Cells are the basic building blocks of all organisms.

A tissue is a group of cells with a similar structure and function

They have a cell membrane, cytoplasm and genetic material (DNA) enclosed in a nucleus

Cytoplasm - where most chemical reactions take place

Cell membrane- controls the passage of substances into and out of the cell. It also contains receptor molecules.

Mitochondria - where aerobic respiration takes place

Chloroplasts absorb light (using chlorophyll) to make food by photosynthesis

Cell wall - made of cellulose and strengthens the cell

They have cytoplasm and a cell membrane surrounded by a cell wall

The genetic material is not enclosed by a nucleus. It is a single DNA loop and there may be one or more small rings of DNA plasmids

Carries enzymes to digest the membrane of the egg

They are long to cover more distance

branched connections at their ends to connect to other nerve cells and form a network throughout the body.

They have lots of mitochondria to generate energy for contraction

phloem have few subcellular structures so that stuff can flow through them

they have a big surface area to maximize opportunity for absorption of water and mineral ions

The energy transferred supplies all the energy needed for living processes.

Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen) to transfer energy.

glucose + oxygen → carbon dioxide + water + energy release

As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.

If insufficient oxygen is supplied, anaerobic respiration takes place in muscles. The incomplete oxidation of glucose causes a build-up of lactic acid and creates an oxygen debt. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.

Does not transfer as much energy as aerobic respiration because the glucose isn't oxidised fully

provides more energy compared to anaerobic respiration and is more efficient

Produces water and carbon dioxide as waste products

The left ventricle has a thicker wall with more muscle to generate a higher pressure to pump blood a longer distance to the rest of the body

elastic fibers and muscles even out the pressure in the artery

Small lumen, making the blood high pressure so it can be distributed around the body quickly

Narrow with thin walls so that oxygen and glucose can diffuse easily

Thin walls and large lumen to make a low pressure

Valves to stop the blood at low pressure flowing back

The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker.

Red blood cells contain haemoglobin which binds to oxygen to transport it from the lungs to the tissues.

Stents are used to keep the coronary arteries open.

Statins are widely used to reduce blood cholesterol levels which slow down the rate of fatty material deposit.

In the case of heart failure a donor heart, or heart and lungs can be transplanted. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery

Photosynthesis is an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.

If there is more light, more photosynthesis can take place

As temperature increases, the rate of photosynthesis increases

Photosynthesis is controlled by enzymes which denature around 40-50 degrees. Therefore, if the temperature gets too high, the enzymes denature and the rate of photosynthesis falls

Increasing the CO2 concentration increases the rate of photosynthesis

On a sunny day, CO2 concentration is usually the limiting factor for photosynthesis.

The CO2 concentrations around a plant rise at night because in the dark, plants respire but don't phtotosynthesize

Cells with no nucleus, can produce toxins that damage tissues, treated with antibiotics

Only reproduce inside host cells, no nucleus (viruses are not made of cells)

Cannot be classed as an animal, plant or fungus, cells have a nucleus

Pathogens may infect plants or animals and can be spread by direct contact, water or air.

Symptoms of recurrent episodes of fever, which can be fatal. Spread is controlled by preventing the mosquito vectors from breeding and by using mosquito nets to avoid being bitten.

The heart drug digitalis originates from foxgloves.

Penicillin was discovered by Alexander Fleming from the Penicillium mould.

Results of testing and trials are published only after scrutiny by peer review to help prevent false claims.

Defects in the immune system that means an individual is more likely to suffer from infectious diseases

Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.

Severe physical ill health can lead to depression and other mental illness.

A large amount of the antibody can be collected and purified.

Diagnosis: in pregnancy tests a monoclonal antibody binds to the hormone hCG produced by the embryo.

In laboratories: monoclonal antibodies are used to measure the levels of hormones and other chemicals in blood, or to detect pathogens.

In research: to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye.

To treat some diseases: for cancer the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing.

Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.

In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides.

Finally the cytoplasm and cell membrane divides to form two identical cells

Produce clones of plants quickly and economically.

Rare species can be cloned to protect from extinction.

Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.

Independent variable = Distance from the lamp (affects light intensity)

Dependent variable = Number of bubbles of oxygen