Tag: biology

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Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

How many quanta are required to reduce one molecule of $CO _2$ and produce one molecule of $O _2$ in green plant photosynthesis?

  1. 1

  2. 8

  3. 16

  4. 32
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to photosynthetic quantum yield requirements, the reduction of one molecule of CO2 and the evolution of one molecule of O2 typically requires 8 light quanta (photons) distributed across both photosystems in standard conditions.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

In $C _4$ plants, agranal chloroplasts are found in?

  1. Mesophyll cells

  2. Epidermal cell chloroplasts of green stem

  3. Bundle sheath cells

  4. Chloroplasts of guard cells
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

C4 plants exhibit Kranz anatomy where bundle sheath cells contain large, agranal chloroplasts (lacking grana) to facilitate the Calvin cycle without oxygen interference.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

The $C _4$ plants are photosynthetically more efficient than $C _3$ plants because.

  1. The $CO _2$ compensation point is low
  2. $CO _2$ generated during photorespiration is trapped and recycled through PEP carboxylase
  3. The $CO _2$ efflux is not prevented

  4. They have more chloroplasts
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In C$ _3$ plants, three molecules of ribulose monophosphate (RuMP), 5C compound, are phosphorylated by ATP to form three molecules of ribulose bisphosphate (RuBP). RuBP is the first CO$ _2$ acceptor. It absorbs CO$ _2$ in presence of enzyme RuBP-carboxylase to form transitory or additive 6C compound, which is unstable. Three molecules of additive 6C compound immediately split up by hydrolysis into six molecules of 3C compound called 3-phosphoglyceric acid (3-PGA). C$ _3$ plants can do photosynthesis only at high concentrations of CO$ _2$. In  C$ _4$ plants, the CO$ _2$ is not directly absorbed by RuBP in presence of enzyme RuBP carboxylase as this enzyme helps to absorb CO$ _2$ having concentration of 50 ppm or more. However, C$ _4$ plants, due to high temperature and high light intensity, keep their stomata partially closed due to which the CO$ _2$ concentration goes down to 2 ppm. Hence the C$ _4$ plants can conduct photosynthesis at low concentrations of CO$ _2$.

So the correct option is 'the CO$ _2$ compensation point is low'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

State whether the following statements are true or false.
Oxygen liberation is absent in bacterial photosynthesis.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Oxygen liberation is absent in bacterial photosynthesis as they have pigment bacteriochlorophyll for photosynthesis and this pigment does not work in the presence of oxygen. Cyanobacteria are the only bacteria which performs oxygenic photosynthesis. 

So, the correct option is 'True'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Choose the correct answer from the alternatives given.
Carbon becomes available to crop plants in the form of:

  1. elemental carbon

  2. carbonates

  3. carbon dioxide

  4. carbohydrates
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plants use carbon dioxide during photosynthesis, the process whereby the plant converts the energy from the sun into a chemical carbohydrate molecule.

So the correct answer is "carbon dioxide".

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Photosynthesis in C$ _4$ plants is relatively less limited by atmospheric C$O _2$ levels because 

  1. effective pumping of CO2 into bundle sheath calls

  2. RuBisCo in C4 plants has higher affinity for CO2

  3. four carbon acids are the initial CO2 fixation products

  4. the primary fixation of CO2 is mediated via PEP carboxylase.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Plants such as sugarcane and sorghum fix atmospheric carbon dioxide into phosphoenol pyruvic acid to produce oxaloacetic acid( a C$ _4$ acid) in the presence of phosphoenol pyruvate carbooxylase(PEP carboxylase). Such plants are called C$ _4$ plants.

In C$ _4$ plants, the primary product of OAA is mediated by PEP carboxylase, so it is relatively less limited by atmospheric CO$ _2$ levels.

So, the correct answer is 'The primary fixation of CO$ _2$ is mediated via PEP carboxylase'.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

...............fixes carbon in green plants as simple sugars

  1. Denitrification

  2. Photosynthesis

  3. Carbonation

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

Photosynthesis is a process that converts $CO _2$ into organic compounds and starch (carbohydrate) using energy from sunlight. $O _2$ is also released during this process.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

The saturation point of $CO _2$ in $C _4$ plants is?

  1. $390$ $\mu l/L$
  2. $450$ $\mu l/L$
  3. $460$ $\mu l/L$
  4. $360$ $\mu l/L$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

C4 plants are highly efficient at capturing CO2 and reach their photosynthetic saturation point at lower concentrations compared to C3 plants, typically around 360 microliters per liter.

Multiple choice c3, c4 and cam plants photosynthesis in higher plants biology

Calculate the death rate if $6$ individuals in a lab population of $60$ fruit flies died during a particular week?

  1. $0.2$
  2. $0.1$
  3. $1$
  4. $5$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Death rate is calculated as the number of individuals dying divided by the initial population size over a given time period. Here, 6 individuals died out of 60, resulting in 6 / 60 = 0.1 per week.

Multiple choice basics of management of water environmental science conservation of resources food production: soil and water management biology

Freshwater protozoans react to a/an __________ environment by removing water through

  1. hypotonic, turgor pressure

  2. isotonic, a contractile vacuole

  3. hypertonic, a contractile vacuole

  4. hypotonic, a contractile vacuole
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Freshwater protozoans live in a hypotonic environment relative to their cytoplasm. Water enters by osmosis, and they use a contractile vacuole to expel excess water.