1.

1 understand how living organisms share the following characteristics

- all living organisms follow

MRS C GREN
Movement
Respiration
Sensitivity
Control
Growth
Reproduction
Excretion
Nutrition

1.2

Eukaryotic organisms: multicellular or singe-celled,nucleus with a distinct membrane

Prokaryotic organisms : always singe-celled, no nucleus (nuclear material is found in cytoplasm) an eg in bacteria.

Animals

• The main features of animals:

They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells do not have cellulose cell walls
Their cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
They feed on organic substances made by other living things
They often store carbohydrates as glycogen
They usually have nervous coordination
They are able to move from place to place

Plants

• The main features of plants:

They are multicellular
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made out of cellulose
Their cells contain chloroplasts (so they can carry out photosynthesis)
They feed by photosynthesis
They store carbohydrates as starch or sucrose
They do not have nervous coordinationI’m
 Fungi

•Main features of fungi:

They are usually multicellular but some are single-celled (e.g. yeast)
Multicellular fungi are mainly made up of thread-like structures known as hyphae that contain many
nuclei, organised into a network known as a mycelium
Their cells contain a nucleus with a distinct membrane
Their cells have cell walls made of chitin
Their cells do not contain chloroplasts
They feed by secreting extracellular digestive enzymes onto the food and then absorbing the digested
molecules. This method of feeding is known as saprotrophic nutrition
Some fungi are parasitic and feed on living material
Some store carbohydrates as glycogen
No nervous coordination
E.g of fungi include: moulds, mushrooms, yeasts
 Protoctists

Some have features making them more like animal cells e.g. Plasmodium (the protoctist that causes
malaria)
Some have features, such as cell walls and chloroplasts, making them more like plant cells e.g. green
algae, such as Chlorella
This means some protoctists photosynthesise and some feed on organic substances made by other living
things
They do not have nervous coordination
Examples of protoctists include: amoeba, Paramecium, Plasmodium, Chlorella

1.3
Bacteria:
microscopic single-celled organisms,
cell wall, cell membrane, cytoplasm and plasmids;
they lack a nucleus but contain a circular chromosome of DNA; some bacteria can carry out photosynthesis but most
feed off other living or dead organisms.
Examples include Lactobacillus bulgaricus, a rod-shaped bacterium used in the production of yoghurt from milk, and
Pneumococcus, a spherical bacterium that acts as the pathogen causing pneumonia.

1.4
Viruses: these are not living organisms.
They are small particles, smaller than bacteria; they are parasitic and can reproduce only inside living cells;
they infect every type of living organism.
a wide variety of shapes and sizes; they have no cellular structure but have a protein coat and contain one type of
nucleic acid, either DNA or RNA.
E.g the tobacco mosaic virus that causes discolouring of the leaves of tobacco plants by preventing the formation of
chloroplasts, the in uenza virus that causes ‘ u’ and the HIV virus that causes AIDS.

2.1
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2.2 and 2.3

2.4
plant cells have cell wall, chloroplast, large centre vacuole animal cells don’t have those qualities
2.7
• Most of the molecules in living organisms fall into three categories: carbohydrates, proteins and lipids
• These all contain carbon and so are described as organic molecules

2.8
Large Molecules are Made from Smaller Molecules

Carbohydrates
• Carbohydrates contain the elements carbon, hydrogen and oxygen
• A monosaccharide is a simple sugar e.g. glucose (C6H12O6) or fructose
Glucose molecules contain lots of energy which can be released in respiration by breaking the bonds
between the carbon atoms
•
• A disaccharide is made when two monosaccharides join together
Maltose is formed from two glucose molecules
Sucrose is formed from one glucose and one fructose molecule
•
• A polysaccharide is formed when lots of monosaccharides join together
Starch, glycogen or cellulose are all formed when lots of glucose molecules join together
Polysaccharides are insoluble and therefore useful as storage molecules

Fats
• Most fats (lipids) in the body are made up of triglycerides
• Their basic unit is one glycerol molecule chemically bonded to three fatty acid chains
• The fatty acids vary in size and structure
• Lipids are divided into fats (solids at room temperature) and oils (liquids at room temperature)

Proteins
• Proteins are formed from long chains of amino acids
• There are 20 different amino acids
• When amino acids are joined together a protein is formed
• Amino acids can be arranged in any order, resulting in hundreds of thousands of different proteins
Examples of proteins include enzymes, haemoglobin, ligaments and keratin
2.9

2.10

• Enzymes are proteins that act as biological catalysts to speed up the rate of a chemical reaction without being
changed or used up in the reaction
• They are biological because they are made in living cells
• Enzymes are necessary to all living organisms as they maintain reaction speeds of all metabolic reactions at a rate
that can sustain life

2.11
• Heating to high temperatures (beyond the optimum) will break the bonds that hold the enzyme together and it will
lose its shape
This is known as denaturation
• Increasing the temperature increases the activity of enzymes as the more kinetic energy the molecules move
faster and the number of collisions with the substrate molecules increases, leading to a faster rate of reaction
 • This means that low temperatures do not denature enzymes, they just make them work more slowly due to a lack
of kinetic energy

2.12

Practical enzymes and temperature

At the optimum temperature, the iodine stopped turning blue-black the fastest
▪ the enzyme is working at its fastest rate and has digested all the starch

At colder temperatures , the iodine took a longer time to stop turning blue-black
▪ the amylase enzyme is working slowly due to low kinetic energy and few collisions between the amylase
and the starch

At hotter temperatures (above optimum) the iodine turned blue-black throughout the whole investigation
▪ the amylase enzyme has become denatured and so can no longer bind with the starch or break it down

2.13
-The optimum pH for most enzymes is 7
• If the pH is too high or too low, the bonds that hold the amino acid chain together to make up the protein can be
disrupted/destroyed
• This will change the shape of the active site, so the substrate can no longer t into it, reducing the rate of activity
• Moving too far away from the optimum pH will cause the enzyme to denature and activity will stop

2.15

Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration
Molecules are said to move down a concentration gradient

Osmosis is the movement of water molecules from a region of higher water concentration (dilute solution) to a region of
lower water concentration (concentrated solution), through a partially permeable membrane
Osmosis is the diffusion of water, as the water is moving down its concentration gradient

Active transport The movement of particles through a cell membrane from a region of lower concentration to a region of
higher concentration

2.16
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2.17
Diffusion practical

• You should notice that at the higher temperature, more of the pigment has leaked out of the beetroot
• This is because:
The cell membrane of the beetroot cells has become damaged so more pigment can leak out
At higher temperatures, particles have more kinetic energy, this results in the faster movement of particles
compared to when they have less energy
•

Osmosis practical
2.18

Photosynthesis is an endothermic reaction in which energy from sunlight is transferred to the chloroplasts in green plants
Energy from sunlight is absorbed by chlorophyll, a green pigment found inside chloroplasts
Green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
 At the same time, oxygen is made and released as a waste product
• Plants use the glucose they make as a source of energy in respiration
• They can use the glucose to make a source of energy
Produce starch for storage
Synthesise lipids for an energy source in seeds
To form cellulose to make cell walls
Produce amino acids (used to make proteins) when combined with nitrogen and other mineral ions
absorbed by roots

2.19

2.20 how these factors affect photosynthesis

Temperature
• The temperature of the environment affects how much kinetic energy all particles have – so temperature affects
the speed at which carbon dioxide and water move through a plant
Light intensity
• The intensity of the light available to the plant will affect the amount of energy that it has to carry out
photosynthesis
Carbon dioxide concentration
-This means the more carbon dioxide that is present, the faster the reaction can occur

Chlorophyll
-The more chloroplasts a plant has, the faster the rate of photosynthesis

2.21
2.22
understand that plants require mineral ions for growth, and that magnesium ions are needed for chlorophyll and nitrate
ions are needed for amino acids.

2.23
Investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the
requirements of light, carbon dioxide and chlorophyll
Evolution of oxygen
-Show that the gas collected is oxygen by relighting a glowing splint
Investigating light&photosynthesis
In a green leaf, the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
The area of the leaf that was covered with aluminium foil will remain orange-brown as it did not receive any sunlight and
could not photosynthesise, while the area exposed to sunlight will turn blue-black
This proves that light is necessary for photosynthesis and the production of starch
 Testing leaf for starch
• In a green leaf, the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
• The area of the leaf that was covered with aluminium foil will remain orange-brown as it did not receive any
sunlight and could not photosynthesise, while the area exposed to sunlight will turn blue-black
• This proves that light is necessary for photosynthesis and the production of starch

Investigating Carbon Dioxide & Photosynthesis

• The leaf from the conical ask containing potassium hydroxide will remain orange-brown as it could not
photosynthesise due to lack of carbon dioxide
• The leaf from the conical ask not containing potassium hydroxide should turn blue-black as it had all necessary
requirements for photosynthesis
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 Investigating Chlorophyll and Photosynthesis

• The white areas of the leaf contain no chlorophyll and when the leaf is tested only the areas that contain
chlorophyll stain blue-black
• The areas that had no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is
stored

2.24

understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals,
water and dietary bre

2.25

2.26
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2.27

Ingestion - the taking in of substances, e.g. food and

drink, into the body through the mouth
Mechanical digestion - the breakdown of food into smaller
pieces without chemical change to the food molecules
Chemical digestion - the breakdown of large, insoluble
molecules into small, soluble molecules
Absorption - the movement of small food molecules and
ions through the wall of the intestine into the blood
Assimilation - the movement of digested food molecules
into the cells of the body where they are used, becoming
part of the cells
Egestion - the passing out of food that has not been
digested or absorbed (as faeces) through the anus
2.28

Peristalsis

• Peristalsis is a mechanism that helps moves food along the alimentary canal

2.29

The role of enzymes

Carbohydrases are enzymes that break down carbohydrates to simple sugars such as glucose
Amylase is a carbohydrase which is made in the salivary glands, the pancreas and the small intestine
Amylase breaks down starch into maltose
Maltase then breaks down maltose into glucose

Proteases are a group of enzymes that break down proteins into amino acids
Pepsin is an enzyme made in the stomach which breaks down proteins into smaller polypeptide chains
Proteases made in the pancreas and small intestine break the peptides into amino acids

Lipase
• Lipases are enzymes that break down lipids (fats) to glycerol and fatty acids
Lipase enzymes are produced in the pancreas and secreted into the small intestine
2.30

bile is produced by the liver and stored in the gall bladder

2.31

Bile has two main roles:

1. Neutralising the hydrochloric acid from the stomach
 ▪ The alkaline properties of bile allow for this to occur
▪ This neutralisation is essential as enzymes in the small intestine have a higher (more alkaline) optimum
pH than those in the stomach
2. Breaking apart large drops of fat into smaller ones (and so increasing their surface area)
▪ This is known as emulsi cation

2.32

Adaptions of the small intestine

Adapted for absorption: very long, highly folded surface, millions of villi, perstasis

Villi: large surface area, short diffusion distance the wall is only one cell thick,steep concentration gradient

2.34

• Respiration is a chemical reaction carried out in all living organisms

• Energy is released from glucose either in the presence of oxygen (aerobic respiration) or the absence of oxygen
(anaerobic respiration)
• The reactions ultimately result in the production of carbon dioxide and water as waste products
• Energy is transferred in the form of ATP

2.35

ATP ( Adenosine Triphosphate )provides energy for cells

2.36

2.37

Aerobic Respiration Chemical Equation

Glucose + Oxygen → Carbon Dioxide + Water

C6H12O6 + 6O2 → 6CO2 + 6H20

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2.38

The balanced chemical equation for anaerobic respiration in animals

Word equation for anaerobic respiration in plants and fungi

2.39

Practical: Investigating Respiration

In this investigation, we would expect to note the following

Tube A should turn yellow as the seeds are respiring and producing carbon dioxide
Tube B should remain orange as the dead seeds produce no carbon dioxide
Tube C should remain orange as there is no living material in there

•
2.46

2.47
2.48
How alveoli are adapted for gas exchange

2.49
Smoking and it effects

Smoking causes : COPD, cancers, coronary heart disease

Chemicals:tar (causes smokers cough,destroys cilia so mucus builds up booking bronchioles ) nicotine (narrows blood
vessel eating to an increased blood pressure, blood cots, increases heart rate) carbon monoxide (binds
irreversibly to haemoglobin, reducing the capacity of blood to carry oxygen, this causes strain on breathing
system as they now need to breath more frequently and in more depth)
2.50
Practical: The Effect of Exercise on Breathing

Frequency of breathing increases when exercising, After exercise has nished, the breathing rate remained elevated for
a period of time

2.51
-unicellular organisms can rely on diffusion for movement of substances in and out of the cell
-Unicellular organisms such as amoeba do not require transport systems due to their large surface area to volume ratio

2.52
-The Need for a Transport System in Multicellular Organisms
-Diffusion cannot occur at a suf cient rate to meet the needs of the organism, so larger organisms usually have transport
systems

2.65
Arteries away veins too
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2.59