photosynthesis Flashcards
What is the photosynthesis equation
Carbon dioxide+ water —–> carbohydrates and oxygen
In what ways are leaves adapted to absorb sunlight?
- large surface area
- arranged to minamise overlap
- transparent waxy cuticle
- transparent and have waxy cuticle
- multiple chloroplasts in the upper palisade mesophyll cells
How are leaves adapted for carbon dioxide capture
- thin so short diffusion pathway
- multiple stomata which let air in
- Stomata that open in sunlight
- Air spaces in the spongey mesophyll so air can circulate around all of the cell.
How are leaves adapted to bring in water
- Xylem transport water from the roots to the leaves
- Phloem delivers the products of photosynthesis to the rest of the plant
Fill in missing words-
- Chlorophyll molecules and other photosynthetic _________ are found on the ________ membranes.
pigments
thylakoid
Why are pigments in the thylakoid membrane useful for photosynthesis?
The different pigments absorb different wavelengths.
Plants have the pigments that will allow them to absorb the most light
Fill in missing words-
- When the light hits the chlorophyll molecule it raises the __________ level of a pair of ________ and they are said to have become excited
energy
electrons
Fill in missing words-
- The electrons are passed along a series of electron _______ in the thylakoid membrane that make up the electron ___________
carriers
transport chain
Fill in missing words-
- Each electron carrier has a slightly _______ energy level than the previous one. Some of the energy that is lost during this process is used to produce a _______concentration gradient
lower
proton (H+)
Fill in missing words-
- The photolysis of _______ releases _______ which adds to the increased proton concentration
water
protons
Fill in missing words-
- The electrons released during photolysis replace the ________ electrons that leave the ________ molecule when light hits it. The _______ released can by used by plants for respiration.
excited
chlorophyll
oxygen
Fill in missing words-
- The enzyme ATP _________ (also called a ______ granule) is a channel protein located on the ________ membrane.
Synthase
Stalked
Thylakoid
Fill in the missing words-
- When the protons move _______ their concentration gradient through the ATP ____________ channels they cause structural changes which allows the enzyme to catalyse the addition of ________________ _______________ to ADP forming ______. This process is known as ___________.
down
synthase
inorganic phosphate
ATP
Phosphorylation
Fill in the missing words-
- The final electron acceptor (NADP+) takes up the protons resulting in the production of __________ NADP (NADPH)
reduced
Fill in the missing words-
- The excited electrons leave the chlorophyll molecule and are taken up by (reduces) an ____________ ____________ and the chlorophyll becomes _____________. This process is called ________________.
electron acceptor
ionised
photoionisation.
How do membrane create a proton concentration gradient?
Membranes are selectively permeable to H+ to create a proton gradient.
Non cyclic phosphorylation vs cyclic phosphorylation
Non cyclic- The electrons that origionated in the chlorophyll molecule in PS11 (photosystem 11) end up in a totally different molecule (NADPH)
Cyclic phosphorylation- Occurs when only the PS1 and the electrons return to the chlorophyll in PS1
Cyclic phosphorylation (tick box)
Photosystem- PS1
Photolysis- No
Fate of electrons- Returns to chlorophyll
Products- ATP
Non cyclic phosphorylation (tick box)
Photosystem- PS1 and PS11
Photolysis- Yes
Fate of electrons- Accepted by NADP+
Products- Oxygen, NADPH, and ATP
Adaptations of chloroplasts
- Large surface area membrane
- Chlorophyll held in place by protein network to maximise absorbsion
- Membranes have ATP synthase channels
- Membranes selectively permeable to H+ to create a gradient
- Own DNA and Ribsosomes to produce the necessary proteins
What is the location of the light dependant reactions
Thylakoid
What are the raw materials needed in the light dependant reactions
Light, water
Products of the light dependant reactions
ATP, oxygen, NADPH
What is the location of the calvin cycle
Stroma
What are the raw materials needed for the calvin cycle
NADPH, ATP, CO2
What are the products of the calvin cycle
Carbohydrates
Fill in the gaps of the calvin cycle-
CO2 from the atmosphere diffuses into the ………………… of the chloroplast
CO2 reacts with RuBP to form an unstable 6 carbon intermediate molecule. This reaction is catalysed by the enzyme ………………………
The unstable 6 carbon intermediate splits into 2 molecules of 3 carbon ………………………. 3 phosphate (GP)
Reduced …………………. is used to reduce GP into …………….. phosphate (TP) using energy supplied by ……….
Most of the TP is used to regenerate RuBP using energy from ……
A small quantity of the TP is converted into organic molecules such as starch, cellulose, lipids, amino acids, and ………………..
Stroma
rubisco
glycerate
NADP
triose
ATP
ATP
nucleotides
Where do the molecules of ATP and NADPH come from?
The light dependant reaction
Suggest what happens to the molecules of ADP and NADP that are produced during the Calvin cycle.
They are re- energised into the light dependant reaction
How many molecules of carbon dioxide (1C) are required to produce on molecule of glucose(6C)?
6
Describe the ways in which the stroma is in ideal environment for the Light Independent Reaction to occur.
- Contains own DNA and ribosomes to produce proteins required (rubulose)
- Double membranes surround the stroma fluid keeping high concentrations of the enzymes and substrates required for the calvin cycle
- The grana are surrounded by the stroma fluid so short diffusion path for the ATP and NADPH produced during the light dependant stage
Describe the law of limiting factors.
At any given moment the rate of a physiological process is limited by the factors that is its least favourable value
Which part of photosynthesis is affected by low CO2 levels?
Calvin cycle
What molecules would you expect to build up if carbon dioxide has become a limiting factor?
RuBP, NADPH, ATP
Describe the relationship between temperature and photosynthesis rates between 0 and 25 oC.
increasing molecular collisions- increased kinetic energy meaning an increased rate of photosynthesis
Describe and explain what happens to photosynthesis at higher temperatures than 25oC.
Hydrogen bonds in the enzymes will break which changes the tertiary structure of the enzymes, and the active site shape changes. This means no enzyme substrate complex is formed.
When measuring photosynthesis (pondweed experiment) what control measures must be taken?
Temperature
Ph of liquid (co2 levels would change)
Plant species
Size of plant
In photosynthesis experiments why is the gas collected not necessarily an accurate measurement of photosynthesis rates
- some of the oxygen is used in respiration or dissolved in the water
- other gases might be dissolved in water
