Unit two: Genes and Heredity

Question 1

Explain why these are false:

Mitosis occurs in prokaryotes

Answer 1

Mitosis is the division of the nucleus and prokaryotes do not have a nucleus so only in eukaryotes

Question 2

Explain why these are false:

Mitosis only occurs in diploid cells

Answer 2

Mitosis can occur in cells with other ploidy levels ex: honey bee is haploid

Question 3

Explain why these are false:

Centrioles are in all eukaryotic cells

Answer 3

Centrioles are in all animal cells. They have not been observed in plants

Question 4

Explain why these are false:

Prokaryotes are haploid

Answer 4

Prokaryotes do not have a ploidy level, most have singular circular chromosome whereas eukaryotes have one or more pairs of linear chromosomes

Question 5

Explain why these are false:

rRNA is used for DNA replication

Answer 5

rRNA is a component of ribosomes and ribosomes synthesizes proteins

Question 6

How can a 3n (triploid) oyster be produced using only one ovum and one sperm ?

Answer 6

One of the gametes is 2n and the other is n, creating a 3n zygote. Since a diploid gamete is abnormal, meiosis 1 would have to be messed up to produce a 2n cell, example, the chromosomes do not separate and they are all compressed into one of the cell, creates 2n gametes

Question 7

Can meiosis happen again and again in a cell ?

Answer 7

No, haploid cells is the product of Meiosis and it starts as a diploid but once it is a haploid it cannot go through mitosis again

Question 8

Mosquitoes have a haploid # of 3. How many ds chr in a mosquitoes cell during G1?

Answer 8

zero: G1 chromosomes are single stranded because it precedes DNA replication

Question 9

Mosquitoes have a haploid # of 3. How many chr in a mosquitoes cell at prophase 1?

Answer 9

prophase 1 is 2n, 2x3= 6 chr

Question 10

Mosquitoes have a haploid # of 3. How many chromatids in a mosquitoes cell during prophase 1?

Answer 10

2n in prophase 1, ds chr, 2x3= 6 chr, 2 chromatids per chromosomes is 12 chromatids

Question 11

Mosquitoes have a haploid # of 3. How many sets of chr in a mosquitoes cell during metaphase 1?

Answer 11

2 sets : how many sets is how many chr of each type, metaphase 1 is 2n (diploid)

Question 12

Which features are present in metaphase and metaphase 1?

Answer 12

ds chromosomes, spindle fibers, kinetochores, centrosomes, homologous chromosomes:

Question 13

Which features are presents in metaphase 1 and 2 ?

Answer 13

spindle fibers, kinetochores, centrosomes, ds chromosomes (since metaphase 2 are haploid, no homologous chr)

Question 14

Identify stage(s) where chr align at the cell equator in Meiosis and mitosis.

Answer 14

Metaphase and Metaphase 2: in metaphase 1, tetrads (bivalents) align at the equator and not chr

Question 15

Identify stage(S) where crossing over occurs.

Answer 15

Prophase 1: crossing over can only occur once the synapsis (pairing) of homologous pairs has happened, since this happens during prophase 1, by the time metaphase 1 starts, crossing over is complete

Question 16

Identify stage(s) where cell is in 2n.

Answer 16

G1 , S-phase, G2, prophase, prometaphase, metaphase, telophase, prophase 1, metaphase 1, anaphase 1 and 2: cells in meiosis 2 are haploid but for a brief moment in anaphase 2 is 2n

Question 17

Select the function of mitosis

Answer 17

Creation of new cells
Replace old, worn and damaged cells
Produce new organisms

Question 18

Identify stage(s) where homologous chr are present

Answer 18

All interphase, prophase, prometaphase, metaphase, telophase, prophase1, metaphase1 (homolgous chr are present when cell is diploid)

Question 19

Which characteristics have chr in metaphase 2.

Answer 19

Aligned at the equator of the cell, ds and haploid

Question 20

Identify all functions of MPF

Answer 20

Initiates assembly of spindle fibers
Initiates breakdown of nuclear membrane
Stimulates chromatin condensed into chromosomes