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141 Cards in this Set
- Front
- Back
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Nucleus |
Controls all the activities of the cell. Contains genetic material that controls the activities of the cell. |
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Cytoplasm |
A liquid gel in which most of the chemical reactions needed for life take place. |
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Cell Membrane |
Controls the passage of the substances into and out of the cell and also holds the cell together. |
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Mitochondria |
Structures in the cytoplasm where oxygen is used and most of the energy is releaased during respiration |
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Ribosomes |
Where protein synthesis takes place. All the proteins needed in the cell are made here. |
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Cell wall |
Made of cellulose. Strengthens the cell and gives it support. |
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Chloroplasts |
Found in the green parts of the plant. They are green because they contain chlorophyll. Chlorophyll absorbs light energy to make food by photosynthesis. |
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Why don't root cells contain chlorophyll? |
Because they are underground and do not photosynthesise |
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Permanent Vacuole |
Space in the cytoplasm filled with cell sap which is a weak solution of sugar and salts. This is needed to keep the cells rigid and support the plant. |
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Bacteria |
Single-celled organisms- much smaller than animal and plant cells. |
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Bacteria Cells |
Contain genetic material which is not contained in a nucleus. They also contain plasmids which are small circular bits of DNA to carry extra genetic information. Also may have a slime capsule around the cell wall. Some have at least one flagellum which is a long protein strand that lashes about to help them move around. |
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Yeast cells |
Cells that can survive a long time even with little oxygen available. When there is a lot of oxygen they use aerobic respiration. They use oxygen to break down sugar to provide energy for the cell. This produces water and carbon dioxide. |
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Yeast&anaerobic respiration |
When there isn't much oxygen yeast can use anaerobic respiration. Yeast breaks down sugar in the absence of oxygen to produce ethanol and carbon dioxide. This is sometimes called fermentation. |
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Fat Cells |
Have small amount of cytoplasm and large amounts of fat, few mitochondria, can expand and end up x1000 bigger. |
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Outer segment of Cone cell |
The Retina(Light sensitive layer). Outer segment contains special chemical that changes chemically in coloured light. Requires energy to change back into original form. |
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Middle Segment of Cone Cell |
Middle segment is packed full of mitochondria. Releases energy to reform the visual pigment. Lets you see continually in colour. |
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Synapse of Cone Cell |
Connects to the optic nerve. When coloured light makes your visual pigment change, an impulse is triggered. This impulse crosses the synapse and travels along the optic nerve to your brain. |
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Root hair cells |
-Increased surface area for more water to move into the cell . -Have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell. |
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Sperm cells |
-Long tail, Whips from side to side and helps move sperm towards the egg. -Middle section is full of mitochondria. Provides energy for the tail to work. -Acrosome stores digestive enzymes for breaking down the outer layers of the egg. -Large nucleus contains genetic information to be passed on. |
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Diffusion |
The net movement of particles from an area of high concentration to an area of lower concentration. |
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The net movement |
The number of particles moving in - particles moving out The greater the difference in concentration, the faster the rate of diffusion. |
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Diffusion and temperature |
An increase of temperature means the particles in a gas move more quickly. Therefore diffusion takes place more rapidly as the random movement of particles speed up. |
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Diffusion and surface area |
More surface area means there is more room for diffusion to take place. By folding up the membrane of a cell, or the tissue lining of an organ, the area is greatly increased. |
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Diffusion in animals |
Oxygen needed for respiration passes from the air into your lungs. Then from to cell red blood cells to the cell membrane. |
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Differentiation |
When multicellular organisms develop different ways of exchanging materials. They become specialised to carry out particular jobs |
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Tissue |
Group of cells with a similar structure and function working together
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Muscular tissue |
Can contract to bring about movement |
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Glandular tissue |
Contains secretory cells that can produce substances such as enzymes and hormones. |
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Epidermal tissues |
Cover the surfaces and protects them. |
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Mesophyll tissues |
Contains a lot of chloroplasts and can carry out photosynthesis. |
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Xylem and Phloem |
Transport tissues in plants Carry water and dissolved mineral ions from the roots up to the leaves and dissolved food from the leaves around the plant. |
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Organs |
Made up of tissues. One organ can contain several tissues all working together. |
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Stomach |
Muscular tissues to churn the food and digestive juices of the stomach together. Glandular tissue to produce digestive juices that break food down Epithelial tissue which covers the inside and outside of the stomach |
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Pancreas |
An organ that makes hormones to control our blood sugar. Also makes some of the enzymes that digest our food. Uses different types of tissue to produce these different secretions. |
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Adaptations for exchange |
Surface area for rapid diffusion Concentration-the steeper the gradient, the faster diffusion takes place. Most organs have a good blood supply, bringing in substances and taking them out to maintain a steep concentration gradient.
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Organ Systems |
Groups of organs that all work together to perform a particular function. The way one organ functions often depends on others in the system. |
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Digestive system |
A muscular tube that squeezes your food through. Starts with your mouth and finishes with your anus. Breaks down the large insoluble molecules from food into smaller, soluble molecules. These can then be absorbed and used by your cells. |
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The Small intestine |
Where the soluble food molecules are absorbed into your blood. Has a very large surface area and therefore increases diffusion from the gut to the blood. |
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The Large intestine |
Where water is absorbed from the undigested food into your blood. The material left forms faeces which is then stored and passes out your body through the rectum and anus back into the environment. |
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Epidermal tissue |
Covers plant |
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Xylem |
Transports water and minerals |
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Mesophyll |
Carries out photosynthesis |
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Phloem |
Transports dissolved food |
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Stem |
Supports leaves and flowers |
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Roots |
Take up water and minerals from the soil |
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Leaf |
Carries out photosynthesis |
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Photosynthesis |
Carbon dioxide+Water--> glucose+oxygen |
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The process of photosynthesis |
Light is absorbed by the chlorophyll in the chloroplasts. This energy is used the convert carbon dioxide from the air and water from the soil into glucose. This reaction also produces oxygen. The gas is released into the air which we breath in. |
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Test for starch |
1. Heat a plant leaf in boiling water for 30 seconds to destroy waxy cuticle and stop chemical reactions.
2. heat it in boiling ethanol for a few minutes to remove colour. 3. wash with water and spread onto a white tile 4. add iodine solution from a dropping pipette After a few minutes, the parts of the leaf that contain starch turn blue-black. |
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Leaf adaptations |
Broad, giving them a big surface area for light to fall on Contain chlorophyll in the chloroplasts to absorb the light energy Has air spaces that allow carbon dioxide to get the cells and oxygen to leave them by diffusion. Has veins which bring plenty of water to the cells of the leaves. |
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Limiting factors and light |
If there is plenty of light lots of photosynthesis can take place. If there is very little light, photosynthesis will stop. It doesn't matter what the other conditions are like around the plant. For most lights,the brighter the light, the faster the rate of photosynthesis. |
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Limiting factors and temperature |
As temperature rises, the rate of photosynthesis rises. However, photosynthesis is controlled by enzymes and most enzymes are denatured once the temperature reaches around 40-50 degrees therefore if the temperature is too high the rate of photosynthesis will fall. |
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Limiting factors and carbon dioxide |
Increasing the of carbon dioxide will increase the rate of photosynthesis. On a sunny day, carbon dioxide levels are the most common limiting factors for plants. The carbon dioxide levels around a plant tend to rise at night because in the dark a plant respires but doesn't photosynthesis. |
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inside a Greenhouse/ lab |
The levels of carbon dioxide can be increased artificially therefore it's no longer limiting. The rate of photosynthesis increases with the rise in carbon dioxide. |
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In Gardens, woodlands or field |
Light, temperature and carbon dioxide levels interact and any one of them might be the factor that limits photosynthesis |
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What do the cells in a plant use glucose for? |
They use it for respiration to provide energy for cell functions such as growth and reproduction |
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What is the energy released in respiration used for? |
To build up smaller molecules into bigger molecules Some glucose is changed into starch for storage Plants and algae build up glucose into more complex carbohydrates like cellulose to strengthen cell walls. Used to make fats and oils which may be used in the cells as an energy store. Can be stored in the seeds to provide lots of energy for new plants as it germinates. |
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How do plants use glucose from photosynthesis to make amino acids |
They combine sugars with nitrate ions and other mineral ions from the soil. These amino acids are build up into proteins to be used in the cells. This requires energy from respiration |
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Why can't glucose be stored in plant cells? |
Glucose is soluble in water therefore it could affect the way water moves into and out of the cells. Lots of glucose could affect the water balance of the whole plant. |
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Why can starch be stored in plant cells? |
Starch is insoluble in water therefore it will have no effect on the water balance of the plant. This means that plants can store large amounts of starch in their cells. |
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How does a green house affect the rate of photosynthesis? |
-Within the glass or plastic structure the environment is much more controllable than outside. -The atmosphere is warmer inside than out. This speeds up the rate of photosynthesis so the plants grow faster. -They will flower and fruit earlier and produce higher yields. -We can use greenhouses to grow fruit like peaches, lemons and oranges which don't normally grow well outside in the UK |
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Hydroponics |
Varying levels of limiting factors to get the fastest possible rates of photosynthesis for example instead of soil, a perfect balance of mineral ions so nothing slows down their growth. |
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Advantages and disadvantages of greenhouses |
Advantage -Turnover is fast so in turn profits can be high -The crops are clean and unspoilt -There is no ploughing or preparing the land and in these systems crops can be grown where the land is poor. Disadvantage -It costs a lot of money to control the big environment -Takes a lot of energy to keep conditions in the greenhouse just right
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Organisms and temperature as a limiting factor |
In cold climates temperature is always a limiting factor for example arctic plants are all small. This in turn affects the numbers of herbivores that can survive in the area. |
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Organisms and nutrients as a limiting factor |
The level of mineral ions available has a big impact on the distribution of plants. Carnivorous plants such as Venus flytraps thrive when nitrate levels are very low because they can trap and digest animal prey. The nitrates they need are provided when they break down animal protein. |
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Organisms and light as a limiting factor |
Light limits photosynthesis so it affects the distribution of plants and animals. Plants need plenty of light to grow well |
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Organisms and water as a limiting factor |
Water is important in the distribution of plants and animals in a desert. As a rule plants and animals are relatively rare in a desert however the distribution changes after it rains. A Large number of plants grow, flower and set seeds very quickly while the water is available. |
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Organisms and oxygen+carbon dioxide as a limiting factor |
Oxygen has a big impact on water limiting organisms. The distribution of land organisms is not affected by oxygen levels as there is plenty of oxygen in the air and levels vary very little. Carbon dioxide levels acts as limiting factor on photosynthesis and plant growth and they also affect organisms such as mosquitoes. Mosquitoes are attracted to animals whose blood has high carbon dioxide levels. |
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Quantitative data on the distribution of organisms in the environment |
Random sampling with quadrats Sampling along a transect |
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Count along a transect |
They are not random. you stretch a tape between two points and sample the organisms along that line at regular intervals using a quadrat. This shows how the distribution of organisms change along that line. You can measure some physical factors such as light, soil pH(anything that affects the grwoth of plants along transect)
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Protein molecules |
Long chains of amino acids |
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Shape of protein |
The shape of a protein depends on its function: Structural components of tissues(muscle) Hormones Antibodies Catalysts |
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Enzymes |
Biological catalysts that speed up reactions |
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The area that a protein can fit into |
Active site |
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Substrate |
Can be held in the active site and either be connected to another molecule or be broken down
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Uses of enzymes
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Build large molecules from many smaller ones(Starch from glucose molecules) Change one molecule into another one(convert one type of sugar into another) Break down large molecules into smaller ones(all digestive enzymes do this) |
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When an enzyme is heated |
Reactions take place faster when it's warmer. At higher temperatures the molecules move around more quickly and so collide with each other more often and with more energy |
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If an enzyme is over heated |
The enzyme stops working because the active site changes shape. The enzyme becomes denatured |
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Enzymes and pH |
Each enzyme works best at a particular pH value. Some work best in acid conditions(stomach) and some need neutral or alkaline conditions. |
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If pH is too acidic or alkaline |
The active site could change shape then the enzyme becomes denatured |
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Amylase(Carbohydrase) |
Produced by the salivary glands, the pancreas and the small intestine. Amylase catalyses the digestion of starch into sugars in the mouth and small intestine |
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Protease |
Produced by the stomach, the pancreas and the small intestine. Protease catalyses the breakdown of proteins into amino acids in the stomach and the small intestine |
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Lipase |
Produced by the pancreas and small intestine. Lipase catalyses the breakdown of lipids(fats and oils) into fatty acids and glycerol |
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Protease enzymes |
Works best in acidic conditions. Glands in the stomach wall produce hydrochloric acid to create very acidic conditions |
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Bile |
Bile is produced in the liver and is stored in the gall bladder. It is alkaline and is squirted into the small intestine and neutralises the stomach acid. Bile makes conditions slightly more alkaline. |
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Biological detergents |
Contains proteases and lipases that digest food stains. They work at lower temperatures than ordinary washing powders This saves energy and money spent on electricity |
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Baby food |
Proteases are used to pre-digest proteins in some baby foods |
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Isomerase |
Used to convert glucose syrup into fructose syrup. Fructose is much sweeter so less is needed in foods therefore foods are less fattening. |
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Carbohydrases |
Used to convert starch into sugar syrup for use in foods. |
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Enzymes and industry |
Enzymes are used to bring about reactions at normal temperatures and pressures. Traditional chemical processes require expensive equipment and a lot of energy to produce high temperatures and pressures. Enzymes can be reused also. |
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Advantages and disadvantages of enzymes in industry |
Advantages -Biological washing powders are very effective at removing stains e.g grass stains -Biological washing powders can be used at low temperatures which saves energy and reduces costs -Some enzymes are used in medicine to diagnose, control or even cure disease -Costs of equipment and energy can be reduced Disadvantage -If people misuse washign powders they may have allergic reactions on their skin. Once powder is on skin, hands cannot be in water. -Enzymes may enter waterways via sewage system -Industrial enzymes can be costly to produce |
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Aerobic respiration |
Glucose+oxygen--> carbon dioxide+ water[+energy] Takes place continually in plants and animals. |
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Uses of aerobic respiration |
Build larger molecules from smaller ones Enable muscle contraction in animals Maintain a constant body temperature in colder surroundings in mammals and birds Build sugars,nitrates and other nutrients into amino acids and then proteins in plants |
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Test for carbon dioxide |
Limewater turns cloudy when carbon dioxide is present. This is an investigation involving aerobic respiration to measure the volume of carbon dioxide produced |
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Investigating temperature rise with aerobic respiration |
If germinating peas are left in a thermos flask, the rise in temperature due to respiration can be monitored. |
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Exercise |
When you exercise, your muscles need more energy so that they can contract. You need to increase the rate at which oxygen and glucose reach the muscle cells for aerobic respiration. This allows more blood containing oxygen and glucose to reach the muscles |
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Exercise and breathing rate |
Your breathing rate and depth of each breath also increase. This allows a greater uptake of oxygen and release of carbon dioxide at the lungs. Muscles store glucose as glycogen. The glycogen can be converted back to glucose for use during exercise |
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Anaerobic respiration |
When you use your muscles over a long period they will get tired and stop contracting efficiently. When our muscles cannot get enough oxygen for aerobic respiration, they start to respire anaerobically. |
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Glucose in anaerobic respiration |
The glucose is not completely broken down in anaerobic respiration and lactic acid is produced. Less energy is released from the glucose in anaerobic respiration. |
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Muscle fatigue |
A build up of lactic acid Blood flowing through the muscles removes lactic acid. |
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Why is anaerobic respiration inefficient? |
Because the breakdown of glucose is not complete. instead of carbon dioxide and water, lactic acid is produced as a waste product. Lactic acid causes muscle fatigue. |
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Oxygen debt |
When you still need to take in a lot of oxygen to fully break down the lactic acid after anaerobic respiration. Eventually the oxygen oxidises lactic acid into carbon dioxide and water. |
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Cell division |
Necessary for the growth of an organism or the repair of damaged tissues |
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Mitosis |
Results in two identical cells being produced from the original cell The chromosomes contain the genes(alleles) which must be passed on to each new cell A copy of each chromosome is made before the cell divides and one of each goes to each new cell |
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Early development of animal and plant embryos |
Cells are unspecialised and are called stem cells |
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Asexual reproduction |
Produced by mitosis from the parent cell. They contain the same alleles as the parents |
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Meiosis |
Before division a copy of each chromosome is made The cell now divides twice to form four gametes(sex cells) Each gamete has a single set of chromosomes each with a different combination of genes |
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Sexual reproduction |
Results in variation as the gametes from each parent fuse so half the genetic information comes from the father and half from the mother. When the gametes join at fertilisation, a single body cell with new pairs of chromosomes is formed. A new individual then develops by this cell repeatedly by mitosis |
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Stem Cells |
Are unspecialised Step cells are found in the human embryo and in adult bone marrow
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Differentiation |
Step cells can change into all the types of body cells, nerve cells, muscle cells. Layers of cells in the embryo differentiate into all the cells the body needs Stem cells in bone marrow can change into all other types e.g blood cells It is hoped that human stem cells can be made to differentiate into many types of cell. |
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How could differentiation help treat conditions |
Could treat conditions such as paralysis By differentiating into new nerve cells |
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Gregor Mendel |
Monk who worked out how characteristics were inherited and suggested the idea of inherited factors(genes). Genes are short sections of DNA Chromosomes are made of DNA which is a very long molecule with a double helix structure Every individual except for identical twins has different DNA. This unique DNA can be used to identify people by their DNA fingerprint
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Genetic code |
Each gene codes for a particular combination of amino acids which make a specific protein |
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Alleles |
Genes controlling the same characteristic |
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Dominant allele |
An allele that masks the effect of another |
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Recessive allele |
An allele where the effect is masked |
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How many pairs of chromosomes do human beings have |
23 pairs, one pair are the sex chromosomes. Females have two X chromosomes (XX) and males have X and Y chromosome (XY) |
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How is a sex determinded |
By the X and Y chromosomes |
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Phenotype |
Physical appearance of the characteristic e.g dimples or no dimples |
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Genotype |
The genetic make up- which alleles does the individual inherit? DD, Dd or dd |
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Homozygous |
Both alleles are the same DD( homozygous dominant) or dd(homozygous recessive) |
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Hetrozygous |
The alleles are different Dd |
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Genetic disorders |
Some caused by dominant allele, some by a recessive allele If dominant, the person only has to inherit one dominant allele to have the genetic disorder |
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Polydactyly |
A baby is born with extra fingers or toes. Caused by dominant allele Can be passed on by one parent who has the allele |
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If allele is recessive |
The person must inherit two recessive alleles to have the disorder |
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Cystic fibrosis |
Caused by a recessive allele. The allele affects the cell membrane and causes the production of thick sticky mucus The mucus can affect several organs, including the lungs and pancreas Must inherit a recessive allele from both parents to develop the disorder. Must be passed on by parents that don't have cystic fibrosis. |
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Carriers |
Parents who don't have the disorder but can pass it on to their children |
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Using genetic diagrams |
Possible to see how a disorder or allele has been inherited and to predict whether future offspring will inherit it. |
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Stem cells ethics advantages |
Adult stem cells are useful in treating some disorders such as leukaemia Doctors have investigated the use of embryonic stem cells which have the potential to differentiate into a wide variety of cells Embryonic stem cells could be used to grow new tissues and organs for transplants. |
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Stem cell ethics disadvantages |
In IVF the embryos are screened and only healthy embryos are implanted into the mother. Embryos carry faulty genes are destroyed and some people think this is unethical Embryo screening involves tests to diagnose disorders before the baby is born The results of tests may give parents choices. Sometimes the parents decide to terminate the pregnancy and others decide this is not ethical and deliver an affected baby |
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Embryo screening |
Tests to diagnose disorders before the baby is born |
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How can we date when different organisms existed |
We can date rocks. Fossils are found in rocks |
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How can fossils be formed |
Hard parts of the animal that may not decay easily(bones,teeth,shells, claws) From parts that may not have decayed because of the conditions for decay are absent (fossils of animals preserved in ice) Parts of the organisms are replaced by other materials such as minerals as they decay As preserved traces of organisms e.g footprints , burrows and rootlet traces |
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hy would organisms that died not leave a fossil |
Because the exact conditions for fossil formation were not present |
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Why are some fossils destroyed over time |
Because of geological activity such as earthquakes |
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Extinction |
When a species which once existed has completely died out |
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How extinction can happen |
A new disease may kill all members of a species The environment changes over geological time A new predator may evolve or be introduced to an area that effectively kills and eats all of a species Natural changes in a species occur over time |
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How can new species arise from existing species |
If a group becomes isolataed from the rest |
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Geographical isolation |
Could occur if an island separates from the mainland or if a new river separates two areas. Mountain ranges and old craters can isolate organisms |
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Organisms left on an island |
May be exposed to different environmental conditions , food availability or predators. Natural selection will occur in both areas but different characteristics will be beneficial in two populations. If the populations are brought together they cannot interbreed as they belong to two separate species. |
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Speciation |
New species can occur following separation of two populations as in geographical isolation Each population has a wide range of alleles that control their characteristics. This is genetic variation Natural selection allows alleles that control characteristic to help the organism survive. The organisms with these alleles will survive and breed Speciation has occurred when the two populations can no longer successfully interbreed |
