Photosynthesis (from maam) Flashcards
process that captures light energy and transforms into the chemical energy of carbohydrates
Photosynthesis
Where does photosynthesis occur
- plasma membranes of some bacteria
- cells of algae
- leaves of plants
- outermost layer of plants, which covers leaves, fruits, flowers, and non-woody stems of higher plants.
- protects plants against drought, extreme temperatures, UV radiation, chemical attack, mechanical injuries, and pathogen/pest infection.
cuticle
- outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant
- this and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection
epidermis
- internal ground tissue located between the two epidermal cell layers of the leaf
- composed of two kinds of tissues
Mesophyll
Two kinds of tissues in the mesophyll
- Palisade mesophyll
- Spongy mesophyll
- where most of the photosynthesis occurs in the leaf
- contain a lot of chloroplasts to help them perform this photosynthesis
- closely packed together to maximize light absorption.
palisade mesophyll layer
site of gaseous exchange for photosynthesis and respiration
Spongy mesophyll layer
- conducting vessel of a plant
- consists of the xylem and phloem.
vascular bundle
- layer of compactly arranged parenchyma surrounding the vasculature
- conduit between the vasculature and the mesophyll cells.
bundle sheath
- pores on the surface of the leaves and other aerial parts of most higher plants
- allow uptake of CO2 for photosynthesis and the loss of water vapor from the transpiration stream
Stomata
Parts of the chloroplast
- outer membrane
- inner membrane
- stroma
- granum
- thylakoid
basic structural unit of the thylakoid membrane network of plant chloroplasts
Granum
fluid-filled internal space of the chloroplasts which encircle the grana and the thylakoids
Stroma
site of photochemical or light-dependent reactions of photosynthesis
Thylakoid
Two reactions that happen in the three stages of photosynthesis
- Light-dependent reactions
- Light-independent reactions (Calvin Cycle)
Three stages of photosynthesis
- Capturing energy from sunlight
- Using energy to make ATP and NADPH
- Using ATP and NADPH to power synthesis of carbohydrates from CO2
first and second stage of photosynthesis
light-dependent reactions
third stage of photosynthesis
light-independent reactions
formula of photosynthesis
6 CO2 + 12 H2O + Light energy –> C6H12O6 + 6 O2
Where does the three stages of photosynthesis occur
chloroplast
pigment of plants that capture light
chlorophyll
- occur in the thylakoid membrane
- Use sun’s energy to excite electrons to higher energy levels
Light-dependent reactions
Excited electrons of light-dependent reactions
- move through an electron transport chain, potential energy converted to some ATP (photosystem 2)
- packed into NADPH (photosystem 1)
The ___ and ___ are then used in the Calvin cycle to synthesize sugars
- ATP
- NADPH
Light consists of tiny packets of energy called ___
photons
High energy photons have ___ ___/___ ___ than low energy photons
- shorter wavelengths
- higher frequency
full range of photons
electromagnetic spectrum
visible light
400nm - 740nm
molecules that absorb light energy
pigments
chlorophylls in plants
- chlorophyll a
- chlorophyll b
- capture wavelengths not efficiently absorbed by chlorophyll
- example of accessory pigments
carotenoids
absorption spectrum of carotenoids
400nm - 500 nm
pigment-protein
complex in the thylakoid membrane forms the
___
photosystem
Chlorophyll is embedded in a __ __ in the thylakoid membrane
protein complex
Five stages of light-dependent reactions
- Capturing light
- Exciting an electron
- Electron transport
- Making ATP
- Making NADPH
The __ __ of photosystem II first captures the photons
antenna complex
antenna complex
- generates high-energy electron that is passed through an electron transport system
- drives synthesis of ATP
The electron is then transferred to __ __
photosystem I
electron of photosystem 1
- gets energy boost from another photon of light
- pass through another electron transport system
- drives synthesis of NADPH
__ __ is transferred between molecules
Excitation energy
Lost electron is replaced by one from __ __
water breakdown
Plants use two photosystems that occur in series. The process is called __ __
noncyclic photophosphorylation
noncyclic photophosphorylation
photosystem II -> electron transport system -> photosystem I -> electron transport system
- Occur in the stroma of the chloroplast
- Occur without the presence of sunlight
- Carbon molecules from CO2 are fixed into glucose.
light-independent reactions
carbon molecules in light-independent reactions
- fixed into glucose
- from CO2
site of calvin cycle
stroma
absorption spectrum of chlorophyll b
mostly 453nm and 642 nm
absorption spectrum of chlorophyll a
around 450-475 nm and 650-675 nm
