mitosis

Question 1

state the 3 importance factors of mitosis

Answer 1

• growth
• asexual reproduction
• tissue repair

Question 2

summarise prophase

Answer 2

• chromatin coils and condenses into molecules which can wrap DNA around histones
• nuclear envelope breaks down
• centrioles move to opposite poles

Question 3

summarise metaphase

Answer 3

• spindle fibres pull chromasomes to middle of cell equator

Question 4

summarise anaphase

Answer 4

• centromeres divide
• chromatids separate to opposite poles

Question 5

summarise telophase

Answer 5

• chromatids are now chromosomes
• nuclear membrane reforms

Question 6

summarise cytokinesis

Answer 6

• the actual division of the 2 diploid daughter cells

Question 7

describe mitosis in plants

Answer 7

• formation of cell plate
• wall material and new membrane deposit here
• no centrioles
• only meristems undergo mitosis

Question 8

describe mitosis in animals

Answer 8

• cytoplasm constricts to create a cleavage furrow
• centrioles present
• most cells capable of mitosis

Question 9

what does mitosis produce?

Answer 9

two genetically identical diploid daughter cells

Question 10

why is mitosis important in repair?

Answer 10

• If cells are damaged through injury the healing process involves mitosis to produce cells which are genetically the same
• When cells need to be replaced constantly throughout life it is mitosis which produces the replacement cells e.g top layer of skin

Question 11

why is mitosis important in growth?

Answer 11

-when sperm cell fertilises an ovum the nuclei fuse together to make a zygote. The zygote divided by mitosis so that all the cells in the new organism have exactly the same information- all the cells will contain exactly same alleles to give the same phenotype

Question 12

why is mitosis important in asexual reproduction?

Answer 12

-asexual reproduction means that one parent plant produces genetically identical clones. This is helpful as one organism can produce many offspring very quickly if weather conditions aren’t changing

Question 13

what is the purpose of chromosomes condensing in prophase?

Answer 13

by condensing the chromosomes become more compact so a large amount of DNA can be fitted into a small space and so that when the 2 daughter cells separate the DNA is organised and doesn’t get tangled up with other chromosomes

Question 14

why is it important that the cell cycle is halted for tissues? (2)

Answer 14

• prevent excessive tissue production
• limits repair capacity of tissue