Biology

Photosynthesis in Plants

1,492 Questions

Photosynthesis is the biological process by which plants convert light energy into chemical energy. This page contains practice questions covering essential topics like chlorophyll, light reactions, and the pathways specific to plants. This material is crucial for medical entrance exams and academic assessments.

Chlorophyll and pigmentsLight reactionsCalvin cycleCAM plantsElectron transportPhotosynthesis factors

Photosynthesis in Plants Questions

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

Choose the correct answers from the alternatives given.
Cyanobacteria, unlike other types of bacteria that photosynthesize, do:

  1. not have a cell wall

  2. not have chlorophyll

  3. give off oxygen

  4. not give off oxygen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Cyanobacteria, also called blue-green algae, were among the earliest organisms on Earth. These primitive bacteria produce oxygen during photosynthesis as they fix CO$ _2$ dissolved in the water. So the correct option is 'Give off oxygen’.
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 biology different types of nutrition in plants experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

Consider the following pigments.
a. Carotenoids
b. Chlorophyll
c. Phycoerythrin
d. Phycocyanin
e. Phytochrome
The most likely sequence of the order in which they appeared during the process of evolution is?

  1. $1, 2, 3, 4, 5$
  2. $1, 2, 4, 3, 5$
  3. $1, 4, 3, 5, 2$
  4. $1, 4, 2, 3, 5$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The evolutionary sequence of pigments is generally accepted as starting from simpler light-harvesting molecules like carotenoids, followed by chlorophyll, then phycobilins (phycoerythrin/phycocyanin), and finally regulatory pigments like phytochrome.

Multiple choice biology plant nutrition experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

When the rate of translocation is slow, the rate of photosynthesis shall:

  1. Decrease

  2. Increase

  3. Remain unchanged

  4. Become zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Water in the plant is transported using a pressure flow mechanism. Translocation is the transport of nutrients and carbohydrates from source to sink, which is performed by the phloem. Pholem and xylem are present adjacent to each other in the vascular bundle of the plant. When the sugar ie sucrose is produced in the mesophyll of the leaves is produced it is transferred to the phloem to be transported. As the sugar concentration in the phloem increases water is diffused in the phloem from the xylem and this is what we call ascent of sap. When the water is diffused in the cells due the rigid wall the pressure in the cell increases. due to increase in the pressure at the source and low pressure at the sink the water along with the sugar is transported. As the sugar reaches the sink and leaves the cell water also moves out of the cell. Therefore the rate of photosynthesis is dependent on translocation rate. As the rate of translocation decreases the rate of photosynthesis also decreases.

  • Therefore, option A is correct. 
Multiple choice biology photosynthesis and respiration experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

Which of the following is the least effective in photosynthesis?

  1. Red light

  2. Blue light

  3. Green light

  4. Violet
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Green is the least effective color of light in driving photosynthesis. Photosynthesis occurs in plants and algae using chlorophyll, and because chlorophyll reflects rather than absorbs green light, green light cannot be used in the photosynthetic process.
So, the correct answer is option C.
Multiple choice biology photosynthesis and respiration experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

The pigment that absorbs red and far red light in plant is 

  1. Cytochrome.

  2. Xanthophyll.

  3. Phytochrome.

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

Phytochrome is a photoreceptor, a pigment that plants, and some bacteria and fungi, use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. It also regulates other responses including the germination of seeds, elongation of seedlings, the size, shape, and number of leaves, the synthesis of chlorophyll, and the straightening of the epicotyl or hypocotyl hook of dicot seedlings. 

So, the correct answer is option C.

Multiple choice botany plant nutrition experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases

During photosynthesis, oxygen in glucose comes from

  1. oxygen in air

  2. water

  3. carbon dioxide

  4. both (B) and (C).
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Isotope labeling experiments (using O-18) have demonstrated that the oxygen released during photosynthesis comes from the splitting of water molecules (photolysis), not from carbon dioxide.

Multiple choice botany plant nutrition experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases

It is advantageous to use a water plant to demonstrate photosynthesis other than a land plant because

  1. It photosynthesize rapidly

  2. It respires slowly

  3. It does not transpire
  4. O$ _2$ bubbles from cut water plant can be collected over H$ _2 $O
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice biology photosynthesis and respiration experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

The phenomenon of response seen in plants towards light is called as 

  1. Phototropism.

  2. Geotropism.

  3. Reflex action.

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

Geotropism (also known as gravitropism) is a turning or growth movement by a plant or fungus in response to gravity. It is a general feature of all higher and many lower plants as well as other organisms. 

Phototropism is the orientation of a plant or other organism in response to light, either toward the source of light (positive phototropism) or away from it (negative phototropism).
A reflex action, differently known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. Scientific use of the term "reflex" refers to a behavior that is mediated via the reflex arc. 
Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. 
So, the correct answer is option A.