1. Requirements of living things

2. Cells exchange matter and energy
In:
Oxygen
Nutrients eg glucose
Water
Ions
Out:
Carbon dioxide
Wastes eg urea
Water
Ions
Heat energy
Processes:
Respiration
Synthesis
Growth
Division

3. Cells need energy Energy in the cell is transported as ATP
Cells can get energy by:
Respiration (all cells) - this takes place mainly in the mitochondria
Glucose + Oxygen  Water + Carbon dioxide + Energy (ATP & heat)
Photosynthesis (plants)- this takes place in the chloroplasts
light energy
Water + Carbon dioxide  Oxygen + glucose
chlorophyll
Energy is used for all the cell’s activities – movement, active transport, synthesis, growth, division, nerve impulses, etc

4. Summary of respiration

5. Fermentation
If there is not enough oxygen, organisms can make energy by anaerobic respiration or fermentation. This takes place in the cytoplasm of cells.
In plants and fungi:
Pyruvate (pyruvic acid) is converted to ethanol (alcohol) and carbon dioxide
In animals:
Pyruvate (pyruvic acid) is converted to lactic acid

6. Summary of photosynthesis

7. ATP and ADP Act as chemical batteries
Carry and release small amounts of energy
ATP is the ‘charged battery’ and ADP is the ‘flat battery’
ATP
adenosine
adenosine
phosphate
ADP
energy

8. Cells need matter Nutrients and essential materials include:
Organic compounds (contain Carbon) eg glucose, proteins, fats, DNA, RNA, ATP
used for body structures, cell components, enzymes, hormones, etc
Inorganic elements or compounds eg nitrogen, phosphorus, calcium, iron, sodium, potassium, etc
used for making organic compounds (eg proteins, DNA & ATP contain nitrogen and phosphorus), maintaining osmotic balance, and pH balance
Gases (oxygen and carbon dioxide) – oxygen is needed for aerobic cellular respiration by all organisms and carbon dioxide is needed for photosynthesis

9. Nutrient groups
Your body needs food, because food contains a number of nutrients needed by the body. These are:
1.Carbohydrates
2.Proteins
3.Lipids
4.Vitamins
5.Minerals
6.Water

10. Carbohydrates (Polysaccharides)
These substances are used by the body mainly for energy
Non digestible carbohydrate (eg cellulose) is called roughage or fibre.
It is important to the body because it helps movement of food through the intestines, and prevents bowel cancer and other problems
Carbohydrates contain the elements Carbon, Hydrogen and Oxygen
Foods containing carbohydrates include: cereals eg rice, wheat, oats; bread, pasta, cakes, biscuits, potatoes and other starchy vegetables

11. Carbohydrates
Carbohydrates are huge molecules. They are made up of many small subunits called saccharides
The simplest kind of sugar is a monosaccharide
eg glucose and fructose
Polysaccharides are long chains of monosaccharides joined together
eg starch, glycogen

12. Proteins (polypeptides)
These substances are used by the body for body structures eg hair, muscle, skin; enzymes; blood components eg haemoglobin, clotting factors
Proteins contain the elements Carbon, Hydrogen, Oxygen and Nitrogen, and sometimes Sulfur and/or Phosphorus.
Foods containing proteins include: meat, fish, poultry, eggs, soy, nuts, legumes – eg peas, beans

13. Proteins The basic unit of a protein is an Amino acid
Amino acids join together in long chains to form polypeptides
These chains can be very long. The hormone Insulin is 55,000 amino acids long.
Sometimes two or more long chains stick together to form one working protein.
Haemoglobin is formed from 4 polypeptide chains working together

14. Types of amino acids
Amino acids differ by having different R groups - for example the amino acid glycine has an R group made of just “H”
There are 20 different types of amino acids, of which 9 are essential amino acids
An essential amino acid is one that the body can’t make . It must get this essential amino acid by eating food that contains the essential amino acid

15. LIPIDS (fats)
These substances are used by the body for energy reserves, insulation an protection and to make cell membranes, hormones and for normal skin and brain function
Fats contain the elements Carbon, Hydrogen and Oxygen
Unlike carbohydrates, lipids always contain much more hydrogen than oxygen.
Lipids are made from two kinds of molecular units joined together in the shape of the letter “E”:
Foods containing lipids include: butter, margarine, oils, milk, cheese, cream, nuts, fish
Glycerol and Fatty acids

16. Lipids Lipids can be saturated or unsaturated.
Saturated means there are no double bonds between the carbon atoms.
This means that they are difficult for the body to break down and use.
Instead they get stored in the adipose cells (fat cells)
Unsaturated fatty acids have double bonds between carbon atoms.
The double bonds make the whole structure unstable so this molecule is easy for the body to break down and release the stored energy

17. Vitamins
There are a number of vitamins needed by the body. Most act as co-factors for enzymes in metabolic reactions.
The fat-soluble vitamins are A, D, E and K and the water-soluble vitamins are B and C.
Sources of vitamins include fruit and vegetables
Water-soluble vitamins are easily lost in cooking and preserving, so the best sources are fresh or raw fruit and vegetables
Excesses of vitamins can also cause problems, including vitamin A toxicity.

18. Vitamin functions Vitamin Function A
Helps with immunity, night vision and skin health, normal growth of foetal cells
B group (including folate, niacin and thiamine)
Helps with metabolism, red blood cell manufacture (making haemoglobin)
Helps prevent spina bifida if taken by pregnant woman C
Prevents scurvy – helps with immune system D
Helps with bones and teeth – prevents osteoporosis and rickets E
Helps with immunity and skin health K
Help with clotting

19. Minerals There are many minerals used by the body.
Most act as cofactors for enzymes in metabolic reactions.
Excesses of some minerals can also cause problems, eg copper is poisonous if taken in large amounts.
Sources of minerals include milk and dairy products, bony fish (eg sardines, tuna), liver, kidney, meat, baked beans, chicken, egg yolk, wheat germ

20. Mineral functions Mineral Function Calcium
Healthy bones and teeth – prevents osteoporosis and rickets
Iron
Haemoglobin manufacture – prevents anaemia
Iodine
Helps metabolism – prevents goitre
Copper
Anaemia
Fluorine
Helps healthy teeth
Zinc
Helps with healthy tooth enamel

21. Water
Water is used for for dissolving chemicals, regulation of body temperature and waste removal
Sources of water include water and other drinks, fruits and vegetables

22. Organisms produce wastes
The wastes produced depend on diet:
Carbohydrates are broken down into carbon dioxide and water
Fats are broken down into carbon dioxide and water
Proteins are broken down into carbohydrates and ammonia
The greater the amount of protein in the diet, the more ammonia produced

23. Cells need to remove wastes
Wastes can have serious effects on cells:
Carbon dioxide toxic waste, decreases pH
Ammonia toxic waste, increases pH
Excess salts alters osmotic pressure – drags in water
Excess water alters osmotic pressure – can burst cells

24. Nitrogenous wastes These come from the breakdown of
Amine group
Carbohydrate
In deamination the amine group is removed
The carbohydrate is then used for energy or stored
The amine group turns into ammonia which can be excreted or turned into urea or uric acid for excretion

25. Wastes depend on lifestyle
Herbivores eat plant material and produce small amounts of nitrogenous wastes
Carnivores eat meat and produce large amounts of nitrogenous wastes