Summary Notes for Science
Form 4 Chapter 1 Scientific method
Observing a phenomenon
Identifying the problem
Makina a hypothesis
Planning the investigation
Conducting the experiment
Collecting data
Analyzing and interpreting data
Making a conclusion
先观察(observing)事项( phenomenon) 识别(identifying)问题( problem) 根据上面所观察的 phenomenon 找出问题 列出假设(hypothesis) !he"the# !he"the 策划( planning)调查(investigation) 策划调查 hypothesis 对不对 做出(conducting)实(experiment) 根据所策划的 investigation !" experiment #$(collecting)%据(data) & experiment '()#$所*+的%据
,-(analyzing)./0(interpreting)%据(data) 根据所#$的 data 做出 Analyzing $ Interpreting 12(Conclusion) 3据 所4 data ,-56列出的 hypothesis 789:
Form4 Chapter 2 %ody coordination
Nervous System ( ;<=> )
Central Nervous System • Brain & Spinal cord ( ?@ ) • Control the centre of nervous system
&eurones
Peripheral Nervous System • Consists of nerves emerging from the brain and the spinal cord (Cranical nerves and Spinal nerves) • Lin receptors and e!ectors "ith CNS
Sensory Neurone # Send nerve impulses from sensory organ $ receptors to CNS
%elay Neurone $ &nterneurone # sends impulses from sensory neurone to motor neurone'
otor Neurone # %eceive nerve impulses from relay neurone and send to e!ector
Structure of a neurone 'endrite ( receive impulse from other neurone 'endron ( transmit impulses from dendrite to cell body Cell bosy ( control all cell activities Axon ( transmit impulses out of cell bodu Myelin shealth ( to ensure the impulses transferred in one d irection to speed up transmission !erminal dendrite ( transmit impulses to dendrite of other neurone
Path)ay of &ervous Impulses *eceptor
*eflex Action
Sensory neurone
C&S
Motor &eurone
+ffector
Involuntary action , does not go through brain -ast
*eflex Arc ( Stimulus
%ecepto r
Sensory neurone
Synapse
%elay Neurone
synapse
(otor neurone
)!ector
%espons e
Proprioceptor
A.k.a Strentch receptor -ound in muscle# tendons# ligaments# /oints -untion ( maintain body balance $ coordination Coordinate movements and make us a)are of our position
%rain Cerebrum0A的1 ( control voluntary action Cerebellum0B的1 ( Maintain body coordination $ maintain body balance Medulla Oblongata ( Controls involuntary action
Endocrine System (hormonal) +ndocrine 2land Pituitary 2land !hyroid 2land Pancreas Adrenal 2land Ovary !estis
3ormone 2ro)th 3ormone
-unction Master gland
!hyroxine
promotes gro)th control metabolism rate
Insulin Adrenaline Progestrone $ Oestrogen !estrosterone
stimulate gro)th Control blood sugar level increase heartbeat -emale secondary sexual development Male secondary sexual development
Form 4 Chapter 3 Mitosis ( 1. 4. 5. 6. 7.
Chromosome thicken and shorten Replication take place Chromosome arrange at the equatorial plate of the cell Chromatids move and divide to opposite poles of the cell# the cell start to separate Two daughter cells produced
Meiosis ( 8. 4. 5. 6. 7. 9. 7. 8.
Chromosome thicken and shorten Replication $ crossing over take place Chromosome arrange at the equatorial plate of the cell Chromatids move and seperate to opposite poles of the cell# the cell start to divide Two daughter cells produced Chromosome arrange at the equatorial plate of the cell Chromatids separate and cells start to divide Four daughter cells are produced
Place occurs Cell division 'aughter cells 2enetic contents of daughter cell &o. of Chromosome Crossing over :ariation
Mitosis
Meiosis
Somatic cells-roots and shoot tips
Reproductive cells in ovary testis
1
!
!
"
Same as parental cell
#i$$erent $rom parental cell
Same num%er as parental cell
&al$ num%er o$ parental cell
'o
(es
'o
(es
-unctions
-)roduce new cells $or growth and replace
-)roduce gamete $or se*ual
damaged cells
reproductions ensure that the chromosome num%er o$ a species is maintained
Sex determination ( Male ; <= -emale ; <<
-ormation of !)ins +dentical Twins > 8 ovum# 8 sperm# 8 placenta 'on-identical Twins ( 4 ova# 4 sperm# 4 placenta ???Siamese !)ins CDE
Mutation Chromosome Mutation ( 8. 'o)n@s syndrome extra chromosome 48# total chromosome 6 instead of usual 69 4. Blinefelter@s syndrome , <<=# small testes and sterile 5. !urner@s syndrome ,
2ene Mutation ( 8. Colour blindness , it gene is recessive and found in < chromosome# male female 4. Albinism , )hen a gene mutation occurs that interferes )ith melanin production# has light coloured skin# pink eyes# )hite hair 5. Sickle cell anaemia , less oxygen being transported by red blood cells
???-actors that cause Mutation ( *adioactive substances# ultraviolet light# chemical substances
:ariation 'iscontinuous ( 不FGHIJK Continuous ( FGHIJK
Form 4 Chapter 4 +ndothermic 0heat adsorbed1 ( Melting# +vaporation# %oiling# Sublimation 0L particle MN1 +xothermic 0heat released1 ( -reezing# Condensation# Sublimation 0N particle ML1 'ifferences bet)een Solid# DiEuid and 2as
Arangement of the
Solid Closely packed $i*ed
Liquid ,oosely packed
Gas ar apart $rom each
particles Movement of the
position nly vi%rate
/ove $reely
other /ove $reely
particles Binectic energy 'ensity Ability to compressd -orces of attraction
,ow high no strong
medium medium no medium
high ,ow (es weak
bet)een particles
Structure of Atom
Proton Neutron Electron
Mass 8 8 negligible
Charge Fve &eutral ve
Symbol P n
??? &GCD+O& &GM%+* ; P*O!O& &GM%+* F &+G!*O& &GM%+*???
Isotopes
Location &ucleus &ucleus Orbit
???Same proton number but different neutron number Gse of isotope ( 8. 4. 5. 6. 7.
Iodine858 ( diagnose thyroid cancer Cobalt9H ( kill cancer cells 2amma ray ( Sterilize medical eEuipment or surgical tools Phosphorus54 ( trace the uptake of )ater and minerals in plant Carbon86 ( determine age of plant ( carbon dating , find out the age of ancient artifact 9. Irradiation ( sterilize canned food# packet foods and processed food . Sodium46 ( detect the leakage of pipe underground pipe
Substances Atoms +lements 0metalnoble gas1
Molecules -ormed by at least 4 atoms
Ions 0metal F nonmetal1
&o charge &ot soluble in )ater -orce attraction bet)een
0nonmetal F nonmetal1 &o charge &ot soluble in )ater -orce attraction bet)een
3ave charge Soluble in )ater -orce attraction bet)een
particles is strong :ery high boiling point and
particles is )eak Do) boiling point and
particles is strong 3igh boiling point and
melting point Conducts electricity in solid
melting point Cannot conduct electricity
melting point Only conduct electricity in
and molten state
molten state
Metals and nonmetals
Physical state Surface appearance Ductility Malleability Density Melting and boiling point Electrical conductiity !eat conductiity "ensile strength
Metals Solid 0 ,iquidmercury2 Shiny #uctile /allea%le &igh &igh (es 3ood &igh
Non-metals Solid ,iquid 0 3as #ull 'ot ductile 'ot mallea%le ,ow ,ow 'o 4eak ,ow
Gses of metals ( 8. 4. 5. 6. 7. 9. . K.
Jinc ( casing of batteries Aluminium ( cooking utensild Iron ( vehicles# bridges and rail)ay tracks !in ( plate iron cans Dead ( cable )rappers# electrodes for car batteries Copper ( kitchen utensils# electric )ires and )ater pipes Silver ( coins# photographic film and /e)ellery 2old ( /e)ellery
Gse of nonmetals 8. 4. 5. 6. 7.
'iamond ( to cut glass Sulphur ( to make fertilisers Chlorine ( disinfectant in s)imming pools and )ater purification for plants 2raphite ( pencil lead &itrogen ( insecticides
Purifying Substances •
!)o )ays ( 'istillation $ Crystalllisation
'istillation(
'istillation ; boiling F condensation separation of petroleum into different fraction at different temperature separation of pure alcohol at the boiling point K@C from a mixture of alcohol and )ater
??? Porcelain chips is to break bubbles Condenser ; liebig condenser
Crystallisation ( • • •
A proses of producing crystals froma saturated solution Cooling the saturated slo)ly produces large crystal Can be used to obtain and purify common salt
Form 4 Chapter 5 • •
Physical change , does not involve ne) substances# revisable Chemical change , involve ne) substances# not revisable
??? +ndothermic ( absorb heat 0ammonium chloride1 ??? +xothermic ( release heat 0sodium hydroxide1
+Euations( Metal F )ater ; metal hydroxide F hydrogen Metal F hydrochloric acid ; metal chloride F hydrogen Metal F nitric acid ; metal nitrate F hydrogen Metal F Sulphuric acid ; metal sulphate F hydrogen Metal F acid ; Salt F hydrogen Metal F oxygen ; metal oxide Carbon F metal oxide ; metal F carbon dioxide
*eactivity series of metals Potassium
Iron
Sodium
!in
Calcium
Dead
Magnesium
Copper
Aluminium
Silver
Carbon
2old
Jinc
Platinium
+xtraction of metals *in o+ide , tin ore Coe , carbon Limestone is used to remove impurities -urnace is heated up to ./001C Slag, impurities 2ot "asted gasses , o+ygen (left)3 carbon dio+ide$furnace gas(right) olten tin is channeled out from the furnace *in o+ide 4 Carbon , *in 4
+lectroplating
???Anode might be copper# silver or chromium ???+lectrolyte might be copper 0II1 sulphate or Silver &itrate • • • •
Anode become thinner Cathode cover )ith a layer of bro)n0copper1 or silver0silver1 solid Gsing small electric current to ensure the bro)n or silver coated on the cathode Coating key in industry
Purification
5node , impure metal (mass decrease) Cathode , pure metal (mass increase)
!he production of electrical energy by a simple cell • •
!)o different metals dipped in an electrolyte give a voltmeter reading. Chemical energy +lectrical energy
:arious type of cells Cells 'ry cell
Advantage Dight and easily
'isadvantage not longlasting
Gsage *adio# calculator#
carry along
not rechargeable
torch
Deadacid
constant current rechargeable
heavy and expensive
:ehicle
accumulator
supplies high
+lectrolyte0sulphuric
voltage for long
acid1 )ill corrodes
period
spills over easily 0can
longlasting
kill people1 not rechargeable
supply higher
more expensive
Silver oxidezinc cell
current than dry cell longlasting
not rechargeable
Latch
&ickelcadmium
constant current longlasting
expensive
Mobile phone
battery
rechargeable
Alkaline battery
Latch# toy# torch