Paper 2

• How are nerve cells adapted for their function? (4)

  1.Axon is very long so easier to communicate over further distances

  2.Dendrites (branched endings) allow connections with many other neurones

  3. Nerve endings contain lots of mitochondria to provide energy to make transmitter chemicals
• How are muscle cells adapted for their function? (4)

  
  

  1. Contain many mitochondria to transfer the energy needed

  2. Can store glycogen which can be used in respiration to transfer the energy needed

  3. Contain special proteins that slide over each other making the fibres contract
• How are xylem cells adapted for their function? (3)

  1. Coated in lignin which kills cells, waterproofs them and creates a long hollow tube

  2. Spirals of lignin make them strong to withstand water pressure and support stem
• How are roots in plants adapted for exchanging materials? (2)

  1. Large surface area, increased by root hair cells

  2. Water moves constantly away from roots in transpiration stream, maintaining concentration gradient
• How is the structure of the root hair cell adapted to their function?

  They have a large surface area to increase absorption and they contain lots of mitochondria , which release energy from glucose during respiration in order to provide the energy needed for active transport.
• What is photosynthesis?

  An endothermic reaction where light energy is tranferred by chloroplasts to produce glucose.
• What is the word equation for photosynthesis?

  carbon dioxide + water -->glucose + oxygen
• What is the symbol equation for photosynthesis?

  CO2 + H2O --> C6H12O6 + O2
• What factors affect the rate of photosynthesis?

  Light intensity, carbon dioxide concentration, temperature and also the amount of chlorophyll.
• Why does temperature affect photosynthesis?


  Photosynthesis is a process that uses enzymes. If the enzymes get warmer, photosynthesis happens at a faster rate, but if the enzymes get too hot, they will denature and photosynthesis will stop.
• What is the glucose produced in photosynthesis used for?

  Respiration by all living cells. Also some is converted into starch, fats/oils, cellulose and amino acids.
• Why do plants store glucose as starch?

  Starch is insoluble, so doesn't affect osmosis. Also it is more compact, so easier to store large amounts. The starch is used by cells as a source of glucose for respiration when it is dark.
• What is respiration?

  An exothermic reaction where energy is released from glucose molecules. It happens continuously in all living cells.
• Why do living cells need to respire?

  Living cells need an energy supply for all the process they carry out (eg, chemical reactions, keeping warm and movement). Without this energy supply, cells would die.
• What are the two types of respiration?

  Aerobic (with oxygen) and anaerobic (without oxygen)
• What is the word equation for aerobic respiration?

  glucose + oxygen --> carbon dioxide + water (plus energy is transferred, but it is not a chemical so can't go in a chemical equation)
• What is the word equation for anaerobic respiration?

  glucose --> lactic acid (plus energy is transferred...not as much as in aerobic respiration as it is not as efficient due to the oxidation of glucose being incomplete)
• What's the anaerobic respiration equation in plants/yeast?

  glucose --> ethanol + carbon dioxide
• Why is anaerobic respiration sometimes called fermentation?

  Fermentation is just anaerobic respiration in plants and yeast, and it is economically important as it is how we produce bread and alcoholic drinks.
• What happens to respiration when we exercise?

  Respiration rate increases as our cells require more energy.
• What happens to heart rate when respiration increases?

  Heart rate increases so that blood circulates faster. This helps supply more oxygen and glucose to muscle cells (and removes lactic acid more quickly too).
• What happens to breathing rate when respiration increases?

  Breathing rate increases so that more oxygen enters the blood. This also helps supply more oxygenated blood to muscle cells (and removes carbon dioxide more quickly too).
• What happens to breath volume when respiration increases?

  Each breath volume is bigger as we breathe more deeply during exercise. This also helps supply more oxygenated blood to muscle cells.
• What if not enough oxygen gets to muscle cells?

  Anaerobic respiration will start to take place (as well as aerobic, with whatever oxygen is delivered to muscle cells). Lactic acid levels will start to build up, creating an oxygen debt.
• What is metabolism?

  The sum of all the reactions in a cell or a body.
• What is the energy transferred from respiration used for?

  Building up new molecules using enzymes inside cells.
• Sperm Cell

  • Long Tail (Flagellum) - to swim to the egg
  • Lots of Mitochondria - release energy through aerobic respiration
• Red Blood Cells

  • Biconcave shape
  • No organelles
  • Disk shape
• Nerve cell

  • Very long
  • Branched at either end
• Root hair cell


  large surface area
• Xylem

  • water & minerals travel in xylem vessels
  • transport from roots to shoots & leaves
  • made of dead cells
• Phloem

  • transport food in the form of sugars
  • made of living cells
  • companion cell keeps it alive
• What happens to the breaking down of glycogen cells when respiration increases?


  Glycogen is stored in the muscles - can be broken down into glucose
• Respiration


  Glucose + Oxygen -> Carbon Dioxide + Water + Energy
• Metabolic rate


  • Factors that affect it: age, exercise, genetics, gender
• Muscle Cell Function


  To generate movement
• Phloem Cell Function


  To transport sugar from the leaves to the rest of the plant (translocation)
• Nerve Cells Function

  To transmit messages from one part of the body to another
• Xylem Cell Function


  To carry water and mineral ions from the roots to the rest of the plant
• How are phloem cells adapted for their function?

  1. Cell walls between cells form sieve plates (tiny holes) which allow dissolved food to move between cells
  2. Supported by companion cells which have mitochondria to transfer energy for translocation