Biology

Photosynthesis in Plants

1,508 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 evs seed becomes plant germination of seed seed germination journey of seed

What is true about phytochrome?

  1. ${P} _{r}$ absorbs red light and becomes ${P} _{fr}$
  2. ${P} _{r}$ absorbs yellow light and becomes ${P} _{fr}$
  3. ${P} _{fr}$ absorbs yellow light and becomes ${P} _{r}$
  4. ${P} _{fr}$ absorbs red light and becomes ${P} _{r}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Phytochrome is a pigment found in plants which is involved in various plant processes like seed germination. Seed germination requires sufficient amount of P$ _{pr}$. P$ _r$ is synthesized by germinating seeds and is converted to P$ _{pr}$ when exposed to red light. However, when seeds are exposed to far-red light, they will not germinate as P$ _{pr}$ is converted to P$ _r$.

Thus, the correct answer is option A.

Multiple choice biology plant taxonomy classification of kingdom plantae features of plant and animal kingdom plant classification

Which best explains why most plants appear green?

  1. They absorb green light.

  2. They do not absorb red light.

  3. They reflect blue light.

  4. They reflect green light.

  5. They generate wavelengths of green light when they absorb sunlight.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Plants appear green due to the presence of chlorophyll. Chlorophyll is a pigment present in the chloroplasts of the plants that absorbs in the blue and red region of light spectrum and reflects green light making the plants to look green. Thus, plants appear green because they reflect green light.
So, the correct answer is they reflect green light.
Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

For photoactive opening of stomata, the proton transport concept was given by

  1. Levitt

  2. Milborrow

  3. Ziegler

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Proton transport concept in stomata was given by Levitt and is most widely accepted theory.
According to this theory, protons formed due to malic acid dissociation in guard cells are transported to subsidiary cells and in exchange potassium ions move into guard cells. This ion exchange requires ATP. The potassium ions are osmotically active. Their influx into the guard cells increases osmotic pressure of guard cells and results in endosmosis, which opens the stomata.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

The proton transport concept for the opening of photoactive stomata was given by

  1. Yin Tung

  2. Levitt

  3. Sachs

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

Levitt in 1974, proposed a synthetic theory on the mechanism of stomatal movement, taking all earlier observations into account. The observed facts are:

(a) During opening of stoma, starch disappears from the guard cells.

(b) Photoactive opening is dependent on the chloroplast of the guard cells.

(c) Low $CO _2$ concentration causes stomatal opening.

(d) High pH in guard cells cause stomatal opening.

(e) There is a direct relation between $K^+$ accumulation and stomatal opening.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

According to sugar concentration theory, during ............, the guard cells begin photosynthesis.

  1. Night

  2. Daytime

  3. Both A and B

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to the sugar concentration theory, during the daytime, the guard cells do photosynthesis. And the sugar is produced during the process and it increases the osmotic pressure which draws in the water from the adjoining cells due to endosmosis.

So the correct option is Daytime.

The correct option is B.

Multiple choice biology mineral nutrition in plants nutrients and nutrition essential and non-essential mineral elements transport in the xylem of plants hydroponics hydroculture

The first acceptor of electrons from an excited chlorophyll molecule of photosystem II is:-

  1. Quinone

  2. Cytochrome

  3. Iron-sulphur protein

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

In the Z-scheme of photosynthesis, the primary electron acceptor from the excited chlorophyll molecule (P680) of photosystem II is Pheophytin, which is a type of Quinone.

Multiple choice biology biology : an introduction introduction to organization of life signs of life what is living?

The release of oxygen by the plant during photosynthesis can be related to which of the following characteristics of the living organism?

  1. Absorption

  2. Movement

  3. Response to stimuli

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Photosynthesis is a metabolic process done by plants to produce starch from carbon dioxide and water in presence of sunlight. During this process, residual oxygen atoms are turned to the oxygen molecules as a byproduct. So it's cannot be compared to absorption, movement, and response to stimuli.

So the correct option is D "none of the above".

Multiple choice biology constitutes of diet nutrients and foodstuffs simple test for nutrients test for nutrients

A green leaf is partially covered and placed in the light for several days. If it is then boiled and tested for starch with iodine, what will be the result? 

  1. Starch will be found only in the part of the leaf exposed to light

  2. Starch will be found in the entire leaf

  3. Starch will be found only in the shaded part of the leaf

  4. Starch will not be found in the leaf at all
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A green leaf is partially covered and placed in the light for several days. If it is then boiled and tested for starch with iodine starch will be found only in the part of the leaf exposed to light. This is because starch is the end product of photosynthesis. The process of photosynthesis will take place only in the location of leaves where light is present. 

In the given question, the leaf is partially covered which means, no photosynthesis takes place in these areas. Thus, when iodine is introduced to these parts after boiling, it cannot give blue-black color. Whereas the other parts which were exposed to sunlight will give blue-black color.
So, the correct answer is option A.

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

Which scientists are related with light reaction and what is its site?

  1. Arnon and Hill, grana

  2. Ruben and Kamen, Stroma

  3. Willstatter, Stoll, inner membrane of chloroplast

  4. Calvin and Benson, outer membrane of choloplast
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chloroplasts contain an internal system of membranes called thylakoids. The thylakoids may be arranged in stacks called as grana. The thylakoid membranes not arranged in stacks and are in direct contact with chloroplast stroma are called as stroma lamellae. During photosynthesis, light reaction occurs in grana.
Hill conducted experiments on isolated chloroplasts, having some oxidants like ferricyanide and benzoquinone (Hill reagents). By placing them in sunlight, he noticed evolution of oxygen from water. Hill concluded that if there was hydrogen acceptor in the medium, it would have been reduced. Arnon in 1951, 1954, repeated the experiment with isolated chloroplast and concluded that -
(i) The hydrogen acceptor present in plants is NADP. It is reduced to $NADPH _2$.
(II) An ADP molecule is converted to ATP in light by utilizing inorganic phosphorous. This phenomenon is called as photophosphorylation.

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

Conversion of light energy into chemical energy within the plant body was first stated by?

  1. Mayer and Anderson

  2. Calvin

  3. Robert Mayer

  4. Willstatter and Stoll
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Robert Mayer, 1942, gave a very important concept in which he stated that plants convert light power (light energy) into chemical difference (chemical energy).

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

Bio-chemical phase in photosynthesis was first discovered by

  1. Calvin

  2. Blackman

  3. Arnon

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

Photosynthesis occurs in two stages in a cell. In the first stage, light-dependent reactions capture the energy of light and use it to make the energy-storage and transport molecules ATP and NADPH. The light-independent Calvin cycle uses the energy from short-lived electronically excited carriers to convert carbon dioxide and water into organic compounds that can be used by the organism (and by animals that feed on it). This set of reactions is also called as carbon fixation. The key enzyme of the cycle is called as RuBisCO. The Calvin cycle or reductive pentose phosphate cycle or $C _3$ cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms. 

The cycle was discovered by Melvin Calvin, James Bassham and Andrew Benson at the University of California, Berkeley by using the radioactive isotope carbon-14. 

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

Which of the following was used during discovery of Calvin cycle?

  1. Spirogya

  2. Volvox

  3. Chlamydomonas

  4. Chlorella
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Carbon fixation pathway in C$ _{3}$ plants was discovered by Calvin, Benson and Basham in unicellular alga Chlorella using C-14 labelled carbon dioxide. They fed radiolabelled carbon dioxide to alga and killed algal cells and isolated the organic compounds at various time intervals, through co-chromatography technique in order to decipher the various compounds into which carbon radio label travels.

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

The term photorespiration was coined by

  1. Decker and Tio.

  2. Julius von Sachs.

  3. Rouhani.

  4. O-leri.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photorespiration is the process of uptake of oxygen and production of carbon dioxide in the light by the photosynthesising tissue. It was discovered by Dicker and Tio (1959), when they observed that the rate of respiration of green leaves is much higher in light than in the dark.

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

Who proposed the cycle of events leading to the fixation of $CO _{2}$ in mesophyll and its reduction in bundle sheath?

  1. Emerson

  2. Melvin Calvin

  3. Hatch and Slack

  4. Hill and Bendall
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hatch and Slack pathway is a metabolic pathway for carbon-dioxide translocation occurring in $C _4$ plants. The overall effect of the pathway is to carry $CO _2$ from the mesophyll cells, which are in contact with air, to the bundle-sheath cells, which are the major sites of photosynthesis.