TERM 3/4 FLASHCARDS
Who first published the idea of cells?
Robert Hooke
Name the characteristics of all living organisms
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
What is the one exception to all organisms being made of cells?
Virus
What is the difference between egestion and excretion
Excretion is getting rid of waste and egestion is getting rid of unwanted nutrients
Where are the chromosomes found?
in the cells nucleus
What are chromosomes made up?
Very long and tightly coiled molecules of DNA
Define mitosis
The process of nuclear division giving rise to genetically identical cells in which the chromosome number is maintained by exact duplication of chromosomes
What does DNA stand for?
Deoxyribo nucleic acid
What is a gamete?
Sex cell containing half the chromosomes of a species
What is a sperm?
Male gamete
What is an ovum?
Female gamete
What is a zygote?
Fertilised egg with 46 chromosomes
What is an embryo?
Developing baby less than 6 months in mothers womb
Define meiosis
The process of a cell division where the number of chromosomes is halved to form sex cells
Define genes
Sections of a chromosome which code for one particular characteristic
Define allele
The code for a particular variety of any gene
Explain dominant/recessive alleles
Since chromosomes come in pairs each gene will have two alleles for each characteristic. The one that is shown is called the dominant allele and the one that is not show is called the recessive allele
Name the 3 possible genotypes
Homozygous Dominant “BB”, Heterozygous “Bb”, Homozygous Recessive “bb”
Define phenotype
The actual appearance of the organism
Define genotype
the gene makeup of an organism
Explain the difference between continuous and discontinuous
Continuous is any value and discontinuous is a discrete category eg. one or the other
What changes could occur during a chemical reaction?
- Colour
- Gas is given off (effervesence)
- Heat is given out or absorbed
- Gives out light
- New smells are noticed
- A solid may form in the liquid (precipitate)
Describe the qualities of an acid
Acids can be dangerous or corrosive chemicals as they react very steadily with many substances. They are known to have a sour taste.
What happens when an acid reacts with litmus paper or solution?
The litmus paper or solution will turn pink
What does Metal + Acid create
Salt + Hydrogen
List the order of reactivity for metals from most reactive
Potassium, Sodium, Calcium, Magnesium, Aluminium, Zinc, Iron, Lead, Copper, Silver, Gold
What does Carbonate + Acid create
Salt + Carbon Dioxide + Water
What is a base?
The oxide or hydroxide of a metal
What is an alkali?
A base that is soluble in water
What are the reactants and products of a neutralisation reaction?
Acid + Base = Salt + Water
What happens when a base reacts with litmus paper or solution?
The litmus paper or solution will turn blue
What is an exothermic reaction?
An exothermic reaction is a reaction that gives off energy often in the form of heat.
What is an endothermic reaction?
An endothermic reaction is a reaction that absorbs energy
What is activation energy?
The energy that is required to break up chemical bonds.
What are the characteristics of an exothermic reaction?
The energy released as the atoms join up is greater than the activation energy which leaves extra energy to be given out as heat
What are the characteristics of an endothermic reaction?
The energy released as the atoms join up is less than the activation energy which means the products must cool down
What two factors allow for chemicals to react?
The molecules or atoms must collide with each other and have enough energy to break their bonds in the reactants before rearrangement of their atoms.
Name the three changes one can make to make the rate of reaction faster or slower.
Changes in the surface area (smaller particles have a greater surface area)
Changes in the concentration of the solutions to have more particles available for reaction
Changes in temperature to increase speeds of molecules and therefore more collisions
What does the rate of reaction depend on?
The number of collisions in a second and speeds at collision.
Why is carbon a unique element?
It can form molecules with long chains, branched chains and rings of carbon atoms
What is the general formula for alkanes?
CnH2n+2
Name the melting point and the boiling point and state in room temperature for methane
-182 -Melting
-164 -Boiling
Gas
Name the melting point and the boiling point and state in room temperature for ethane
-183 -Melting
-88 - Boiling
Gas
Name the melting point and the boiling point and state in room temperature for propane
-190 - Melting
-139 -Boiling
Gas
Name the melting point and the boiling point and state in room temperature for butane
-139 -Melting
0 Boiling
Gas
Name the melting point and the boiling point and state in room temperature for pentane
-130 -Melting
36 -Boiling
Liquid
Name the melting point and the boiling point and state in room temperature for hexane
-95 -Melting
69 -Boiling
Liquid
Describe the function of a power supply
To provide power to an electrical load
Describe the function of a switch
Used to conduct or not conduct electricity
Describe the function of a light bulb
Used to determine whether or not electricity is flowing
Describe the function of a analogue voltmeter
Shows the voltage reading
Describe the function of a analogue ammeter
Shows the ampere reading
Describe the function of a resistor
A resistor converts electrical energy to heat and restricts or controls the flow of current
Describe the function of a variable resistor (rheostat)
Change the amount of current that can flow through the circuit
Describe the function of a fuse
Break circuit in the event of excessive current in order to protect appliance
Describe the function of a multimeter
Measures amperes and volts
What is the unit of current?
Ampere
What is the unit of charge?
Coulomb, defined in terms of the current- If one coulomb of charge passes a point in a circuit in one second then the current flowing is one Ampere.
Describe current in a series circuit
The current is the same at all points in a series circuit
Describe current in a parallel circuit
The sum of the currents in the branches of a parallel circuit equals the total current supplied.
What is voltage?
A measure of energy
Describe voltage in a series circuit
The components share the voltage of the power supply evenly
Explain how the colour coding works on a resistor
The first colour represents the first digit and the second colour represents the second digit. This number is then multiplied by the third colour which is the multiplier. The last colour represents the tolerance
Name the colours on a resistor starting with digit 0, multiplier x1
Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White
Name the colours of tolerance on a resistor and the values they represent
Gold=5%
Silver=10%
None=20%
What is a rheostat and describe how it works
A rheostat is a variable resistor used in applications that require the adjustment of current or the varying of resistance in an electric circuit. It works by adjusting the length of the coil of resistance wire the current has to flow through. When the sliding contact is closest to the entrance of the current the resistance would be the lowest as the length of the wire is the shortest.
Who introduced the idea of resistance?
Georg Ohm around 1826
Name the equation that defines the resistance
R=V/I, V=IR, I=V/R
Power is a measure of…
how much electrical energy a component uses in a unit time (per second)
What is the unit for power?
Watt, W
State the two equations for power
Power (W) = Voltage (V) x Current (A)
Power (W) = energy used (J) over time taken (seconds)
What are the colour codes for electrical cable?
Earth: Green with yellow stripes (new), Green (old)
Neutral: Blue (new), Black (old)
Phase: Brown (new), Red (old)
Name the unit used to measure the electricity use of a household
kilowatt-hour (kWh) is the electrical energy used by a 1 kilowatt appliance in 1 hour. 1 kilowatt hour is known as one unit
What are magnetic materials called? Name 3 examples
Ferro-magnetic substances. Iron, some steels, nickel, cobalt
What are magnetic poles?
Poles are the places on a magnet to which magnetic materials are attracted. magnetic poles are near the ends of the magnet.
What is the law of magnetic poles?
Like poles of magnets repel. North repels north. Similarly south repels south. Unlike poles attract. North attracts south.
Describe the magnetic field lines of a single bar magnet.
The lines comes out of the north and head around towards and into south.
What are electromagnets?
Temporary magnets that are made by passing an electric current through a coil of wire. The magnetic field can be increased more by putting an iron bar in the coil. This is called a solenoid
Describe how an electric bell works.
When the switch is closed current flows. The electromagnet is energized and attracts the soft iron armature. This causes the striker to hit the bell or gong. At the same time the circuit is broken and current stops flowing. The armature springs back, this completing the circuit. The cycle starts again.
What is a relay?
A relay is a switch. It switches a smaller current placed through a coil and in turn switches a larger current of around 10A plus - through a set of contacts
How does a relay work?
When a current is passed through the coil, it generates a magnetic field - through the middle of the coil, through the iron armature (which is on the top and to the right of the coil int his picture) and back down to the bottom of the coil. This magnetic field pulls the iron armature down from above the coil and in turn pulls the movable contact down with it. The result is that the top two contacts are no longer connected, but the bottom two
Explain how a relay is drawn
a square with dotted lines which represent electromagnetic force. A switch with the iron armature and two terminals one representing closed and one representing open.
Explain how a DC motor works.
A motor is an electrical machine which converts electrical energy into mechanical energy. The principle of working of a DC motor is that “whenever a current carrying conductor is placed in a magnetic field, it experiences a mechanical force”.
Explain how a diode is drawn
a line with a triangle and a line at the tip of the triangle lol hard to explain
Name the three types of diodes
Power diode
Zener diode
Light emitting diode
What is a diode?
A diode is a simple silicon based device that allows conventional current to flow in only one direction. It is made of two wafers of silicon that have had small amounts of elements like phosphorous or boron added to each wafer.
What is doping?
Adding small amounts of other elements to silicon to change its electrical properties.
Name the two ways a diode can be connected into a circuit.
Forward bias and Reverse bias
Explain forward bias (position of diode in circuit)
This allows the diode to pass current in a circuit once the voltage across it has equaled or exceeded about 0.7V in the forward bias direction
Explain reverse bias (position of diode in circuit)
The diode is connected in the circuit the other way around. It will not conduct electricity this way until the voltage gets very high. This is normally around 1000V. At this point the diode breaks down and conducts
