I and meiosis II.

Answer 31

interkinesis

Question 32

This is similar to interphase of mitosis, except that, here, there is no replication of chromosomes.

Answer 32

interkinesis

Question 33

At this stage, there are 23 double stranded chromosomes, which is equivalent to 46 chromatids

Answer 33

prophase 2

Question 34

Each chromosome is composed of two sister chromatids that are joined by a centromere and are attached to the spindle fiber

Answer 34

metaphase 2

Question 35

The sister chromatids are now called sister chromosomes as they move toward the opposite poles.

Answer 35

anaphase 2

Question 36

The cleavage furrow eventually produces a total two daughter cells, each with a haploid set of chromosomes.

Answer 36

telophase 2

Question 37

Homologous (matching) chromosomes pair up before _____

Answer 37

1st cell division

Question 38

Homologous chromosomes:

Answer 38

-look alike -code for same traits -receive one from each parent

Question 39

During 1st division, homologous chromosomes exchange genes during process called “_______”

Answer 39

crossing over

Question 40

These homologous chromosomes separate during _____ of meiosis – so chromosomes in gametes are different from each other due to ________

Answer 40

2nd division; crossing over

Question 41

Crossing over increases _______ and is the reason why siblings look different

Answer 41

genetic variation

Question 42

______ – process by which an egg and sperm unite

Answer 42

Fertilization

Question 43

______ – fertilized egg

Answer 43

Zygote

Question 44

______ – organism in early stage of development

Answer 44

Embryo