module 5 - 17.3 photosynthesis (1) Flashcards
what is photosynthesis?
the process by which the Sun’s energy is used to synthesise organic molecules from 2 small inorganic molecules: carbon dioxide and water
what happens to light energy?
it is transferred to chemical energy stored in organic molecules such as glucose
what does it mean if an organism is autotrophic?
organisms that photosynthesise
what does it mean if an organism is heterotrophic?
organisms obtain organic molecules by eating autotrophs or heterotrophs
what do both autotrophs and heterotrophs use in respiration?
both use organic molecules such as glucose, as respiratory substrates to synthesise ATP from ADP and Pi by respiration
what are the adaptations, for photosynthesis, for a dicotyledonous leaf?
- large SA in chloroplasts
- flattened sacs called thylakoids (SA)
- short diffusion distance
- stomata
- vascular bundle
why are the apical surfaces of the upper and lower mesophyll moist?
for gas exchange
why do the lower or spongy mesophyll have air spaces?
to maintain concentration gradient and maintain bulk flow of the leaf
why is the cuticle transparent?
to allow light to get through for photosynthesis
why is the upper epidermis this and have no chloroplasts?
so light can get all the way through, no photosynthesis
how many membranes does a chloroplast have?
2 + thylakoids = 3 membranes
what are thylakoid membranes?
flattened sacs
what are grana?
stacked thylakoids
what are lanellae?
membranous channels
what is the stroma?
aqueous solution membrane
where are chlorophyll molecules located in a chloroplast?
embedded in thylakoid membrane
how is a large surface area of thylakoid membranes achieved in a chloroplast?
folded and flattened
what do photosynthetic pigments red, blue and green show?
red - long wavelength of visible light spectrum
green - middle length wavelength of visible light spectrum
blue - short wavelength of visible light spectrum
what are photosynthetic pigments?
coloured molecules that absorb and reflect different wavelengths or colours of visible light
what do photosynthetic pigments transfer?
light energy into chemical energy with high energy electrons
what is chlorophyll A?
the primary photosynthetic pigment and absorbs red and blue light or reflects blue/green
what are the 3 secondary photosynthetic pigments?
chlorophyll b - reflects yellow green
xanthophyll - reflects yellow
carotene - reflects orange
what is a photosystem?
functional unit in the thylakoid membranes that absorb light energy and transfer the energy to electrons to make high energy electrons
what are the 2 components of photosystems?
- antennae complex
- reaction centre
what is the antennae complex?
- contains secondary photosynthetic pigments bound to proteins or bound to chlorophyll a/b binding to a protein
- these pigments harvest light energy in the form of high energy electrons and amplify energy until it reaches reaction centre
what is the reaction centre?
contains chlorophyll a molecules nound to chlorophyll a/b binding protein, embedded in thylakoid membrane
