paper 1 Flashcards

Question

what is the acronym of chemical molecules in carbs, lipids and protein

Answer 1

CHO CHO CHON

Answer 2

large molecules made up of smaller basic units. (polysaccharide) starch and glycogen from simple sugars (smallest unit of carbs). complex carbs are made up of 1000s of simple sugars joined together.

Answer 3

large molecules made up of smaller basic units. fatty acids and glycerol. made of 3 fatty acids joined to a glycerol.

Answer 4

large molecules made up of smaller basic units. made of many amino acids joined together. 20 different amino acids can be joined together in any order to create millions of different proteins. the shape of a protein helps it carry out its job

Answer 5

less soluble as simple sugars so have less effect on osmosis

Answer 6

plants store glucose as starch animals and fungi store glucose as glycogen

Answer 7

glucose - benedicts test 1. add benedicts solution to a sample of food 2. place in water bath at 80'c for 5 mins 3. colour changes from blue -> brick red

Answer 8

- thermal insulation - electrical insulation (around nerve cells) - buoyancy - part of cell membranes - energy storage (can be used in respn)

Answer 9

- structural molecules - controlling chemical reactions (enzymes are proteins) - messenger molecules (hormones are proteins) - combatting disease (antibodies are proteins) - transport (haemoglobin and cell membrane proteins)

Answer 10

starch - iodine test 1. add a few drops of orange iodine solution to the sample on a spotting tile 2. color changes from orange to blue/black

Answer 11

protein - buriets test 1. add 2cm water to a food sample and shake 2. add buriets solution 4. blue -> pale purple

Answer 12

lipid - emulsion (ethanol) 1. food sample is placed in test tube 2. add a small volume of absolute ethanol and shake to dissolve any lipid in the alcohol 3. add equal volume of water 4. original colour -> cloudy white

Answer 13

a biological catalyst for metabolic reactions

Answer 14

as temperature increases the enzyme and substates have more kinetic energy which means they move faster so have more successful collisions once temperature has got to a certain point the temperature breaks the bonds that hold together the amino acids (which make the proteins) which changes the shape of the enzyme. this is denaturing once the enzyme has denatured the substrate can no longer fit in the active site (as it has lost its shape) meaning that the reaction will stop

Answer 15

amylase digests starch 1. mix 10cm of 10% starch solution with 5cm of 5% amylase in a boiling tube. 2. heat in a water bath 3. every minute add 1 drop of this solution to 1 drop of iodine in a spotting tile 4. repeat using different temps of water baths when the starch has been fully digested (so none is present) iodine will stay orange

Answer 16

the random movement of particles from a high to a lower concentration so particles of O2 will move out of the lungs into the RBCs as the lower conc of O2 is in the RBCs

Answer 17

the movement of molecules from a low to high concentration using ATP plants use active transport in their root hair cells to absorb mineral ions. organisms have special carrier proteins in the cell membrane. These use ATP to provide the energy to move the substances across the membrane against the concentration gradient.

Answer 18

the movement of water molecules from a high potential to a lower potential across a partially permeable membrane

Answer 19

A larger surface area speeds up the rate of diffusion as there are more opportunities for the molecules to move, which is why surfaces such as alveoli in lungs are so large. Surface area to volume ratio is more significant, as the two counteract (oppose) each other: an efficient exchange surface has a surface area which is very large compared to the distance the molecules must travel. SA:V is increased when structures are small.

Answer 20

Diffusion takes longer if the molecules have to travel further. Therefore cells are small (smaller volume reduces distance).

Answer 21

At higher temperatures, molecules have more kinetic energy and so move faster.

Answer 22

If there is a very large difference in concentration between to areas, molecules will diffuse from the higher to the lower concentration quickly. If the concentration gradient (difference) is small, diffusion will happen more slowly.

Answer 23

1. Make a 5 different concentration of sucrose solutions 2. Measure 5cm3 of each dilution into separate test tubes. 3. Use a cork borer to cut out six potato chips and cut down the sections into identically sized chips. Dry each chip using a paper towel to remove excess water but do not squeeze. 4. Weigh each before the start of the experiment. 5. Place a potato chip in each test tube (one per sucrose concentration) and leave for 20 minutes. 6. Remove each potato chip, dry gently using paper towel, and weigh them in turn. 7. Calculate the percentage change in mass for each sucrose solution.

Answer 24

1. Add sucrose solution to a section of Visking tubing – a selectively permeable substance used to model a cell membrane. 2. Weigh the Visking tubing and its contents. 3. Add the Visking tubing to a beaker of water. 4. Leave for 1 hour. 5. Pat the Visking tubing dry to remove excess water. 6. Reweigh the Visking tubing and its contents.

Answer 25

plants produce glucose from simple inorganic molecules – carbon dioxide and water – using light energy

Answer 26

water + carbon dioxide -> (light energy) oxygen + glucose

Answer 27

6CO2 + 6H2O → C6H12O6 + 6O2

Answer 28

adding more CO2 increases rate of reaction because there are more molecules for the enzymes to collide with. there is a point where it doesn't matter how much CO2 there is as other factors are now limiting

Answer 29

adding more light (increasing brightness) increases rate of reaction because there is more energy for the reaction to occur. there is a point where it doesn't matter how much light there is as other factors are now limiting

Answer 30

increasing temperature increases the rate of reaction because the enzymes and substrates have more kinetic energy up until a point where the temperature increases too much when the enzymes will denature

Answer 31

large SA and thin, to maximize SA of the leaf absorption of sunlight by the photosynthesis cells. it also increases the amount of stomata, so CO2 can diffuse quicker

Answer 32

upper epidermis is transparent which allows light to pass through to the mesophyll

Answer 33

palisade mesophylls are long and thin and tightly packed. they contain large numbers of chloroplasts which maximize sunlight absorption. the palisade mesophylls is the main site of photosynthesis

Answer 34

stomata allow gas to diffuse into the air spaces of the leaf. this allows a short diffusion distance for CO2. also can close to reduce water loss (at night)

Answer 35

xylem transports the water into the leaves. this provides a short distance for the water to diffuse into the photosynthesis cells

Answer 36

for chlorophyll

Answer 37

for amino acids

Answer 38

1. Take a bundle of shoots of a pondweed 2. Submerge them in a beaker of water 3. Use a light a set distance from the plant (measure with a ruler) As oxygen is produced, the bubbles of gas will appear 4. count the number of bubbles over a set time, eg 60 secs Repeat steps for different distances of the light and calculate mean

Answer 39

carbohydrates, proteins, lipid, vitamins, minerals, water, dietary fiber

Answer 40

bread, potatoes, pasta, rice, cereals, fruit

Answer 41

meat, eggs, fish, quinoa, quorn

Answer 42

butter, cooking oils, cream, avocados

Answer 43

fuel for respiration

Answer 44

growth and repair of cells and tissues fuel for respiration

Answer 45

store of energy fuel for respiration insulation for (thermal and electrical)

Answer 46

red meat, liver, spinach

Answer 47

fish liver oil, liver, butter, carrots

Answer 48

milk and dairy products

Answer 49

fresh fruit and vegetables

Answer 50

forms part of hemoglobin which binds to oxygen

Answer 51

dairy products, oily fish

Answer 52

needed to form bones and teeth

Answer 53

making a chemical retina and also protects the surface of the eye

Answer 54

needed for cells and tissues to stick together

Answer 55

needed to absorb calcium and phosphate ions from food

Answer 56

night blindness and damaged corena

Answer 57

rickets caused from weak bones

Answer 58

water is an essential solvent and is used to transport the components of blood and is crucial for temperature regulation by sweating

Answer 59

fiber helps the movement of food through the intestine, preventing constipation and bowel cancer.

Answer 60

Young people need more energy requirements as it is used for growth and muscle development

Answer 61

When a person is more active there is more energy requires as there are more muscle contractions which requires more respiration as it needs more energy

Answer 62

Energy requirements increase as energy is needed to support fetus, and the larger mass the mother needs to carry

Answer 63

taking food in through the mouth and swallowing

Answer 64

breaking down large insoluble molecules into smaller pieces (physical digestion) and smaller soluble molecules

Answer 65

movement of small soluble molecules out of the gut and into the blood by diffusion and active transport

Answer 66

passing out undigested food out through the anus

Answer 67

building larger biomolecules from the small soluble molecules in all cells

Answer 68

mouth + oesophogus

Answer 69

mechanical + chemical digestion + swallowing mechanical - food is broken down into smaller molecules by chewing. this increases SA for enzymes and prevents discomfort when swallowing chemical - saliva is released by the salivary glands. saliva makes food easier to swallow and it contains amylase swallowing - before swallowing food is shaped into a ball and pushed to the back of the mouth by the tongue. this ball is called a bolus. there is a flap called epiglottis which blocks food from entering the trachea

Answer 70

food broken down into smaller soluble molecules by enzymes, bile and acids

Answer 71

food broken down via physical methods such as churning, grinding and chewing

Answer 72

long tube that connects the mouth and the stomach. the bolus is pushed down/through by peristalsis

Answer 73

the gut muscles contracting and relaxing to form a wave to push the bolus down/through the oesophagus. circular muscles contract + longitudinal muscles relax circular muscles relax + longitudinal muscles contract

Answer 74

the gastric glands in the stomach walls secrete pepsin which starts to digest protein contractions of the stomach wall causes the contents to mix maximizing the contact between the enzymes and food the stomach is acidic because HCl is released from the gastric glands as the optimum pH for pepsin is acidic. the low pH would burn through the stomach walls so they are covered in mucus to prevent this. the HCl also kills most bacteria and fungi present in the food.

Answer 75

both digestion and absorption happen in the small intestine made up of duodenum and ileum

Answer 76

the final place of chemical digestion. the pancreas makes several enzymes and secretes them into the duodenum. trypsin, amylase, lipase the duodenum also contains glands which secrete the enzymes they produce into the duodenum maltase, pepsin the duodenum also contains bile

Answer 77

bile is produced by the liver and stored in the gall bladder 1. neutralizes the stomach acid because the duodenum enzymes work best at 7-8 pH 2. emulsifies lipids - breaks down the large droplets into smaller droplets, increasing SA for lipase to digest the fat

Answer 78

absorption begins. the small soluble molecules are absorbed. some by diffusion but some such as glucose by active transport.

Answer 79

large SA - folding of the ileum, villi & microvilli (folds on the surface of cells lining the villi) increase SA short diffusion distance - the villi cells are one cell thick high concentration gradient - provided by capillary network and lacteals removing absorbed molecules

Answer 80

site of all reabsorption of water

Answer 81

the faeces are stored in the rectum and egested from the anus

Answer 82

the removal of waste products by chemical reactions eg urea removed by the kidneys and sweating

Answer 83

produces and secretes amylase, trypsin, lipase into the duodenum secretes an alkaline fluid into the duodenum to neutralize the acidity of the stomach

Answer 84

1. Drop a variegated leaf in boiling water (heated by a bunsen burner) This denatures the enzymes in the leaf and breaks down the cell walls (meaning photosynthesis stops) 2. Turn off the bunsen burner 3. Transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes This removes the chlorophyll so color changes from iodine can be seen more clearly 4. Rinse the leaf in cold water This is done to soften the leaf tissue after being in ethanol 5. Spread the leaf out on a white tile and cover it with iodine solution In a variegated leaf, the green parts of the leaf will turn blue-black as photosynthesis is occurring in these areas of the leaf as they contain chlorophyll. The area of the leaf that was white will remain orange-brown as it does not contain any chlorophyll and so could not photosynthesize, while the green area will turn blue-black these results show chlorophyll is essential to photosynthesis

Answer 85

Destarch a plant by placing it in a dark cupboard for 24 hours This ensures that any starch already present in the leaves will be used up and will not affect the results of the experiment Following de-starching, cover a leaf of the plant with aluminium foil and place the plant in sunlight for a day Remove a covered leaf and a uncovered leaf and test for starch using iodine using the method below 1. Drop a the leaves in boiling water (heated by a bunsen burner) This denatures the enzymes in the leaf and breaks down the cell walls (meaning photosynthesis stops) 2. Turn off the bunsen burner 3. Transfer the leaves into hot ethanol in a boiling tube for 5-10 minutes This removes the chlorophyll so color changes from iodine can be seen more clearly 4. Rinse the leaf in cold water This is done to soften the leaf tissue after being in ethanol 5. Spread the leaves out on a white tile and cover it with iodine solution the uncovered leaf will turn blue/black because it had access to light in order to photosynthesis. the covered leaf will stay orange/brown because it did not have access to light which stops photosynthesis occurring

Answer 86

place one leaf into a conical flask containing soda lime (which absorbs CO2) place another leaf into a conical flask without anything in 1. Drop a the leaves in boiling water (heated by a bunsen burner) This denatures the enzymes in the leaf and breaks down the cell walls (meaning photosynthesis stops) 2. Turn off the bunsen burner 3. Transfer the leaves into hot ethanol in a boiling tube for 5-10 minutes This removes the chlorophyll so color changes from iodine can be seen more clearly 4. Rinse the leaf in cold water This is done to soften the leaf tissue after being in ethanol 5. Spread the leaves out on a white tile and cover it with iodine solution the leaf in the soda lime will remain orange/brown as there was no CO2 which is required to photosynthesis the leaf without soda lime will turn black/blue as there is CO2 so it can photosynthesis

Answer 87

villi and micro villi very long which increase SA and time for diffusion and active transport peristalsis mixes food together and keeps things moving

Answer 88

leaves are the site of photosynthesis which produces glucose. any excess glucose is stored as starch which is why the starch test proves photosynthesis is occurring

Answer 89

starch --(amylase)--> maltose

Answer 90

maltose --(maltase)--> glucose

Answer 91

protein --(pepsin)--> peptides

Answer 92

peptides --(trypsin)--> amino acids

Answer 93

lipid --(lipase)--> glycerol and 3 fatty acids

Answer 94

respiration!!

Answer 95

ATP from respiration

Answer 96

cells constantly break down food molecules to produce ATP this happens continuously because without it the cell would have no energy and die

Answer 97

yes it is part of the process as they photosynthesis to create glucose and then respire the glucose to create energy

Answer 98

aerobic respiration requires O2 whereas anaerobic respiration does not aerobic respiration completely breaks down glucose whereas anaerobic respiration does not aerobic respiration releases a lot of energy whereas anaerobic respiration only produces a little

Answer 99

they are enzymes that break down carbohydrates into simple sugars amylase and maltase

Answer 100

they are enzymes that break down protein into amino acids pepsin, trypsin, proteases

Answer 101

they are enzymes that break down lipids into glycerol and fatty acids lipase

Answer 102

oxgyen + glucose ---> water + carbon dioxide

Answer 103

C6 H12 O6 + 6O2 → 6CO2 + 6H20

Answer 104

aerobic respiration fully oxidizes glucose whereas anaerobic respiration doesn't

Answer 105

glucose ----> lactic acid

Answer 106

glucose ----> ethanol + carbon dioxide

Answer 107

1. place some alive seeds soaked in Milton solution (bleach which kills any bacteria present which would also respire affects results) in a thermos flask 2. place some dead seeds (boiled to denature enzymes) soaked in Milton solution in another thermos flask 3. Make sure the cotton wool is plugging the top of each flask 4. place a thermometer and the flasks 5. place a delivery tube into the flasks and collect the gas produced 6. Record the initial temperature 7. After 4 days, record the final temperature The thermometer in the flask with the germinating seeds should show an increase in temperature the dead seeds should remain at room temperature This is because the alive seeds are respiring and producing heat energy in the process This shows that respiration is an exothermic reaction The dead seeds are not respiring because they are dead, so the temperature remains the same bubble the collected gas though limewater which will turn cloudy is CO2 is present the gas produced from respiration is CO2 so the gas from the alive seeds will turn limewater cloudy the gas from the dead seeds won't as they haven't produced CO2 as they can't respire

Answer 108

coronary arteries supply heart muscle tissue with blood. this blood provides muscle cells with O2 and glucose for aerobic respiration and the blood also removes CO2 produced from aerobic respiration. fatty deposits will build up in your artery walls which narrow the lumen (space for blood) in the arteries. this reduces the amount of blood that can pass through to the arteries and therefore the amount of blood that reaches the heart muscle cells. less blood reaching the working muscle cells means that less O2 (and glucose) meaning the cells respire aerobically less have to respire anaerobically more. anaerobic respiration produces lactic acid which is poisonous. this poisoning of the heart muscle cells will lead to a heart attack

Answer 109

diet - eating lots of saturated fats increases blood cholesterol and increases the risk of fatty deposits smoking - increases blood pressure and increases the risk of fatty deposits forming high blood pressure - damages artery lining and increases the rick of fatty deposits occurring obesity - being obese will increase blood pressure

Answer 110

nicotine tar carbon monoxide + more than 4000 others

Answer 111

narrows blood vessels leading to an increased blood pressure increases heart rate both of these effects can cause blood clots to form in arteries leading to a heart attack or a stroke

Answer 112

CO binds permanently to haemoglobin (forming carboxyhaemoglobin) which reduces the capacity to carry oxygen this puts more stress on the breathing system as breathing frequency and depth need to increase to get the same amount of oxygen into the blood also puts more strain on the circulatory system to pump blood faster around the body and increases the risk of coronary heart disease and strokes

Answer 113

tar is a carcinogen + mutagen carcinogens are chemicals that can alter the DNA and increase the risk of cancer (rapid, uncontrolled cell growth)

Answer 114

in a healthy person the trachea and bronchi are specialized to prevent dirt and bacteria entering the lungs. goblet cells produce mucus which traps dirt and pathogens the cilia of the lining cells waft the mucus up the airways the chemicals from smoking destroy the cilia. at the same time the mucus production will increase because of the smoke (with all of the bad stuff in it) the destroyed cilia cells cannot then waft the mucus up so the mucus builds up resulting in a cough (smokers cough) and increases the risk of infection. bronchitis is a disease resulting in the build up of infected mucus in the bronchi and bronchioles

Answer 115

the smoke breaks down the alveoli's walls and so fuse together forming larger irregular air spaces. this decreases SA and so less oxygen diffuses into the blood

Answer 116

1. get 2 or more students 2. Work out student A's breathing rate at rest 3. Count their number breaths for 15 seconds and multiply by 4 4. Repeat several times to calculate an average 5. Student A should then exercise for a set time (at least 4 minutes) 6. Immediately after exercising, count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute 7. Compare the result to the breathing rate at rest in order to work out the change in breathing rate as a result of exercise 8. Repeat this last step every minute after exercise for 5 minutes Repeat the process for student B Frequency of breathing increases when exercising This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid After exercise has finished, the breathing rate remained elevated for a period of time This is because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalyzing cell reactions It can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’ This can be tested by seeing how long it takes after exercise for the breathing rate to return to normal The longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid and therefore the more unfit the student is

Answer 117

the removal of toxic waste products that have been made by cells

Answer 118

skin, lungs, kidneys

Answer 119

organelle - a component within a cell that carries out a specific task (mitochondria) cell - basic functional and structural units in a living organism tissues - a group of cells of similar structure working together to perform a particular function organs - made from a group of different tissues working together to perform a particular function organ system - made from a group of organs with related functions, working together to perform body functions within the organism

Answer 120

If the pH is too high or too low, the bonds that hold the amino acid chain together to make up the protein can be disrupted/destroyed This will change the shape of the active site, so the substrate can no longer fit into it, reducing the rate of activity Moving too far away from the optimum pH will cause the enzyme to denature and activity will stop

Answer 121

the exchange of gases from an organism to the enviroment or vice versa

Answer 122

ribs - bone structure which protects internal organs intercostel muscles - muscles between ribs which control the movement of the ribs diaphragm - sheet of conective tissue and muscle at the bottom of the thorax to allow inhalation and exhalation trachea - windpipe that connects the mout and nose to the lungs bronchi - large tubes branching off the trachea with one bronchus for each lung bronchioles - bronchi split to form smaller tubes connected to the alveoli alveoli - tiny air sacs where gas exchange takes place pleural membranes - thin layers that cover each lung that reduce friction between the lungs and chest wall

Answer 123

During inhalation The diaphragm contracts and flattens The external set of intercostal muscles contract to pull the ribs up and out: This increases the volume of the chest cavity (thorax) Leading to a decrease in air pressure inside the lungs relative to outside the body Air is drawn in During exhalation The diaphragm relaxes it moves upwards back into its domed shape The external set of intercostal muscles relax so the ribs drop down and in This decreases the volume of the chest cavity (thorax) Leading to an increase in air pressure inside the lungs relative to outside the body Air is forced out The external and internal intercostal muscles work as antagonistic pairs (meaning they work in different directions to each other) When we need to increase the rate of gas exchange (for example during strenuous activity) the internal intercostal muscles will also work to pull the ribs down and in to decrease the volume of the thorax more, forcing air out more forcefully and quickly – this is called forced exhalation There is a greater need to rid the body of increased levels of carbon dioxide produced during strenuous activity

Answer 124

There are many rounded alveolar sacs which give a very large surface area to volume ratio Alveoli (and the capillaries around them) have thin, single layers of cells to minimise diffusion distance A good blood supply ensures constant supply of blood high in carbon dioxide and low in oxygen maintaining the concentration gradient A layer of moisture on the surface of the alveoli helps diffusion as gases dissolve

Answer 125

In order for any organism to function properly, it needs to exchange substances, such as food molecules and waste products, between itself and its environment This exchange of substances occurs across the cell membrane There are three transport processes that living organisms use for exchange: diffusion, osmosis and active transport Unicellular (single-celled) organisms like amoeba have very large surface areas (SA) in comparison to their volumes This means that the distance between the surface of the organism to its centre is very small As a result, unicellular organisms do not need to have specialist exchange surfaces or transport systems; as diffusion, osmosis and active transport through the cell membrane occur at a sufficient rate to meet the organisms needs

Answer 126

The bodies of these organisms contain many layers of cells, meaning that the distance between the surface of the organism to its centre is relatively long and the diffusion distance is too great to rely on diffusion alone Diffusion to all of the cells would take far too long Diffusion cannot occur at a sufficient rate to meet the needs of the organism, so larger organisms usually have transport systems The transport system in animals is the circulatory system which carries the necessary substances around the body in the blood

Answer 127

transporting sucrose and amino acids from the leaves (where they are made in photosynthesis) to other parts of the plant the cells are living cells and are not hollow. The substances move from cell to cell through the pores in the end walls in each cell

Answer 128

transporting water and mineral ions from the roots to other parts of the plant composed of dead cells which form hollow tubes Xylem cells are strengthened by lignin and so are adapted for the transport of water in the transpiration stream

Answer 129

the zylem and phloem in a plant (they are always arranged together in the root, stem and leaves)

Answer 130

red blood cells white blood cells platelets plasma Over half of the volume of the blood is made up of plasma The majority of the other half is made up of red blood cells The remaining fraction consists of white blood cells and platelets

Answer 131

Plasma is a straw coloured liquid which the other components of the blood are suspended within Plasma is important for the transport of many substances including: Carbon dioxide - the waste product of respiration, dissolved in the plasma as hydrogencarbonate ions and transported from respiring cells to the lungs Digested food and mineral ions - dissolved particles absorbed from the small intestine and delivered to requiring cells around the body Urea - the waste substance produced in the breakdown of proteins by the liver. Urea is dissolved in the plasma and transported to the kidneys Hormones - chemical messengers released into the blood from the endocrine organs (glands) and delivered to target tissues/organs of the body Heat energy - created in respiration (an exothermic reaction), heat energy is transferred to cooler parts of the body or to the skin where heat can be lost

Answer 132

Red blood cells are specialised cells which carry oxygen to respiring cells They are full of haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin They have no nucleus which allows more space for haemoglobin to be packed in The shape of a red blood cell is described as being a 'biconcave disc' this shape gives them a large surface area to volume ratio to maximise diffusion of oxygen in and out

Answer 133

Phagocytes engulf and digest pathogens Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it This is a non-specific immune response Phagocytes can be easily recognised under the microscope by their multi-lobed nucleus and their granular cytoplasm

Answer 134

Lymphocytes produce antibodies Antibodies are Y-shaped proteins with a shape that is specific (complementary) to the antigens (sticky outie bits) on the surface of the pathogen This is a specific type of immune response as the antibodies produced will only fit one type of antigen on a pathogen Antibodies attach to the antigens and so stick several pathogens together (more efficient for phagocytes to engulf) This means the pathogenic cells cannot move very easily or reproduce At the same time, chemicals are released that signal to phagocytes that there are cells present that need to be destroyed Lymphocytes also produce antitoxins to neutralise toxins released by pathogens Lymphocytes can easily be recognised under the microscope by their large round nucleus which takes up nearly the whole cell and their clear, non-granular cytoplasm

Answer 135

The heart organ is a double pump Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body (the systemic circuit) The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs (the pulmonary circuit) The right ventricle is pumping blood at lower pressure to the lungs A muscle wall called the septum separates the two sides of the heart Blood is pumped towards the heart in veins and away from the heart in arteries The coronary arteries supply the cardiac muscle tissue of the heart with oxygenated blood As the heart is a muscle it needs a constant supply of oxygen (and glucose) for aerobic respiration to release energy to allow continued muscle contraction Valves are present to prevent blood flowing backwards

Answer 136

Deoxygenated blood coming from the body flows through the vena cava and into the right atrium The atrium contracts and the blood is forced through the tricuspid (atrioventricular) valve into the right ventricle The ventricle contracts and the blood is pushed through the semilunar valve into the pulmonary artery The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs Oxygenated blood returns via the pulmonary vein to the left atrium The atrium contracts and forces the blood through the bicuspid (atrioventricular) valve into the left ventricle The ventricle contracts and the blood is forced through the semilunar valve and out through the aorta Thicker muscle walls of the left ventricle produce a high enough pressure for the blood to travel around the whole body

Answer 137

The heart pumps blood around the body in order to supply oxygen and glucose to respiring cells The blood also removes waste products from the respiring cells During exercise, the cells of the muscles respire more rapidly in order to provide energy for muscle contraction Respiration may be aerobic if exercise is moderate, or anaerobic if exercise is more intense An increase in respiration means an increase in requirement for oxygen and glucose as well as an increase in production of waste products that need to be removed The nervous system responds to this requirement by stimulating the following changes Heart rate increases to deliver oxygen and glucose and remove waste more frequently The volume of blood pumped out of the heart also increases to deliver bigger quantities of oxygen and glucose At the end of a period of exercise, the heart rate may remain high for a period of time as oxygen is required in the muscles to break down the lactic acid from anaerobic respiration This is how the oxygen debt is paid off

Answer 138

binding to specific receptors on heart cells called beta-1 adrenergic receptors. When adrenaline binds to these receptors, it triggers a series of reactions inside the cell causing the heart to beat faster. This effect prepares the body for action, especially in situations where a quick response may be needed allowing the muscles to have a good supply of oxygen for respiration

Answer 139

High cholesterol - Speeds up the build up of fatty plaques in the arteries leading to blockages Smoking - Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure amd Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells diet - eating lots of saturated fats increases blood cholesterol high blood pressure - damages the artery lining and increases the risk of fatty deposits forming

Answer 140

Carry blood at high pressure away from the heart Carry oxygenated blood (except the pulmonary artery) Have thick muscular walls containing elastic fibres Have a narrow lumen Blood flows through at a fast speed Thick muscular walls containing elastic fibres withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through A narrow lumen also helps to maintain high pressure

Answer 141

Carry blood at low pressure towards the heart Carry deoxygenated blood (other than the pulmonary vein) Have thin walls Have a large lumen Contain valves Blood flows through at a slow speed A large lumen reduces resistance to blood flow under low pressure Valves prevent the backflow of blood as it is under low pressure

Answer 142

Carry blood at low pressure within tissues Carry both oxygenated and deoxygenated blood Have walls that are one cell thick Have ‘leaky’ walls Speed of blood flow is slow Capillaries have walls that are one cell thick (short diffusion distance) so substances can easily diffuse in and out of them The ‘leaky’ walls allow blood plasma to leak out and form tissue fluid surrounding cells

Answer 143

heart - vena cava + aorta lungs - pulmonary artery + vein liver - hepatic artery + vein kidney - renal artery + vein

Answer 144

heart -> lungs -> heart -> liver -> (gut -> liver) -> kidneys -> other organs -> heart

Answer 145

Oxygen and carbon dioxide can be both reactants and waste products within a plant The amount or intensity of light affects the waste products within plants During the day, when there is sufficient light: The rate of photosynthesis is higher than the rate of respiration More oxygen is released than used in respiration Less carbon dioxide is released than used in photosynthesis Net effect - oxygen is in excess and a waste product During the night, when there is insufficient light: There is no photosynthesis, only respiration Oxygen is used in respiration and carbon dioxide is produced No photosynthesis means that no carbon dioxide is used Net effect - carbon dioxide is in excess and a waste product Whichever gas is in excess diffuses out of the plant via the leaf organ The gases exit through the stomata

Answer 146

blood goes through the kidneys where urea and other substances are filtered out. these substances are transported through the ureters into the bladder then they are transported via the urethra which carries urine to the outside

Answer 147

colon and rectum

Answer 148

homeostasis

Answer 149

the maintenance of a constant internal environment examples of homeostasis: body water content body temperature

Answer 150

stimulus, receptor and effector

Answer 151

information is sent as electrical impulses down neurones at high speeds allowing rapid responses to stimuli it coordinates activities of sensory receptors, decision making centers and effectors it is used to control functions that need instant response

Answer 152

information is sent as chemical substances (eg hormones) in the blood stream and so can circulate the whole body hormones transmit information from one part of the organism to another and bring about a change (they provide a signal that triggers a response) they alter the activity of one or more specific target organs hormones control functions that do not need instant responses hormones are produced by endocrine glands

Answer 153

nervous system is made up of Nerves (bundles of neurones), brain, spinal cord endocrine system is made up of glands nervous system sends electrical impulses endocrine system sends chemical hormones nervous system is very fast acting endocrine system is slower acting nervous system has a short duration of effect endocrine has a longer duration effect

Answer 154

the brain and spinal cord which are linked to sense organs by nerves

Answer 155

stimulation of receptors in the sense organs which send electrical impulses along nerves into and out of the CNS

Answer 156

neurones don't touch each other Where the dendrites of two neurones meet (to make a connection between the neurones) a junction known as a synapse is formed at the synapse there is a very small gap between the neurones (synaptic gap) the electrical impulses cannot travel directly from one neurone to the other to the next due to the gap Instead, the electrical signal is briefly converted to a chemical signal that can cross the gap The chemical signalling molecules used to transfer the signal between neurones at a synapse are known as neurotransmitters Once these neurotransmitters cross the synaptic cleft and meet the neurone on the opposite side, the signal is converted back into an electrical impulse, which can then pass along the neurone

Answer 157

The electrical impulse travels along the axon of the first neurone (known as the presynaptic neurone) This triggers the end of the presynaptic neurone to release chemicals called neurotransmitters from vesicles These vesicles fuse with the presynaptic membrane, releasing their contents into the gap The neurotransmitters diffuse across the synaptic cleft and bind with receptor molecules on the membrane of the second neurone (known as the postsynaptic membrane) This stimulates the second neurone to generate an electrical impulse (which then travels down the second axon) The neurotransmitters are then destroyed to prevent continued stimulation of the second neurone (otherwise the neurotransmitters would cause repeated impulses to be sent) Synapses ensure that impulses only travel in one direction, avoiding the confusion that would be caused within the nervous system if impulses were able to travel in both directions

Answer 158

the hot object touching the skin (stimulus) temperature receptors detect change in temperature (receptor) sensory neurone sends electrical impulses to the spinal cord (coordinator) sensory neurone connects a synapse to a relay neurone which then connects to a motor neurone impulse travels along motor neuron and out of the spinal cord to the arm muscles (effector) muscle contracts and arm moves off hot object (response)

Answer 159

involuntary response which is automatic and rapid – this helps to minimise damage to the body and aids survival

Answer 160

the pathway of a reflex response (specifically, the pathway taken by electrical impulses as they travel along neurones)

Answer 161

When an object is close up: The ciliary muscles contract (the ring of muscle decreases in diameter) This causes the suspensory ligaments to loosen This stops the suspensory ligaments from pulling on the lens, which allows the lens to become fatter Light is refracted more

Answer 162

sweat glands - are active, they secrete sweat which evaporates from the skin carrying heat away from the body cooling the skin muscles - not shivering hairs - the hair erector muscles in the skin relax , causing the hairs to lie flat which stops them from forming an insulating layer as they can't trap any air which allows air to circulate over the skin and allows heat loss via radiation capillaries near skin - dilate due to the shunt vessel constricting so more blood flows closer to the skin allowing more heat loss via radiation (vasodilation)

Answer 163

The pupil reflex is a reflex action carried out to protect the retina from damage In bright light, the pupil constricts (narrows) in order to prevent too much light from entering the eye and damaging the retina bright light: photoreceptors (receptor) detect brighter light (stimulus) brain (coordinator) radial muscles relax (effector) circular muscles contract (effector) pupils constricts (response) less light enters the eye

Answer 164

sweat glands - no sweat released as less heat is lost if no sweat is evaporated muscles - contract to cause shivering as this increases muscle respiration which then releases heat energy hairs - hair erector muscles contract causing hairs to stand on end which forms an insulating layer over the skins surface trapping air between the hairs preventing heat being lost by radiation capillaries - constrict near the surface so more blood flows along the shunt vessel further away from the skin so less heat loss via radiation

Answer 165

produced in adrenal gland targets lots of organs (heart, iris, liver muscles) effect - fight or flight response so increased breathing rate, heart rate, eye dilation, liver muscles -> causes glycogen to convert to glucose in preparation for respn

Answer 166

produced in pancreas targets the liver effect - causes glucose to convert to glycogen for storage (glycogen is less soluble so does not effect osmosis)

Answer 167

produced in testes targets the testes effect - sperm production (and causes secondary sexual characteristics)

Answer 168

produced corpus luteum in ovaries targets the ovaries effect - maintains the uterus lining and inhibits LH and FSH production

Answer 169

produced in the ovaries targets the ovaries effect - thickens uterus lining and inhibits FSH production and stimulates LH production. Causes secondary sexual characteristics

Answer 170

light + gravity

Answer 171

a response to gravity roots grow downwards into soil away from light to gravity (negative phototropic response - grows away from light) (positive geotropic response - grows to gravity)

Answer 172

a response to light shoots grow up towards light (positively phototropic - grows to light) (negatively geotropic - grows away from gravity)

Answer 173

is produced in the tips of the growing shoots auxin then diffuse down to where cell division occurs (just below the tip) auxin diffuses to the shaded part of the cell division area and causes the cells to elongate and grow faster this means that the shaded side is longer than the sunny side so the shoot bends towards the sun (if there is even light then the auxin diffuses evenly and so all cells elongate evenly so it grows straight up)

Answer 174

The pupil reflex is a reflex action carried out to protect the retina from damage In dim light, the pupil dilates (widens) in order to allow as much light into the eye as possible to improve vision dim light: photoreceptors (receptor) detect dimmer light (stimulus) brain (coordinator) radial muscles contract (effector) circular muscles relax (effector) pupils dilates (response) more light enters the eye

Answer 175

When an object is close: The ciliary muscles contract This causes the suspensory ligaments to slacken The suspensory ligaments dont pull on the lens, causing it to become fatter Light is refracted more

Answer 176

transparent lens that refracts light as it enters the eye

Answer 177

controls how much light enters the pupil

Answer 178

transparent disc that can change shape to focus light onto the retina

Answer 179

contains light receptor cells – rods (detect light intensity) and cones (detect colour)

Answer 180

sensory neuron that carries impulses between the eye and the brain

Answer 181

hole that allows light to enter the eye

Answer 182

a ring of muscle that contracts and relaxes to change the shape of the lens

Answer 183

ligaments that connect the ciliary muscle to the lens

Answer 184

area of the retina with the largest number of photoreceptors so where the light is focused onto

Answer 185

spot where there are no photoreceptor cells

Answer 186

inhibits FSH production (stops another egg being matured) stimulates LH production thickens uterus lining

Answer 187

inhibits FSH and LH (stops further egg being matured and released) maintains the thickness of the uterus lining

Answer 188

levels rise from day 1 to peak just before day 14 The peak in oestrogen occurs just before the egg is released have a small hump after ovulation which finishes before the bleeding starts

Answer 189

stays low from day 1 – 14 and starts to rise once ovulation has occurred and falls just before bleeding

Answer 190

AS only needs 1 parent organim whereas S needs 2 AS uses mitosis whereas S uses meiosis AS produces genetically identical offspring whereas S produces genetically unique offspring AS is usually a quick process whereas S takes much longer

Answer 191

fusion of a male and female gamete to produce a zygote that undergoes cell division and developes into an embryo

Answer 192

petals - small and dull, often green or brown in colour ( as the plant does not need to attract insects) Scent and nectar - absent as theres no need to waste energy producing these as there is no need to attract insects number of pollen grains - large amounts as most do not get to another flower to the more produced the higher chance that successfull pollination happens pollen grains - smooth, small and light so they are easily blown by the wind anthers - outside the flower, swinging loose on long filaments to release pollen easily stigma - outside the flower, feathery to catch drifting pollen grains

Answer 193

petals - large and brightly coloured to attract insects scent and nector - present as it entices insects to visit the flower and push past the stamen to get nectar number of pollon grains - moderate as insects transfer pollon grains efficiently with a high chance of successful pollination pollen grains - larger, sticky, and or spiky to attach to insects to be carried away anthers - inside the flower, stiff and firmly attached to brush against insects stigma - inside flower, sticky so pollen grains stick to it when an insect brushes past

Answer 194

In plants, fertilisation occurs when the pollen grain nucleus fuses with the ovum nucleus in order to reach the ovum nucleus, the pollen grain grows a pollen tube This only happens if the pollen grain has landed on the right kind of stigma (i.e. of the same species as the flower the pollen came from) The nucleus inside the pollen grain moves down the tube as the tube grows down the style towards the ovary (which contains the ovule that, in turn, contains the ovum) Once the nucleus of the pollen grain and the nucleus of the ovum have fused (joined together), that particular ovule has been fertilised and a zygote has been formed The zygote will then start to divide (it is the structure that eventually develops into an embryo plant) After fertilisation, the ovule (that contains the zygote) develops into the seed The wall of the ovule develops into the seed coat, known as the testa The parts of the flower surrounding the ovule (mainly the ovary walls) develop into the fruit, which contains the seeds

Answer 195

set up 5 test tubes Tube A is put in a fridge (no warmth) and the rest are kept on a windowsill.  In tube C, the cotton wool is moistened with boiled water and an oxygen absorber such as sodium pyrogallol is added (no oxygen).  Tube E is wrapped in foil (no light).  The cotton wool in tube B is kept dry (no water).  Tube D has all the conditions present. Check for germination after 2-3 days - you could combine class results and calculate % germination or mean length of seed for each condition.

Answer 196

When the seed germinates, this embryo begins to grow into the young seedling cotyledons surround the embryo The cotyledons contain food reserves that supply the young seedling with food (and, therefore, energy for growth) when the seed starts to germinate The cotyledons fulfil this role until the young plant grows its own leaves and becomes capable of making its own food via photosynthesis Once water has entered the seed, the seed coat (testa) splits This leads to the production of the plumule (the first emerging shoot) and radicle (the first emerging root) The cotyledon provides carbohydrate stores which are broken down to provide glucose for respn. This continues until the plant has sprouted leaves and starts photosynthesising

Answer 197

plants can reproduce asexually by natural and artificial methods natural some plants grow side branches, known as runners, that have small plantlets at their ends Runners are horizontal stems that grow sideways out of the parent plant Once they touch the soil, these plantlets will grow roots and the new plantlets will grow and become independent from the parent plant as a genetically identical plant artificial A simple method to clone plants (mainly used by gardeners) is by taking cuttings This is an artificial method of asexual reproduction The method for taking cuttings is as follows: Gardeners take cuttings from good parent plants (i.e. those that are healthiest and best-looking) A section of the parent plant with a new bud is cut off This cutting can either be placed into water until new roots grow or can sometimes be placed directly into soil Sometimes, the stem of the cutting may first be dipped into 'rooting powder', which contains plant growth regulators (rooting hormones) that encourage new root growth These cuttings are then planted and eventually grow into adult plants that are genetically identical to the original plant Plants cloned by taking cuttings can be produced cheaply and quickly

Answer 198

prostate gland - produces fluid called semen that provide sperm cells with nutrients sperm duct - sperm passes through the sperm duct to be mixed with fluids produced by the glands before being passed into the urethra for ejaculation urethra - tube running down the center of the penis that can carry out urine or semen, a ring of muscle in the urethra stops urine and semen from mixing testis - contained in a bag of skin (scrotum) and produces sperm and testosterone scotum - sac supporting the testes outside the body to ensure sperm are kept at the temperature slightly lower than body temperature penis - passes urine out of the body from the bladder and allows semen to pass into the vagina of a women during sex

Answer 199

oviduct - connects the ovary to the uterus and is lined with ciliated cells to push the released ovum down it. fertilisation occurs here ovary - contains ova which will mature and develop when hormones are released uterus - muscular bag with a soft lining where the fertilised egg will be implanted to develop into a foetus cervix - a ring of muscle at the lower end of the uterus to keep the developing foetus in place during pregnancy vagina - muscular tube that leads to the inside of the womans body, where the males penis will enter during sex and where sperm are deposited

Answer 200

the placenta allows: - Nutrients (i.e. glucose, amino acids and salts) and oxygen to move from the mother to the embryo - Metabolic wastes - carbon dioxide and urea - to move from the embryo to the mother These materials pass from one to the other by diffusion

Answer 201

During pregnancy a membrane called the amnion encloses the developing embryo. The amnion secretes a fluid called amniotic fluid, which protects the developing embryo against jolts and bumps (mechanical shocks), drying out, and temperature fluctuations (due to waters high specific heat capacity)

Answer 202

Secondary sexual characteristics are the changes that occur during puberty as children become adolescents breasts develope body hair grows menstrual cycle begins hips get wider

Answer 203

growth of penis and testes growth of facial and body hair muscles develope voice breaks testes start to produce sperm

Answer 204

an entire section of DNA of an organism

Answer 205

a section of a molecule of DNA that codes for a specific protein

Answer 206

Contains chromosomes on which genes are located

Answer 207

Alleles are variations of the same gene

Answer 208

a dominant allele is always expressed even if only one copy is present

Answer 209

a recessive allele is only expressed if 2 copies are present (so no dominant)

Answer 210

when both alleles of a gene is are the same

Answer 211

when the 2 alleles of the gene are different

Answer 212

the observable characteristics of an organism (hair colour)

Answer 213

the combination of alleles that control each characteristic

Answer 214

Characteristics that are controlled by more than one gene most phenotypic features are a result of polygenic inheritance

Answer 215

by one pair of chromosomes, XX in a female and XY in a male

Answer 216

during growth, repair, cloning and asexual reproduction

Answer 217

diploid = 46 ( diploid is when each cell has 2 copies of each chromosome) haploid = 23

Answer 218

genetic, enviromental or a combo of the 2

Answer 219

a rare, random change in genetic material that can be inherited

Answer 220

2 cells containing identical sets of chromosomes

Answer 221

DNA is duplicated nuclear membrane breaks down chromosomes line up along the centre of the cell chromotids are pulled to each end of the cell the cell divides 2 genetically identical daughter cells are produced

Answer 222

four cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes

Answer 223

DNA is duplicated nuclear membrane breaks down chromosomes line up along the centre of the cell in pairs sections of DNA are swapped between chromosome pairs chromosome pairs seperate, moving to the opposite ends of the cell the cell divides the chromosomes line up along the centre the chromosomes are pulled apart to opposite ends of the cell (like in mitosis) four haploid daughter cells will be produced

Answer 224

Meiosis creates genetic variation between the gametes produced by an individual This means each gamete carries substantially different alleles During fertilization, any male gamete can fuse with any female gamete to form a zygote This random fusion of gametes at fertilization creates genetic variation between zygotes as each will have a unique combination of alleles

Answer 225

natural selection drives evolutionary changes

Answer 226

individuals in a species naturally show variation caused by different genes individuals with characteristics which are advantageous to their environment are more likely to survive (eg a snail with a white shell in a snowy environment) individuals which survive for longer are more likely to reproduce and so more likely to pass on their advantageous alleles over many generations the characteristics become more common as they are passed on more and more

Answer 227

a random mutation can give rise to a new bacterial allele what codes for antibiotic resistance when the bacterial population is exposed to an antibiotic, any individuals without resistance allele die so only ones with the resistance allele survive. The surviving bacteria are more likely to reproduce, passing on their resistance alleles to offspring over several generations the frequency of the resistance allele increases eventually resulting in a antibiotic resistant strain this makes it much harder to kill bacteria with only one anti biotic meaning several need to be used which make bacterial infections more more difficult to control

Answer 228

all individuals of one species at one place at one time. E.g. all magpies in my garden at one time

Answer 229

all populations at one place at one time. E.g. every living organism (animals, plants) in my garden at one time

Answer 230

the places where a specific organism lives (whales - the ocean)

Answer 231

as all the biotic factors and all the abiotic factors that interact within an area at one time (eg a garden pond)

Answer 232

one type of creature (eg hoeosapions)

Answer 233

1. use 2 tape measures to lay out a survey area (eg 10m x 10m) 2. use a random number generator to create a set of coordinates to place the quadrat 3. count the number of chosen species within the quadrat 4. repeat steps 2-3 10x 5. estimate the number of species in entire area with the formula: find mean species per quadrat x total area of survey area repeat entire process in a different area

Answer 234

Quadrats are square frames made of wood or wire They can be a variety of sizes eg. 0.25m2 or 1m2 They are placed on the ground and the organisms within them are recorded

Answer 235

The number of an individual species: the total number of individuals of a single species (eg. buttercups) is recorded Species richness: the total number of different species (but not the number of individuals of each species) is recorded Percentage cover: the approximate percentage of the quadrat area in which an individual species is found is recorded (this method is used when it is difficult to count individuals of the plant species being recorded eg. grass or moss

Answer 236

living factors: disease Competition Predator-prey relationships Interactions with other organisms within the food chain or food web

Answer 237

non-living Light intensity Mineral availability Water availability pH Temperature

Answer 238

measurement of relative abundance of a species in an area for example if there was 2 oak trees, 2 spruce trees and 2 birch trees in one place and 4 oak trees, 1 spruce tree and 1 birch tree in another place the first place would have the good evenness

Answer 239

the number of different species present in a place eg. oak, spruce, birch, jungle = 4

Answer 240

abiotic light is needed to photosynthesis. more light leads to an increase in photosynthesis rate and an increase in plant growth

Answer 241

abiotic affects photosynthesis rate in plants and therefore growth in plants

Answer 242

abiotic plants and animals require water to survive

Answer 243

abiotic less mineral ions will negatively affect plants as they won't be able to osmosis as well changing pH affects plants as they are adapted for certain conditions

Answer 244

abiotic CO2 is required for photosynthesis so CO2 conc affects photosynthesis rate

Answer 245

abiotic affects aquatic animals as they can only survive in water with high O2 conc

Answer 246

biotic more food means organisms have a higher chance of survival and reproducing. this means the population will increase

Answer 247

biotic in balanced ecosystems predators catch enough prey to survive but not enough to wipe out the population. if a new predator is introduced then it could unbalance the ecosystem

Answer 248

biotic if a new pathogen enters an ecosystem the populations living their will no longer have immunity which will put the populations in decline

Answer 249

biotic if 2 species compete for the same resources and one is better equipped to to take advantage of the food, the better equipped one will get the resources meaning the other species will decline

Answer 250

they produce their own energy eg plants photosynthesing

Answer 251

the organisms which eat the producer eg sheep who eat the grass

Answer 252

feed on the secondary consumer

Answer 253

feed on the primary consumer

Answer 254

a different stage of a food chain eg one trophic level might be the primary consumers

Answer 255

organisms (bacteria and fungi) which secrete digestive enzymes to decay dead organic matter to obtain their food, these help recycle nutrients

Answer 256

a simple way to show the feeding interactions between organisms in a community the arrows show the direction that the energy is travelling in

Answer 257

shows a more complex version and accurate version of the feeding interactions between the organisms in a community can also show interdependence (how the change in one population can affect others)

Answer 258

A pyramid of numbers shows how many organisms at each level of a food chain. You cannot change the trophic level of the organisms - they must stay in the same order as in the food chain with producers on the bottom, followed by primary consumers, then secondary consumers, then tertiary consumers this is why the pyramid of number is slightly flawed the pyramids always has the first thing on the food chain at the bottom and then the second and etc

Answer 259

shows the total mass of the organisms in each trophic level (i.e. the mass of an individual x the number of individuals). These are a more accurate way of looking at the relative amounts of organisms these are always more like a normal pyramid This is because the mass of organisms has to decrease as you go up a food chain – if we take our first food chain as an example, it’s impossible to have 10kg of grass-feeding 50kg of voles feeding 100kg of barn owls

Answer 260

Pyramids of energy illustrate the amount of energy contained within the biomass of individuals within different trophic levels The area of each box represents the quantity of energy present These pyramids always have a wide base (due to the large amount of energy contained within the biomass of producers) As you move up the pyramid to higher trophic levels the quantity of energy decreases as not all energy is transferred to the biomass of the next trophic level (roughly only 10 % of the energy is passed on)

Answer 261

Energy flows from the sun to the first trophic level (producers) in the form of light Producers convert light energy into chemical energy This occurs during photosynthesis, when producers convert carbon dioxide and water into glucose and oxygen Producers use this glucose (during respiration) to produce their own biomass When primary consumers consume (eat) producers, they break down the biomass of the producer (digestion) and use the chemical energy to increase or sustain their own biomass When secondary consumers consume (eat) primary consumers, they break down the biomass of the primary consumer (digestion) and use the chemical energy to increase or sustain their own biomass, and so on In this way, as chemical energy is transferred from one trophic level to the next, biomass is also transferred

Answer 262

total mass of living organisms (or recently living) in a given area or ecosystem at a specific time.

Answer 263

ruffly 90% is lost between each trophic level

Answer 264

the total amount of energy available eventually becomes too small to support another trophic level as 90% is lost between each level

Answer 265

Organisms rarely eat every part of the organism they are consuming – some of the biological material of plants and animals may be inedible Not all the ingested material is digested and absorbed, some is egested as faeces Energy is used for movement Energy is used to generate heat Energy is used for metabolic processes Some absorbed material is lost as waste: Carbon dioxide and water are waste products of respiration Water and urea are the waste products in the urine, which is produced when proteins are broken down

Answer 266

Nitrogen as an element is required to make proteins

Answer 267

decaying waste fossilisation of dead plants and animals occurs in specific conditions

Answer 268

carbon in dead and decaying matter is broken down by decomposers carbon stored in fossil fuels is extracted

Answer 269

carbon is released when fossil fuels are burned in factories or cars or planes (combustion) carbon is released during respiration of plants, animals and decomposers plants are eaten by animals which then respire as well

Answer 270

photosynthesis from plants

Answer 271

acid rain can damage plants and animals and also make rivers + lakes acidic damaging aquatic organisms. can also cause leaching of toxic minerals into lakes

Answer 272

Water vapour Carbon dioxide Methane Nitrous oxides CFCs - Chlorofluorocarbons

Answer 273

CO binds irreversibly to hemoglobin in red blood cells forming (carboxyhaemoglobin), preventing them from carrying oxygen to vital organs like the heart and brain

Answer 274

The Sun emits rays that enter the Earth’s atmosphere The heat bounces back from the Earth’s surface Some heat is reflected back out into space Some heat is absorbed by greenhouse gases and is trapped within the Earth’s atmosphere – this is normal However, as the levels of greenhouse gases in the atmosphere rise due to human activities the atmosphere gets thicker and traps more heat causing the earth to heat up more than usual making it the enhanced greenhouse effect

Answer 275

Carbon dioxide is produced during the combustion of fossil fuel Methane is produced by cattle as they digest grass and released by rice paddy fields Deforestation: Clearing forests reduces the Earth’s capacity to absorb CO₂ through photosynthesis

Answer 276

Ocean temperatures increasing, causing melting of polar ice caps / rising sea levels / flooding / coral bleaching Increasing temperatures causing extreme weather like super storms, flooding, droughts Changes in or loss of habitats due to these extreme weather events Decreases in biodiversity as food chains are disrupted and extinction rates increase Increases in migration of species to new places, including increased spread of pests and disease

Answer 277

toxic chemicals can't be broken down and so build up and bioaccumulation and may even build up to toxic levels (biomagnifacation) untreated sewage - sewage provides a good source of food for decomposers which therefore breed and with more they use up oxygen in the water when respiring aerobically. This lack of oxygen in the water causes death of other aquatic organisms as they don't have enough oxygen. The death of these organisms causes more food for decomposers and the process repeats. (eutrphacation)

Answer 278

fertilisers - cause increase in growth in aquatic plants meaning less light reaches the bottom of the water so plants die when provides more food for the decomposers which therefore breed and with more they use up oxygen in the water when respiring aerobically. This lack of oxygen in the water causes death of other aquatic organisms as they don't have enough oxygen. The death of these organisms causes more food for decomposers and the process repeats. (eutrphacation)

Answer 279

Microorganisms can be used by humans to produce foods and other useful substances

Answer 280

contains starch which the yeast can break down into glucose for respiration

Answer 281

to bind the ingredients to active the dry yeast

Answer 282

respires the glucose which creates air pockets in the bread making it rise

Answer 283

to mix all the ingredients together and to increase the SA

Answer 284

prove at 35-40c which is optimum temperature for yeast which allows them to respire quickly allows the yeast to respire and rise and create the air bubbles (CO2) in the bread

Answer 285

the high temperature denatures the enzymes in the bread stopping them from respiring further high temperature also evaporates the ethanol produced from anaerobic respiration

Answer 286

1. Dissolve sugar in previously boiled water. 2. Add yeast and mix to form a suspension, and pour into a boiling tube. 3. Add a layer of vegetable oil. (prevents any oxygen getting to the yeast making the yeast respire anaerobically) 4. Connect a delivery tube to a second boiling tube, this time containing limewater to investigate temperature place the boiling tube with the yeast into a warm water bath (not too hot other the enzymes would denature) to investigate sugar concentration change the amount of sugar added to the yeast the limewater will turn cloudy as the yeast respires as it will produce CO2

Answer 287

glucose --> ethanol + carbon dioxide

Answer 288

lactobacillus bulgaricus

Answer 289

Lactobacillus respires anaerobically producing lactic acid. This lowers the pH, acting as a preservative. The acid also coagulates the milk protein, as the acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour

Answer 290

treated at 90c to remove oxygen, kill any harmful bacteria present, change proteins cooled to 46c which is the optimum temperature for the bacteria bacteria then respires and creates lactic acid which creates the acidic taste in yogurt

Answer 291

growing plants outside does not allow the farmer to control any factors affecting photosynthesis by growing plants in an enclosed environment the farmer can control these factors better

Answer 292

several conditions can be manipulated and controlled artificial heating - enzymes controlling photosynthesis can work faster due to more kinetic energy artificial lighting - plants can photosynthesis for longer increasing cardon dioxide content - plants can photosynthesis quicker regular watering - plants can photosynthesis quicker high moisture content - lots of water water vapour reduces water loss via transpiration allowing the plants to keep stomata open burning fossil fuels or wood raises the temperature and also produces CO2 and water vapour they also protect crops from effects of the weather: - excessive wind - excessive rain - extreme temperatures

Answer 293

plants can photosynthesis quicker and so grow quicker the more CO2 present the more photosynthesis however at some point other factors will become limiting

Answer 294

enzymes controlling photosynthesis can work faster due to more kinetic energy so more photosynthesis and growth if temperature increases too much then the enzymes will denature

Answer 295

fertilisers increase the amounts of key nutrients in the soil for crop plants meaning the plants can grow larger and quicker and are more healthy which increase yields

Answer 296

Nitrogen: Absorbed in the form of nitrates Needed to make amino acids which are the building blocks of proteins Lack of nitrogen causes weak growth and yellowing of the leaves of plants Phosphorous: Absorbed in the form of phosphates Needed to make DNA and cell membranes Lack of phosphorus can cause poor root growth and discoloured leaves Potassium: Absorbed in the form of various compounds of potassium needed in vital processes such as photosynthesis and water + nutrient transport Lack of potassium can cause poor growth of flowers and fruits, as well as brown spots on leaves

Answer 297

improves soil structure greater range of minerals releases minerals over a longer time period less cost

Answer 298

slow acting may contain pests harder to apply then inorganic ones

Answer 299

releases minerals quickly contents known easy to apply

Answer 300

can lead to eutrophication requires regular reapplication

Answer 301

Pests such as insects and other animals can damage crops by eating them Weeds can outcompete crop plants for space, water and soil nutrients Fungi can infect crop plants and spread disease which can affect growth and yield

Answer 302

easily accessible and relatively cheap immediate effect kill entire population of pests

Answer 303

the organisms can develope a resistance to the pesticide non-specific chemicals which kill other organisms the chemicals don't break down so can lead to bioaccumulation need to be repeatedly applied

Answer 304

natural method so no pollution no resistance can be built up can target specific species long lasting does not need to be repeatedly applied

Answer 305

may eat other organisms instead of the pest takes a longer time to be effective cannot kill entire population so some pests will always be present may not adapt to the new enviroment or may move out of the area may become a pest itself

Answer 306

pick 2 best plants with desired characteristics and breed them pick 2 best offspring and breed again this reduces the gene pool and increases the chances of getting desired genes

Answer 307

pick 2 best animals with desired characteristics and breed them pick 2 best offspring and breed again this reduces the gene pool and increases the chances of getting desired genes

Answer 308

disease resistance quicker growing quicker reproduction fur coat colour

Answer 309

aseptic precuations - must clean fermenter with steam to kill other microorganisms and prevent chemical contamination to ensure only desired organisms grow nutrients - nutrients are needed in respiration to ensure the bacteria can reproduce optimum temp + pH - must be kept at optimum temp + pH for the enzymes of the desired microorganisms to allow them to reproduce as quick as possible oxygenation - oxygen is needed for aerobic respiration agitation - stirring paddles ensures that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed

Answer 310

Fermenters are containers used to grow (‘culture’) microorganisms like bacteria and fungi in large amounts These can then be used for brewing beer, making yoghurt and mycoprotein and other processes not involving food, like producing genetically modified bacteria and moulds that produce antibiotics (e.g. penicillin) The advantage of using a fermenter is that conditions can be carefully controlled to produce large quantities of exactly the right type of microorganism

Answer 311

the transfer of genetic material from one species to a different species

Answer 312

insulin hormone gene cut from a human chromosome using restriction enzymes plasmid opened up using restriction enzymes (same restriction enzymes must be used from cutting out the insulin so the sticky ends (short sections of single stranded DNA which want to join to their corresponding base) are matching allowing the plasmid to join together) insulin hormone gene inserted into plasmid by ligase enzyme which joins the sticky ends together if they are corresponding plasmid with insulin gene inserted into a bacteria cell which becomes transgenic organism copies of insulin gene created when bacteria reproduce inside fermenter molecules of insulin hormone purified and packaged

Answer 313

transfer and carry pathogens from one organism to another without being affected

Answer 314

lots of food for respiration oxygen for aerobic respiration stirrer to increase SA to mix food and bacteria and oxygen cooling jacket to keep cool as temp will increase due to respiration and this prevents enzymes (DNA and RNA polymerase) denaturing

Answer 315

crop plants can be GM to contain a gene which produces a poison which kills insects making the plant resistant to insect pests which improves crop yield crop plants can be GM to make them resistant to some herbicides so when herbicide is sprayed on field it only kills weeds allowing crop plants to get more nutrients crops can be GM to improve additional vitamins and improved nutritional value which helps improve deficiency diseases in the world crops can be GM to be drought resistant which improves crop yields

Answer 316

more precise than selective breeding higher crop yield less pesticides/herbicides used so less pollution disease/pest/herbicide resistant

Answer 317

ethical issues unknown long term affects may affect food chains and the environment reduces variation

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