Science Flashcards
Breathing
When muscles contract and relax to move air in and out of the lungs
What do we need to stay alive?
Energy
Where do we get our energy from?
From nutrients, especially glucose
Respiration
A chemical reaction that happens inside every living cell in which energy is released for glucose so that the cell can use it
What happens inside the cell for aerobic respiration?
A chemical reaction takes place where the glucose from digested starch in the small intestine combines with oxygen taken from air in breathing and the chemical potential energy released
What is the word equation for aerobic respiration?
Glucose+ oxygen –> Carbon dioxide + water + energy
What do the different colours mean on a thermogram?
Black is the coldest then purple, red, orange, yellow and finally white
Being fit
Being able to do moderate exercise easily without getting tired too quickly e.g a professional tennis player has to be able to play a match that may last up to 5 hours
What happens when we exercise?
Our muscles need energy which they get from respiration so then the energy will be transferred to movement energy in the muscles. When we exercise we need more energy because the faster our muscles work, the faster they respire, so more oxygen and glucose for respiration. They are brought to the muscles in the blood so the heart will beat faster when we exercise. We also breathe faster when we exercise so that air moves in and out faster
What happens when an ice hockey player uses a lot of energy?
- The heart will pump quickly to send blood to the leg muscles
- Blood, containing glucose and oxygen, flows to the leg muscles
- Energy is supplied to the muscles by combining glucose and oxygen
- Oxygen diffuses in the blood from the air inside the lungs
- The breathing muscles work quickly to bring extra air into the lungs
Doing regular exercise will help you to keep fit. How?
- It helps your heart and breathing muscles to get strong so they can work hard for you when you need them to.
- It strengthens your muscles
The type of food that you eat affects your fitness. How?
- If someone eats too much and gets
overweight they will become unfit because :
1-The extra mass of the body needs more energy to move it around.
2-The heart works harder to push blood around the larger body.
3-The space inside arteries gets narrower because fat deposits build up inside them
Why does extra mass around the body would make it difficult to do exercise?
Extra mass body means :
- More energy
- More respiration
- More oxygen and glucose
- The heart and lungs work harder
Why does the heart working harder make it difficult to do exercise?
This makes it less likely that it will be able to supply oxygen and glucose to the muscles as fast as they require them
Why do narrow arteries make it difficult to do exercise?
They can’t carry as much blood as healthy arteries. This means that less oxygen and glucose are transported to the muscles per minute. So muscles can’t respire as quickly and therefore don’t have as much energy to use for contraction
Where does aerobic respiration take place?
Inside the mitochondria of the cell
What energy is released in respiration?
Chemical potential energy and heat energy because everything that respires releases heat energy
What is one of the easiest ways to make yourself unfit?
To smoke cigarettes
What does the World heath organisation estimate each year?
- 4.2 million people will die early as a result of smoking cigarettes
- Cigarettes kill half of all the people who smoke them regularly
- Smoking kills more people each year than all the deaths from HIV / AIDS, drugs and road accidents added together
What will happen to people who breathe in other people’s cigarette smoke?
They may get ill and children are especially at risk, if adults in their home regularly smoke cigarettes
What is in cigarettes smoke?
- Nicotine
- Tar
- Carbon monoxide
- Particulates
Nicotine
- It’s a harmful drug and addictive
- Makes your blood vessels get narrower, so the heart has to work harder to push blood through them so they are more likely to develop heart disease than non smokers
Drug
A substance that changes the way the body works
Tar
- Causes cancer and increases the risk of developing all types of cancer, but especially lung cancer
Addictive
Once your body has got used to it, it’s very difficult to stop taking it
Cancer
A disease in which some cells divide uncontrollably forming a lump called a tumour
Carbon monoxide
- An invisible gas
- Combines with haemoglobin in the red blood cells, so they can’t carry as much oxygen
Particulates
- Tiny particles of soot and other substances that get into the lungs to damage cells and the thin walls of the air sacs
- This makes it much more difficult for oxygen to get from the air sacs into the blood
How many cells have our body created?
Millions of cells, but we began our lives as a single cell
How was our 1st cell created?
When an egg cell and a sperm cell join together
Gametes
The 2 special cells that are adapted for reproduction (egg cell and sperm cell)
Chromosomes
A long thread-like structure in the nucleus of a cell, which is made up of genetic material (DNA) that contains information about how the cell will develop
How many chromosomes do we have in every cell?
46 but gametes have only 23
Egg cell
- Female gametes
- They are bigger than most cells because they store food in their cytoplasm
- They have a cell surface membrane
Sperm cell
- Male gametes
- They are smaller than most cells
- They have only a small amount of cytoplasm
- They have a long tail, so that they can swim
- They have a cell surface membrane
Fertilisation
When a sperm cell meets an egg cell the head of the sperm goes inside the egg cell and the nucleuses join together and produce a zygote
List 3 ways in which an egg cell differs from other cells in the human body
- It’s larger
- Has food stored in its cytoplasm
- Has 23 chromosomes instead of 46
Growth
Growth is about getting bigger physically, like getting taller or gaining weight
What happens when we grow?
The embryo forms into a foetus and then into a baby. Each cell grows then divides, grows, then divides. This process continues all through childhood
What does the change from zygote to an adult involve?
Growth and development
Development
Development is about progress and changes in all aspects of life, including physical, mental, and emotional.
What happens when a baby is born and it develops?
It has all of its organs then it’s muscles become stronger as it learns to crawl, walk and run and its brain will develop as it learns to talk and play with toys
What are the main stages in development that everyone passes through?
Baby, toddler, child, adolescent, adult but there are no sharp changes from one stage to another
Adolescence
The time of a change from childhood to adulthood
When does adolescence happen for girls?
10 or 11 years old
When does adolescence happen for boys?
12 or 13 years old
What happens at the age of 12 or 13 for boys and 10 or 11 for girls?
The reproductive organs and the brain undergo large changes and there is often a growth spurt at this time
What changes in the reproductive organs happen in girls in adolescence?
Menstruation begins. Hormones produced by the reproductive organs cause body shape changes as breasts develop, hips widen and hair begins to grow in the armpits and other parts of the body
What changes in the reproductive organs happen in boys adolescence?
Sperm production begins. Hormones produced by the reproductive organs cause body shape changes as shoulders broaden, the voice becomes deeper and hair begins to grow on the face, in the armpits and other parts of the body
What changes in the brain happen during adolescence?
The brain does not go any larger during adolescence, but there is quite a lot of reorganisation which makes a person think and feel differently from when they were a child.
- The person becomes better at making decisions, planning ahead, thinking logically and learns quickly
- Emotions may become stronger, people may worry more, have romantic feelings, and become more self-aware
- There is often a strong need for approval from friends and others and young people may want to be like their role models so they set themselves impossible standards trying to be like someone on TV
What does glucose contain?
Chemical potential energy
Aerobic respiration
The release of energy from glucose by reacting it with oxygen inside living cells so that the cells can use it
Name the two new substances that are made when glucose reacts with oxygen inside a cell
Water and carbon dioxide
how does glucose get to a cell in a muscle?
Glucose is produced when starch is digested inside the digestive system. It is absorbed into the blood through the walls of the small intestine, and then the glucose is dissolved in the blood plasma, the blood carries it to the heart, and the heart pumps it to the body cells in the muscles.
how does oxygen get into a cell in a muscle?
Oxygen diffuses into the capillaries from the air sacs in the lungs. It diffuses into red blood cells, combining with haemoglobin to form oxyhaemoglobin, then the blood flows to the heart and is pumped out and delivered to the muscle cells
What is the difference between respiration and breathing?
Respiration is a chemical reaction inside all living cells when glucose combines with oxygen, producing water and carbon dioxide and releasing energy in a form the cell can use.
Breathing is how muscles contract and relax to move air into and out of the lungs.
Explain why a professional sportsperson often has a diet that contains carbohydrates just before a competition
These foods contain starch. Starch is digested to produce
glucose, which is used by cells to provide energy in respiration
Why do most professional sportsmen and women don’t smoke?
Smoking would make it more difficult for them to perform at the top of their sport. Their muscles would not get as much oxygen, so would not be able to work as efficiently as in a non-smoker
How many chromosomes will there be in a human zygote?
46
Explain why it is important that an egg cell and a sperm cell only have half of the normal number of choromosones
Because when they fuse together they will have the normal amount
List 3 ways in which a sperm cell differs from other cells in the human body
- It’s smaller
- Has a long tail and can swim
- Has 23 chromosomes instead of 46
By what age have most people become adults?
19 years old
Physical change
A change in a substance that doesn’t change what the substance is or its chemical properties, it only changes the appearance of a substance, so no new substances are formed.
Chemical change
When a substance combines with another and a new substance is formed.
Give examples of physical changes
Changes in shape, size, and state of matter
Give examples of how physical changes can be formed
Cutting, crushing, breaking
Can all physical changes be reversed?
Some, but not all physical changes can be reversed
Give examples of chemical changes
Burning, rusting, decomposing
What happens to the reactions in chemical reactions?
In a chemical reaction, the reactants combine together to form a new substance with different properties, energy can be given out in the form of heat or light and the change cannot be reversed.
Name some chemical reactions in living things
Digestion, respiration, photosynthesis
Word equation
They show the chemicals that react and are produced in a chemical reaction
Reactants
The substances that react together
Product
The new substances that are made in the reaction
Types of chemical reactions
When the reactants combine and form a new product and when the product breaks apart to produce 2 or more new substances
Burning
A chemical reaction in which a substance reacts with oxygen gas from the air, releasing heat and often light, and producing new substances
Is burning a physical or chemical change?
Chemical change
What is the new substance formed when burning?
Sometimes ash forms as the new substance
How can we compare the properties of reactants and products?
By comparing their physical state, color and chemical composition
What are the properties of magnesium?
It is soft and shiny, malleable, conducts electricity and is an element
Melting point: 651
What are the properties of oxygen?
It is a colourless gas, element and has no smell
Melting point: -214
What is the formula for reacting with metals and acids?
Metal + acid —-> salt + hydrogen
What happens when magnesium is placed in hydrochloric acid?
They react and form magnesium chloride (a salt) and hydrogen
What happens when zinc is placed in sulfuric acid?
They react and form zinc sulfate (a salt) and hydrogen
Write the word equation for magnesium and hydrochloric acid?
Magnesium + hydrochloric acid —–> magnesium chloride + hydrogen
Write the word equation for zinc and sulfuric acid?
Zinc + sulfuric acid —–> zinc sulfate + hydrogen
How can we test for hydrogen?
By using a burning splint. If we get a squeaky pop, hydrogen has been produced
What happens when hydrogen pops?
Hydrogen + oxygen —-> water
What is the formula for reacting with carbonates and acids?
Carbonate + acid —-> salt + water + carbon dioxide
What happen when limestone is placed in hydrochloric acid?
They react and form calcium chloride + water + carbon dioxide
Write the word equation for limestone and hydrochloric acid
calcium carbonate + hydrochloric —–> calcium chloride + water + carbon dioxide
What happen when copper carbonate is placed in hydrochloric acid?
They react and form copper chloride + water + carbon dioxide
Write the word equation for copper carbonate and hydrochloric acid
copper carbonate + hydrochloric —–> copper chloride + water + carbon dioxide
How can we test for carbon dioxide?
- We can use a lighted splint
- We can use limewater, to see if it goes cloudy
What happens in a chemical reaction when they get heated?
They form new combinations so no atoms are lost and no new atoms are produced
What will happen to the mass of calcium carbonate and hydrochloric acid with a stopper?
The mass will stay the same because there is a stopper so no atoms can leave or enter
Conservation of mass
The rule that no mass is lost or gained in a chemical reaction
Who is Antoine Lavoisier?
A French scientist who carried out an experiment using the crucible in 1772. He repeated it a lot of times and found out he had an increase in mass every time so he came up with the idea that when we burn something it combines with a gas from the air that he named oxygen (He also found out that this gas is used in respiration as well)
What will happen to the mass of calcium carbonate and hydrochloric acid without a stopper?
The gas escapes into the air because the flask is open. We cant measure the mass so it appears as if the mass decreases
What will happen to the mass of magnesium and oxygen in a crucible?
The gas will increase because we are allowing oxygen to come into the crucible so the Magnesium oxide will be heavier
How can we detect chemical reactions?
- A color change
- A gas is given off
- Heat is produced
- A change in pH
- A precipitate is formed
Color change
e.g when we heat black copper oxide with sulfuric acid produces a blue solution of copper sulfate
What happens when copper oxide and sulfuric acid react together?
Copper oxide + sulfuric acid —> copper sulfate + water
Gas is given off
e.g when magnesium is placed in hydrochloric acid bubbles of hydrogen gas are given off
What happens when magnesium and hydrochloric acid react together?
Magnesium + hydrochloric —> magnesium chloride + hydrogen
Change in pH
If you add potassium to water that contains a universal indicator you see the indicator change color from green to purple. This shows that the solution has become alkaline the pH has changed
Heat is produced
e.g when potassium is placed in water, hydrogen gas is given off
What happens when potassium and water react together?
potassium + water —> potassium hydroxide + hydrogen
Neutralization reaction
A reaction in which an acid and an alkali form a salt and water and when an acid is used to neutralize an alkali, there is also a change in ph
A precipitate is formed
If you mix solutions of silver nitrate and calcium chloride, a chemical reaction takes place reaction, and an insoluble solid is formed (silver chloride). This is called a precipitate.
You might have used limewater to detect carbon dioxide.
What happens when sodium hydroxide and hydrochloric acid react together?
sodium hydroxide + hydrochloric acid —> sodium chloride + water
Why does carbon dioxide make limewater cloudy?
Carbon dioxide makes lime water turn cloudy because a precipitate of calcium carbonate forms.
What is a solution of calcium hydroxide?
Limewater
What happens when calcium hydroxide and carbon dioxide react together?
calcium hydroxide + carbon dioxde —> calcium carbonate + water
Rusting
A chemical reaction in which iron combines with oxygen in the presence of water to form iron oxide. It breaks down iron objects
Name an unuseful chemical reaction
Rusting
What is the chemical formula for rusting?
Iron + Oxygen —> iron oxide
Is rusting a chemical or physical change?
Chemical change
Rust is only formed when both ______ and _______ are present
Oxygen and water
What colour is iron oxide?
It’s an orange-brown solid
What causes iron to rust?
Water and air (or damp air)
Does iron rust if only air is available?
No, because no water is available
Does iron rust if air and water is available?
Yes, because water and air are available
Does iron rust when calcium chloride is available?
No, because calcium chloride absorbs water so the air will be dry (dry air)
Changes in all metals are _______________ but they aren’t rusting
Chemical changes
Does iron rust when water and oil are available?
No, because oil stops any air from entering
Give examples of changes in metal
Rusting and when a copper roof turns green
How can iron be protected
- It can be painted, so this stops the oxygen in the air from reaching the iron
- It can be galvanised, so this stops the oxygen in the air from reaching the iron
Galvanised
Covering iron with a layer of zinc
______ isn’t apart of the rusting reaction but it’s needed for the reaction to happen
Water
What is the word equation for iron and sulfur?
Iron + sulfur —> iron sulfide
What are the reactants for iron sulfide?
iron and sulfur
What is the product of iron and sulfur?
iron sulfide
What are the properties of magnesium oxide?
It is a white and powdery compound
Melting point: 2800
Magnet
A piece of material that is capable of attracting certain metals.
Name some uses of magnets
In MRI machines, food processing, inside TVs, Sound speakers and radios, headphones and loudspeakers, generators
Permanent magnets
A magnet which remains magnetic without the need for an electric current because of the internal structure of the magnet. They can be used to attract other objects e.g. paperclips made of steel
Give some examples of permanent magnets
Paper clips, bar magnet, Horse shoe magnet, Compass, Button magnet
Magnetic material
A material which is attracted by a magnet
Non-magnetic material
A material which is not attracted by a magnet
Give examples of magnetic materials
Iron ,steel, nickel ,cobalt
Give examples of non-magnetic material
Wood, cotton, paper, aluminium, tin
What are strong magnets made out of nowadays?
Neodymium
How can we separate different material?
By using a strong magnet that can attract magnetic material and the non-magnetic material will be left behind
Magnetic poles
The regions of a permanent magnet where the magnetic strength is strongest
Magnetic force
The force of a magnet on another magnet or on a piece of magnetic material
What are the magnet rules?
Like poles repel and unlike poles attract
How can we magnetise a magnetic material?
- Lay it on the bench
- Using one pole of the magnet, stroke it from one end to the other.
- Stroke it several times, using the same pole.
- Make sure you always stroke it in the same direction
Where will the north and south pole of a magnet turn?
The north pole of a magnet will turn to point north and the south pole of a magnet will turn to point south
When to unlike poles attract what does that mean?
It can be a magnet or a magnetic material
When to like poles repel what does that mean?
They are permanent magnets
Magnetic field
A region where there is a force on a magnet or a piece of magnetic material
What will happen when a magnetic material is placed in the field of a magnet?
It will be attracted by the magnet
How can we show the shape of a magnetic field?
- By using iron fillings to form a line
- Using plotting compasses to show the direction of the field
How can we represent a magnetic field?
By drawing magnetic field lines
What do magnetic fields show?
- They go from north to south
- The arrows show the direction of the field
- Where the lines are closest together is where the field is the strongest
Why do people use a compass?
Because the Earth has a magnetic field that can help us find our way around
Where will a compass needle point towards?
Earth’s magnetic north pole which is near to the geographical north pole
Electromagnet
A coil of wire with an electric current in it that works using electricity and it can be switched on and off
How can we construct an electromagnet?
By winding a coil and then connecting the ends of the wire to a battery or power supply
Name 2 differences between an electromagnet and a permanent magnet
- An electromagnet uses electricity but a permanent magnet doesn’t
- An electromagnet can be switched on and off, while a permanent magnet can’t.
Why can we switch an electromagnet on and off?
Because it’s easy to switch electricity
How can we make an improved electromagnet?
We can wrap the wire around a magnetic material (e.g iron) called a core so that when the iron becomes magnetised and this makes the magnetic field of the electromagnet stronger
Core
A piece of iron inside the coil of an electromagnet to make it stronger
Name 3 uses of an electromagnet
- For carrying heavy scarp cars
- In electric motors and generations
- In doorbells and in electric switches called relays
How can we make an electromagnet stronger?
- Make a coil with more turns of wire
- Make a bigger electric current flow in the coil of wire by connecting 2 batteries end-to-end
Ammeter
A meter used for measuring electric current
Amps
The unit in which electric current is measured, symbol A
What makes the magnetic field in an electromagnet?
The current makes the magnetic field
How is the field of an electromagnet like the field of a bar magnet?
- The magnetic field lines come out of one end of the electromagnet (the north pole)
- The field lines go round and back into the other end electromagnet (the south pole)
Who is Hans Christian Oersted?
A Danish scientist who thought that there might be a connection between electricity and magnetism in 1820
What happened in 1820?
Hans gave a lecture about electric circuits and a compass was nearby. When he switched on the circuit, he noticed the compass needle change directions
How does an electromagnet work in terms of it’s magnetic field?
The magnetic field around an electromagnet is weak so when we wind the wore into a coil you concentrate the magnetic field into a smaller space making it much stronger
What shape are the magnetic fields in an electric current?
Circle
Where is the magnetic field the strongest in an electric current?
The field is strongest close to the wire
______ is mostly made of iron
Steel
