Photosynthesis and Partitioning Flashcards

1
Q

What is a source?

A

Provides assimilates. e.g. green photosynthesising leaves.

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2
Q

What is a sink?

A

Uses assimilates. e.g. flowers, seeds, developing leaves.

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3
Q

How much solar energy is outside of the spectrum so cannot be used by plants?

A

51.3%

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4
Q

How is energy lost?

A

Energy lost by reflection
NPQ- energy dissipated as heat
Carbohydrate synthesis loss

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5
Q

What is photorespiration?

A

Carbon or O2 is fixed into sugars.
Wasted energy

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6
Q

What is the reaction of photorespiration, and what do the products do?

A

RuBisCO + O2 ~> 2 phosphoglyolate + 3 phosphoglycerate

2 phosphoglycolate: Useless, costs energy to turn it into something useful
3 phosphoglycerate: Stores energy

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7
Q

What is non photochemical quenching (NPQ)?

A

Photosynthetic proteins absorb excess energy and dissipate it as heat.
Done by the Xanthophyll cycle.

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8
Q

What is the Xanthophyll cycle?

A

Violaxanthin ~> Antheraxanthin ~> Zeaxanthin
Done by light stress

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9
Q

What does Zeaxanthin do?

A

Protects lipid membranes
Stimulates NPQ

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10
Q

What is partitioning?

A

Fewer assimilates go to roots, stems and tillers and more go into growth and grain filling

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11
Q

What did the sugar beet ten year breeding programme do to the ratio of AGM : BGM and Marc : Sugar

A

AGM : BGM
1:2 ~> 1:2.8
Marc : Sugar
1:3 ~> 1:3.8

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12
Q

What is sink strength determined by?

A

Determined by genetics
Also by biotic and abiotic stresses.

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13
Q

What is SWEET11?

A

A group of sugar transporters.
Expressed heavily in developing grains

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