Cell cycle

Question 1

what is the spindle made from ?

Answer 1

microtubules

Question 2

what is the order of mitosis?

Answer 2

Interphase (G1, S, G2) - prophase - meta phase - anaphase - telophase - (cytokinesis)

Question 3

Describe the chromosomes in interphase

Answer 3

uncoiled and invisible

Question 4

Describe G1

Answer 4

Longest stage of cell cycle, highly metabolically active, cell grows, chromosomes consist of one chromatid

Question 5

Describe S

Answer 5

DNA replicates so chromosomes contain 2 identical sister chromatids

Question 6

Describe G2

Answer 6

Further intense cellular activity, mitochondrion divide, ATP stores increase

Question 7

Describe prophase

Answer 7

Chromosomes coil (spiralisation) making them visible, spindle forms, nucleolus disappears

Question 8

Describe metaphase

Answer 8

Chromosomes move to the equator of spindle and attach to spindle fibres by their centromeres, lined up

Question 9

Describe anaphase

Answer 9

Centromere splits, spindle fibres pull chromatids by centromere to opposite poles
Chromosomes now only 1 chromatid, so cell is 4n

Question 10

Describe telophase

Answer 10

Chromosomes uncoil and become invisible, nuclear envelopes from around two groups of chromosomes, new nucleoli forms, spindle breaks down, (centrioles replicate in animals)

Question 11

Describe cytokinesis

Answer 11

Cell divides into 2 identical diploid daughter cells (2n)

Question 12

Describe animal cytokinesis

Answer 12

micro tubules constrict the cell around the equator, pinching the cell into two

Question 13

Describe plant cytokinesis

Answer 13

cell plate forms along equator, from which cell wall forms, diving the cell into two

Question 14

what are stem cells ?

Answer 14

unspecialized cells that develop to become specialized cells by the process of differentiation

Question 15

what is the difference between embryo stem cells and adult stem cells ?

Answer 15

embryo stem cells are pluripotent, adult stem cells are multipotent

Question 16

where are most adult stem cells in humans ?

Answer 16

bone marrow - to produce erythrocytes and neutrophils

Question 17

define homologous pair

Answer 17

Pair of chromosomes, one maternal and one paternal, that carry the same genes at same loci, although may have different alleles. They pair at meiosis to form bivalent

Question 18

how are phloem sieve tubes developed ?

Answer 18

stem cells of the vascular cambium divide and differentiate into them

Question 19

how can stem cells be used for Alzheimer’s ?

Answer 19

Use them to grow and replace dead nerve cells in the brain

Question 20

how can stem cells be used for Parkinson’s ?

Answer 20

Transplanted stem cells may help regenerate dopamine- producing cells (that controls movement)

Question 21

What is difference between squamous epithelial / epithelium ?

Answer 21

epithelial - cell

epithelium - tissue

Question 22

what are the three things in meiosis that gives variation ?

Answer 22

• crossing over
• recombination
• independent assortment

Question 23

Describe prophase I

Answer 23

• chromosomes condense (visible)
• chromosomes arrange in homologous pairs and crossing over occurs
• nuclear envelop breaks down

Question 24

Describe metaphase I

Answer 24

homologous pairs line across center and attach to spindle fibres by centromeres

Question 25

Describe anaphase I

Answer 25

spindles contract, separating chromosome pairs

Question 26

Describe telophase I

Answer 26

nuclear envelop forms around each group of chromosomes

Question 27

Describe cytokinesis I

Answer 27

two haploid daughter cells produced

Question 28

name the differences between prophase I and II

Answer 28

• 1 has and interphase before, 2 doesn’t
• 1 has crossing over and recombination, 2 doesn’t
• 1 has homologous pairs, 2 doesn’t

Question 29

Describe anaphase II

Answer 29

pair of sister chromatids separate

Question 30

what is crossing - over ?

Answer 30

bit of chromatids swap in the homologous pairs, mixing the combination of alleles

Question 31

what is a bivalent ?

Answer 31

two homologous chromosomes who have come together

Question 32

what is chiasma ?

Answer 32

the cross - shaped link between the chromosomes in crossing over

Question 33

what is the function of the xylem ?

Answer 33

transports water and supports plant

Question 34

what is the function of the phloem ?

Answer 34

transports sugas around the plant

Question 35

where are most stem cells in plants ?

Answer 35

meristems - parts which grow (so roots and shoots)

Question 36

define multi cellular organisms

Answer 36

organisms made up form many different cell types that are specialized for a function

Question 37

what are bones ?

Answer 37

living organs containing nerves and blood vessels

Question 38

describe specialised structure of neutrophil

Answer 38

• flexible shape allows them to engulf foreign pathogens

- lysosomes in cytoplasm contain digestive enzymes, break down particles

Question 39

describe specialised structure of erythrocytes

Answer 39

• biconcave disc shape provides large SA (gas exchange)

- no nucleus for more haemoglobin

Question 40

describe specialised structure of epithelial cells

Answer 40

• cilia (move substances)

- squamous are thin

Question 41

describe specialised structure of sperm

Answer 41

• flagellum to swim
• lots of mitochondrion for energy
• acrosome contains digestive enzymes to penetrate egg

Question 42

describe specialised structure of RHC

Answer 42

• large SA
• thin permeable wall
• cytoplasm has extra mitochondrion for active transport