In ‘regular’ C4 and CAM plants, the enzyme that first fixes CO2 into an organic
ID: 203798 • Letter: I
Question
In ‘regular’ C4 and CAM plants, the enzyme that first fixes CO2 into an organic molecule is
Ribulose 1,5-bisphosphate carboxylase/oxygenase for both
Phosphoenolpyruvate carboxylase for both
NADP-malic enzyme for both
Rubisco in CAM, PEPCase in ‘regular’ C4
Rubisco in ‘regular’ C4, PEPCase in CAM
Leaves exposed to full sunlight absorb a lot of energy and need to dissipate heat effectively to prevent damage. Which of the following are used by leaves to dissipate excess heat energy?
Radiative heat loss
Sensible heat loss
Latent heat loss
All of the above
A and C only.
The driving force for long-distance phloem transport is
Tension created by H2O evaporation from leaves
Pressure created by accumulated solutes and osmosis
The proton-motif force
Photosynthesis
Pressure created by H2O evaporation from leaves
Classify the following as either a source tissue or a sink tissue (note: for proper grading use only the words "sink" or "source" without quotation marks).
A) Cotyledon in a developing seed
B) Cotyledon in a germinating seed:
C) Mature leaf:
D) Immature leaf:
E) Mature flower:
F) Immature flower:
Explanation / Answer
1) The correct option 'C'
all types (Radiative, sensible and latent heat loss) is required to dissipate extra energy
explanation: The heat transfer between plants and environment occurs essentially in 3 ways mentioned above, plant temperature is one of the important factor for its health, with respect to c4 and CAM plants, the photorespiartion is waste metabolic pathway occuring when rubisco , the carbon fixing enzyme found in calvin cycle. absorbs oxygen rather than carbondioxide to reduce water loss by using fixed carbon, wasting energy and this occurs when plants close thier stomata. so if there is proper balance with heat loss, the temperature of the plant increases which will result in worst effects of photorespiration.
2) Sinks : these are the tissues indeed of nutrients,it is a sievre like tube that conducts products of photosynthesis to growing tissues, when they have low in supply of nutrients, it is usually transported from storage areas like roots and stem, Phloem helps in transport of sugar molecules from source to sinks
Soruce: these are tissue which stores the products of photosynthesis and supllies to sink sink tissue when they need it. this is the place of manufacturing.
sinks:1) Cotyledon in a developing seed
2) Immature leaf
3) Immature flower
Source: 1) Cotyledon in a germinating seed
2) Mature Leaf
3) Mature flower
Source and sinks of cotyledon was based on the study of amino acid leakge, where as flower leaf help in the storage and transport of sugars