Chapter 13 (Meiosis)

Question 1

Which type of cell division is related to reproduction?

Answer 1

meiosis

Question 2

What are the advantages of sexual reproduction? (2)

Answer 2

1. Variation in offsprings2. Increase survival of population

Question 3

Sexual reproduction (3)

Answer 3

1. Gametes2. Two parents3. Different offsprings

Question 4

What are homologous pairs? (5)

Answer 4

1. Pair of chromosomes, one from each parent2. Same length and shape3. Same banding patterns4. Same order of genes5. Similar dna sequences

Question 5

What is a karyotype?

Answer 5

display of chromosomes in metaphase ➡️ shows banding pattern

Question 6

What is diploid and haploid?

Answer 6

✅ Diploid (2n) → Cells with two sets of chromosomes (one from each parent).• Humans: 46 chromosomes (23 pairs)• 2n = 46 → n = 23✅ Haploid (n) → Cells with one set of chromosomes (gametes: sperm/egg).• Humans: 23 chromosomes.

Question 7

Do somatic cells have haploid or diploid chromosomes?

Answer 7

Diploid (2n)➡️ two copies of every chromosome➡️ Human 2n = 46 [Image]

Question 8

Aregametes cells haploid or diploid?

Answer 8

Haploid (n)➡️ Because gametes are either sperm or egg cells therefore they need to be haploid because they’ll need to combine that for fertilization➡️ 1 copy of every chromosome [Image]

Question 9

Identify each letter and number [Image]

Answer 9

A ➡️ Haploid (n)B ➡️ Diploid (2n)1 ➡️ Ovary2 ➡️ Testis3 ➡️ Meiosis4 ➡️ sperm (n)5 ➡️ haploid gametes (n=23)6 ➡️ Egg (n)7 ➡️ fertilization8 ➡️ Diploid zygote (2n =46)9 ➡️ Mitosis and development10 ➡️ Multicellular diploid adults (2n =46)

Question 10

By how many does meiosis divide the number of chromosomes

Answer 10

BY HALF

Question 11

If both parents are diploid (2n), what will be the gametes formed?

Answer 11

haploid (n)

Question 12

What happens during fertilization?

Answer 12

The gametes unite to restore the diploid number n + n = 2n

Question 13

How many nuclear divisions does Meiosis have?

Answer 13

2 ➡️ Meiosis I and Meiosis II

Question 14

True or False, DNA replication occurs twice

Answer 14

False, ONLY ONCE during interphase

Question 15

What do we call when 2 homologous chromosomes pair up?

Answer 15

synapsis

Question 16

What happens in meiosis I?

Answer 16

1. Separation of homologous chromosomes2. Number of chromosomes reduced 2n ➡️ n3. Twodaughter cells [Image]

Question 17

What happens in meiosis 2?

Answer 17

1. The sister chromatids seperates2. Four daughter cells ➡️ Gametes [Image]

Question 18

When does the “crossing over” occur?

Answer 18

prophase 1

Question 19

What do we call the formation of 4 sisters ?

Answer 19

Tetrad

Question 20

ProphaseI (3)

Answer 20

1. Chromosomes condense2. Synapsis ➡️ Homologous chromosomes pair up3. Crossing over ➡️ Exchange segments of dna

Question 21

Metaphase I (3)

Answer 21

1. Alignment of tetrads along the equator2. Homologous chromosomes are held tgt by chiasmata ➡️ Crossing over site3. Independent assortment ➡️ Homologous chromosomes align randomly [Image]

Question 22

Anaphase I

Answer 22

homologous chromosome pairs are split we end up with chromosomes only (sister chromatids)

Question 23

Telophase I:

Answer 23

1. Chromosomes decondenses (spindle bye bye and nuclear envelope hi)2. Not necessarily cytokinesis3. Nuclei are haploid [Image]

Question 24

prophase II

Answer 24

1. Chromosomes recondenses ➡️ Centriole duplications, nuclear envelope bye bye and spindle reforms

Question 25

metaphase II

Answer 25

chromosomes align at equator

Question 26

Anaphase II

Answer 26

The “sister” chromatids are separated ➡️ not real sister chromatids because of crossing over

Question 27

Telophase II

Answer 27

1. Chromosomes decondenses 2. cytokinesis ➡️ 4 different haploid cells➡️ 4 different haploid nuclei reform

Question 28

what are factors that can increase variation in traits of offsprings? (3)

Answer 28

1. Crossing over ➡️ Prophase I2. Independent assortment ➡️ Metaphase I3. Random fertilization

Question 29

Crossing over happens for all _______________

Answer 29

homologous chromosomes pair

Question 30

independent assortment

Answer 30

1. During metaphase I2. How homologous chromosome pairs (tetrads) randomly line up at equator

Question 31

Which type of cells are involved in mitosis and meiosis?

Answer 31

Mitosis: somatic cells, embryonic Meiosis: germ cells (gametes)

Question 32

What’s the number of division in mitosis and meiosis?

Answer 32

Mitosis = 1Meiosis = 2

Question 33

Which type of cells division involve crossing over at prophase I?

Answer 33

Meiosis only

Question 34

Which type of cells division does independent assortment occur?

Answer 34

Meiosis only

Question 35

How many tImes is DNA synthesized (replicated) in mitosis and meiosis?

Answer 35

ONLY ONCE at the S phase of interphase

Question 36

How many cells are produced at the end of each cell division?

Answer 36

Mitosis = 2Meiosis = 4

Question 37

Whats the ploidy (haploid/diploid) of cells reduced in each type of cell division?

Answer 37

Mitosis = diploid (2n = 46)meiosis = haploid (n=23)

Question 38

Which number of meiosis is very similar to mitosis?

Answer 38

Meiosis 2 ➡️ sister chromatids are seperated [Image]

Question 39

Whats the formula to calculate the number of different possibilities of gametes based only on independent assortment?

Answer 39

2^n where  n = # of homologous chromosomes pairs Ex: humans have 23 pairs of chromosomes (n=23) ➡️ 2^23

Question 40

Let’s say the diploid number is 2n =2 ➡️ find the number of chromosomes and chromatids in each phase of meiosis (G1, P1, P2, gametes)

Answer 40

G1:➡️ chromosomes = 2➡️ Chromatids = 0 (chromatids is when sister chromatids are attached by their centromere)P1:➡️ Chromosomes = 2➡️ Chromatids = 4P2:➡️ Chromosomes = 1➡️ Chromatids = 2Gametes:➡️ Chromosomes = 1➡️ chromatids = 0

Question 41

Let’s say the diploid number is 2n =2 ➡️ find the number of chromosomes and chromatids in each phase of mitosis (G1, P, M, A, T)

Answer 41

G1:➡️ chromosomes = 2➡️ Chromatids = 0P:➡️ Chromosomes = 2➡️ Chromatids = 4M:➡️ Chromosomes = 2➡️ Chromatids = 4A:‼️➡️ Chromosomes = 4 ➡️ Chromatids = 0T:➡️ Chromosomes = 2➡️ Chromatids = 0

Question 42

How do you calculate the number of different possible offspring combinations?

Answer 42

🔢 Formula: (2^n)^2• 2^n → Number of possible gametes (where n is the haploid chromosome number)• Squaring it accounts for the fusion of sperm and egg (fertilization)• This gives the total number of unique offspring combinations! 👶

Question 43

What does the calculation of number of different possible offspring combination involve in terms of genetic variation?

Answer 43

✅ Independent assortment → Random distribution of chromosomes in meiosis✅ Random fertilization → Any sperm can fuse with any egg❌ Does NOT include crossing over, since the formula (2^n) only considers chromosome assortment