biology paper 1

• photosynthesis produces glucose using light
• photosynthesis uses energy to change carbon dioxide and water to glucose and oxygen
• photosynthesis takes place in the chloroplasts in green plant cells
• chloroplasts contain pigment like chlorophyll that absorb light
• energy is transferred to chloroplasts from environment by light
• equation for photosynthesis


  co2 and water uses light to get glucose and oxygen
• symbol equation for photosynthesis

      6CO2        +    6H2O  →   C6H12O6   +    6O2  
• uses of glucose in plants

  respiration, making cellulose, making amino acids, stored as oil or fat, stored as starch
• plants use glucose in respiration by transferring energy from glucose enabling plants to convert into useful substances
• plants use glucose to make cellulose for making strong cell walls
• glucose is used in plants for making amino acids when glucose is combined with nitrate ions to make amino acids made into proteins
• glucose used in plants for storage of oil and fat , glucose turned into lipid for storing in seeds
• glucose stored as starch , where it is stored in roots , stem,leaves ready for photosynthesis
• starch is insoluble making it better for storing glucose , as it wont contains lots of glucose meaning it wont draw in water and swell
• limiting factor affecting photosynthesis rate is light intensity, temperature, carbon dioxide concentration, water availability
• chlorophyll is a limiting factor of photosynthesis
• amount f chlorophyll is affected by disease or environmental stress , e.g lack of nutrients, causing chloroplasts to become damaged and not make enough chlorophyll, meaning rate photosynthesis reduced meaning cant absorb as much light
• to artificially create ideal conditions for farming you can use greenhouse to help trap sun heat, so temperature doesn't become limiting. supply artificial light in winter or night , uses paraffin heater to maintain carbon dioxide levels
• keeping pants enclosed in greenhouse prevent them from pest and disease
• farmers can add fertiliser to soil so plants are getting nutrients needed for growth
• respiration is the process of transferring energy from glucose to the cell's molecules
• respiration reaction is exothermic
• organisms use energy transferred by respiration to build larger molecules like proteins from amino acids, in animals used for muscles to contract, in mammals for their body temperature to be kept
• metabolism is the sum of all the chemical reactions in a cell or organism
• lots of small glucose molecules join to make starch,glycogen,cellulose
• lipid molecule made from one molecule glycerol and three fatty acid
• glucose and nitrate ion make amino acid , made into protein
• enzymes speed up metabolic processes
• aerobic respiration uses oxygen , happens inside mitochondria
• aerobic respiration reaction


  C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O
• anaerobic respiration used if not enough oxygen
• anaerobic respiration is the incomplete breakdown of gucose making lactic acid
• anaerobic respiration equation in muscle cells

  glucose ----> lactic acid
• anaerobic respiration doesn't transfer nearly as much energy as aerobic respiration , this is because glucose is not fully oxidised
• anaerobic useful in emergencies
• plant and yeast cells respire without oxygen producing ethanol (alcohol), and carbon dioxide
• anaerobic respiration in yeast cells is fermentation
• muscles need energy from respiration to contract
• when during exercise muscles contract more frequently than normal so need more energy this comes from increased respiration
• increase in respiration in cells means you need more oxygen into them