Tag: photosynthesis

Quizzes (18) Questions (162)

Questions Related to photosynthesis

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

$CO _{2} : NADPH _{2} : ATP$ ratio for $C _{4}$ plants is

  1. $1 : 2 : 3$
  2. $2 : 3 : 4$
  3. $1 : 2 : 5$
  4. $1 : 5 : 10$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In C$ _4$ pathway for production of one molecule of glucose we require 12 NADPH$ _2$, 30 ATP and 6CO$ _2$ are required.

CO$ _2$ : NADPH$ _2$ : ATP =  6 : 12 : 30

CO$ _2$ : NADPH$ _2$ : ATP =  1 : 2 : 5

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Read the given statements and select the correct option. 
Statement 1 : Crassulacean acid metabolism occurs in succulent plants which grow in xeric conditions. 
Statement 2 : Stomata are generally sunken in succulent plants. 

  1. Both statements are correct

  2. Statement 1 s correct but statement 2 is incorrect.

  3. Statement 1 is incorrect but statement 2 is correct.

  4. Both statement are incorrect.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Crassulacean acid metabolism is a mechanism of photosynthesis involving double fixation of $CO _2$ which occurs in succulents belonging to Crassulaceae, Cacti, Euphorbias and some other plants of dry habitats. Here, the stomata remains closed during the daytime and opens only at night, e.g Sedum,Kalanchoe,Opuntia. Sunken stomata are deep seated stomata in which subsidiary cells lie above the guard cells.  So, the correct answer is 'Both statements are correct'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Internal source of CO2 in CAM plants is

  1. Oxaloacetic acid

  2. Malic acid

  3. RUBP

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

In  CAM plant, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at night to collect CO$ _{2}$. This CO$ _{2}$ is fixed into oxaloacetate by PEP carboxylase, which is then converted to malate. The CO$ _{2}$ is stored as malate in vacuoles at night, and then in the daytime, it is transported to chloroplasts where it is converted back to CO$ _{2}$, which is then used during photosynthesis.  

So, the correct option is 'Oxalo acetic acid'.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, $ C{ O } _{ 2 } $ acceptor is

  1. RuBP

  2. PEP

  3. OAA

  4. PGA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Crassulacean Acid Metabolism (CAM) is a specialised photosynthetic process which is characterized by the following criteria given by  Osmond (1978) and Cluge and Tuge (1978). These are:

  1. CO$ _2$ uptake takes place mainly at night
  2. stomata are open during the night and closed during the day when CO$ _2$ uptake is mostly negligible.
  3. Malate accumulates at night by carboxylation of PEP.
  4. Decarboxylation of malate during the day yields CO$ _2$ which is fixed up by RuBP carboxylase. 
During the night time when the stomata are open, the CO$ _2$ is absorbed and fixed by phosphoenol pyruvic acid (PEP, 3C) in presence of enzyme PEP carboxylase. As a result of this PEP gets converted into oxaloacetic acid (OAA, 4C).
So the correct option is 'PEP'

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants the site of  light reaction and glucose synthesis are 

  1. Mesophyll, Bundle seath

  2. Bundle sheath, Mesophyll

  3. Mesophyll, Mesophyll

  4. Bundle seath, Bundle seath
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Unlike C4 plants which segregate light reactions and carbon fixation between mesophyll and bundle sheath cells, CAM plants perform both processes within the mesophyll cells. The temporal separation (night vs day) allows both the light-dependent reactions and glucose synthesis (Calvin cycle) to occur inside the mesophyll cells.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

Which of the following metabolic cycle is an adaptation against Glycolate metabolism?

  1. Crassulacean acid metabolism

  2. Co-operative photosynthesis

  3. Reductive pentose phosphate pathway

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

Photorespiration involves the production of glycolate. C4 and CAM pathways are adaptations that concentrate CO2 around Rubisco to minimize photorespiration.

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'.