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 business organisation and correspondence environmental pollution and industries air pollution and its effects the environment and us environment and conservation

Which of the atmospheric pollutant causes general chlorosis destruction of chlorophyll?

  1. SO$ _2$

  2. Hydrocarbons

  3. CO
  4. CO$ _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The increase in the concentration of the air pollutants results in an adverse effect on the plants and animal health. SO$ _2$ is considered as one of the pollutants which causes bleaching of the plants. The chlorophyll pigments in the leaves of the plants are destroyed in the presence of increased amounts of sulfuric acid which is formed by reacting with the water in plants. 

Thus, the correct answer is option A. 

Multiple choice biology living in harmony climate factors abiotic components organisms and environment

Maximum contribution of $O _2$ is from

  1. Phytoplankton

  2. Grasslands

  3. Herbs and shrubs

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

In nature, major source of liberation of oxygen is photosynthesis. Photodissociation liberates oxygen from water during the process of photosynthesis. Phytoplanktons are the most abundant photosynthesizers in nature.

Multiple choice movement in plants living world of plants - plant physiology biology

Reversal of etiolation effect by light is called as

  1. Richmond Lang effect

  2. Red-far red light interaction

  3. Photomorphogenesis

  4. Anisotropic wall expansion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The definition of photomorphogenesis is any change in form or function of an organism occurring in response to changes in the light environment. Photomorphogenesis is often defined as light-regulated plant development, but there are also changes in morphology and/or cell structure and function, which occur as transient acclimatizations to a changing environment, which are also light regulated.

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

Which was the first photosynthetic organism?

  1. Green algae

  2. Red algae

  3. Cyanobacteria

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

Photosynthesis is the process by which light energy from the sun is used to synthesise sugars from carbon dioxide, releasing oxygen as a waste product. In primitive days, cyanobacteria were only the primary producers because the redox structure of oceans favoured them to fix nitrogen and also they had the capacity to use water as the source of electrons in photosynthesis. They made the atmosphere oxygen rich and allowed the appearance of aerobic organisms. 

Thus, the correct answer is option C.

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Cyanobacteria are commonly called blue-green algae. This is because they possess in addition to chlorophylls a blue pigment called

  1. Phycoerythrin

  2. Cyanophycin

  3. Phycocyanin

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Phycocyanin Antioxidant. Phycocyanin is the main component in Linablue Spirulina Extract. It is a blue pigment that is important in the photosynthesis (food production) of cyanobacteria. It assists the function of chlorophyll, especially during low light conditions. So, the correct option is "C" (Phycocyanin).

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Nostoc is known to do

  1. Photosynthesis
  2. Photosynthesis and $N _2$ fixation simultaneously
  3. $N _2$ fixation only
  4. Either photosynthesis or $N _2$ fixation at a time
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nostoc is a genus of blue green algae. It is photosynthetic cyanobacteria. It contains chlorophyll pigment and carries out photosynthesis. It also has ability to fix atmospheric nitrogen and make it available to the plants. It is a non-symbiotic nitrogen fixer.

Thus, the correct answer is 'Photosynthesis and N$ _2$ fixation simultaneously.'

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In blue green algae, photosynthesis occurs at

  1. Chromatophore

  2. Chloroplast

  3. Photosynthetic lamellae or thylakoids

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

Since, BGA is a prokaryotic organism, they lack true nucleus and membrane bound organelles which means that chloroplast (double membrane bound chlorophyll containing plastids) is absent in them. Thus, option B is incorrect. Chromatophores are light reflecting, pigment containing cells. The peripheral region of BGA protoplast contains thylakoids and is termed as chromoplast. Thylakoids contain photosynthetic pigments (chrolophyll a, xanthophylls, phycobilin) in their membranes and serve as site for photosynthesis. Thus, option C is correct and D is incorrect.

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

Blue colour of blue-green algae is due to

  1. Phycocyanin and allophycocynanin

  2. Phycoerythrin

  3. Anthocyanin

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

Blue-green algae are also called as cyanobacteria. The blue colour of blue-green algae is due to presence of pigments phycocyanin and allophycocyanin. The green colour is due to presence of chlorophyll pigment. Phycoerythrin pigment results in the red colour. Anthocyanins pigment gives red, purple and blue colours in many fruits and vegetables. Anthoxanthin pigment gives white or colorless to a creamy to yellow color to petals of flowers.

Thus, the correct answer is 'Phycocyanin and allophycocynanin.'

Multiple choice zoology microbes in human welfare biofertilizers microbes as biocontrol agents and biofertilizers manuring

Pigment containing membranous extensions in some cyanobacteria are

  1. Chromatophores

  2. Heterocysts

  3. Basal bodies

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

In cyanobacteria, the pigment-containing membranous extensions that facilitate photosynthesis are called chromatophores (or thylakoids). Heterocysts are specialized cells for nitrogen fixation, not pigment storage.

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What is the photosynthetic product in blue-green algae?

  1. Normal starch

  2. Glycogen

  3. Cyanophycean starch resembling glycogen

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Blue-green algae, also called cyanobacteria, any of a large, heterogeneous group of prokaryotic, principally photosynthetic organisms. Cyanobacteria resemble the eukaryotic algae in many ways, including morphological characteristics and ecological niches, and were at one time treated as algae, hence the common name of blue-green algae. The process of photosynthesis goes on in cyanobacteria in the same manner as in plants. The storage food products in cyanobacteria are somewhat different from those of green plants. The storage product is usually a starch like substance similar to glycogen and is different from the starch produced in plants. This is known as Cyanophycean starch.

So, the correct answer is 'Cyanophycean starch resembling glycogen'.
Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

How many ATPs are required by $C _4$ plants in synthesis of one molecule of glucose

  1. 18 ATP

  2. 30 ATP

  3. 12 ATP

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

Most of the plants that are adapted to dry tropical regions have the $C _{4}$ pathway. e.g. Sugarcane, Maize, Sorghum,etc. These plants are known as $C _{4}$ plants.For the formation of sugars, $C _{4}$ plants undergo $C _{4}$ cycle as well as $C _{3}$ cycle or Calvin cycle. In these plants double fixation of carbon dioxide occurs.

ATP consumed in $C _{4}$ plants:
$C _{4}$ cycle - 2 ATP per $CO _{2}$ fixed
$C _{3}$ cycle - 3 ATP per $CO _{2}$ fixed 
Total - 5 ATP per $CO _{2}$ fixed
Thus, to form one molecule of glucose or to fix 6 $CO _{2}$, 6 X 5 = 30 ATP are consumed.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell
How many ATP and NADPH molecules are respectively required to make one molecule of glucose through the Calvin cycle?

  1. 3 and 2

  2. 9 and 6

  3. 18 and 12

  4. 12 and 18
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For every $CO _{2}$ molecule entering the Calvin cycle, $3$ molecules of $ATP$ and $2$ molecules of NADPH are required. To make one molecule of glucose, $6$ turns of the cycles are required 

$(6\times 3 ATP =18 ATP$ and $6\times 2 NADPH=12 NADPH)$.

In                            Out   
$6$ $CO _{2}$ $1\,\, glucose$
$18 ATP$ $18 ADP$
$12 NADPH$  $12 NADP$ So, the correct answer is '

18 and 12'.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

Both photosynthesis and cellular respiration are metabolic processes that occur in eukaryotic cells. Each process involves several steps and chemical reactions.
All of the following occur during the processes of photosynthesis and cellular respiration except

  1. The production of large amounts of ATP.

  2. Oxidation-reduction reactions.

  3. The use of multiple enzymes to catalyze reactions.

  4. An electron transport chain.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Production of large amount of ATP takes place exclusively during respiration. However a small number of ATP is produced during the light reaction of photosynthesis, which is utilized for fixing or reducing CO$ _2$

So, the correct answer is 'The production of large amounts of ATP'