Yr 11 - SCB - B2.4 - Photosynethesis Flashcards Preview

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Flashcards in Yr 11 - SCB - B2.4 - Photosynethesis Deck (13):

purpose of photosynthesis

convert solar energy into chemical energy and then store that chemical energy for future use


chloroplast diagram



Function of chloroplast

contains all the enzymes necessary for the photosynthesis reactions, and chlorophyll necessary for the capture of light energy.


Adaptations of chloroplast

1. oval in shape with a double membrane (inner and outer). means they have a large SA:Vol ratio for rapid diffusion of CO2 and H2O into the chloroplasts
2 flattened shape of the grana gives large SA where light dependant reaction happen. Chlorophyl is found within the thylakoid membrane of the grana. The grana’s increase in SA makes large number of chlorophyll to be in same areas to absorb as much light energy as possible.
3. stroma contains enzymes involved in the final stages of photosynthesis when glucose is produced. It is a clear fluid so allows light to pass through it. It also allows a temporary store for the products of photosynthesis such as starch granules.


PALISADE - Amounts of chlorophyl in different plant cells

- contain the most chloroplasts as they are at the top of the leaf
- cells are upright and close packed
- Just under the epidermis to get a higher light intensity
- Cytoplasm moves the chloroplast around like conveyor belt to maximise absorption
- Located to cell membrane for quick diffusion


SPONGY MESOPHYLL - Amounts of chlorophyl in different plant cells

Contain some chloroplasts as they undergo photosynthesis but their lower position in the leaf and lose-pack arrangement means they are not the main site of photosynthesis. Their loose-pack arrangement serves to provide large air spaces for fast diffusion/gas exchange.

- contain some chloroplast as they do photosynthesis but not many because at a lower position
- Loose arrangement of cells allows for arge air spaces for fast diffusion/gas exchange but less light absorption


UPER EPIDERMIS - Amounts of chlorophyl in different plant cells

These cells contain no chlorophyll as is not involved in photosynthesis but protect the cells below and have a waxy cuticle on their outside surface to prevent loss of water. They are transparent so the light passes easily through them to photosynthetic cells below.

- no chlorophyll as no photosynthesis occurs instead they protect cells below and have waxy cuticle to stop water loss
- transparent so the light passes easily through to other cells


Onion cells/root cells

No chloroplasts as never exposed to light


Word equation

Glucose + carbon dioxide --> water + oxygen + ATP energy


What is light dependant reaction

• occurs in grana (location of chlorophyll molecules)
• ATP synthesised
• Hydrogen produced which is passed on to stage

ATP and NADPH are passed onto the light independent reaction

NADPH is used to


limiting factors of photosynthesis

light intensity - how much light is available
temperature - temp of plant
CO2 concentration - availability


factors graph



2 stages of photosynthesis

1. Light dependant
- Water and sunlight used, oxygen released
- NADPH + H (hydrogen bus) and ATP are passed onto next stage

2. Light independent