Tag: photosynthetic cycle

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Questions Related to photosynthetic cycle

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, the acceptor of ${CO _2}$ is

  1. Pyruvic acid.

  2. Oxaloacetate.

  3. Phosphoenol pyruvate.

  4. Nucleic acid.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions.
  •  At low temperatures (frequently at night), plants using CAM open their stomata, CO2 molecules diffuse into the spongy mesophyll's intracellular spaces and then into the cytoplasm. Here, they can meet phosphoenolpyruvate (PEP), the CO2 acceptor.
  • Hence, In CAM plants, the acceptor of CO2 is Phosphoenolpyruvate. 
  •  So, the correct answer is 'Phosphoenol pyruvate'.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

The plant adaptation not suitable for hot and dry climates is
I. CAM
II. Mycorrhizae
III. ${C} _{4}$ photosynthesis

  1. I only

  2. II only

  3. I and II

  4. I and III

  5. I, II, and III
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Spatial separation of carbon dioxide fixation and RUBISCO activity in mesophyll and bundle sheath cells of $C _4$ plants respectively avoids photorespiration by concentrating $CO _2$ in bundle sheath cells to scale down the oxygenase activity of RUBISCO and increase the RUBISCO efficiency. The increased RUBISCO efficiency allows higher rates of photosynthesis even when stomata are closed for the longer time as well as reduces photorespiration and water loss. CAM plants reduce water loss by opening the stomata at night only. Mycorrhizae are the symbiotic fungi that reside in roots of higher plants and increase soil fertility by nitrogen fixation; it does not impart any adaptive feature to plant to cope with hot and dry conditions. 

Therefore, the correct answer is option B.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

The internal source of $C{ O } _{ 2 }$ in CAM plants is

  1. Oxalo-acetic acid

  2. Malic acid

  3. RUBP

  4. PEPA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide (CO$ _2$). So the correct option is 'Oxalo-acetic acid'.
Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In which of the following respects the photosynthetic adaptations of $C _4$ plants and CAM plants are similar?

  1. In both cases, stomata normally close during the day

  2. Both types of plants make their sugar without the Calvin cycle

  3. In both cases, an enzyme other than rubisco carries out the first step in carbon fixation
  4. Neither $C _4$ plants nor CAM plants have grana in their chloroplasts
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$C _4$ and CAM  plants are plants that use certain special compounds to gather carbon dioxide (CO 2 ) during photosynthesis. Exploitation of dry and arid habitats required adaptations in the form of $C _4$ and CAM photosynthesis, which independently evolved many times during periods of low atmospheric $CO _2$ levels carried out by carried out by a non-rubisco enzyme, PEP carboxylase, that has no tendency to bind $O _2$.

So, the correct option is, 'In both cases, an enzyme other than rubisco carries out the first step in carbon fixation'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In kranz anatomy, the bundle sheath cells have

  1. thin walls, many intercellular spaces and no chloroplasts

  2. thick walls, no intercellular spaces and large number of chloroplasts

  3. thin walls, no intercellular spaces and several chloroplasts

  4. thick walls, many intercellular spaces and few chloroplasts.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In Kranz anatomy, the bundle sheath cells are characterized by having a large number of agranal chloroplasts, thick walls impervious to gaseous exchange and no intercellular spaces.
Thus, the correct answer is 'thick walls, no intercellular spaces and large number of chloroplasts.'