Organisation GCSE AQA Biology

Define cells

The basic building blocks of all living organisms

Define tissues

Groups of cells with a similar structure and functions

Define organs

Aggregations of tissues performing specific functions

Define organ systems

Organised organs which work together to form organisms

What is the purpose of the digestive system?

To digest and absorb food molecules

What is the stomach? Describe how it is adapted for its role.

A sac where food is mixed with hydrochloric acid to start the digestion of protein and kill microorganisms. It has muscular walls to churn food, it produces pepsin (protease) to break down protein, and the hydrochloric acid kills bacteria and provides the right pH for pepsin (protease).

What is the small intestine? Describe how it is adapted for its role.

Upper part of the intestine where digestion is completed and nutrients are absorbed by the blood. It produces protease, lipase and amylase to aid digestion, and it has microvilli to absorb nutrients by diffusion and active transport.

What is the large intestine?

Lower part of the intestine from which water is absorbed and where faeces are formed.

State the path of food through the digestive system.

Mouth -> Oesophagus -> Stomach -> Small Intestine -> Large Intestine -> Rectum -> Anus

Where is food mechanically broken down in the digestive system?

Mouth, Stomach

What level of organisation is the digestive system?

Organ system

Describe and explain the effect of temperature on enzyme activity

If the temperature is above the optimum, the enzyme activity will decrease because the enzymes active site denatures. If the temperature is below the optimum, the enzyme activity will be lower because the reactants and enzymes have less energy

Describe and explain the effect of pH on enzyme activity

If the pH is too high or too low, the enzyme activity will decrease because the enzyme is denatured.

What is the purpose of an enzyme?

To catalyse specific reactions in living organisms

Why can't enzymes catalyse every reaction?

The shape of their active site

Describe the lock and key model.

An enzyme and the substrate have complementary shapes. This allows them to bind together to form an enzyme-substate complex (like a lock and a key fitting together). The enzyme then splits the substrate into products.

State where amylase is produced and where it acts.

Produced: Salivary glands, pancreas, small intestine

Acts: Mouth, Small Intestine

State where protease is produced and where it acts

Produced: Stomach, Pancreas, Small Intestine

Acts: Stomach, Small Intestine

State where lipase is produced and where it acts.

Produced: Pancreas, Small Intestine

Acts: Small Intestine

Name 3 types of enzyme.

Protease

Lipase

Carbohydrase/Amylase

Name a type of carbohydrase.

Amylase

Give a simple word equation for reactions catalysed by carbohydrases.

Carbohydrate -> Simple Sugars

Give a simple word equation for reactions catalysed by amylase.

Starch -> Simple Sugars

Give a simple word equation for reactions catalysed by proteases.

Protein -> Amino Acids

Give a simple word equation for reactions catalysed by lipases.

Lipids/Fats -> Glycerol + Fatty Acids

Give four uses of the products of digestion.

Build new carbohydrates, build new proteins, build new fats, respiration

What product of digestion is needed for respiration?

Glucose

Where is bile made, stored and used?

Liver, Gallbladder, Small Intestine

State three uses of bile in the digestive system

Neutralises hydrochloric acid from stomach, emulsifies fats, provides optimal conditions for lipase

Is bile acidic or alkaline?

Alkaline

Describe why it is good for fat to be emulsified in the small intestine.

It forms small droplets which increases surface area, increasing rate of fat breakdown by lipase

Describe how you would test a substance for carbohydrates, fats and proteins. State any colour changes

Take a food sample, grind it with mortar and pestle, transfer paste to beaker, add distilled water, stir. Pour 1/4 into Test Tube 1. Filter remaining solution. Split remaining solution into 3 test tubes - 2, 3 and 4. Add Benedict's solution to Test Tube 3 and start heating Test Tube 4 for 5 minutes using water bath. Add some Sudan III stain to Test Tube 1 - if fat is present then it will go from colourless to having a red layer on top. Add iodine to Test Tube 2 - brown->black if starch present. Add Biuret's solution to Test Tube 3 - if protein is present, it will turn from blue to purple. Go back to Test Tube 4after the 5 minutes - if it contained a reducing sugar, it would have turned from blue to green (low sugar), yellow (medium sugar) or brick-red (high sugar)

For the Food Tests Practical, why do we usually filter the solution?

To remove suspended food particles

For the Food Tests required practical, suggest one way of reducing risk from the use of dangerous chemicals

Wearing safety goggles

Describe how you would investigate the effect of pH on amylase .

Put iodine solution into each well of a spotting tile. After heating in water bath to 30°C, mix set amount of starch solution, amylase solution and buffer solution (e.g. pH 5) and replace in water bath, stir and start a stopwatch. Every 30 seconds, use pipette to take one drop and put it onto spotting tile until there is no colour change detected. Repeat for other pH buffer solutions.

For the Enzymes required practical, state 2 sources of error and give a resolution

Too large intervals between testing -> reduce intervals

Hard to tell when no colour change occurs -> adk many people for their judgement

State the path of carbon dioxide from the veins to the mouth and nose

Veins -> Capillaries -> Alveoli -> Bronchi(oles) -> Trachea -> Mouth and nose

State the path of blood around the circulatory system, starting and ending in the veins. Do not include capillaries.

Veins -> Vena Cava -> Right atrium -> Right ventricle -> Pulmonary Vein -> Lungs -> Pulmonary Artery -> Left Atrium -> Left Ventricle -> Aorta -> Arteries -> Body Cells -> Veins

What is the purpose of the lungs?

Where gaseous exchange takes place

What is the purpose of the heart?

To pump blood around the body

Describe the function of valves and name two places where valves may be found.

They prevent the backflow of blood in the veins and in the heart.

What side of the heart is larger? Explain why

The left - it needs more muscle to pump blood around whole body as opposed to the lungs

Why is the circulatory system often referred to as a double circulatory system?

Blood passes through the heart twice in each cycle

Name the blood vessels that supply blood to the heart muscle

Coronary Arteries

Describe the natural pacemaker's job and role

A group of cells in the right atrium which control the natural resting heart

State what an artificial pacemaker is.

An electrical device used to correct irregularities in the heart rate.

Name the types of blood vessel and state each one's function.

Arteries - carry blood away from heart

Veins - carry blood to heart

Capillaries - involved in the exchange of materials at tissues

Describe the structure and pressure of an artery

They are strong, elastic and have small lumen made of muscles and fibres. They have a high pressure

Describe the structure and pressure of a vein

They are thin, have a large lumen and have valves. They have a low pressure.

Describe the structure and pressure of a capillary

They have a small lumen, have permeable walls and are one cell thick. They have a medium pressure.

What level of organisation is the blood?

Tissue

Name the four components of blood and describe their size and shape.

Plasma - liquid

Red blood cells - mediumly-sized, biconcave

White blood cells - large, spiky

Platelets - small, flaky

Explain how plasma is adapted for its function

Plasma is a liquid, so can carry red blood cells, white blood cells, platelets, carbon dioxide, urea, glucose, amino acids, fatty acids, glycerol, antibodies, antitoxins and hormones around the body

Explain how red blood cells are adapted for their role.

They have no nucleus so they can pack more haemoglobin which allows oxygen to bind on to it to form oxyhaemoglobin. They are biconcave and thin to maximise surface area for blood absorption

Explain how white blood cells are adapted for their function

Some white blood cells called lymphocytes produce antibodies which attack pathogens that enter the body. Other white blood cells called phagocytes can engulf pathogens that enter the blood by phagocytosis

Explain how platelets are adapted for their function

Platelets have proteins on their surface which allow them to stick to breaks in a blood vessel and clump together, and they secrete proteins that result in a series of chemical reactions that makes blood clot.

Evaluate the use of blood products. Do not give your own opinion.

Blood products can save someone's life after an accident, are screened for infectious diseases and can be given to a patient according to their needs, but they must be of the same blood type as the patient, sometimes the body will have an immune reaction and white blood cells cannot be transferred

What is coronary heart disease and why is it bad?

Where layers of fatty materials build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle.

Evaluate the use of stents to treat coronary heart disease. Do not give your own opinion.

They are mechanical devices that are used keep the coronary arteries open. They lower the risk of having a heart attack, they work for a long time and the recovery time from the surgery is relatively quick. However, there is a risk of complication during the operation, there is a risk of infection and a risk of developing a blood clot near the stent (thrombosis)

Evaluate the use of statins to treat coronary heart disease. Do not give your own opinion

Statins are a drug widely used to reduce blood cholesterol levels, reducing rate of fatty material deposit. They reduce risk of strokes and heart attacks and they increase the amount of good/HDL cholesterol in the body; however, they must be taken long-term, often have negative side effects and can't fix coronary heart disease instantly.

Describe faulty heart valves and their consequences

It could become faulty, preventing it from opening fully, or it might develop a leak; blood won't circulate as effectively as normal and there may be some backflow of blood..

Evaluate the use of replacement valves to treat coronary heart disease

Faulty valves can be treated using artificial valves or biological valves - they are good because it is a less risky procedure than a full heart transpplant, and the replacement valves are widely available from either a manufacturer or an animal. However, there is still risk of complications during surgery, biological valves can be rejected and mechanical valves can cause blood clots.

Evaluate the use of heart transplants to treat coronary heart disease. Do not give your own opinion

Heart transplants are hearts given to patients with heart failure. They are very effective and allow blood to flow smoothly, however they aren't very available, surgery can lead to complications and have a high chance of rejection.

Name seven ways of treating heart failure

Stents/mechanical

Statins/drugs

(Heart) Transplant

Biological valves

Artificial valves

Heart and lung transplant

Artificial heart

Evaluate the use of artificial hearts to treat coronary heart disease

They can be used keep patients alive whilst waiting for a heart transplant since they are widely available, or to allow the heart to rest as an aid to recovery, and they are unlikely to be rejected. However, there is always a risk of complications during surgery, they are easily damaged or broken and people with artificial hearts have to take drugs to prevent strokes, which have side effects.

Define health

A state of physical and mental wellbeing

Describe the relationship between health and disease

Diseases are major causes of ill health

Name four factors which can influence health

Disease, diet, stress, life situations

Briefly describe four ways diseases can interact with each other.

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

Viruses in cells can be the trigger for cancers

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

Define risk factors

Things that are linked to an increased rate of disease

Name the two types of risk factor

Aspects of a person's lifestyle

Substances in the person's body or environment

Has a causal mechanism been proven for every risk factor?

No

Name six diseases which are causally linked to risk factors.

Diet, smoking and exercise as risk factors of cardiovascular disease

Obesity as a risk factor for Type 2 diabetes

Alcohol as a risk factor for liver/brain damage

Smoking as a risk factor for lung cancer/disease

Alcohol and smoking as risk factors for diseases in unborn babies

Carcigogens (such as ionising radiation) as risk factors in cancer

Can multiple risk factors contribute to a disease?

Yes