Science Flashcards
Heat
Describe the mechanism of heat loss by conduction.
Energy transferred by vibration between particles. Can occur in a solid and is best in a metal.
Heat
Describe the mechanism of heat loss by convection.
Energy transferred by a particle (with energy) moving from a hot to cold region – taking it’s energy with it.
Heat
Why are convection currents created?
As particles heat up they vibrate more, this makes the substance expand, become less dense and then rise.
What is an element?
A substance made up of only one type of atom.
What is a compound?
A substance made of two or more different types of atoms chemically joined together.
What is a mixture?
Two or more substances that are mixed together but not chemically joined together.
What is a pure substance?
A substance is pure when all particles are the same.
What is ‘miscible’?
A word used by chemists to explain why some liquids mix together well, while others do not.
What is a solute?
A substance that has dissolved in a solvent.
What is a solvent?
A substance that dissolved a solute resulting in a solution.
What is a solution?
A mixture of a solvent and one or more solutes.
What is a saturated solution?
A solution that has the maximum amount of solute dissolved in a solvent.
Density
what is the density equation?
p=m/v
Density
What is mass?
the amount of matter something is made of (in g or kg)
Density
What is volume?
the amount of space an object occupies (in cm cubed or m cubed)
Density
What is the definition for density?
the amount of matter (stuff) per unit volume, measured in g/m cubed or kg/m cubed
Density
What are the three states of matter?
solid, gas and liquid
Density
Mass of a liquid = ?
mass of a liquid =mass of (cylinder+objecy) - mass of cylinder
Density
What happens to the density of an object if the mass is doubled but the volume remains the same?
it doubles
Density
What happens to the density of an object if the volume is doubled but the mass remains the same?
it halves
Density
What happens to the density of an object if the mass is doubled but the volume is halved?
it quadruples
Static liquid pressure and proportionality
what happens to static pressure when the depth increases?
It increases
Static liquid pressure and proportionality
Is static pressure proportional to depth? (h)
yes - static pressure is proportional to depth (h)
Static liquid pressure and proportionality
On a graph is a straight line goes through the origin then what does it mean about the two variables?
They are proportional
Static liquid pressure and proportionality
What happens if one variable double for a graph that is a straight line going through the origin ?
if one variable doubles the other doubles
Conduction
good conductors include:
copper
Conduction
poor conductors / insulators include
plastic or wood
Conduction
describe the mechanism of heat loss by conduction
conduction is energy transferred by vibration between particles and can occur in a solid state. It is best in metal.
Convection
Describe the mechanism of heat loss by convection
Convection heat loss is energy transferred by a particle (with energy) moving from a hot region to a cold region - taking its energy with it.
Convection
Why are convection currents created?
as particles heat up they vibrate more, this makes the substance expand, become less dense and then rise.
Convection
how do air pockets reduce heat loss?
by conduction and by convection
Conduction: Air is a poor conductor
Convection: The design of air pockets restricts the flow of air currents
Radiation
What does radiation radiate from?
hot objects
Radiation
what radiates more, hot or cool objects?
hot
Radiation
What colour surface radiates well and cool quickly?
matt black surfaces
Radiation
What colour surfaces radiate poorly and cool slowly?
shiny silver surfaces
Radiation
why on a cooling curve does heat loss decrease over time?
because hotter objects radiate more heat than cooler objects
What three ways can heat transfer happen?
conduction
convection
radiation
How does surface area to volume ratio affect cooling rate - for large objects?
Large objects (Emperor Penguins) have a low surface area to volume ratio and as a result they cool more slowly
How does surface area to volume ratio affect cooling rate - for small objects?
small objects (Galapagos Penguins) have a high surface area to volume ratio and as a result they cool more quickly
Respiration
what is the word equation for aerobic respiration?
(Occurring in the mitochondria of cells)
glucose + oxygen –> carbon dioxide + water (+energy released)
Respiration
what type of reaction is aerobic respiration?
an exothermic reaction, it releases energy for life processes
Respiration
what is the word equation for anaerobic respiration in an animal cell?
(does not use oxygen)
glucose –> lactic acid (+energy released)
it is also an exothermic reaction
Conduction
what type of conductors are solids, liquids and gasses?
Solids tend to be good conductors and gasses tend to be poor conductors (liquid in between)
Nutrition
what are the six basic nutrient groups?
carbohydrates. fats, protein, fibre, vitamins and minerals
Nutrition
how do you define a carbohydrate?
a group of energy-rich substances which are an immediate source of energy
Nutrition
What are fats used for?
fats are used as an energy store, used if the body runs out of carbohydrates
and
fats insulate the body
Nutrition
what is protein needed for
growth and repair of tissues
Nutrition
what is fibre and how does it work in the digestive system?
fibre is indigestible
fibre keeps your digestive system working properly
Nutrition
what does the body need water for?
water
- helps chemical reactions take place
- regulate body temperature
- transport nutrients
- help get rid of waste
Nutrition
What is vitamin A needed for?
healthy skin
good eyesight
Nutrition
What happens if you dont have enough vitamin A?
night blindness
Nutrition
What is vitamin C needed for?
healthy gums and skin
help body absorb iron
Nutrition
What happens if you dont have enough vitamin C?
Scurvy
Nutrition
What is vitamin D needed for?
strong teeth and bones
helps body absorb calcium
Nutrition
What happens if you dont have enough vitamin D?
rickets
Nutrition
What is Calcium needed for?
healthy teeth and bones
Nutrition
What happens if you dont have enough Calcium?
osteoporisis
Nutrition
What is Iron needed for?
helps blood carry oxygen
Nutrition
What happens if you dont have enough Iron?
anaemic
Preserving Food
What are the five animal kingdoms?
animal plant fungi bacteria protoctista
Preserving Food
What are microbes or micro organisms?
tiny living things such as viruses, bacteria or fungi
Preserving Food
What three things do microbes need to multiply?
water
food source (energy)
suitable temperature
Preserving Food
What are the two bad effects of some microbes?
make food go off
make people feel unwell
Preserving Food
how do people control the growth of microbes on food? (3 things)
salt
vinegar
drying or heating
Preserving Food
How do you separate salt from rock salt?
dissolving, filtering and evaporation
Reproduction - Selective Breeding
What does it involve?
choosing parents with particular characteristics to breed together and produce offspring with more desirable characteristics
Reproduction - Selective Breeding
what is the difference between sexual and asexual reproduction?
sexual reproduction is the combining of genetic material from two parents
asexual reproduction is produces offspring genetically identical to one parent
Reproduction - Selective Breeding
what are the five main stages of internal fertilisation in humans?
ovulation ejaculation fertilisation cell division implantation
Reproduction - Selective Breeding
What are the 3 main stages of the menstrual cycle?
day 1- period begins and uterus lining breaks down, egg matures and uterus lining thickens
day 14- ovulation occurs, uterus ready to receive embryo
day 28- lining breaks down if no egg implantation takes place
Reproduction - Selective Breeding
how might chemicals in a woman get to a foetus?
chemicals in the mother’s blood can diffuse through the placenta to the blood of the foetus.
Combustion
Miscible means?
how well something mixes
Combustion
Miscible liquids form what type of solution?
homogenous
Combustion
How do immiscible liquids combine?
they don’t
they separate from each other leaving the least dense liquid on top
Combustion
How do you separate two immiscible liquids?
using a separating funnel
Combustion
the word equations for complete combustion is ?
fuel + oxygen –> carbon dioxide + water
Combustion
what is the test for water?
cobalt chloride paper turns blue to pink
Combustion
The test for carbon dioxide is ?
limewater turns cloudy
Combustion
The test for carbon dioxide is ?
limewater turns cloudy
Combustion
What happens with an exothermic reaction?
releases energy resulting in the surroundings increasing in temperature
Combustion
What happens with an endothermic reaction?
take in energy resulting in the surroundings decreasing in energy
Combustion
If fuel burns without sufficient oxygen, what is formed?
Carbon monoxide
Combustion
If fuel burns without sufficient oxygen, carbon monoxide is formed.
The word equation is…?
Fuel + oxygen –> carbon monoxide + carbon (soot) + water
Combustion
What happens to a human when they take in carbon monoxide?
It is toxic
it reduces the amount of oxygen in your blood
it causes asphyxiation
Electricity
What is an ammeter?
it measures the rate of flow of charge in amperes (A) and is connected in series
Electricity
What is voltage?
the electrical pressure exerted on a circuit or component
Elements. compounds and mixtures
What is an element?
a substance made up of only one type of atom
Elements. compounds and mixtures
what is a pure compound?
a pure substance made up of two or more different types of atoms chemically joined together
Elements. compounds and mixtures
Molecules are …?
a group of atoms that are chemically joined together
Elements. compounds and mixtures
what is a mixture?
two or more substances that are mixed together but not chemically joined together
Elements. compounds and mixtures
what is a heterogeneous mixture like?
a mixture that is not uniform in composition
Elements. compounds and mixtures
what is a homogeneous mixture like?
a mixture that is uniform in composition
Solutions
what is a solute?
a substance that has dissolved in a solvent
Solutions
what is a solvent?
a substance that dissolves a solute resulting in a solutions
Solutions
what is a solution?
a mixture of a solvent and one or more solutes
Solutions
What is a saturated solution?
a solution that has the maximum amount of solute dissolved in a solvent
Solutions
What is solubility?
a chemical property referring to the ability of a solute to dissolve in a solvent.
