Biology A Flashcards
(23 cards)
Give one reason for using 25 degrees as a maximum temperature to incubate agar plates in a school laboratory
Reduces the Risk of growth of pathogens
In industrial laboratories higher temperatures are used to incubate agar plates.
Give one reason why?
Microorganisms grow faster
Describe how crude oil is separated into fractions by fractional distillation
Crude oil is heated
Crude oil evaporates
Vapour condenses
At different temperatures
Some properties of hydrocarbons change as the size of the molecules increases.
Describe the trends in boiling point and viscosity as the number of carbon atoms in the molecule increases
As the number of carbon atoms increases
Boiling point increases
Viscosity increases
Burning fuels releases energy.
Name two products formed when LPG is burnt
Any two from:
•carbon dioxide
•water
- carbon monoxide
- carbon
Some cars are now designed to use LPG as a fuel. LPG is about 50p per litre cheaper than petrol.
Suggest one reason why most car owners use cars designed to use petrol and not LPG dad a fuel.
Any one from:
•lack of availability of LPG
•cars need to be modified
A lithium atom has an atomic number of 3 and a mass number of 7.
describe the atomic structure of lithium.
Include in your answer:
•the number of each type of particle
• where in the atom each particle is found.
Any four from: •3 protons •4 neutrons •3 electrons •nucleus contains protons and neutrons •electrons in energy levels/shells
Name one other element with similar chemical properties to lithium.
Any one from: •sodium •potassium •rubidium •caesium •Francium
Why are lithium and sodium classed as different elements?
Contains different number of protons
Compare solids, liquids and gases in term of their particles.
Solids:
•arranger in a regular pattern
•particles vibrate about fixed points
•particles have low energy
Liquids:
•pattern is irregular
•particles are not fixed in place/can move freely
•particles have more energy than solids and/or less energy than gases
Gases:
•particles are in a random pattern
•particles move freely/randomly
•particles have high energy
The mirror changed from being dry to being covered with small drops of water.
name the process causing this Change on the mirror.
Condensation
The towel will dry faster if it is hung from the unheated towel rail instead of the towel ring
Explain why.
•Larger (exposed) surface area
So
•water can evaporate faster
•more water can escape
One advantage of calculating a mean
Reduces random errors
Why are antibiotics not effective against viral infections?
Viruses live / reproduce inside cells
(So) the drug cannot reach the virus
What must be done to make sure we will be able to treat bacterial infections in the future?
Developed new antibiotics
Not prescribe antibiotics for viral infections
What is the junction between neurones called?
Synapse
How does information cross the junction between neurones
Chemical
Describe main stages of IVF
Any 4 from
•women is given FSH/LH
•(FSH/LH hormones) to stimulate egg maturation/ release/ production
•eggs and sperm are collected/ mixed
Fertilisation happens
•embryos inserted into the woman’s uterus/ womb
Suggest reasons for and against women in their 50s and 60s having IVF treatment to have children
Three arguments given from- For: • more money/time to support child •may make better parents •allows women who have late marriage to have a family
Against :
•mother may die before child has grown up
•baby may not be as healthy
•mother may have more problems during birth
•mother may have less energy
Limestone is used to make cement.
What is added to limestone to make cement?
Clay
Suggest why the total amount of carbon dioxide produced by the manufacturing process is high
Burning of (fossil) fuels (to provide energy)
Why is gold found in the earths crust as the element
Gold is Unreactive
Scientists were not able to extract aluminium until the 11th century.
Explain why.
Aluminium is high on the reactivity series
Or
Aluminium is more reactive than carbon.
(So) cannot be extracted with carbon
Or
(So) requires electrolysis
