| 6348389558 | In which type of cell would you find a cell wall, chloroplasts and a vacuole? | plant cell | | 0 |
| 6348389559 | What does an animal cell have? | - cytoplasm
- nucleus
- ribosomes
- cell membrane
- mitochondria | | 1 |
| 6511340543 | What does the nucleus do? | contains genetic material that controls the activities of the cell | | 2 |
| 6511341738 | What is the cytoplasm? | gel-like substance where most of the chemical reactions happen. It contains enzymes which control these chemical reactions | | 3 |
| 6511344727 | What is the cell membrane | holds the cell together and controls what goes in and out | | 4 |
| 6511346519 | What happens in the mitochondria? | these are where most of the reactions for respiration take place. Respiration releases energy that the cell needs to work | | 5 |
| 6348389560 | What happens in the ribosomes? | these are where proteins are made in the cell | | 6 |
| 6348389561 | What does a bacterial cell NOT have? | a nucleus- genetic material floats in the cytoplasm | | 7 |
| 6348389562 | What is a yeast cell an example of? | a single cell organism | | 8 |
| 6511349666 | What does a yeast cell have? | - nucleus
- cytoplasm
- cell membrane
- surrounding cell wall | | 9 |
| 6669869056 | How is a leaf cell different from a yeast cell? | leaf cells have chloroplasts and a cellulose cell wall. yeast cells have neither | | 10 |
| 6348389563 | What is the definition of diffusion? | the SPREADING OUT of PARTICLES from an area of HIGH CONCENTRATION to an area of LOW CONCENTRATION
or
the NET MOVEMENT of PARTICLES down a CONCENTRATION GRADIENT | | 11 |
| 6511360969 | What substances can diffuse through cell membranes? | small molecules like oxygen, glucose, amino acids and water | | 12 |
| 6511364021 | What substances can't diffuse through cell membranes? | big molecules like starch and proteins | | 13 |
| 6669659097 | What are some examples of diffusion? | - the diffusion of oxygen into the cells of the body from the bloodstream as the cells are respiring (and using up oxygen)
- the diffusion of carbon dioxide into actively photosynthesising plant cells
- the diffusion of simple sugars and amino acids for the gut through cell membranes | | 14 |
| 6669896801 | When, and in which direction, will diffusion take place in solutions and in gases? | - if two solutions are separated by a cell membrane, particles will move from a region of high concentration to a region of low concentration
- gases will also diffuse through the air from a region of high concentration to a region of low concentration | | 15 |
| 6669928443 | How is a leaf cell adapted to carry out photosynthesis? | - the leaf has mesophyll tissue
- the mesophyll cells contain chloroplasts which can photosynthesise | | 16 |
| 6511368664 | How are palisade cells adapted for photosynthesis? | - packed will chloroplasts for photosynthesis
- tall shape means a lot of surface area exposed down the side for absorbing carbon dioxide from the air in the leaf
- they are grouped together at the top of the leaf so that they can absorb more sunlight | | 17 |
| 6511376067 | How are red blood cells adapted to carry oxygen? | - concave shape gives a big surface area for absorbing oxygen. it also helps them pass smoothly through capillaries to reach body cells
- packed with haemoglobin which absorbs oxygen
- they have no nucleus to leave even more room for haemoglobin | | 18 |
| 6511384286 | How are sperm cells adapted for swimming to the egg? | - streamlined head and flagella to help it swim to the egg
- there are a lot of mitochondria in the cell to provide the energy needed
- carry enzymes in their heads to digest through the egg cell membrane | | 19 |
| 6669712920 | If a cell has many mitochondria... | it must need a lot of energy, e.g. muscle cell, sperm cell | | 20 |
| 6669719087 | If a cell has many ribosomes... | it is making a lot of protein, e.g. gland cells which produce enzymes | | 21 |
| 6669727848 | If a cell has flagella.. | it must be able to move, e.g. sperm cells | | 22 |
| 6348389564 | What is the process by which cells become specialised? | differentiation | | 23 |
| 6669840803 | What is meant by the term differentiation of cells? | - when cells start to divide they are very similar
- as the tissues develop the cells change to form particular function | | 24 |
| 6348389565 | What is a tissue? | a group of similar cells that work together to carry out a particular function | | 25 |
| 6518534299 | What sort of tissue can you find in mammals? | - Epithelial tissue: covers some parts of the body, e.g. the inside and outside of the gut
- Muscular tissue: contracts to move whatever its attached to
- Glandular tissue: makes and secretes chemicals like hormones and enzymes | | 26 |
| 6518543906 | What is an organ? | a group of different tissues that work together to perform a certain function, e.g. stomach | | 27 |
| 6518549648 | What tissues are the stomach made up of and what are their purposes? | - Epithelial tissue: covers the inside and outside of the stomach
- Muscular tissue: contracts the stomach wall to churn up the food
- Glandular tissue: produces digestive juices to digest food | | 28 |
| 6518558188 | What is an organ system? | a group of organs working together to perform a particular function, e.g. the digestive system breaks down food | | 29 |
| 6518562942 | What organs does the digestive system include? | - glands
- the stomach
- the liver
- the small intestine
-the large intestine | | 30 |
| 6348389566 | What two glands produce digestive juices? | pancreas and salivary glands | | 31 |
| 6518581160 | what does both the stomach and small intestine do? | digest food | | 32 |
| 6518578573 | What does the liver do? | produces bile | | 33 |
| 6348389567 | What does the small intestine do? | absorbs soluble food molecules | | 34 |
| 6348389568 | What does the large intestine do? | absorbs water from undigested food leaving faeces | | 35 |
| 6669953046 | Describe in detail what happens to food as it passes through the digestive system? | - the insoluble food is mixed with digestive juices produces by glands
- it is digested in the stomach and small intestine
- bile produced by the liver is added to the food to help digestion
- absorption of the soluble food takes place in the small intestine
- water is absorbed by the large intestine | | 36 |
| 6518587109 | What are the plant organs? | stems, leaves and roots | | 37 |
| 6518590310 | What are the tissues found in plants? | -Mesophyll tissue- where most of the photosynthesis occurs in the plant
- Xylem and Phloem- transport things like water, mineral ions and sucrose around the plant
- Epidermal tissue- this covers the whole plant | | 38 |
| 6518606271 | What is photosynthesis? | the process that produces 'food' in plants and algae. the 'food' it produces is glucose | | 39 |
| 6670145589 | Name the solution used to test a leaf for starch? | iodine solution | | 40 |
| 6670151542 | What is the result of iodine test for start | - the regions containing starch will turn blue-black
- the regions without starch will turn yellow-brown | | 41 |
| 6670183036 | What does the test for starch show us? | if photosynethsis has occurred | | 42 |
| 6518610861 | Where does photosynthesis happen? | inside the chloroplasts | | 43 |
| 6518620028 | What is chlorophyll? | a green substance found in chloroplasts which absorbs sunlight and uses it to convert carbon dioxide (from the air) and water (from the soil) into glucose. oxygen is a by-product | | 44 |
| 6348389572 | What are the top, middle and bottom layers of a leaf? | top - upper epidermis
middle - spongy mesophyll
bottom - lower epidermis | | 45 |
| 6348389573 | Where is chlorophyll found? | in the chloroplasts | | 46 |
| 6348389574 | How is water transported in the plant? | through the xylem | | 47 |
| 6348389575 | How are sugars transported in plants? | through the phloem | | 48 |
| 6348389577 | What is the equation for photosynthesis? | Carbon dioxide + Water ---(sunlight)---> Glucose + Oxygen | | 49 |
| 6348389580 | What is a limiting factor? | something that is stopping photosynthesis happening faster | | 50 |
| 6348389581 | What are the three limiting factors in photosynthesis? | - light
- temperature
- carbon dioxide | | 51 |
| 6348389582 | Why do limiting factor graphs 'level off' after a certain point? | because the rate of photosynthesis can only be raised up to a certain point, until something else becomes a limiting factor | | 52 |
| 6348389583 | At what temperature do the enzymes for photosynthesis become denatured? | 45 degrees Celsius | | 53 |
| 6348389584 | How is light controlled in a green house? | light is always needed for photosynthesis so artificial light can be provided once the sun goes down to give plants more photosynthesis time | | 54 |
| 6348389585 | How is temperature controlled in a green house? | - greenhouses help trap the suns heat and make sure that the temperature doesn't become limiting.
- heater may be used during the winter to keep the temperature at the ideal level
- shades and ventilation if it's too hot to cool things down | | 55 |
| 6348389586 | How are carbon dioxide levels controlled in a green house? | increase carbon dioxide levels by using a paraffin heater. as the paraffin burns it makes CO2 as a by-product | | 56 |
| 6518677975 | How are plants protected from pests and diseases? | - kept enclosed in a greenhouse
- add fertilizers to the soil as well, to provide minerals for healthy growth | | 57 |
| 6670207205 | What is the independent variable? | the one being tested, e.g. concentration of carbon dioxide (x axis) | | 58 |
| 6670216474 | What is the dependent variable? | the one you measure, e.g. usually the volume of oxygen produced (y axis) | | 59 |
| 6348389587 | What are the four ways in which plants use glucose? | - for respiration
- making cell walls
- making proteins
- storage as lipids in seeds
- storage as starch | | 60 |
| 6670202565 | Name three substances used for storage in plants? | starch, fats and oil | | 61 |
| 6348389588 | How is glucose made from photosynthesis used to make cell walls? | glucose converted to cellulose for making strong cell walls, especially in a rapidly growing plant | | 62 |
| 6348389589 | How is glucose made from photosynthesis used to make proteins? | glucose is combined with nitrate ions (absorbed from soil) to make amino acids, which are then made into proteins | | 63 |
| 6348389590 | How is glucose made from photosynthesis stored in seeds? | glucose is turned into lipids (fats & oils) for storing in seeds, e.g. sunflower seeds contain a lot of oil (we get cooking oil and margarine) | | 64 |
| 6348389591 | Where is glucose made from photosynthesis stored as starch? | Glucose is turned into starch and stored in the roots, stems and leaves for when photosynthesis isn't happening e.g. winter. | | 65 |
| 6348389592 | Why is starch good for storing in plants? | starch is insoluble which makes it much better for storing than glucose - a cell with lots of glucose in would draw in loads of water and swell up | | 66 |
| 6518719118 | What is a habitat? | the place where an organism lives, e.g. a playing field | | 67 |
| 6518724663 | What is the distribution of an organism? | where an organism is found, e.g. in a part of the playing field | | 68 |
| 6348389593 | What five things affect the distribution of organisms? | - temperature
- amount of light
- availability of:
- water
- nutrients
- oxygen & carbon dioxide | | 69 |
| 6348389594 | What are two ways that you can study the distribution of small organisms? | - by using quadrats we can measure how common an organism is in two sample areas and compare them
- by placing quadrats along a transect we can study how the distribution changes across and area | | 70 |
| 6518765976 | What is a quadrat? | a square frame enclosing a known area | | 71 |
| 6518777201 | How to use a quadrat. | 1. place a quadrat on the ground at a random point within the first sample area
2. count all the organisms within the quadrat
3. repeat steps 1 and 2 as many times as you can
4. work out the mean number of organisms per quadrat with in the first sample area (TOTAL number of organisms ÷ NUMBER of quadrats)
5. repeat steps 1-4 in the second area
6. compare two means | | 72 |
| 6518816128 | How do you work out the population size? | mean number of organisms per m² x total area (in m²) of the habitat | | 73 |
| 6518835225 | What is a transect? | lines used to help find out how organisms (like plants) are distributed across an area, e.g. if an organisms becomes more or less common as you move from a hedge towards the middle of a field | | 74 |
| 6518846663 | How to use a transect with a tape measure. | 1. mark out a line in the area you want to study using a tape measure
2. then collect data along the line
3. you can do this by just counting all the organisms you're interested in that touch the line | | 75 |
| 6670035968 | What is the range? | the difference between the minimum and maximum reading | | 76 |
| 6518860613 | How to use a transect with a quadrat. | quadrats can be placed next to each other along the line or at intervals, e.g. every 2m | | 77 |
| 6670040086 | What is the mean? | the sum of the readings divided by the number of readings taken | | 78 |
| 6670046804 | What is the median? | the middle value of the readings when written in order | | 79 |
| 6670052730 | What is the mode? | the reading that appears most frequently | | 80 |
| 6518870540 | How can you make your results more reliable (valid, reproducible, repeatable)? | take a large sample size e.g. use as many quadrats and transects as possible in your sample area. bigger samples are more representative of the whole population so its more reliable | | 81 |
| 6518881121 | How can you make your results valid | - control variables, e.g. do it at the same time of day
- use random samples e.g. randomly put down or mark out your quadrat or transect. if all your samples are in one spot, and everywhere else is different, the results wont be valid | | 82 |
| 6670086438 | How can you make your results repeatable? | - if the original experimenter repeats the investigation using the same method and equipment and obtains the same results
- however sometimes the experimenter may be making the same mistake every time and get repeatable results
- so it may also be necessary to check the results to ensure that they are reproducible | | 83 |
| 6670119580 | What is meant by 'reproducible'? | if the investigation is repeated by another person or by using different equipment or techniques, and the same results are obtained | | 84 |
| 6348389595 | What do enzymes act as? | biological catalysts- they speed-up reactions | | 85 |
| 6348389596 | What is a catalyst? | a substance that INCREASES the speed of a reaction without being CHANGED or USED UP in the reaction | | 86 |
| 6348389597 | What are enzymes made up of? | proteins, which are made up of chains of amino acids | | 87 |
| 6528570341 | Why are enzymes picky? | - the shape of an enzyme is vital for its function
- this shape has an area where other molecules can fit (the active site)
- the substrate in a reaction can be held in the active site and either be connected to another molecule or broken down | | 88 |
| 6670294995 | Enzymes can... | - build large molecules from many smaller ones, e.g. building starch from glucose molecules
- change one molecule into another one, e.g. convert one type of sugar into another one
- break down large molecules into smaller ones, e.g. all the digestive enzymes to this | | 89 |
| 6528585314 | What happens when the temperature is too high? | - at first the higher temperature increases the rate of reaction
- but if it gets too hot, the bonds holding the enzyme together will break
- this destroys the enzymes special shape, and so it wont work anymore | | 90 |
| 6348389598 | What temperature do enzymes in the human body usually work best at? | 37 degrees Celsius | | 91 |
| 6348389599 | What happens to enzymes if the pH is too high or too low? | It interferes with the bonds holding the enzyme together - changing its's shape and denaturing it | | 92 |
| 6528593388 | Whats the most common optimum pH | its often pH 7- neutral but not always | | 93 |
| 6528590749 | Whats the optimum pH of enzymes in the stomach? | pH 2- well-suited to acidic conditions | | 94 |
| 6348389601 | What do digestive enzymes do? | break down big molecules into smaller ones | | 95 |
| 6348389602 | What are examples of big molecules (in digestion)? | starch, proteins and fats
- they're too big to pass through the walls of the digestive system | | 96 |
| 6348389603 | What are examples of smaller molecules (in digestion)? | sugars, amino acids, glycerol and fatty acids
- they can pass easily through the walls of the digestive system | | 97 |
| 6348389604 | What does amylase do? | converts starch to sugars in the mouth and small intestine | | 98 |
| 6348389606 | What does protease do? | converts proteins to amino acids in the stomach and small intestine | | 99 |
| 6348389605 | Where is amylase made? | - salivary glands
- pancreas
- small intestine | | 100 |
| 6348389607 | Where is protease made? | - stomach
- pancreas
- small intestine | | 101 |
| 6348389608 | What is protease called in the stomach? | pepsin | | 102 |
| 6348389609 | What does lipase do? | converts lipids (fats and oils) into glycerol and fatty acids | | 103 |
| 6348389610 | Where is lipase made? | - pancreas
- small intestine | | 104 |
| 6348389611 | What does bile do? | bile is alkaline and neutralises hydrocholoric acid to make conditions alkaline
Emulsifies fats | | 105 |
| 6348389612 | Where is bile produced, stored and then released? | produced - liver
stored - gall bladder
seleased - small intestine | | 106 |
| 6348389613 | Why is it important that bile neutralises the hydrochloric acid? | Because the enzymes in the small intestine work best in alkaline conditions | | 107 |
| 6348389614 | "Bile emulsifies fats" what does this mean? | - it breaks down fats into tiny droplets
- this gives a much bigger surface area of fat for the enzyme lipase to work on
- making digestion faster | | 108 |
| 6348389615 | What enzyme is produced in the stomach? | protease enzyme, pepsin | | 109 |
| 6348389616 | Which enzymes are produced in the pancreas? | - amylase
- protease
- lipase | | 110 |
| 6348389617 | Which enzymes are produced in the small intestine? | - amylase
- protease
- lipase | | 111 |
| 6348389618 | What is respiration? | The process of releasing energy from the breakdown of glucose - it goes on in every cell of the body | | 112 |
| 6348389619 | What is aerobic respiration? | respiration using oxygen - most efficient way to release energy from glucose | | 113 |
| 6348389620 | Where does most of the reactions in aerobic respiration happen? | inside the mitochondria and are controlled by enzymes | | 114 |
| 6348389621 | What is the word equation for aerobic respiration? | glucose + oxygen -----> carbon dioxide + water + energy | | 115 |
| 6348389622 | What four things is the energy released from respiration used for? | - to building larger molecules from smaller ones (e.g. proteins from amino acids)
- in animals, allowing muscles to contract (allows movement)
- in mammals and birds the energy is used to maintain body temperature
- Plants: build sugars, nitrates, other nutrients into amino acids, which are then built up into proteins | | 116 |
| 6348389623 | Why does blood flow faster when you exercise? | - to increase the rate at which oxygen and glucose reach mucle cells for aerobic respiration
you also need to remove extra waste carbon dioxide produced more quickly
therefore, blood has to flow at a faster rate | | 117 |
| 6348389624 | What two things increase when you exercise? | -increases your breathing rate and depth of each breath. this allows a greater uptake of oxygen and release of carbon dioxide at the lungs
- heart rate increases and the blood vessels supplying the muscles dilate. this allows more blood containing oxygen and glucose to reach the muscles | | 118 |
| 6348389625 | How do muscles store glucose? | as glycogen | | 119 |
| 6348389626 | Where is glycogen mainly stored? | liver, but each muscle has its own store | | 120 |
| 6348389627 | How is glycogen converted back to glucose? | - through releasing the hormone glucagon, which converts the glycogen back into glucose
- either when blood levels are too low, or when it's needed to provide more energy (during exercize | | 121 |
| 6679489430 | What do you need when you exercise? | - you will need more energy
- therefore, need more oxygen and glucose
- and you need to remove more carbon dioxide | | 122 |
| 6348389628 | What is anaerobic respiration? | respiration without oxygen | | 123 |
| 6348389631 | What is the word equation for anaerobic respiration? | Glucose -----> Energy + Lactic Acid | | 124 |
| 6348389629 | What produces lactic acid? | anaerobic respiration and the incomplete breakdown of glucose | | 125 |
| 6679500856 | How can lactic acid be removed? | - blood flowing through the muscles
- take in a lot of oxygen
- the extra oxygen needed is known as the oxygen debt
- eventually the oxygen oxidizes lactic acid into carbon dioxide and water | | 126 |
| 6348389630 | What causes muscle fatigue? | - when muscles work hard for a long time they may have too little oxygen and get tired and so don't contract efficiently
- one cause of muscle fatigue is the build up of lactic acid | | 127 |
| 6348389632 | What is the oxygen debt? | the amount of oxygen you would need to oxidise the lactic acid into carbon dioxide and water | | 128 |
| 6348389633 | How do you remove lactic acid from your muscles? | - through breathing harder, you get more oxygen into your blood.
- blood flows through the muscles to remove the lactic acid by oxidising it to harmless carbon dioxide and water | | 129 |
| 6348389634 | How are enzymes used in the home? | as biological detergents | | 130 |
| 6348389635 | What are biological detergents made of? | protein and fat digesting enzymes: protease & lipase | | 131 |
| 6348389636 | Why are biological detergents good? | - because the enzymes break down animal and plant matter, they're ideal for removing stains like food or blood
- because they work more effectively at lower temperatures (e.g. 30°C) making it more eco friendly | | 132 |
| 6348389637 | How are enzymes used in baby foods? | the proteins in some baby foods are 'pre-digested' using protein-digesting enzymes (proteases) , making it easier for the baby to digest | | 133 |
| 6348389638 | What is a use for carbohydrase? | carbohydrate-digesting enzymes (carbohydrases) can be used to turn starch syrup (yuk) into sugar syrup (yum) | | 134 |
| 6348389639 | What is isomerase used for, and why is this useful? | - glucose syrup can be turned into fructose syrup. - fructose is sweeter and so you can use less of it which is good for slimming foods and drinks as it is less fattening | | 135 |
| 6348389640 | What are 5 benefits of using enzymes in industry? | - they're specific, so they only catalyse the reaction you want them to
- using lower temperatures and pressures means a lower cost as it saves energy
- they work for a long time
- biodegradable - less environmental pollution | | 136 |
| 6348389641 | What are 4 disadvantages of using enzymes in industry? | - some people can develop allergies to the enzyme (e.g. in biological washing powders)
- denatured very easily, conditions need to be very tightly controlled
- expensive to produce
- contamination of the enzyme with other substances can affect the reaction | | 137 |
| 6348389642 | What are chromosomes? | Long molecules of DNA with a double helix structure | | 138 |
| 6348389643 | What is a gene? | a short section of DNA- each gene codes for a particular combination of amino acids which make a specific protein | | 139 |
| 6679562387 | What molecule are genes made of? | DNA | | 140 |
| 6348389644 | How do cells make proteins? | stringing amino acids together in a particular order | | 141 |
| 6528778726 | How many amino acids are used? | 20, but they make up thousands of different proteins | | 142 |
| 6528744621 | What is DNA finger printing? | a way of cutting up a persons DNA into small sections and separating them | | 143 |
| 6528752196 | What is DNA fingerprinting used in? | - forensic science
- paternity testing | | 144 |
| 6528765652 | What is forensic science? | DNA taken from a crime scene is compared with a DNA sample taken from a suspect. | | 145 |
| 6528770073 | What is paternity testing? | to see if a man is the father of a particular child | | 146 |
| 6348389645 | What does mitosis create new cells for? | grow or to replace cells that have been damaged | | 147 |
| 6348389646 | How many chromosomes does a human body cell have? | 46 chromosomes, 23 pairs | | 148 |
| 6348389647 | Explain the process of mitosis. | - the cell gets the signal to divide and duplicates its DNA so that there is one copy for each new cell
- chromosomes line up at the centre of the cell
- cell fibres pull them apart (the two arms of each chromosome go to opposite ends of the cell)
- Membranes form around each set of chromosomes, these become nuclei of two new cells
- cytoplasm divides
- Two IDENTICAL new cells |  | 149 |
| 6538233660 | What is mitosis an example of? | - asexual reproduction
- the offspring have exactly the same genes as the parent, so there's no variation | | 150 |
| 6348389648 | How many chromosomes do gametes have? | 23 individual chromosomes | | 151 |
| 6348389649 | Explain the process of meiosis | - before the cell divides it duplicates DNA
- in the first division of meiosis the chromosome pairs line up in the centre of the cell
- the pairs are pulled apart, so each new cell only has one copy of each chromosome. some of the fathers chromosomes and some of the mothers chromosomes go into each cell
- in the second division the chromosomes line up again in the centre of the cell, the arms of the chromosomes are pulled apart
- 4 gametes each with a single set of chromosomes | | 152 |
| 6538259158 | Whats the difference between meiosis and mitosis? | - meiosis makes half the original amount of chromosomes and only happens in reproductive organs and creates sex cells
- after two gametes join at fertilization, the cell grows repeatedly by mitosis. mitosis creates 2 identical cells | | 153 |
| 6538269360 | What are stem cells? | undifferentiated cells that can differentiate into any type of cell depending on what instructions they're given | | 154 |
| 6348389650 | Where can stem cells be found? | - embryos
- adult bone marrow | | 155 |
| 6538275518 | How are stem cells able to cure disease? | - blood disease, treated with bone marrow transplant
bone marrow contains stem cells that can turn into new blood cells to replace faulty old ones | | 156 |
| 6538280805 | How can embryonic stem cells be used in sick people? | - to replace faulty cells
e.g. you could make beating heart muscle cells for people with heart disease
e.g. you could make insulin producing cells for people with diabetes
e.g. you could make nerve cells for people paralysed by spinal injuries | | 157 |
| 6348389651 | What can an undifferentiated embryonic stem cell differentiate into? | - nerve cells, helps paralysis
- muscle cells
- whole organs | | 158 |
| 6538286221 | Why are some people against stem cell research? | - human embryos shouldn't be used for experiments since each one is potential human life
- the embryos have the potential to be babies and are destroyed
- the embryo can't give permission
- research is expensive | | 159 |
| 6679552919 | What is stem cell research? | - embryonic stem cells care taken from spare embryos from IVF or created from adult cells or may be taken from the umbilical cord of new born babies
- embryonic stem cells could be used to grow new tissue and organs for transplant | | 160 |
| 6679532505 | What is sex determined by? | X and Y chromosomes | | 161 |
| 6348389652 | Is XY male or female? | male | | 162 |
| 6348389653 | Is XX male or female? | female | | 163 |
| 6538297996 | Why do we use genetic diagrams? | to find the probability of inheritance of a certain characteristic | | 164 |
| 6538300155 | Who is Gregor Mendel? | - Austrian monk
- trained in mathematics and natural history at university of vienna
- on his garden plot in the monastery, Mendel noted how characteristics in plants were passed on from one generation to the next | | 165 |
| 6348389654 | What did Mendel do genetic experiments with? | Pea plants, looking at heights | | 166 |
| 6348389655 | What were Mendel's 3 conclusions? | - Characteristics in plants determined by 'hereditary units' (genes)
- Hereditary units passed on from both parents, one unit from each parent
- Hereditary units can be dominant or recessive- if the individual has both the dominant and recessive unit for a characteristic the dominant characteristic will be expressed | | 167 |
| 6538309603 | Why was the significance of his work only realised until after his death? | no one knew anything about genes or DNA | | 168 |
| 6538311443 | What are alleles? | a versions of a particular gene | | 169 |
| 6538313393 | What does homozygous mean? | when an organism has two alleles of the same gene, e.g. BB or bb | | 170 |
| 6538316382 | What does heterozygous mean? | when an organism has two alleles of different genes, e.g. Bb | | 171 |
| 6538321408 | If the two alleles are different which characteristic is present? | - the allele for the characteristic that is shown is called the dominant allele (use capital letter for dominant allele, e.g. C)
- The other one is called recessive (you show these will lower case letters, e.g. c) | | 172 |
| 6538324951 | How can an organism display recessive characteristics? | - if both alleles are recessive (e.g. cc)
- dominant over rules recessive if the organism is heterozygous | | 173 |
| 6538330718 | What is meant by genotype? | the genetic makeup- which alleles does the individual inherit? DD, Dd, or dd | | 174 |
| 6538331785 | What is meant by phenotype? | physical appearance of the characteristic, e.g. dimples or no dimples | | 175 |
| 6348389656 | What is a genetic disorder caused by a recessive allele, and what is it? | cystic fibrosis - genetic disorder of cell membranes, resulting in the body producing alot of thick, sticky mucus in air passage and pancreas | | 176 |
| 6538336228 | Why will people not get cystic fibrosis if they only have one copy of the allele? | because its recessive, however if they have one copy they're known as cariiers | | 177 |
| 6538338509 | How can a child get cystic fibrosis? | if their parents are carriers or sufferers | | 178 |
| 6348389657 | What is a genetic disorder caused by a dominant allele, and what is it? | polydactyly- baby born with extra fingers or toes (not life threatening) | | 179 |
| 6538346183 | How can a child get polydactyly? | - can be inherited if just one parent carries the defective gene
- the parent that has the defective allele will be a sufferer too since the allele is dominant | | 180 |
| 6538350232 | What is embryonic-screening? | - when cells are removed from each embryo to analyse its genes before implanted in the mother during IVF
- many genetic disorders can be detected this way
- embryos with good alleles would be implanted back into the mother- the ones with bad alleles are destroyed | | 181 |
| 6538356929 | Arguments against embryonic screening? | - rejected embryos are destroyed when they could have developed into humans
- it implies that genetic disorders are undesirable which may increase prejudice
- screening is expensive | | 182 |
| 6538361207 | Arguments for embryonic screening? | - it helps to stop people from suffering
- during IVF, most of the embryos are destroyed anyway, screening just allows the selected one to be healthy
- treating disorders costs the government (and tax payers) a lot of money | | 183 |
| 6538367944 | What are fossils? | - the remains of organisms from many years ago, which are found in rocks
- they provide evidence that organisms lived ages ago | | 184 |
| 6348389658 | What are the 3 ways in which fossils are formed? | - from preservation in places where no decay happens
- from gradual replacement by minerals
- from casts and impressions | | 185 |
| 6538374706 | How are fossils formed from presevation in places where no decay happens? | - in amber and tar pits there in no oxygen or moisture so decay microbes can't survive
- in glaciers its too cold for the decay microbes to work
- peat bog are to acidic for decay microbes | | 186 |
| 6538378805 | How are fossils formed from gradual replacement by minerals? | - thinks like teeth, shells and bones, which don't decay easily, can last a long time when buried
- these eventually get replaced by minerals as they decay, forming a rock-like substance shaped like the original hard part
- the surrounding sediments also turn into rock, but the fossils stay distinct inside the rock and eventually someone digs it up | | 187 |
| 6547401617 | How are fossils formed from casts and impressions? | - sometimes, fossils are formed when an organism is buried in a soft material like clay, the clay later hardens around it and the organism decays, leaving a cast of itself, e.g. animal burrows or plant roots
- thinks like footprints can be pressed into these materials when soft, leaving an impression when it hardens | | 188 |
| 6547415245 | Why is the fossil record incomplete? | - fossils that formed millions of years ago may have been destroyed by geological activity
- many early organisms were soft bodied, and soft tissue tends to decay away completely. so no traces were left behind
- we haven't found all the fossils yet | | 189 |
| 6679571372 | What does the fossil record show us? | how much, or how little organisms have changed over time | | 190 |
| 6679576516 | What is extinction? | means that species which once existed has completely died out | | 191 |
| 6348389659 | What are 6 causes of extinction? | - environment changes over geological time
- new predator kills them all (e.g. humans hunting them)
- new disease kills them all
- new competitor may evolve or be introduced to an area (competition for food)
- single catastrophic event kills them all (e.g. asteroid or volcanic eruption)
- new species develops (speciation) | | 192 |
| 6679582087 | Changes in the environment that may cause extinction? | - climate change- a species well adapted to a hot climate may become extinct in an Ice Age. it could be that there is insufficient food or it is too cold to breed
- climate change may make it too cold or hot, or wet or dry, for a species and reduce its food supply | | 193 |
| 6679588509 | What are the theories for dinosaur extinction? | - the collision od a giant asteroid caused huge fires, earthquakes, landslide and tsunamis. the dust which rose masked the sun causing darkness and lower temperatures. plants could not grow and temperatures fell
- the extinction was a slower process due to sea ice melting and cooling the sea temperature by about 9°C, therefore there was less plankton- less food available | | 194 |
| 6547428901 | What is a species? | a group of similar organisms that can reproduce to give fertile offspring | | 195 |
| 6348389660 | New species may arise because... (4 reasons) | - speciation - population so different, successful interbreeding no longer possible
- natural selection
- genetic variation
- isolation | | 196 |
| 6348389661 | What is speciation? | - the development of new species
- occurs when populations of the same species become so different they can no longer breed together to produce fertile offspring | | 197 |
| 6348389662 | What two factors can lead to speciation? | - isolation
- natural selection | | 198 |
| 6547434177 | How can isolation lead to speciation | - a physical barrier geographically isolated some individuals from the main population
- conditions on either side of the barrier are slightly different
- each population shows variation due to their wide range of alleles
- in each population, individuals with characteristics that make them better adapted to their environment have a better chance of survival and are more likely to breed successfully.
- this means that the alleles that control beneficial characteristics are more likely to be passed on to the next generation
- the two populations can no longer breed together to produce fertile offspring- new species | | 199 |
| 6547454189 | What is meant by the term isolation? | where populations of a species are separated | | 200 |
| 6348389663 | How does isolation and natural selection lead to speciation? | Populations of the same species may become separated by physical barrier and geographically isolated. Conditions will be slightly different on each side, and so different characteristics will become more common.
1) Population shows variation due to wide range of alleles
2) Individuals with characteristics that make them better adapted are more likely to survive & breed successfully
3) Alleles controlling beneficial characteristics more likely to be passed on | | 201 |
