Unit 3.2 - Photosynthesis uses light energy to synthesise organic molecules Flashcards
(201 cards)
Location of photosynthesis
Chloroplasts
What do chloroplasts contain that absorb light energy?
Photosynthetic pigments
What do the photosynthetic pigments of chloroplasts do?
Absorb light energy at particular wavelengths of light
Photosynthetic pigments in chloroplasts
Xanthophylls
Carotene
Chlorophyll a
Chlorophyll b
Where are chloroplasts found?
In mesophyll tissues
Where predominantly in mesophyll tissues are chloroplasts found?
In the palisade mesophyll cells
Which other mesophyll tissue apart from the palisade mesophyll contains some chloroplasts?
Spongey mesophyll
Adaptations of leaves for photosynthesis
Large surface area
Thin
Air spaces in spongy mesophyll
Palisade cells are packed with chloroplasts and arranged with their long axes perpendicular to the surface
Cuticle and epidermis are transparent
Palisade mesophyll cells are elongated and densely arranged in layers
What does the large surface area of a leaf allow it to do?
Capture as much light as possible
Why has a leaf adapted to be thin for photosynthesis?
Allows light to penetrate through the leaf
Why do chloroplasts rotate and move within mesophyll cells?
Move into the best position for maximum absorption of light
What do the air spaces in the spongey mesophyll of leaves allow to happen?
Allows CO2 to diffuse to photosynthesising cells
Why are palisade cells packed with chloroplasts and arranged with their long axes perpendicular to the surface?
To capture as much light as possible
Why are the cuticle and epidermis of a leaf transparent?
So that light penetrates to the mesophyll
Why have leaves adapted so that palisade mesophyll cells are elongated and densely arranged in layers?
Can accommodate a large number and no cross walls to prevent light from penetrating through the cell = capture as much light as possible
What’s the main purpose of photosynthesis?
To synthesise carbohydrates by taking in simple inorganic compounds like CO2 and H2O and combining them to make complex carbohydrates
What’s the purpose of the starch granule in chloroplasts?
Glucose phosphorylised during photosynthesis is stored here as starch
Where are the photosynthetic pigments in chloroplasts?
Thylakoids
What are thylakoids?
Internal membranes of chloroplasts
How would thylakoids appear on an electron microscope photo?
Stained black
What’s a stack of thylakoids known as?
Granum
How are granum connected in chloroplasts?
By lamellae
What is the stroma of a chloroplast?
Fluid filled space
What provide evidence for the endosymbiotic theory of chloroplasts in chloroplasts? Explain
Circular DNA, like in prokaryotes
Theory states that Chloroplasts and mitochondria in eukaryotic cells were once free-living aerobic, prokaryotic organisms, that were then ingested by a large anaerobic, prokaryotic bacteria