B2

• Cells definition

  the basic building blocks of all living organisms.
• Tissue definition

  a group of cells with a similar structure and function
• What is an organ?


  An aggregation of tissues performing specific functions.
• How are organs organized?

  Organs are organized into organ systems, which work together to form organisms.
• Which factors affect enzyme function?

  Temperature (too high, denatures the enzyme; too low, not enough collision speed with the substrate and enzyme to get to activation energy) and pH (too high or low, denatures the enzyme)
• What is the function of enzymes?

  Enzymes catalyse specific reactions in living organisms due to the shape of their active site, similarily to a lock and key mechanism. Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream.
• How are carbohydrates digested?

  Carbohydrases, produced by the salivary glands, the pancreas and the wall of the ileum and used in the mouth and small intestine break down carbohydrates into simple sugars (e.g . Amylase is a carbohydrase, which breaks down starch into maltose and then glucose.)
• How are proteins digested?

  Proteases, which are produced in the gastric glands of the stomach, pancreas and wall of the ileum and used in the stomach and small intestine, break down proteins into amino acids.
• How are lipids digested?

  Lipases (produced in the pancreas and used in the small intestine) break down lipids (fats) to glycerol and fatty acids.
• Define and explain the purpose of bile

  Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.
• what is the test for reducing sugar (e.g glucose)?

  Reducing sugars give a red-brown precipitate when heated with Benedict's solution.
• What is the test for starch?

  Foods containing starch will turn a blue-black colour when brown iodine solution is added
• What is the test for proteins?

  The biuret reagent will turn purple when it is mixed in to a solution containing proteins.
• What is the test for lipids?

  The emulsion test is an alternative test for lipids.
• Describe the movement of blood through the heart and lungs coming in from the body to going out to the body

  Deoxygenated blood enters the right side of the heart through the vena cava into the right atrium, then the right ventricle and is carried by the pulmonary artery to the lungs

  Oxygenated blood is brought back to the heart through the pulmonary vein. It then goes through the right atrium and the right ventricle and is pumped to the body through the

  
• What is the heart's place in the circulatory system?

  The heart is an organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle (with a thicker wall) pumps blood around the rest of the body.
• What are coronary arteries?

  Arteries that branch off the aorta & surround the heart, ensuring that it gets all the oxygenated blood it needs
• What is the structure of the lungs?

  - the trachea leads to 2 bronchi

  - bronchi branch into bronchioles

  - bronchioles lead to alveoli

  - alveoli are surrounded by capillaries which get rid of CO2 dissolved in blood and attach O2 to the hemoglobin in red blood cells
• How are alveoli adapted for better gas exchange?

  -1 cell thick wall (short diffusion pathways)

  -large amount of oxygen in air, small amount in blood (large concentration gradient)

  -small alveoli (large surface area:volume ratio)

  - alveoli are moist (easier to diffuse)
• What are pacemaker cells?

  Cells located in the wall of the right atrium that send electrical signals through the heart that keep it beating at a steady rythm. Artificial pacemakers are electrical device which correct irregularities in heart rate.
• What is the equation for cardiac output?

  cardiac output (ml/min) = heart rate (beats/min) X stroke volume (ml/beat)
• What is the structure of arteries?

  -Thick and muscular walls which have

  -elastic fibres to stretch and recoil as the heart beats

  -small lumen

  -this helps maintain high pressure.
• What is the structure of veins?

  Larger lumen (center of tube) than arteries, internal valves are present to aid movement of blood in one direction. Lower pressure, less muscle and less elastic fibres than arteries
• What is the structure of capillaries?

  -single layer of endothelial cells for shorter diffusion pathway

  -thinner than arteries and veins for larger surface area;volume ratio

  - effective diffusion needed as oxygen diffuses out of and waste products (e.g urea and CO2) diffuse into the blood here
• What are the components of blood?

  -mostly plasma

  -red blood cells

  -white blood cells

  -platelets
• what are red blood cells?

  bi-concaved disks (large surface area for diffusion in alveoli and capillaries) that do not have a nucleus and contain haemoglobin, which binds to oxygen to become oxyhaemoglobin to transport oxygen around the body
• what does plasma contain?

  Water, proteins, nutrients, hormones (proteins, glucose), red/white blood cells, platelets, waste products (e.g urea and CO2)
• what are platelets?


  Small fragments of cells that clots and forms scabs around wounds to prevent blood loss and infection
• How does coronary heart disease happen?

  In coronary heart disease layers of fatty material 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.
• How do stents treat coronary heart disease?

  A balloon in the metal mesh stent inflates to open the artery then the stent holds the artery open
• How do statins prevent coronary heart disease?

  Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit.
• How can faulty heart valves be treated?

  In some people heart valves may become faulty, preventing the valve from opening fully, or the heart valve might develop a leak. Faulty heart valves can be replaced using biological or mechanical valves.
• How can heart failure be treated?

  -a donor heart can be transplanted, though a donor can be difficult to find, the organ may be rejected by the body and the new heart may be susceptible to disease.

  -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 but these may cause blood clots and the patient must take blood thinning medication.
• What is health?

  Health is the state of physical and mental well-being. Diseases diet, stress and life situations may have a profound effect on both physical and mental health.
• Give examples of different diseases interacting

  -Defects in the immune system -> more likely to suffer from infectious diseases.

  -Viruses can trigger cancers.

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

  -Severe physical ill health -> more likely to suffer from depression and other mental illness.
• What are common risk factors for non-communicable diseases?

  -poor diet & obesity: type 2 diabetes, cardiovascular disease

  -alcohol: cardiovascular disease, liver (cirrhosis) and brain function, effects on foetuses

  -smoking: cardiovascular disease, effects on foetuses (addiction and carbon monoxide limiting oxygen), lung disease, lung cancer

  -carcinogens e.g radiation: cancer
• How does the lifestyle of a population affect the economy?

  -If more people have an unhealthy lifestyle (E.g more people in a population smoke)

  -more people are at higher risk of cardiovascular disease and lung diseases such as cancer

  -more money has to be spent on healthcare, taking care of those people
• Describe the two types of cancer

  -both are the result of changes in a cell's DNA that lead to uncontrolled growth and division.

  -benign tumours are slow, contained in one area, usually within a membrane

  -malignant tumours are fast, cells from the primary tumour invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours
• How can we treat cancer?

  chemotherapy, radiation, surgery

  can reduce risk factors (e.g smoking, exposure to carcinogens such as radiation,
• Which tissues/structures are in the leaf (plant organ)?

  -waxy cuticle (reduces water loss)

  -epidermal tissues (transparent to allow photosynthesis)

  -palisade mesophyll (carries out photosynthesis, many chloroplasts)

  spongy mesophyll (air space for oxygen/carbon dioxide diffusion)

  -xylem and phloem (carries water & minerals and glucose)

  -meristem (tissue found at the growing tips of shoots and roots which differentiate)

  -guard cells (open and close stomata-air holes)