Level of organisation smallest to biggest Definition Example

Level of organisation (smallest to biggest) Definition Example in plants Example in animals Cells The smallest unit of an organism Palisade cell Glandular cells Tissues A group of cells with a similar structure and function, which all work together to do a particular job. Leaf epithelium Stomach lining Organs Made from a group of different tissues, which all work together to do a particular job Leaves Stomach Organ system Made from a group of different organs, which all work together to do a particular job. Photosynthetic system Digestive system Daffodil Human Organism An individual plant, animal, or single-celled organism.

Organ systems are groups of organs that carry out a particular function. For example, the digestive system:

Enzymes • Biological catalysts: speed up reactions • Enzymes are protein molecules, and so are made up of amino acids.

What happens at the active site? The enzyme is the lock, and the reactant is the key. + enzyme + reactant ↔ ↔ enzyme-reactant complex ↔ ↔ + enzyme + products

Temperature and enzymes Most enzymes in the human body work best at about 37 o. C. Over 40 o. C most enzymes will stop working. The amino acids they are made form start to unravel and the shape of the active site changes. We say that the enzyme is denatured. The substrate no longer fits into the enzyme

p. H and enzymes Changes in p. H alter an enzyme’s shape. The best p. H for an enzyme depends on where it normally works. For example, intestinal enzymes have an optimum p. H of about 7. 5 (alkaline). Enzymes in the stomach have an optimum p. H of about 2 (acidic).

Amylase Made in the salivary glands, pancreas and small intestine It breaks down carbohydrates/starch into glucose It works in the mouth and small intestine

Protease Made in the stomach, pancreas and small intestine It breaks down protein into amino acids It works in the stomach and small intestine

Lipase Made in the pancreas and small intestine It breaks down lipids (fats and oils) into fatty acids and glycerol It works in the small intestine

The enzymes made in the pancreas and small intestine work best in alkaline conditions. The liver produces bile which is released into the small intestine. Bile emulsifies the fats and neutralises the acid that was added to the food in the stomach.

Digestive enzymes Enzyme Produced Breaks down… Into… Amylase Salivary glands, pancreas, small intestine Starch Glucose Protease Stomach, pancreas, small intestine Proteins Amino acids Fatty acids and glycerol Lipase Pancreas, small intestine Bile Liver (released by the gall bladder) Fats (emulsifies and Smaller fats to neutralises) increase surface area

Testing for foods – Glucose Use Benedict’s solution (light blue solution) Warm up in water bath Turns brick red if simple sugars are present

Testing for foods – Starch Use Iodine solution (orange solution) Turns blue/black if starch is present

Testing for foods – Proteins Use Biuret solution (blue solution) Turns purple if protein is present

Testing for foods – Required Practical Food group Reducing sugar (glucose) Reagent used Additional steps… Positive result Benedict’s Warm up in water bath Brick red Biuret N/A Turns purple Lipids Ethanol add a bit of distilled water Cloudy white layer Starch Iodine N/A Blue/black Protein

The effect of p. H on Rate of Reaction – RP Put the starch and amylase (in separate test tubes) into a water bath to get both up to temperature Mix the two solutions together then start adding to the dropping tile. 1. 2. 3. 4. 5. 6. Use a range of at least 3 p. H values / use of buffer solutions Control variables / keep amount or concentration of starch and amylase the same Keep temperature of the reagents the same using water bath / electric heater Use iodine test to make qualitative observations (when does it stop turning blue-black) Observe colour changes at different p. Hs Do repeats at each p. H

If there was 0. 8 g of starch to start with, what rate is it broken down at 33 OC? Broken down in 3. 4 minutes. Therefore 0. 8 / 3. 4 = 0. 24 g/min

Circulatory system

• You can also talk about the differences in pressure. Blood to the lungs goes at far less pressure

Natural pacemaker • Located in the right atrium

The lungs

Blood vessels • Arteries – carry (oxygenated) blood away from the heart under high pressure. Has a thick layer muscle and is elastic • Veins – carry (deoxygenated) blood towards the heart under low pressure. They have valves to prevent backflow of blood • Capillaries – one cell thick, links arteries to veins

Components of blood • Red blood cells – contain haemoglobin which oxygen binds to. Contain no nucleus • Platelets – small fragments of cells. Important in helping the blood clot at a wound • White blood cells – much bigger than red blood cells • Plasma – carries all the above as well as other dissolved substances such as glucose

Cardiovascular disease can be treated in 4 main ways 1. Drugs (statins) – used to reduce blood cholesterol and prevent fatty build up 2. Valve transplants (for heart valve disease) – can be mechanical or biological (from pigs). Used when valves become faulty 3. Heart transplants – when someone has heart failure 4. Stents – used to keep coronary arteries open 5. Artificial pacemakers

Disease When a person is in good health, they do not have any type of disease. A disease is a condition that is caused by any part of the body not functioning properly. Diseases can affect mental and physical health. Communicable Disease: infectious disease caused by pathogens such as bacteria, viruses & fungi. They can be transmitted from person to person. What is a pathogen? E. g. tuberculosis, flu A disease causing microorganism Non-communicable disease: cannot be transmitted from person to person. E. g. arthritis, heart disease

Blue are communicable, red are non communicable 1. 2. 3. 4. 5. 6. 7. 8. 9. Flu Cystic fibrosis (genetic disease) Tuberculosis (bacterial infection) Cancer HIV Arthritis Athlete’s foot (fungus) Scurvy (lack of vitamin C) Malaria Some diseases will interact: 1. Human papilloma virus – can cause cancer 2. Immune reactions caused by a pathogen cause allergic reactions 3. Serious physical ill health can lead to depression

What is epidemiology? Epidemiology is the study of the incidence (number of cases) of disease and pattern of a disease with a view to finding the means of preventing or controlling it. Epidemiology is concerned with: Morbidity of a disease – the number of people currently living in the diseased state. Mortality of a disease – the number of people who die from a specific disease (within a time frame).

Causal links between risk factors and disease 1. Diet high in saturated fat • Can cause cardiovascular disease because of a build up of cholesterol in your body which can grow in your arteries, eventually rupturing and causing a blood clot 2. Smoking • Smoking damages the lining your lungs leading to lung disease and cancer. Smoking while pregnant seriously affects the unborn child 3. Lack of exercise • Improves circulation, lowering risk of blood clots forming. Indirectly linked to obesity and which is a risk factor for CHD. Obesity increases risk of diabetes 4. Drinking alcohol • Damages liver and brain function 5. Carcinogens (including ionising radiations) • Cause cancer Video

• Describe three differences between the palisade mesophyll layer and the spongy mesophyll layer

Phloem • Phloem are composed of tubes of elongated cells. Cell sap can move from one phloem cell to the next through pores in the end walls • The movement of food molecules through the phloem is called translocation Dissolved sugars

Xylem • Contains hollow tubes strengthened with lignin • The movement of water through xylem is called the transpiration stream • Ions also move through the xylem

Stomata The underside of leaves have small holes called stomata. Each stoma is surrounded by two guard cells. During photosynthesis, low carbon dioxide levels inside the plant cause guard cells to gain water and become turgid. They curve out, opening the stoma and allowing gases in and out. Water also evaporates through the stomata.

Investigating transpiration A potometer can be used to investigate the different factors that effect the rate of transpiration.