topic 2

Question 1

2.1- parts of the cell cycle

Answer 1

interphase- DNA replication, making extra sub-cellular parts

mitosis- PMATC- makes 2 identical cells

Question 2

2.1- stages of mitosis

Answer 2

prophase- nucleus starts to break down and spindle fibres appear
metaphase- chromosomes line up in the middle of the cell on spindle fibres
anaphase- chromosome copies are separated and move to either end on spindle fibres
telophase- membrane forms around chromosomes to make new cells
cytokinesis-membrane forms to separate cells, cell wall forms in plants

Question 3

2.2 importance of mitosis

Answer 3

growth
repair
asexual reproduction- this produces clones

Question 4

2.3- products of mitosis

Answer 4

produces 2 identical daughter cells with same chromosomes as parents, diploid

Question 5

2.4 - cancer

Answer 5

rate of division by mitosis is controlled by genes.
if there’s a change in the genes uncontrollable growth happens forming a tumour
if it invades tissue its cancer

Question 6

2.5- growth in animals

Answer 6

happens by cell differentiation and cell division (mitosis)

division is faster when young but slower when old as its just for repair

Question 7

2.5- plant growth

Answer 7

happens by cell division, elongation and differentiation

happens in meristems in tips of shoots and roots

Question 8

2.5- importance of differentiation in animals

Answer 8

changes cells into specialised ones- this allows organisms to work more efficiently

Question 9

2.6- importance of differentiation in plants

Answer 9

allow plant to carry out many different processes effectively

Question 10

2.7- percentile charts

Answer 10

used to assess growth over time so a pattern of development can be seen
25% will have a mass below the 25th percentile
curved lines show rate of growth for a baby who stays at the same percentile in the population
helps to show if a child is growing normally
investigate is above top percentile, below bottom or an inconsistent pattern

Question 11

2.8- stem cells in animals

Answer 11

embryonic- found in embryos, produce any type of cell, used for growth and development of organisms
adult- found in bone marrow, only produce certain cells, used to replace damaged cells

Question 12

2.8- stem cells in plants

Answer 12

found in meristems, produce any type of cell throughout life of the plant

Question 13

2.9- risks of stem cells

Answer 13

cause cancer is the rate of division isn’t controlled
rejection
diseases- viruses live in cells
ethics - each cell is a new life

Question 14

2.9- uses of stem cells

Answer 14

treat diseases like diabetes by stimulating stem cells to produce specialised cells needed and then injecting where they’re needed

Question 15

2.10 - parts of the brain

Answer 15

cerebal hemispheres- the cerebal cortex is divided Into 2 hemispheres, right side controls left, memory, senses, language
cerebellum- in 2 halves, balance, muscle coordination
medula oblongata- heart and breathing rate, reflexes like vomiting and swallowing, connects brain to spinal chord

Question 16

2.11- use of ct scans

Answer 16

uses X-rays to produce an image of the brain
shows structure
if it shows damaged parts and the patients behaviour has changed then the function of the part can be found

Question 17

2.11- use of pet scans

Answer 17

patient injected with radioactive glucose (more active cells take in more for respiration) the radioactive atoms cause gamma rays which the machine detects, more come from more reactive cells
shows brain activity

Question 18

2.11-how can problems in brain surgery be overcome by scans

Answer 18

brain surgery involves cutting the skull open which is risky
scans mean the brain can be visualised without surgery

Question 19

2.12- problems in treating spinal chord problems

Answer 19

damage to lower chord can cause loss of feeling in legs
damage to neck can cause quadriplegia
there are no adult stem cells in the spinal chord so new neurones can’t be made to repair damage

Question 20

2.12- problems in treating brain tumours

Answer 20

can be cut out or killed by radiotherapy or chemotherapy but all of these can damage the body and chemo may not work due to blood brain barrier

Question 21

2.13- receptor cells

Answer 21

found in sense organs and detect different stimuli

create impulses which travel to the brain

Question 22

2.13- sensory neurones

Answer 22

carry impulses form receptor cells to cns
one long dendron carry impulses from receptor cells
one short axon goes from cell body to cns

Question 23

2.13- relay neurones

Answer 23

in spinal chord
link motor and sensory neurones
no dendron so dendrites are on cells body, many dendrites go from sensory neurone to cell body
axon carries impulses to motor neurone

Question 24

2.13- motor neurones

Answer 24

carry impulses from cns to effectors
no dendron so dendrites are on cell body
dendrites carry impulses from cns to cell body
axon foes form cell body to effectors

Question 25

2.13- parts of a neurone

Answer 25

dendrons and axons are long so neurotransmission is fast | myelin sheath insulates neurone stopping the signal losing energy so speeding up neurotransmission

Question 26

2.13- synapses

Answer 26

the connection between 2 neurones when an impulse reaches and axon terminal a neurotransmitter is released into the gap which is detected by the next neurone which generates a impulse

Question 27

2.13- uses of synapses

Answer 27

slows down neurotransmission but neurones only flow in one direction so the allow many impulses to be generated in many neurones connected to one neurone

Question 28

2.14 - reflex arc

Answer 28

bypass sections of the brain involved in processing info so reflexes are faster than responses that need processing receptors cause an impulse to be generated in sensory neurone, replay neurones in spinal chord, motor neurone - impulses from motor neurone pass into effectors via synapses

Question 29

2.15- retina

Answer 29

contain receptor cells called cones and rods

Question 30

2.15- cones

Answer 30

sensitive to colour of light generate impulses in sensory neurones which lead into brain through optic nerve, the info is processed into full colour vision at the back of the cerebal hemisphere works in bright light

Question 31

2.15- rods

Answer 31

detect differences in light intensity | work well in dim light

Question 32

2.15- pupil and lens

Answer 32

pupil- where light enters | iris- controls the amount of light entering the pupil, can restrict or dilate the pupil

Question 33

2.15- looking at distant and near objects

Answer 33

distant- clearly muscles relax which makes the lens thicker so light is reflected less near- clearly muscles contract which makes lens fatter so light is refracted more

Question 34

2.15- cornea, lens, cillarly muscles

Answer 34

cornea- refracts light rays to bring them together lens- fine tunes focusing of cornea cillarly muscles- makes lens fatter to focus near objects, thinner to look at distant ones

Question 35

2.16- short sightedness

Answer 35

distant objects are blurred because rays are focused infront of retina because eyeball is too long or cornea is too curved fixed by diverging lens to spread rays out before they reach the eye

Question 36

2.16- long sightedness

Answer 36

near objects are blury because rays are focused behind retina because eyeball is too short or cornea isn't curved enough fixed by converging lens to bend rays before they reach the eye

Question 37

2.17- cataract

Answer 37

when a protein builds up on the lens making it cloudy | replacing cloudy lens with a plastic one

Question 38

2.17- colour blindness

Answer 38

some cones don't work properly so can't see some colours | can't be corrected