Cells and control

Question 1

what is mitosis used for?

Answer 1

growth and repair of cells

Question 2

Interphase

Answer 2

cell grows
increases amount of subcelluclar structures
DNA duplicates and copied

Question 3

prophase

Answer 3

chromosomes condense
membrane around nucleus breaks down
chromosomes lie free in cytoplasm

Question 4

metaphase

Answer 4

chromosomes line up at centre of cell

Question 5

anaphase

Answer 5

cell fibres pull chromosomes apart

two arms go to opposite ends of cell

Question 6

telophase

Answer 6

membranes form around each set of chromosomes

nucleus divides to become nuclei

Question 7

cytokinesis

Answer 7

cytoplasm and cell membrane divide to form two separate cells

Question 8

what does mitosis produce?

Answer 8

two new daughter cells

genetically identical diploid cells

Question 9

how to calculate number of cells after divisions

Answer 9

2 to the power of n

n = number of divisions

Question 10

what is cell differentiation?

Answer 10

process by which a cell changes to become specialised for its job so it can work more efficiently

Question 11

what is cell elongation?

Answer 11

a plant cell expands making the cell bigger so the plant can grow

Question 12

growth in animals

Answer 12

cells divide at fast rate when are young to grow

adults use cell division for repair and replace damaged cells

Question 13

where does cell division occur in plants?

Answer 13

tip of roots and shoots

Question 14

how is cancer made?

Answer 14

uncontrolled cell division which makes abnormal cells called a tumour which invades and destroys tissues

Question 15

what are stem cells?

Answer 15

undifferentiated cells

Question 16

what can stem cells do?

Answer 16

divide and produce any type of cell

Question 17

Where are stem cells found ?

Answer 17

human embryos

bone marrow in adults

Question 18

what are stem cells used for in adults?

Answer 18

to repair and replace damaged cells

Question 19

what are meristems?

Answer 19

plant tissues where cells that divide by mitosis are found

Question 20

what do meristems do?

Answer 20

produce unspecialised cells that can form any cell for as long as a plant lives

Question 21

How are stem cells used in medicine?

Answer 21

adult stem cells cure some diseases
create specialised cells to replace those that are damaged
new cures for diseases

Question 22

risks of stem cells

Answer 22

divide very quickly leading to a tumour if can’t be controlled
if they are infected with a virus it could be passed on without knowing
the body could reject them as seen as foreign cells and trigger immune system to get rid
ethical issues

Question 23

sensory receptors

Answer 23

groups of cells that can detect a change in your environment

Question 24

what happens with a stimulus is detected?

Answer 24

information is converted to a nervous electrical impulse and sent along sensory neurone to the CNS

Question 25

What does the CNS do when it has received the stimulus?

Answer 25

co-ordinates the response and impulses travel through the CNS along relay neurones - sends info to effector sling motor neurone and effector responds accordingly

Question 26

what is reaction time?

Answer 26

time it takes to respond to a stimulus

Question 27

what do dendrites and dendrons do?

Answer 27

carry nerve impulses towards the cell body

Question 28

what do axons do?

Answer 28

carry nerve impulses away from the cell body

Question 29

what is a myelin sheath?

Answer 29

electrical insulator surrounding an a on which speeds up the electrical impulse

Question 30

how is it an advantage if a neurone is long?

Answer 30

speed up the impulse as quicker than travelling across two neurones

Question 31

sensory neurone

Answer 31

one long dendron carrying nerve impulses from receptor cells to the cell body which is located in the middle of the neurone - one short axon carries nerve impulses to CNS

Question 32

motor neurone

Answer 32

many short dendrites carry nerve impulses from CNS to cell body - one long axon carries nerve impulses to effector cells - myelin sheath

Question 33

relay neurone

Answer 33

many short dendrites carry nerve impulses from sensory neurones to cell body - an axon carries never impulses to motor neurones

Question 34

what is a synapse?

Answer 34

the connection between two neurones

Question 35

what are neurotransmitters and what do they do?

Answer 35

nerve signal that transfers chemicals and diffusers across the gaps set off new electrical signals in next neurone

Question 36

why does a transmission of nerve impulses slow down?

Answer 36

because the diffusion of neurotransmitters across a gap takes time

Question 37

what are reflex’s?

Answer 37

automatic rapid responses to a stimulus

Question 38

what is a reflex arc?

Answer 38

reflex from receptor to effector

Question 39

how does a reflex prevent injury?

Answer 39

1- simulation of the pain receptor 2- impulses travel along sensory neurone 3- impulses passed through relay neurone via a synapse 4- impulses travel along a motor neurone via a synapse 5- when impulse reaches muscle it contracts