GCSE Biology Organisation Active Recall Questions

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a key ▾ How does the shape of an active site make the enzyme specific? the shape of the active site matches the shape of its substrate molecules. each enzyme can only catalyse one type of reaction ▼ Factors affecting the rate of reaction of enzymes. Temperature the rate of the reaction increases as the temperature increases. if the temp is too high- the bonds holding the enzyme together break, causing active site to change shape and denature ▼ pH if the pH is too alkaline or too acidic the shape of the enzyme is altered so it becomes denatured ▾ Digestive Enzymes. Carbohydrase ▼ What does it catalyse? carbohydrates to simple sugars Where? mouth, small intestine ▼ Protease Unit 2 - Organisation What does it catalyse? 2 Breakdown of proteins into amino acids ▼ Where? Stomach, small intestine ▾ Lipase ▼ What does it catalyse? Breakdown of fats and oils into fatty acids and glycerol ▼ Where? Small intestine ▼ Amylase What does it catalyse? Breakdown of starch into maltose ▼ Where? Mouth and small intestine Functions of Bile neutralises acid provides alkaline conditions needed in small intestines emulsifies fats provides a larger surface area for lipase enzymes to work Unit 2 - Organisation increase the rate of fat breakdown by lipase ▼ Where is bile produced and released from? produced by the liver, stored in the gall bladder Circulatory System ▾ Describe the structure of the human heart. 3 ▼ 1 pulmonary artery ▼ 2 vena cava ▼ 3 right atrium ▼4 right ventricle ▼5 left ventricle ▼6 left atrium ▼7 pulmonary vein ▼8 aorta Blood Circulation. ▼ Body heart → Unit 2 - Organisation lungs 4 deoxygenated blood from body vena cava → right atrium right ventricle → pulmonary artery → lungs ▼ Lungs heart body oxygenated blood ▾ What is the purpose of the coronary arteries? provide oxygen in muscle cells of the heart. used in respiration to provide energy for contraction. ▾ How is the natural resting heart rate controlled? by the pacemaker - right atrium pulmonary vein → left atrium → left ventricle → aorta ▾ How are irregularities in a person's resting heart rate corrected? via an artificial pacemaker- a small electrical device ▼ Lungs ▾ How does air pass into the lungs? air enters body through mouth and nose. enters trachea (which is divided into two bronchi) air travels through brochioles. air enters many millions of alveoli. ▾ How are lungs adapted for gas exchange? thin walls one cell thick for short diffusion distance ▾ moist walls gases dissolve easier permeable membrane so gases can pass through ▾ large surface area Unit 2 - Organisation faster rate of diffusion Blood ▾ What is the function of the red blood cell? 5 transport oxygen from the lungs to body cells ▼ What are the adaptations of red blood cells? ▼ haemoglobin carries oxygen to form oxyhaemoglobin. no nucleus larger surface area for more haemoglobin bioconcave shape gre surface area ▾ What is the function of the white blood cell? form part of the immune system in making antibodies ▾ What are the adaptations of white blood cells? ▾ irregular shape to squeeze out of blood vessels and get to the site of infection ▾ cytoplasm to change shape and engulf pathogens What is the function of the platelet? tiny fragments of cells which help form blood clots ▾ What does plasma transport? glucose, hormones, urea etc ▾ Blood Vessels ▼ What is the structure and adaptations of arteries? thick wall consisting of muscle and elastic fibres. fibres stretch when a surge of blood passes through and recoil between surges narrow lumen- keeps the blood pressure high ▾ What is the function of the arteries? carry very high pressure blood from the heart to the organs in the body ▾ What are the structure and adaptations of the capillaries? Unit 2 - Organisation 6 thin walls for short diffusion pathway wide lumen- carries blood at low pressure narrow walls - one cell thick permeable membrane for efficient diffusion What is the function of the capillaries? controls the exchange of substances in the blood and cells (glucose + oxygen blood cells) (carbon dioxide cells blood) ▾ What is the structure and adaptations of veins? thin wall due to low blood pressure. have valves to stop blood flowing backwards relatively wide lumen- low pressure What is the function of veins? carry deoxygenated blood to the heart. (except for pulmonary vein) Heart Disease ▼ What happens during coronary heart disease? coronary arteries (supply blood to the heart muscle). they can become blocked by a build-up of fatty plaques containing cholesterol = CHD What are the uses of statins? drug to lower cholesterol in the blood. they lower the production in the liver. ▾ What are the treatments for CHD? drugs, heart transplant. replacement of heart valves ▾ What are the advantages and disadvantages of using drugs? ▾ Advantages reduce the risk of a heart attack. reduce high cholesterol, cheap, have other benefits ▾ Disadvantages not suitable for people with liver disease, side-effects, have to be taken for life, cannot take if pregnant or breastfeeding Unit 2 - Organisation 7 ▾ What are the advantages and disadvantages of having a heart transplant? improves quality of life, lifesaving few donor hearts available, recovery time is long, risk of rejection by the immune system, expensive operation and aftercare. ▼ What are the advantages and disadvantages of having replacement heart valves? ▾ Advantages restores blood flow through heart, less risk of complications in surgery compared to heart transplant ▾ Disadvantages biological valves can wear out, blood clots may stick to mechanical valves- anti-blood-clotting drugs may need to be taken for life which increases risk of further illness How can heart valves become faulty? may not open as wide as they should- restricts blood flow, less blood reaches heart and build-up in lungs can form may not close properly and blood can leak back into atrium ▾ How can patients be treated in the case of heart failure? surgery or drugs, coronary bypass where veins from leg are grafted into heart to bypass blocked arteries. Non-Communicable Diseases ▾ Define health. the state of physical, mental and social well-being What are some causes of ill-health? diet, lifestyle factors, stress, events ▾ How may different types of disease interact? some non-communicable diseases can increase the likelihood of developing communicable diseases eg viruses in cells can trigger cancer What is a risk factor? Unit 2 - Organisation 8 a factor that increases the chance of getting a disease smoking lung cancer ▾ Define the term 'causal mechanism'. when a direct link has been made between a risk factor and a disease ▾ Define the term 'time lag'. when there is a substantial period of time between being exposed to the risk factor and developing the disease ▼ What is cancer? a number of damaged cells that multiply and damage the body. happens when the cell escapes a checkpoint in the cell cycle and multiplies. ▾ What is a benign tumour? growth and multiplication of damaged cells that are surrounded by a membrane, therefore do not spread across the body- not cancerous ▾ What is a malignant tumour? growth and multiplication of damaged cells that are notsurrounded by a membrane, therefore spread locally to distant sites- cancerous What are the environmental risk factors of cancer? exposure to radiation chemical carcinogens What are the lifestyle risk factors of cancer? viruses linked with cancer eg HPV chemical carcinogens in cigarette smoke alcohol intake exposure to ultraviolet radiation poor diet Food Tests ▾ How do you test for different carbohydrates (starch and sugars)? Starch Unit 2 - Organisation 9 add iodine solution to the substance no colour change - no starch starch present - turns blue black ▾ Reducing Sugars add benedict's solution to the substance heat for 2 minutes in a water bath at boiling point look for a colour change brick red with reducing sugars (green/yellow) if less sugar is present ▾ How do you test for different proteins and lipids? ▼ protein add biuret's solution to the substance purple if protein is present ▼ lipids add ethanol (sudan iii) to the solution and shake thoroughly add water and look for a colour change cloudy/ milky if lipids present How do you investigate the effect of pH on the enzyme amylase? one drop of iodine solution into each well of a spotting tile. three test tubes. 1= 2cm3 of starch solution. 2= amylase solution. 3= 2cm3 pH 5 buffer solution (controls pH). place test tubes in a water bath at 30c. leave for 10 minutes to allow the correct temp reached. combine solutions into a test tube. mix with stirring rod. return into water bath and start a stopwatch. at 30 secs use stirring rod to drop one drop into spotting tile. should turn blue-black- starch is present. take sample every thirty seconds. Unit 2 - Organisation 10 continue until iodine remains orange. starch is not present anymore. reaction is complete. repeat using different pH buffers. ▼ What are the problems with this experiment? only taking samples every thirty seconds- only have an approximate time for reaction to complete. looking for when solution isn't blue-black. not always obvious. colour change is gradual. - ask several people. Plant Organisation ▼ Structure of a leaf ▼ What is the function of the upper epidermis? transparent- allows light to pass through to cells that are below, protects plant from surroundings ▾ What is the function of the lower epidermis? regulates gas exchange and limits water loss ▾ What is the function of the palisade mesophyll? packed with chloroplasts- contains chlorophyll which absorbs light energy for photosynthesis ▼ What is the function of the spongy mesophyll? air spaces for CO2 to diffuse from stomata to palisade mesophyll. and 02 can diffuse out. What is the function of the waxy cuticle? reduces water evaporation from leaf surface, prevents drying out. ▾ What is the function of the stomata? allows gases to diffuse in and out. controls the amount of water that can pass out of the leaf. ▾ What is the function of the xylem tissue? transports water from roots to stem and leaves. also transports minerals ions ▼ What is the function of the phloem tissue? Unit 2 - Organisation 11 transports glucose from photosynthesis from leaves to rest of plant. used for respiration or stored as starch ▾ What is the function of the meristem tissue? in shoots and roots. contains stem cells What are the properties of a leaf? large surface area for maximum absorption of light. ▼ thin not much space to diffuse, diffusion can happen faster ▼air spaces so gases can diffuse ▼ How is a root hair cell adapted to its function? large surface area- transports more mineral ions and water, to maximise absorption. ▾ How is a xylem cell adapted to its function? no end walls so xylem forms a long, continuous tube contains lignin which strengthens and supports the plant ▾ How is a phloem cell adapted to its function? have sieve tubes which are specialised for transloaction, has companion cells that provide the cell with energy ▾ Describe the process of transpiration. when water is constantly evaporating from the surface of leaves. water evaporates through the stomata, xylem brings water from the roots to replace the lost water. What are the factors that affect transpiration? Why? ▾ temperature increased temp increases the rate. particles have more kinetic energy to move quicker and evaporate faster ▼ light intensity Unit 2 - Organisation 12 increased light intensity increases the rate. guard cells allow stomata to open for photosynthesis and more water is lost ▼ humidity increased humidity decreases the rate. water can't evaporate as fast because there is no concentration gradient. ▼ air flow (wind) increased wind increases the rate. water vapour moves faster so there is more concentration gradient. Describe translocation. the movement of sugars produced by photosynthesis to other parts of the plant for respiration. ▼ What is the role of the stomata? control gas exchange and water loss by opening and closing. ▼ What is the role of the guard cells? control the stomata. therefore minimise water loss by controlling transpiration and gas exchange Unit 2 - Organisation 13