Requirements of living things

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

Cells need energyEnergy in the cell is transported as ATP

Cells can get energy by: Respiration (all cells) - this takes place mainly in the

mitochondriaGlucose + Oxygen Water + Carbon dioxide + Energy

(ATP & heat)Photosynthesis (plants)- this takes place in the chloroplasts

light energyWater + Carbon dioxide Oxygen + glucose

chlorophyllEnergy is used for all the cell’s activities – movement, active

transport, synthesis, growth, division, nerve impulses, etc

Summary of respiration

Fermentation

In plants and fungi:

Pyruvate (pyruvic acid) is converted to ethanol (alcohol) and carbon dioxide

If there is not enough oxygen, organisms can make energy by anaerobic respiration or fermentation. This takes place in the cytoplasm of cells.

In animals:Pyruvate (pyruvic acid) is

converted to lactic acid

Summary of photosynthesis

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’

energy

adenosine

phosphateadenosine

ATP

ADP

Cells need matterNutrients and essential materials include:• Organic compounds (contain Carbon) eg glucose,

proteins, fats, DNA, RNA, ATPused for body structures, cell components, enzymes,

hormones, etc• Inorganic elements or compounds eg nitrogen,

phosphorus, calcium, iron, sodium, potassium, etcused 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

Nutrient groups

Your body needs food, because food contains a number of nutrients needed by the body. These are:

1.Carbohydrates2.Proteins3.Lipids4.Vitamins5.Minerals6.Water

Carbohydrates (Polysaccharides)These substances are used by the body mainly for

energyNon 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

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

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

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

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

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, fishGlycerol and Fatty acids

LipidsLipids 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

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.

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

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

Mineral functionsMineral 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

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

Organisms produce wastes

The wastes produced depend on diet:Carbohydrates are broken down into carbon

dioxide and waterFats are broken down into carbon dioxide and

waterProteins are broken down into carbohydrates

and ammoniaThe greater the amount of protein in the diet,

the more ammonia produced

Cells need to remove wastesWastes 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

Nitrogenous wastes

These come from the breakdown of

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

Carbohydrate

Amine group

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