Biology Flashcards

Question

RPA : Microscope

Answer 1

Equipment List * a small piece of onion * a knife * a white tile * forceps * a microscope slide * a coverslip * a microscope (Some microscopes have a built-in light instead of a mirror) * iodine solution in a dropping bottle * prepared animal and plant cells * Perspex ruler. **Method** 1. Use a dropping pipette to put one drop of water onto a microscope slide. 2. Separate one of the thin layers of the onion. 3. Peel off a thin layer of epidermal tissue from the inner surface. 4. Use forceps to put this thin layer on to the drop of water that you have placed on the microscope slide. 5. Make sure that the layer of onion cells is flat on the slide. 6. Put two drops of iodine solution onto the onion tissue. 7. Carefully lower a coverslip onto the slide. Do this by placing one edge of the coverslip on the slide and using the forceps to lower the other edge onto the slide 8. There may be some liquid around the edge of the coverslip. Use a piece of paper to soak this liquid up. 9. Put the slide on the microscope stage. 10. Use the lowest power objective lens. Turn the nosepiece to do this. 11. The end of the objective lens needs to almost touch the slide. Do this by turning the coarse adjustment knob. Look from the side (not through the eyepiece) when doing this. 12. Now looking through the eyepiece, turn the coarse adjustment knob in the direction to increase the distance between the objective lens and the slide. Do this until the cells come into focus. 13. Now rotate the nosepiece to use a higher power objective lens. 14. Slightly rotate the fine adjustment knob to bring the cells into a clear focus and use the low-power objective (totalling 40 magnification) to look at the cells. 15. When you have found some onion epidermal cells, switch to a higher power (100 or 400 magnification). 16. Make a clear, labelled drawing of some of these cells. Make sure that you draw and label any component parts of the cell. 17. Write the magnification underneath your drawing. 18. Use this technique to draw a range of animal and plant cells on prepared slides. **Variables** **Independent** - Magnification **Dependent** - Size of the cell **Control** - Cell type

Answer 2

**Equipment List** * a nutrient agar plate * a Bunsen burner * a heatproof mat * a disposable plastic pipette * a culture of bacteria (E. coli) * a glass spreader * filter paper discs * disinfectant bench spray * a ‘discard beaker’ of disinfectant * 1% VirKon disinfectant * forceps * clear tape * hand wash * a wax pencil * access to an incubator (set to 30oC) * three antiseptics (such as mouthwash, TCP, and antiseptic cream) **Method** 1. Spraying the bench where you are working with disinfectant spray. Then wipe with paper towels. 2. Put the Bunsen burner on the heatproof mat in the middle of where you are working. Light the Bunsen on a yellow flame. 3. Mark the underneath of a nutrient agar plate (not the lid) with the wax pencil as follows (make sure that the lid stays in place to avoid contamination): * divide the plate into three equal sections and number them 1, 2 and 3 around the edge * place a dot into the middle of each section * around the edge write your initials, the date and the name of the bacteria (E. coli) 4. Wash your hands with the antibacterial hand wash. 5. Turn the Bunsen flame to blue. 6. Remove the lid of the bottle containing the culture of bacteria (keep the lid in your hand). Then flame the neck of the bottle through the Bunsen flame. Do this by quickly twisting the bottle from side to side. Use the disposable pipette to collect approximately 1 ml of the bacterial culture. 7. Quickly flame the neck of the bottle again and replace the lid. 8. Carefully lift the lid of the agar plate at an angle. Do not open it fully. The lid should only be fully open on the Bunsen burner side. 9. Pipette the bacteria onto the agar plate and replace the lid. 10. Place the pipette into the ‘discard beaker’. Turn the Bunsen burner flame back to yellow. 11. Dip the glass spreader into the VirKon disinfectant. Remove the glass spreader and tap off the excess. Then pass the glass spreader through the flame. Hold the glass spreader horizontally to ensure nothing drips down onto your hand. 12. Allow the spreader to cool for a count of 20 seconds. 13. Lift the lid of the agar plate. Again, the lid should be at an angle so only the side next to the Bunsen burner is fully open. Spread the bacteria around the plate using the glass spreader. 14. Remove the glass spreader and put into the discard beaker. Lower the lid of the agar plate. 15. Put different antiseptics onto the three filter paper discs. This can be done by either soaking them in the liquid or spreading the cream or paste onto them. 16. Lift the lid of the agar plate as in step 8. Use forceps to carefully put each disc onto one of the dots drawn on with the wax pencil. 17. Make a note of which antiseptic is in each of the three numbered sections of the plate. 18. Secure the lid of the agar plate in place using two small pieces of clear tape. Do not seal the lid all the way around as this creates anaerobic conditions. Anaerobic conditions will prevent the E. coli bacteria from growing and can encourage some other very nasty bacteria to grow. 19. Incubate the plate at 30 °C for 48 hours. 20. Measure the diameter of the clear zone around each disc by placing the ruler across the centre of the disc. Measure again at 90° to the first measurement so that the mean diameter can be calculated. 21. Record your results in a table. **Variables** **Independent** - Temperature incubated at **Dependent** - Diameter of the zone **Control** - Surrounding temps, Moisture of surface

Answer 3

**Equipment List** * a potato * a cork borer or potato chipper/ vegetable stick cutter * a ruler * a 10 cm3 measuring cylinder * labels * three boiling tubes * a test tube rack * paper towels * a sharp knife * a white tile * a range of sugar solutions * distilled water * a top-pan balance. **Method** 1. Use a cork borer to cut three potato cylinders of the same diameter. 2. Trim the cylinders so that they are all the same length (about 3 cm). 3. Accurately measure and record the length and mass of each potato cylinder. 4. Measure 10 cm3 of the 0.5 M sugar solution and put into the first boiling tube. Label boiling tube as: 0.5M sugar. 5. Measure 10 cm3 of 0.25 M sugar solution and put into the second boiling tube. Label boiling tube as: 0.25M sugar. 6. Measure 10 cm3 of the distilled water and put into the third boiling tube. Label boiling tube as water. 7. Add one potato cylinder to each boiling tube. Make sure you know the length and mass of each potato cylinder in each boiling tube. 8. Record the lengths and masses of each potato cylinder in a table. 9. Leave the potato cylinders in the boiling tubes overnight in the test tube rack. 9. Remove the cylinders from the boiling tubes and carefully blot them dry with the paper towels. 10. Re-measure the length and mass of each cylinder (make sure you know which is which). Record your measurements in the table. Then calculate the changes in length and mass of each potato cylinder. 12. Plot a graph with ‘Change in mass in g’ on the y-axis and ‘Concentration of sugar solution’ on the xaxis. 13. Plot another graph with ‘Change in length in mm’ on the y-axis and ‘Concentration of sugar solution’ on the x-axis. 14. Compare the two graphs that you have drawn **Variables** **Independent** - Sugar Contents in liquid **Dependent** - Rate of Osmosis **Control** - Liquid amount, Mass of potato

Answer 4

**Equipment List** * food to be tested * a pestle and mortar * a stirring rod * a filter funnel and filter paper * 2  beaker, 250 ml * a test tube * Biuret solution * safety goggles. **Method** 1. Use a pestle and mortar to grind up a small sample of food. 2. Transfer the ground up food into a small beaker. Then add distilled water. 3. Stir the mixture so that some of the food dissolves in the water. 4. Filter using a funnel with filter paper to obtain as clear a solution as possible. The solution should be collected in a conical flask. 5. Put 2 cm3 of this solution into a test tube. 6. Add 2 cm3 of Biuret solution to the solution in the test tube. Shake gently to mix. 7. Note any colour change. Proteins will turn the solution pink or purple. **Colour** - Purple **Solution** Biuret Solution

Answer 5

**Equipment List** * food to be tested * a pestle and mortar * a stirring rod * filter funnel and filter paper * 2  beaker, 250 ml * a conical flask * 2  test tube * Benedict’s solution * iodine solution * kettle for boiling water * a thermometer * safety goggles. **Method** 1. Use a pestle and mortar to grind up a small sample of food. 2. Transfer the ground up food into a small beaker. Then add distilled water. 3. Stir the mixture so that some of the food dissolves in the water. 4. Filter using a funnel with filter paper to obtain as clear a solution as possible. The solution should be collected in a conical flask. 5. Half fill a test tube with some of this solution. 6. Add 10 drops of Benedict’s solution to the solution in the test tube. 7. Put hot water from a kettle in a beaker. The water should not be boiling. Put the test tube in the beaker for about five minutes. 8. Note any colour change. If a reducing sugar (such as glucose) is present, the solution will turn green, yellow, or brick-red. The colour depends on the sugar concentration. 9. Take 5 ml of the solution from the conical flask and put it into a clean test tube. 10. Add a few drops of iodine solution and note any colour change. If starch is present, you should see a black or blue-black colour appear. 11. Record your results in a table. **Colour** - Black/blue colour **Solution** - Iodine Solution

Answer 6

Equipment List * food to be tested * a pestle and mortar * a stirring rod * 2  beaker, 250 ml * a test tube * Sudan III stain solution. * safety goggles **Method** 1. Use a pestle and mortar to grind up a small sample of food. 2. Transfer the ground up food into a small beaker. Then add distilled water. 3. Stir the mixture so that some of the food dissolves in the water. Do not filter. 4. Half fill a test tube with some of this solution. 5. Add 3 drops of Sudan III stain to the solution in the test tube. Shake gently to mix. 6. If fat is present: a red-stained oil layer will separate out and float on the water surface. **Colour** - Red will appear if present ** Solution** - Sudan 3

Answer 7

**Equipment List** * food to be tested * a pestle and mortar * a stirring rod * filter funnel and filter paper * 2  beaker, 250 ml * a conical flask * 2  test tube * Benedict’s solution * iodine solution * kettle for boiling water * a thermometer * safety goggles. **Method** 1. Use a pestle and mortar to grind up a small sample of food. 2. Transfer the ground up food into a small beaker. Then add distilled water. 3. Stir the mixture so that some of the food dissolves in the water. 4. Filter using a funnel with filter paper to obtain as clear a solution as possible. The solution should be collected in a conical flask. 5. Half fill a test tube with some of this solution. 6. Add 10 drops of Benedict’s solution to the solution in the test tube. 7. Put hot water from a kettle in a beaker. The water should not be boiling. Put the test tube in the beaker for about five minutes. 8. Note any colour change. If a reducing sugar (such as glucose) is present, the solution will turn green, yellow, or brick-red. The colour depends on the sugar concentration. 9. Take 5 ml of the solution from the conical flask and put it into a clean test tube. 10. Add a few drops of iodine solution and note any colour change. If starch is present, you should see a black or blue-black colour appear. 11. Record your results in a table. **Colour** - Solution will turn brick red **Solution** - Benedicts Solution

Answer 8

**Equipment List** * test tubes * a test tube rack * spotting tiles * 5cm3 measuring cylinder * syringes * a stop clock * starch solution * amylase solution * iodine solution * syringes * water bath (electrical or bunsen burner and beakers) * buffered solutions covering a range of pH, each with a labelled syringe/ plastic pipette **Method** 1. Place one drop of iodine solution into each depression on the spotting tile. 2. Place labelled test tubes containing the buffered pH solutions, amylase solution and starch solutions in to the water bath 3. Allow the solutions to reach 30 °C 4. Add 2cm3 of one of the buffered solutions to a test tube. 5. Use the syringe to place 2 cm3 of amylase into the buffered pH solution. 6. Use another syringe to add 2 cm3 of starch to the amylase/buffer solution. 7. Immediately start the stop clock and leave it on throughout the test. 8. Mix using a glass rod. 9. After 10 seconds, remove one drop of the mixture with a glass rod. 10. Place this drop on the first depression of the spotting tile with the iodine solution. The iodine solution should turn blue-black. 11. Use the glass rod to remove one drop of the mixture every 10 seconds. Put each drop onto the iodine solution in the next depression on the spotting tile. Rinse the glass rod with water after each drop. Continue until the iodine solution and the amylase/ buffer/ starch mixture remain orange. 12. Repeat the procedure with solutions of other pH values. 13. Record your results in a table **Variables** **Independent** - Concentration of Iodine solution **Dependent** - pH values of solutions **Control** - measurement of mixtures as well as equipment

Answer 9

**Method** Equipment List * a boiling tube * freshly cut 10 cm piece of pondweed * a light source * a ruler * a test tube rack * a stop watch * 0.2% solution of sodium hydrogen carbonate mix. * a glass rod. **Method** 1. Set up a test tube rack containing a boiling tube at a distance of 10 cm away from the light source 2. Fill the boiling tube with the sodium hydrogen carbonate solution. 3. Put the piece of pondweed into the boiling tube with the cut end at the top. Gently push the pondweed down with the glass rod. 4. Leave the boiling tube for 5 minutes. 5. Start the stop watch and count the number of bubbles produced in one minute. 6. Record the results in a table. 7. Repeat the count twice more. Then use the data to calculate the mean number of bubbles per minute. 8. Repeat steps 1‒7 with the test tube rack and boiling tube at distances of 20 cm, 30 cm and 40 cm from the light source. **Variables** **Independent** - Distance of the LED light source away. **Dependent** - Amount of bubbles in one minute **Control** - Temperature, Water, Other light sources.

Answer 10

**Equipment List** * a metre ruler * a chair * a table * a partne **Method** 1. Use your weaker hand for this experiment. If you are right handed then your left hand is your weaker hand. 2. Sit down on the chair with good upright posture and eyes looking across the room. 3. Place the forearm of your weaker arm across the table with your hand overhanging the edge of the table. 4. Your partner will hold a ruler vertically with the bottom end (the end with the 0 cm) in between your thumb and first finger. Practice holding the ruler with those two fingers. 5. Your partner will take hold of the ruler and ask you to remove your fingers. 6. Your partner will hold the ruler so the zero mark is level with the top of your thumb. They will tell you to prepare to catch the ruler. 7. Your partner will then drop the ruler without telling you. 8. You must catch the ruler as quickly as you can when you sense that the ruler is dropping. 9. After catching the ruler, look at the number level with the top of your thumb. Record this in a table. 10. Have a short rest and then repeat the test. Record the number on the ruler as attempt 2. 11. Continue to repeat the test several times. 12. Swap places with your partner. Repeat the experiment to get their results. 13. Use a conversion table to convert your ruler measurements into reaction times. **Variables** **Independent** - Time when ruler is dropped **Dependent** - Distance travelled before caught **Control** - Tiredness, Point of beginning, which finger is being measured.

Answer 11

**Equipment List** * white mustard seeds * petri-dishes * cotton wool * a ruler * water * access to a light windowsill and a dark cupboard. **Method** 1. Set up three petri dishes containing cotton wool soaked in equal amounts of water. 2. Put ten mustard seeds in each petri dish. 3. Put the petri dishes in a warm place. They must not be disturbed or moved. 4. Allow the mustard seeds to germinate. Add more water if the cotton wool gets dry (equal amounts of water to each petri dish). 5. Each petri dish should have the same number of seedlings after the seeds have geminated. Remove excess seedlings from any dish that has too many. For example, one dish has eight seedlings which are the fewest compared to the other petri dishes. Therefore, remove seedlings from the other petri dishes so that each dish has eight. 6. Move the petri dishes into position. * One should be placed on a windowsill in full sunlight. * One should be placed in partial light. * The third should be placed in darkness. 7. Measure the height of each seedling. Do this every day, for at least a week. 8. Record the heights in a table, including full sunlight, partial light and darkness. 9. Calculate the mean height of the seedlings each day. 10. Plot a graph with ‘Mean height in mm’ on the y-axis and ‘Day’ on the x-axis. 11. The graph should include data for full sunlight, partial light and darkness. Compare the data **Variables** **Independent** - postions of the petri dish **Dependent** - Height of the shoot **Control** - Sunlight, light source, water amount.

Answer 12

**Equipment List** * white mustard seeds * petri-dishes * cotton wool * a ruler * water * access to a light windowsill and a dark cupboard. **Method** 1. Set up three petri dishes containing cotton wool soaked in equal amounts of water. 2. Put ten mustard seeds in each petri dish. 3. Put the petri dishes in a warm place. They must not be disturbed or moved. 4. Allow the mustard seeds to germinate. Add more water if the cotton wool gets dry (equal amounts of water to each petri dish). 5. Each petri dish should have the same number of seedlings after the seeds have geminated. Remove excess seedlings from any dish that has too many. For example, one dish has eight seedlings which are the fewest compared to the other petri dishes. Therefore, remove seedlings from the other petri dishes so that each dish has eight. 6. Move the petri dishes into position. * One should be placed on a windowsill in full sunlight. * One should be placed in partial light. * The third should be placed in darkness. 7. Measure the height of each seedling. Do this every day, for at least a week. 8. Record the heights in a table, including full sunlight, partial light and darkness. 9. Calculate the mean height of the seedlings each day. 10. Plot a graph with ‘Mean height in mm’ on the y-axis and ‘Day’ on the x-axis. 11. The graph should include data for full sunlight, partial light and darkness. Compare the data **Variables** **Independent** - Location/conditions of the survey **Dependent** - Items in different areas of investigation **Control** - area covered, abiotic and biotic factors

Answer 13

**Equipment List** * a small beaker containing full fat milk or single cream * a small beaker containing sodium carbonate solution * a small beaker containing lipase solution * 250 cm3 beakers, to be used as water baths * test tubes * a test tube rack * a marker pen * 10 cm3 plastic syringes * a stirring thermometer * a stop clock * Cresol red, in a dropper bottle * an electric kettle, for heating water * ice, for investigating temperatures below room temperature. **Method** 1. Half fill one of the 250cm3 beakers with hot water from the kettle. This will be the water bath. 2. Label two test tubes as ‘lipase’ and ‘milk’. 3. In the ‘lipase’ test tube put 5cm3 of lipase solution. 4. In the ‘milk’ test tube put five drops of Cresol red solution. 5. Use a calibrated dropping pipette to add 5cm3 of milk to the ‘milk’ test tube. 6. Use another pipette to add 7cm3 of sodium carbonate solution to the ‘milk’ test tube. The solution should be purple. 7. Put a thermometer into the ‘milk’ test tube. 8. Put both test tubes into the water bath. Wait until the contents reach the same temperature as the water bath. 9. Use another dropping pipette to transfer 1cm3 of lipase into the ‘milk’ test tube. Immediately start timing. 10. Stir the contents of the ‘milk’ test tube until the solution turns yellow. 11. Record the time taken for the colour to change to yellow, in seconds. 12. Repeat steps 1‒11 for different temperatures of water bath. You can obtain temperatures below room temperature by using ice in the beaker instead of hot water. 13. Record your results in a table. 14. Plot a graph of your results. **Variables** **Independent** - Temperature of water bath **Dependent** - Record time taken for the solution to become yellow **Control** - Expiry date, Moisture.

Answer 14

**Random errors** are due to things you have no control over, such as a change in room temperature whilst you were collecting the results. Repeating your measurements and finding a mean will reduce the effect of random errors. **Systematic errors** are due to problems with the equipment you used. For example, the balances you used may have been out by 0.1 g for every measurement. Solution to **Random** - Repeat the experiment - Controlled Environment - Keep conditions the same Solutions to **Systematic** - "Zero" your equipment - Swap Equipment for more accurate equipment. - Subtract the error from the final results.

Answer 15

Classification systems have continued to be developed by other scientists, such as **Carl Woese** who developed the three-domain system. This is based on evidence now available from chemical analysis. The updated system divides organisms into: - **Archaea** (primitive bacteria usually living in extreme environments) - **Bacteria** (true bacteria) - **Eukaryotic** (including protists, fungi, plants and animals)

Answer 16

Information is brought to the central nervous system and taken away by **nerves which are bundles of neurons.** **Neurons are long cells** which carry **electrical** signals along their length Where two neurons meet there is a tiny gap called a synapse. Signals pass chemically across the synapse where the impulse continues from the next neuron ** Process For Central Nervous System (CNS)** - **Receptors** Sensory organs (Smell, sight, sound, touch and Taste) Start the chain sensing danger or something requiring response. - **Sensory Neurons** - **Coordinator** For example the brain, Coordinates an effective response to the impulse. - **Motor Neuron** - **effector** e.g Muscles or glands which respond to the problem based on the coordinators signal. **Process for detecting and responding** - **Stimulus ** e.g Feeling of Increased heat - **Receptor ** e.g touch on the skin - **Sensory Neuron ** - ** Relay Neuron ** - ** Motor neuron** - ** Effector** e.g Hand - **Response** e.g remove hand away from flame

Answer 17

Sexual reproduction uses the process of **meiosis** which creates **gametes** Only happens in **Sperm and egg cells in animals** and **pollen and ova in plants** **Key Information** - Copies of Genetic information are made - The cell divides twice to form four **Gametes**, Each with a single set of chromosomes. - Gametes are **haploid** - All gametes are genetically different from each other **Stages** - Parent cell - Chromosomes make **Identical** Copies - Similar chromosomes pair up - Sections of DNA get swapped (Creates diversity) - First cell division - chromosomes pairs separate - Second cell division

Answer 18

Mitosis and Meiosis differ as Mitosis is a form of cell division which produces two **diploid body cells** Meiosis Produces Four Non Identical ** Haploid sex cells** or Gametes

Answer 19

A growing and dividing cell goes through a series of stages called the **Cell Cycle** The first stages of the cell cycle involve cell growth then synthesis of DNA. The single strand of DNA is an exact copy of itself ** Stages** - Cell growth - DNA synthesis - the chromosomes are now double stranded - Further growth occurs and DNA checks for errors - **Mitosis** - Cytoplasm Separates creating two cells - ** Temporary cell resting period or the cell stops dividing** - (Repeat)

Answer 20

**Cells** - Smallest Unit of life that can replicate independently Some cells are whole organisms (Bacteria) so complete Asexual reproduction Adults contain over 40 Trillion cells altogether Known as Organelles or subcellular Structures **Animal Cells** - Eukaryotic - Cell Membrane, Controls what gets in and out of a cell - Nucleus, Contains genetic Material/DNA - Cytoplasm, Where chemical reactions take place - Mitochondria, Provide cells with the energy they need to function - Ribosomes, site of Protien synthesis **Plant Cells** - Eukaryotic - Cell Membrane, Controls what gets in and out of a cell - Nucleus, Contains genetic Material/DNA - Cytoplasm, Where chemical reactions take place - Mitochondria, Provide cells with the energy they need to function - Ribosomes, site of Protien synthesis - Rigid Cell wall to provide support and structure to the cell - Permanent Vacuole, Contains cell sap (Sugar, salts and waters) - Chloroplast, used for photosynthesis contains chlorophyll **Bacteria Cell** - Prokaryotic/Unicellular - Cell Membrane - Cell wall - Cytoplasm - Ribosomes - No Nucleus, No mitochondria - Contains a circular strand of DNA, Contain need to survive and reproduce - Plasmids - Extra Genes, antibiotic resistance - Some may have flagella to allow movement

Answer 21

**Equation** Magnification = Image Size / object size (Real Size) **Microscopes** - Base - Arm - Light Source - Stage - Microscope slide - Objective Lenses (Different Magnifications) - Eyepiece lens (Fixed Magnification) - Body tube - Coarse focusing nobs **Object** - The real object or sample that you're looking at **Image** - The image that we see when we look down the microscope **How it works** - Light from the room hits the mirror, pushing light through the sample through a lens, through the eye piece lens and into your eye to magnify the sample **Magnification** - How may times larger the image is than the object **Equation** Image Size / Object Size **Resolution** - The shortest distance between two points on an object that can still be distingued as two separate entities

Answer 22

**Light Microscopes** - Easy to use - Relatively cheap - Rely on light - Limited to 0.2 Micrometers - Any smaller will appear blurry - Max resolution is 0.2 Micrometers **Electron Microscopes** - Large - Expensive - Hard to use - Use electrons instead of light - Wavelength of 0.1 Nanometers - Max resolution is 0.1 Nanometers - 2000x better than light microscopes

Answer 23

**Scale** Nano Meter (Smallest) Micrometers Millimeters Meters Kilo Meters (Largest) Gets 1000x larger further you go e.g 6mm = 0.006m **Size Examples** Nanometer - Glucose Micrometer - Bacteria Millimeter - Insects Meter - Planes Kilometers - Planes

Answer 24

**Cell Cycle** Requires a continues supply of new cells for -Growth -development -repair 3 Stages - Growth - DNA replication Division **Growth** - Grows in size - Increases the amount of sub cellular structures e.g mitochondria and ribosomes - DNA then duplicates When not dividing long strings when dividing goes to chromosomes **Eukaryotic** - Pair of cells one from father and mother - Humans have 23 Pairs of Chromosomes **Replication** Duplicates each chromosomes but stays attached to the original creating an X shape When its ready to divide the chromosomes line up Cell fibers pull the arms of the chromosomes to each pole of the cell , Separating them **Division/ cytokinesis** - Forms two daughter cells - Each cell has the same DNA and are identical - Used for growth, development and repair - Will undergo the cell cycle eventually

Answer 25

**Stem Cells** - Able to divide by Mitosis to from more cells - Able to differentiate into specialized cells When sperm and egg fertilize called a Zygote and uses mitosis Forms a group of cells called an Embryo Embryonic Stem Cell **Adult Stem Cells** - Can differentiate but only into blood cells - Can do mitosis - found in bone marrow **Two types of stem cells found in animals** - Adult Stem Cells - Embryonic Stem Cells **Plant Stem Cells** - Meristems area of the plant that are continually growing - Found in places that will continue to grow - Last for the plants entire life - Can differenarte

Answer 26

**Specialized cells example** **Human** - Muscle Cells - Sperm Cells - Nerve cells **Plant** Root Hair cells Phloem Cells Xylem Cells

Answer 27

**Stem Cells** - They can divide by mitosis - Can differentiate into specialized cells - Embryonic (Any) - Adult Stem cells (Different Blood cells) A lot of conditions are due to faulty or damaged cells e.g type 1 diabetes or paralysis **Process** 1. Extract embryonic stem cells from embryos 2. grow them in a laboratory 3. stimulate them to differentiate into whichever type of specialized cell they want 4. Then give them to the patient to replace the faulty cells **Cons** - Requires an embryo e.g limited supply and ethical issues - Rejection; Patient genomes may reject the cells - Side effects **Alternative** - Use adult stem cells - Can be taken from the patient themselves - Only used on blood cells - Limited usage **Risks** 1 - Virus transmission; If infected with a virus then following transition would pass the virus on 2 - Tumor Development ; Divide too quickly so could cause a tumor or a cancer **Ethical Issue** - Potential for human Life - Religious ideas of who can affect and change life

Answer 28

**Diffusion** - Net movement of particles from an area of **Higher concentration** to an area of **lower concentration** Can happen in both liquids and gases Can only take place through patrially permeable membranes - Only some molecules can diffuse through **Diffusion is a Passive Process** **Rate of Diffusion** - Concentration gradient between two places (Bigger difference means a quicker Rate of Reaction) - Temperature (Higher temp means greater rate of diffusion) - Surface area ( Larger area means quicker rate of diffusion)

Answer 29

**Osmosis** - Net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentraion - Special case of Diffusion **Water Concentration** - The amount of water, as compared to other molecules, like sugars or salts "solutes" that are dissolved in the water Red blood cells would gain water and swell if placed in water

Answer 30

**Active Transport** - Movement of molecules against their concentration gradient from a lower concentration to a higher concentration - Requires Energy from the cell (Active Process) - Always takes place across a membrane **Energy for active transport ** - From cellular respiration stored in ATP molecules Plants require Active transport to take in Minerals as there is a higher concentration inside than outside however still need them

Answer 31

**Definition** - Parts of an organism which they exchange substances with the environment **Human** - Aleveoli Carbon dioxide and oxygen in the lungs - Villi Lining of the small intestines to absorb nutrients like glucose **plants** - Root hair cells, Absorb water and mineral ions from the soil - leaves absorb the co2 from the air **Common features** - Large surface area so more can diffuse so rate of diffusion is higher - Exchange surfaces are usually very thing so shorter distance to diffuse - Permeable to the substances they need to exchange **Animal only** - Good blood supply to maintain concentration gradient - Good supply of external medium, So a good supply of something for it maintain concentration gradient

Answer 32

**Organelles** - Sub cellular structures - E.g Nucleus, Ribosomes and Mitochondria - Multiple form a single cell **cell** - From different number of organelles - Specialised cells - Glandular , Muscle, Epithelial **tissues** - Group of similar cells used to carry out a particular function - Epithelial tissue, Muscle Tissue, Glandular tissue **Organ** - A group of different tissues that work together to form a particular function - Different tissues working together to complete their role - Skin, Teeth lungs, Stomach, Testes **Organ system** - Group of organs that work together to perform specific function - Digestive system , Reproductive system and Cardiovascular system **Organism** - Highest level, - Multiple Organ systems working together

Answer 33

**Purpose** - In order for a living cell to function must carry out a lot of reactions, Most chemical reactions are very slow. - Increasing the temperature but has drawbacks - Catalyst is the best way **Catalyst** - A substance that increases the speed of a reaction without being changed or used up in the process - Enzyme is a type of catalyst made by living organisms known as a biological catalyst. - Made from a long chain of Amino Acids **How it works** Reactant using an enzyme to speed up the production of the product - Has a location of the active site that is complementary to the substance - Must fit or wont be catalyzed **Lock and Key model** - Fits perfectly like a lock and key **Induced fit** - Active site is complementry to the substrate - Slightly changes shape to bind and fit the cell

Answer 34

**Temperature** As temp increases so does rate of reaction as all particles have more kinetic energy After 37 degrees the bonds break apart holding the active site, if they break too much the enzymes become denatured Damage is permanent Optimum temperature is the point where reaction is the highest **pH** Measure of Acidity If pH too low or high then it will lower the rate of reaction as some of the bonds begin to break active site changes shape leading to the rate of reaction slowing Each has different Phs Enzymes break food down during digestion

Answer 35

Foods usually have a mix of different nutrients in them **Carbohydrates/Lipids/Proteins** Carbs - Starchy foods - Energy source for chemical reactions Lipids - Fats, Refers to fats and oils - Found in oily fish, nuts an seeds - Provide energy longer term stores - Insulator and protects organs Proteins - Nuts and seeds, Meats and fish - Required for growth and damaged tissue - Emergency energy stores **Vitamin/Mineral Ions** - Lots of different - Need small amount Vitamins - Organic Molecules - From leafy veg - Good vision and for skin and hair health Mineral Ion - Found in dairy items - Needed for stronger bones **Fiber/ Water** Fiber - Type of carbohydrate - From whole meal foods - Fruits and veg - Help food move through intestines properly Water - Most foods and drinks - Needed for a lot of things including chemical reactions - 70% water

Answer 36

**Why?** - Are big molecules so too big too consume into the small intestines - Requires Enzymes **Carbohydrates** - Form of starch, Polymer of glucose - Use the enzyme Amylase, breaking it down into maltose molecules, - Maltose broken down using Maltase to produce glucose which is small enough to absorb **Protien** - Broken down by Protease into amino acids - Protease refers to a group of enzymes like Trypsin and Pepsin **Lipids** - Broken down by Lipase, into glycerol and fatty acids, Helps broken down by Bile, isn't an acid however breaks them down into smaller molecules for quicker rate of break **Location** - All three made by small intestine and pancreases - Protease made in the stomach, Amylase made in the Slavia

Answer 37

**Role** Two main roles, Digestion and absorption **Digestion** - Process by which we break down the large food molecules that we eat into smaller molecules **Absorption** - Process by which we absorb theme molecules into minerals, vitamins and water to be sent around the body **Organs** Mouth - Starts in the mouth, contains teeth and salivary gland - Teeth, increases surface area by breaking food down easier to swallow - Salivary gland - Release Saliva which contains amylase, Stomach - Contracts muscular walls, to mix the mixture of foods - Produces Pepsin a Protease Enzyme - Produces Hydrochloric Acid, Kills bacteria and produces correct pH Small intestine - Where most of the digestion takes place - Site of absorption into the blood - Carbs and Proteins already partially digested, large amount happens in the small intestine - Releases Digestive Enzymes - Absorbed through villi which have a large surface area for diffusion, Single layer of surface cell, small diffusion distance, Really good blood supply Pancreases - Releases pancreatic juices into the small intestine - Help digest the food Gall bladder - Releases bile into the small intestine - Neutralizes the pH of the stomach acid - Break down the big lipids into smaller droplets, larger surface area Liver - Makes Bile Large Intestine - Absorbs additional water Rectum - Stores waste Anus - Removes Waste

Answer 38

**Different tests** Benedicts test Sugar Biuret Test Protien Iodine Test Starch **Steps** - Prepare food, Crush down, mix in a water mixture and filter solution and that solution is the usage for the tests **Sugars** - Benedicts only tests for Reducing sugars - Transfer 5cm 3 of sample - 75 degree water bath - Add 10 drops of solution and place into the water bath - If non present will remain blue, If there is will change to **Brick Red if high concentration** **Starch** - 5cm of sample - Add a few drops of Iodine - Will turn brownly orange - Gentle shake - If solution will go from **orange to black** **Biuret test** - 2 cm of sample - 2 cm of Biuret solution - Gentle shake - From **blue to pink or purple** **Lipids** - 5 cm Not filtered - 3 drops of Sudan 3 solution - Shake - Red layer forms on the top

Answer 39

All cells to get energy require to complete Cellular respiration which requires oxygen First passes through Mouth/Nose, Down windpipe and through Bronchi, going past Bronchioles - Reaches Alveoli site of gas exchange **Alveolus** - 1 Cell thick wall, Increases rate of carbon dioxide and oxygen can diffuse - Very large surface area - Moist surface area which allows gases to dissolve increasing rate of diffusion - Borders red blood cells - Unoxygenated blood gets oxygen from the alveoli diffusing from it to the blood cells - Carbon dioxide higher concentration in the blood cells than in alveoli so diffuses the other way Number of Breathe / Number of Minutes

Answer 40

**Circulatory System** - Organ system - Made up of a group of organs to complete a common function - Heart, Blood vessels and blood - Transport substances around the body **Double** - Called due to the two separate circuits **Pulmonary Circuit ** - Blood flows from the heart to the lungs back to heart **Systemic Circuit** - From heart to all of the body and goes back to the heart Both circuits work in pattern together **Heart** 4 chambers 2 On the top called Atria 2 on the bottom called ventricles Either side has Atrioventricular values ensuring it only flows in one direction Heart is back to front from viewing it e.g left side is the right Right atrium and right ventricle - Pulmonary Circuit Left Atrium and Left ventricle - Systemic Circuit - Top left vessel called **Vena Cava** largest veu=in - Deoxygenated blood flows from the body to heart - In right atrium - Contracts into right ventricle - Contracts into the **Pulmonary artery** - Pumped into **Pulmonary vein** - Goes into left atrium - Contracts - Left ventricle - Contracts - Into the **Aorta** around the body, largest artery **Conernoury artery's** - Make sure that the tissue gets all the oxygen it needs to propel around the body

Answer 41

**Vessels** - Arteries, Carry blood away from the heart **Capillaries** - Exchange nutrients with tissue **Veins** - Carry blood back to the heart **Arteries** - Blood will be at a high pressure - Arteries are strong and elastic - Thing layer of muscle and elastic tissue - Wall is quite thick compared to lumen **Capillaries** - Very small - Exchange substances with cells - Take away waste products - Single cell thick - Permeable - Large quantity **Veins** - Large - Biggest Lumens - Thin walls - Blood is low pressures - Contain valves to stop from flowing backwards

Answer 42

**4 things blood consistes off** Red blood cells White blood cells **Red Blood cells** - Half our blood by volume - Carry oxygen to the body to complete cellular respiration using oxy hemoglobin - Diffuse into tissues - No nucleas - Shaped like a disk for a large surface area **White blood cells** Less than 1% of blood - Defends against infection - Phagocytosis, engulf pathogen - Antibodies, Bind onto pathogens - Antitoxins, neutralize toxins - Have a nucleas **Platelets** - Small fragments of cell - Float in blood - No nuclease - Clot for any sort of injury from cuts - Forms a scab **Plasma** 50% of blood volume - Carries everything and nutrients - Makes it watery so it can flow - Contains a lot of different things 5 liters of blood at any one time **Types of blood transfer** Artificial blood, - Salt water, - Adds volume - Doesn't contain red blood cells Blood transfusion - Real blood - Has red blood cells - from donations

Answer 43

**Examples** - Heart attacks - Coronary heart disease - Faulty valves - Heart failure **Coronary heart disease** - When the arties get blocked by fatty material, lumen gets smaller less blood and oxygen - Causes strain on the heart **Treatment** Stent - Expandable tube inside artery, ensures blood can flow - Surgery, Lasts a long time Statins - Medication altering balance of cholesterol in blood stream - ldl has too much taking this pill will decrease the bad increasing the good type - Lower risk and other diseases - Taken regularly - Side effects **Damaged Valve** - Not enough blood can pass through or doesn't close properly so blood leaks backwards - Replaced by new ones from other humans or animals - Manmade mechanical valve - Both require surgery **Heart Failure** - Cant pump blood correctly - New heart only treatment - Real biological hearts or artificial hearts - Artificial hearts only temporary fix - Pig and cow hearts wont work - Long waiting list that must be a match Artificial, the immune system doesn't destroy them

Answer 44

**Health** State of physicals and mental wellbeing - Several factors affecting health, no direct understanding of what accounts for positive or negative life styles **Communicable disease** - From person to person - Infectious disease - Viruses, Bacteria, Parasites, Fungi - Common cold, Malaria, Meningitis **Non communicable disease** - Cannot be spread - Asthma, Cancer **Ill Health** - Wont be able to defend against communicable disease - Can lead to other virus/illness - Skin rashes immune system overreacting to a pathogen - Physical and mental health

Answer 45

**Risk factor** - Anything that increases the chance of a person developing a certain disease Split into environment and lifestyle that impact on different risk factors Smoking - Increases cancer, Lung disease and cardiovascular disease Drinking - Too much alcohol liver disease Obesity - Type 2 diabetes Exposure - Cancer to IR or asbestos **Disease effects** - Illness means more off work, more spent on health and less working so less economic growth - Scientist make estimations on who Developed countries lead to obesity and sedentary lifestyles Cancer common in deprived areas

Answer 46

**Cancer** - Cancer is a disease when abnormal cells grow uncontrollably and spread to other parts of the body **Tumours** - Abnormal mass of cells tat undergo uncontrolled growth and division **Benign** and **malignant** tumours **Benign** - Stay in one play - Contained by membrane - Not dangerous or cancerous **Malignant** - Enter the blood stream - Travel to different parts - Invade different tissues - Lead to cancer - Very dangerous **Risk factor** - Smoking and lung cancer as well as mouth and stomach cancer - Obesity and bowl cancer - UV and Skin cancer

Answer 47

Similar cells - Tissues - Organs - Organ systems **Structure of a Leaf** - Function, Site of photosynthesis, requires co2 and water to make sugars - Carbon dioxide diffuses through the stomata directly, found in the lower epidermis - Upper epidermis almost transparent so sunlight can pass through - Palisade Mesophyll photosynthesis palisade cells full of chloroplast - Phloem carries sugar to plant - Xylem brings water from roots Problem is water loss from top and bottom of leaf - Stomata open for as short as possible - Each stoma contains different guard cells, if full and bloated gap opens Turgid and shuts to flaccid if shortage of water - Close during night as sensitive to night - Lower surface more shaded so less water evaporates **Meristem Tissue** - Growing tips at roots and shoots differentiate

Answer 48

**Translocation** - Sugars move and transported - Through Phloem tubes, contains small pores to allow movement of cell sap - Can be transported long distances - Used for energy or stored for energy later - Phloem can transport in either direction - Xylem tubes, column of cells, dead xylem cells, one long hollow tube strengthened with lignin **Transpiration** Water move and transported - Driven by evaporation of water from leaf - As one evaporates it drags the rest up the plant - Chain of water molecules known as transpiration stream - Rate varies, Effected by, Light intensity, Temperature, Airflow and humidity

Answer 49

**Fungi** - Eukaryotic Organisms, Unicellular or Multicellular - Multicellular have hyphae penetrate skin **Rose Black Spot** - Purple or black spots killing the leaf and reduces amount of photosynthesis - Fungicides to treat - Chop off and destroy leaves **Protists** - Eukaryotes, Single or Multicellular - Classed as parasites' at the other organisms expense - Transported by vectors, dont get disease **Malaria** - Parasitic protist, needs a host by mosquitoes - Spread to new host

Answer 50

**Viruses** - Not cells, Not living, considered organisms - 10,000 x smaller than animal cells, - Cannot reproduce by themselves using a cells technology to overcome and eventually bursts the cells **Example** Measles - Spread by droplets when someone coughs or sneezes, red rash across body, fever and can be fatal HIV, - Sexual contact, Causes inadequate immune system, flu like symptoms including tiredness and aches. Start to feel better, Develops into aids when the immune system cannot cope, can take pills to cope Tobacoo Mosaic virus - Affects plants - Tobacco and Tomato plants - Photosynthesis cannot take place over the patches

Answer 51

**Bacteria** - Most are positive bacteria - Damage our cells **Salmonella** - Causes food poisoning, fever, stomach cramps and diarrhoea **Gonorrhoea** - Sexual contact - Pain when urinating - Thich discharge from genitalia - Preventation unsafe sex - Treatment - Expensive anti- biotics

Answer 52

**Microorganisms** - A group of tiny organisms like bacteria, viruses, protists and fungi, **Pathogens** - Microorganisms that can cause disease **Spread** - Through the air, Many influenza or measles through droplets in the air - Contaminated food or water, such as cholera or Salmonella - Direct contact, such as athletes foot through contact Stop spread - Good Hygiene - Kill the vectors (Organisms that transport the pathogens) - Vaccinations - Isolate or quarantine the diseased person

Answer 53

**Defense system** - Protects against pathogens **Physical Barriers** - Skin acts a physical barrier to stop pathogens from entering the skin - enter through holes like mouth or nose - Several little hairs or mucus to stop the pathogens Trachea all covered in mucus to trap particles Stomachs hydrochloric acid kills all pathogens, some will make it in **Immune system** - White blood cells, Circulating in the blood system **Phagocytosis** - Engulf pathogens, Binding and destroying them **Anti toxins** - Produce toxins that can damage our cells **Antibodies** - Small proteins made by our white blood cells, locking on antigens and acting as signals to get them to destroy it - Rapidly produces anti bodies and remembers its genetic code

Answer 54

**Vaccines** - Once they have been exposed to that pathogen we become immune as a result of the antibodies genetic code - Must somehow get the immunity and learn the code without catching the strain - Vaccines contain weakened or inactive pathogens our body treats them like normal and produces antibodies and develops an immunity - Bacteria and Viruses can be used for **Pro** - Protect against horrible diseases - Control a lot of diseases - Prevent big outbreaks of disease - Herd immunity - Pathogen can no longer spread and overcome the disease **Cons** - Dont always work - Dont grant full immunity - Bad reaction to vaccine -

Answer 55

NHS Spends 17 billion on medicines a year Split into relieve the symptoms and treat the disease itself Negatively effect the quality of life of people intended to help them feel better as well as against the root courses of the disease

Answer 56

**Development** - Plant developments so we can use them directly or modify them **Examples** Aspirin - Bark of willow trees Digitalis - Chemical found in foxgloves Penicillin - From a fungus **Testing** Tests efficacy of how well it works Dosage - Requirements of how much is needed Side effects - If there is any other side effects *Preclinical* Stage 1 - Human cells and tissues testing Stage 2 - Testing on a live animals *Clinical* stage 3 - Healthy volunteers low dosage - Increase dose until limit reached - Given to those suffering with illness, looking for the optimum dosage **Placebo** - Substance like the real drug however doesn't do anything, completely blind and random, do not tell who is getting what to limit the **Placebo** effect They are peer reviewed

Answer 57

**Photosynthesis** - Takes place in the leaf, in the chloroplast in the pigment of chlorophyll which absorb light - CO2 and water to Glucose and oxygen **Glucose usage** - Cellular Respiration, Produces energy - Combined to make Cellulose, strengthen cell walls - Combined to make Starch, no function strong energy store - Making amino acids glucose = nitrate ions - Making oils and fats for future energy resource

Answer 58

**Factors** **Light intensity ** - As it increases so does the rate until a point when it plateaus as there is another limiting factor **Carbon Dioxide** - Increases so does the rate of reaction until it plateaus as there is another limiting factor **Chlorophyll** - Less of it means less photosynthesis, different plants have different amounts of it, can be effected by environmental stress, disease or lack of nutrients **Temperature** - Increases in the beginning until it summits and begins to decrease as the enzymes denature due to the increased heat **Ways to maximize** - Fertilizer, Heater, Artificial light, Greenhouses, Pesticide

Answer 59

**Respiration** - An exothermic reaction which transfers energy from glucose and continuously occurs in a living cells **Example** - Build larger molecules from smaller ones e.g amino acids to proteins - Muscular contractions - Maintaining body temperature **Two types** **Aerobic** - Involves enough oxygen, efficient way to transfer energy and takes place continuously glucose = oxygen -> carbon dioxide + water **Anaerobic** - Respiration without water - Small scale high intensity exercise Glucose -> Lactic Acid - Partially broken down not optimal - Lactic acid is produced which is toxic **Plants and yeast** Glucose -> Ethanol + Carbon Dioxide - Fermentation - Used for economical ways

Answer 60

**Exercise** - Requires more respiration, so needs more oxygen from the air, Need to move the oxygen around the body, increasing heart rate increasing energy, Hopefully it will be enough to keep up If not we use anaerobic too, will lead to muscle cramping's through lactic acids Gets rid of reacting with oxygen so more acid, more oxygen needed **Oxygen debt** Blood -> Liver -> Reacts the acid with oxygen Breathing rate - Amount the chest raises and falls in a given time frame Heart rate - Measure pulse in a time frame

Biology Flashcards

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