Question

The type of mycorrhizal symbiosis common in northern hemisphere temperate zone forest trees is:

Group of answer choices

Ectomycorrhizae (ECM)

Orchidaceous mycorrhizae

Arbuscular mycorrhizae (AM)

Endomycorrhizae

Ericoid mycorrhizae

Photorespiration: (choose all that apply)

Group of answer choices

Is favored under low CO2 concentrations and warm temperatures

Results in the formation of ATP through photophosphorylation

Does not use Rubisco for it's initial catalyzation

Reduces photosynthetic yield of oxygen

Consumes O2 and releases CO2

Answer 1

1. Correct ans is e. Ericoid mycorrhizae

They are the most dominant and widely spread mycorrhizal symbiosis in northern hemisphere of temperate zone, because the sand here is acidic and has low plant nutrients. Soil cannot hold water for long time. They occur on barren ,sandy land. The hyphae can go inside the epidermal cells and they forms loose network over hair root surface.

Orchidaceous mycorrhizae and arbuscular mycorrhizae needs tropical climatic conditions. Ectomycorrhizae can be seen in temperate and subtropical zones.

2. Correct ans is a, d, e

a. Basically, when CO2 levels inside a leaf are low, photorespiration occurs. Hot, dry days favors photorespiration. During these days, plant leaves close their stomata to prevent water loss. This triggers rubisco enzyme which is temperature sensitive. It fixes O2 insead of CO2 and this inhibits water requiring light conditions. Atlast, this enzyme oxidizes ribulose-1,5 phosphate and produces 3-phosphoglycerate (3 carbon compound) and 2-phosphoglycolate (2 carbon compound). There is a oxidation of carbon.

b.Photosynthesis results in formation of ATP through photophosphorylation and not photorespiration

c. Photorespiration begins with Rubisco enzyme by fixing O2 instead of CO2. This is rather the first step.

d. This reduces photosynthetic yield of oxygen, by adding oxygen to carbon. In this process, lot of energy is consumed. In this carbon is oxidized wheras in photosynthesis oxygen is oxidized. Since in this process there is no generation of ATP, it reduces photosynthetic yield of oxygen.

e. Photorespiration consumes O2 and it release C02 without ATP's production, because oxygen is utilized as a substrate instead of CO2.