Photosynthesis Flashcards
what happens during photosynthesis?
light energy is converted to chemical energy in the form of glucose
what is the equation for photosynthesis?
6CO2 + 6H2O –> C6H12O6 + 6O2
when is the chemical energy released?
photosynthesising organisms release it during respiration
how do animals obtain their glucose?
eating plants or other animals that have eaten plants, then respire glucose to release energy
what are examples of metabolic pathways?
- photosynthesis
- aerobic respiration
- anaerobic respiration
what are metabolic pathways?
process that occurs in series of small reactions controlled by enzymes
what is anaerobic respiration?
- without oxygen
- plants + yeast cells: produce ethanol and CO2 and release energy
- humans: lactate produced and energy released
what is aerobic respiration?
- with oxygen
- produces CO2 and H2O and releases energy
can cells make their energy directly from glucose?
- no
- in respiration, energy released from glucose is used to make ATP
- ATP synthesised via condensation reaction, this uses energy from an energy-releasing reaction
= for example the breakdown of glucose during respiration - energy is stored as chemical energy in the phosphate bond
what is phosphorylation?
adding a phosphate to a molecule
what are properties of ATP?
- stores or releases small, manageable amounts of energy so no energy is wasted as heat
- small, soluble molecule so it can easily be transported around the cell
- easily broken down, so energy can easily be released
- quickly remade
- make other molecules more reactive by phosphorylation
- ATP can’t pass out the cell, so cell always has an immediate supply of energy
what is the compensation point of light intensity?
- when there’s a particular level of light intensity at which the rate of photosynthesis exactly matches the rate of respiration
how can we measure the compensation point?
- measure rate at which oxygen is produced and used by a plant at different light intensities
- compensation point of light intensity is when oxygen is being used as quickly as its being produced
where does photosynthesis take place?
chloroplasts
what type of membrane do chloroplasts have?
double membrane
what do chloroplasts contain?
photosynthetic pigments
what are photosynthetic pigments?
coloured substances that absorb light energy needed for photosynthesis
where are photosynthetic pigments found?
- found in thylakoid membranes and are attached to proteins
what does the protein and the photosynthetic pigment make?
photosystem
what are the two types of photosystems?
- Photosystem I (PSI)
- Photosystem II (PSII)
what is a photosystem I?
absorbs light best at a wavelength of 700nm