cell division

Question 1

what are the 3 stages in the interphase?

Answer 1

GAP PHASE 1

SYNTHESIS

GAP PHASE 2

Question 2

what is the M phase?

Answer 2

Mitosis and cytokinesis

Question 3

what is the gap phase 1

Answer 3

when the cell grows and new organelles and proteins are made

Question 4

what is gap phase 2

Answer 4

cell keeps growing and proteins needed for division are made

Question 5

what is synthesis

Answer 5

cell replicates its dna ready to divide by mitosis

Question 6

in which stage does the g1 checkpoint occur

Answer 6

in the gap phase 1

Question 7

in which stage does the g2 checkpoint occur

Answer 7

gap phase 2

Question 8

what happens in the g1 checkpoint?

Answer 8

cell checks that the chemicals needed for replication are present and for any damage to the DNA before entering the s phase

Question 9

what happens in the g2 checkpoint?

Answer 9

cell checks whether all the DNA has been replicated without any damage

Question 10

what occurs in the interphase?

Answer 10

the cells DNA is unravelled and replicated. the organelles are also replicated, ATP content is increased

Question 11

what occurs in the prophase?

Answer 11

chromosomes condense, centrioles move to the opposite ends of the cell forming a spindle of protein fibres, nuclear envelope breaks down

Question 12

what occurs in the metaphase?

Answer 12

chromosomes line up along the middle of the cell and become attached to the spindle by their centromere

Question 13

what occurs in the anaphase?

Answer 13

centromeres divide, separating each pair of sister chromatids. the spindles contract pulling chromatids to the opposite ends of the cell

Question 14

what occurs in the telophase?

Answer 14

The chromatids reach the opposite poles on the spindle, uncoil and become long and thin, they are now chromosomes. a nuclear envelope forms around each group of chromosomes

Question 15

what occurs in cytokinesis?

Answer 15

a cleavage furrow forms to divide the cell membrane, cytoplasm divides

usually begins in anaphase and ends in telophase

Question 16

what is the outcome of mitosis

Answer 16

2 genetically identical daughter cells are formed

Question 17

define meiosis

Answer 17

production of gametes for sexual reproduction, all cells formed are genetically different to each other

Question 18

how chromosomes do humans have?

Answer 18

46 chromosomes

Question 19

what are homologous pairs of chromosomes?

Answer 19

have the same size and the same genes although they can have different version of those genes (alleles)

Question 20

what happens in meiosis 1, prophase 1?

Answer 20

chromosomes condense
chromosomes arrange themselves in homologous pairs
centrioles move to opposite ends of cell
spindle fibres form
nuclear envelope breaks down

Question 21

what happens in meiosis 1, metaphase 1?

Answer 21

homologous pairs line up across the centre of the cell and attach to the spindle fibres by their centromeres

Question 22

what happens in meiosis 1, anaphase 1?

Answer 22

spindles contract separating homologous pairs, one chromosome to each end of cell

Question 23

what happens in meiosis 1, telophase 1?

Answer 23

nuclear envelope forms, around each group of chromosomes, cytokinesis occurs and 2 haploid daughter cells are produced.

Question 24

what happens in meiosis 2, anaphase 2?

Answer 24

pairs of sister chromatids are separated, each new daughter cell inherits one chromatid from each chromosome.

4 genetically identical haploid daughter cells are produced. these are the gametes

Question 25

what are 2 events in meiosis that lead to genetic variation?

Answer 25

crossing over of chromatids independent assortment of chromosomes

Question 26

in which stage of meiosis does crossing over of chromatids occur?

Answer 26

meiosis 1, prophase 1

Question 27

in which stage of meiosis does independent assortment of chromosomes occur?

Answer 27

metaphase 1 and prophase 1

Question 28

what are stem cells?

Answer 28

unspecialised cells

Question 29

where in humans are stem cells found?

Answer 29

early embryos and bone marrow

Question 30

why is it better to have stem cells from early embryos rather than the bone marrow?

Answer 30

as they can develop into any type of cell whereas in adults it can only develop into a limited range of cells

Question 31

what do cells in the bone marrow differentiate into?

Answer 31

bloods cells, erythrocytes RBC and neutrophils WBC

Question 32

what do cells in meristems differentiate into?

Answer 32

xylem and phloem

Question 34

how might stem cells be used to treat Parkinson's disease?

Answer 34

the disease causes a loss of a type of nerve cell in the brain, these cells release a chemical called dopamine which is needed to control movement, transplanted stem cells may help to regenerate the dopamine producing cells

Question 35

how does neutrophils structure help them perform their function?

Answer 35

they have flexible shape which allows them to engulf foreign particles they have many lysosomes in their cytoplasm which contain digestive enzymes to break down engulfed particles

Question 36

how does erythrocytes structure help them perform their function?

Answer 36

have a biconcave disc shape which gives a large surface area for gas exchange no nucleus so more room for haemoglobin

Question 37

how does epithelial cells structure help them perform their function?

Answer 37

ciliated epithelia (AIRWAY) have cilia that beat to move particles away squamous epithelia (LUNGS) are very thin to allow efficient diffusion of gases.

Question 38

how does sperm cells structure help them perform their function?

Answer 38

have a flagellum, so they can swim to the egg lots of mitochondria to provide energy to swim the acrosome contains digestive enzymes to enable sperm to penetrate the surface of the egg.

Question 39

how does palisade mesophyll cells structure help them perform their function?

Answer 39

many chloroplasts for photosynthesis, absorb a lot of sunlight thin walls so co2 can diffuse into the cell

Question 40

how does root hair cells structure help them perform their function?

Answer 40

large surface area for absorption of mineral ions and water from soil thin permeable cell wall for entry of water and ions cytoplasm contains extra mitochondria to provide energy needed for active transport

Question 41

how does guard cells structure help them perform their function?

Answer 41

thin outer walls and thickened inner walls force them to bend outwards opening the stomata allowing the leaf to exchange gases for photosynthesis

Question 42

what is a tissue?

Answer 42

a group of cells that are specialised to work together to carry out a particular function, a tissue can contain more than one type of cell

Question 43

name 2 examples of animal tissues

Answer 43

muscle tissue and cartilage

Question 44

name 2 types of plant tissues

Answer 44

xylem tissue and phloem tissue

Question 45

what is an organ?

Answer 45

is a group of different tissues that work together to perform a particular function

Question 46

what is a example of an organ?

Answer 46

the lungs have squamous epithelial tissues, ciliated epithelia tissue and vascular and elastic connective tissue.

Question 47

what is an organ system?

Answer 47

organs that work together to make up an organ system, each system has a particular function

Question 48

what are 2 examples of an organ system?

Answer 48

the respiratory system the circulatory system