5.6 Flashcards
(116 cards)
Granum
Inner part of chloroplasts made of stacks of thylakoids membranes where light-dependant stage of photosynthesis occurs
Photosynthetic pigment
Pigment that absorbs specific wavelengths of light and traps energy associated with light, such pigments include chlorophyll a and b, carotene and xanthophyll
Photosystem
System of photosynthetic pigments found in thylakoids of chloroplasts, each photosystem contains about 300 molecules of chlorophyll that traps photons and pass their energy to a primary pigment reaction centre, a molecule of chlorophyll a, during light dependant stage of photosynthesis
Stroma
Fluid filled matrix of chloroplasts where light independent stage of photosynthesis takes place
Thylakoid
Flattened membrane bound sac found inside chloroplasts, contains photosynthetic pigments/photosystems and is the site of light dependent stage of photosynthesis
What is photosynthesis
A physiological process used by plants, algae and some bacteria to covert light energy from sunlight into chemical energy
What do organisms do with chemical energy converted form light energy
Use chemical energy to synthesise large organic molecules which form building blocks of living cells from simple inorganic molecules like water and CO2 (autotrophic nutrition)
What are organisms that photosynthesise called
Photoautotrophs as they use light as an energy source for autotrophic nutrition, they are described as producers as they’re at the beginning of the food chain and provide energy and organic molecules to other non-photosynthetic organisms
What is photosynthesis equation
6CO2 +6H2O + energy from photons -> C6H12O6 + 6O2
What is a photon
A light particle, each photon contains an amount of energy
What is main product of photosynthesis
Monosaccharide sugar which can be converted to disaccharides for transport and then starch for storage
What is photosynthesis an example of
Carbon fixation
What is carbon fixation
Process by which CO2 is converted into sugars, carbon for synthesising all types of organic molecules is provided by carbon fixation
What reaction is carbon fixation
Endothermic so needs energy, carbon fixation also needs electrons, the addition of electrons is a reduction reaction
What does carbon fixation help
Helps regulate concentration of CO2 in atmosphere and oceans, most forms of life on earth rely directly or indirectly on photosynthesis
What do plants that photosynthesise also do
Respire, during respiration they oxidise organic molecules that they have previously synthesised by photosynthesis and stored releasing chemicals
What are heterotrophs
Non-photosynthetic organisms like fungi, animals, many protoctists and many bacteria, they get energy by digesting complex organic molecules of food to smaller molecules that are used as respiratory substrates, they obtain energy from digestion products by respiration
What happens during respiration
Glucose and other organic compounds are oxidised to produce CO2 and h20, respiration releases chemical energy (exothermic) that can drive organisms metabolism
What is respiration equation
C6H12O6 + 6O2 -> 6H2O + 6CO2 + energy
What are both photosynthesis and aerobic respiration important in
Cycling of CO2 and o2 in atmosphere, products of one process are raw materials for the other process (aerobic respiration removes oxygen from atmosphere and adds CO2 while photosynthesis does opposite
What is the circle of aerobic respiration and photosynthesis
Photosynthesis in photoautotrophs-> carbohydrate + oxygen -> respiration in all living organisms -> carbon dioxide + water -> photosynthesis in photoautotrophs
Plants respire all the time but when does photosynthesis occur
Only during daylight
Why do plants often compete with each other
For light, intensity of light has to be sufficient to allow photosynthesis at a rate that replenishes carbohydrate stores used up in respiration
When photosynthesis and respiration occur at the same rate what is the net gain of plants and what’s this called
No net gain or loss of carbohydrates, the plant is at its compensation point