Plant Physiology & Biochemistry MCQ Quiz - Objective Question with Answer for Plant Physiology & Biochemistry - Download Free PDF

The correct answer is Nitrogen.

Key Points

• Rhizobium is a symbiotic bacterium that forms nodules on the roots of leguminous plants and helps in the fixation of atmospheric nitrogen into ammonia.
• Blue-green algae (cyanobacteria) such as Anabaena and Nostoc also play a crucial role in nitrogen fixation, especially in aquatic ecosystems and rice paddies.
• Nitrogen fixation is the process of converting inert atmospheric nitrogen (N₂) into bioavailable forms such as ammonia (NH₃), which plants can absorb and use for growth.
• The process of biological nitrogen fixation contributes significantly to the nitrogen cycle, which is essential for maintaining soil fertility and agricultural productivity.
• These microorganisms form a mutualistic relationship with plants, where they provide nitrogen in exchange for carbohydrates and shelter.

Additional Information

• Nitrogen Cycle:
  • The nitrogen cycle is a biogeochemical cycle that describes the transformation and movement of nitrogen through the atmosphere, biosphere, and lithosphere.
  • Key processes include nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.
• Biological Nitrogen Fixation:
  • It is carried out by prokaryotic organisms, including free-living bacteria (e.g., Azotobacter) and symbiotic bacteria (e.g., Rhizobium).
  • The enzyme nitrogenase is key to this process, as it catalyzes the conversion of atmospheric nitrogen to ammonia.
• Importance of Nitrogen for Plants:
  • Nitrogen is a critical component of chlorophyll, which is essential for photosynthesis.
  • It is also a part of amino acids, nucleic acids (DNA and RNA), and ATP, all of which are fundamental to plant growth and development.
• Symbiotic Relationships:
  • In the case of Rhizobium, the bacteria infect the plant roots and form nodules, where nitrogen fixation occurs in an oxygen-free environment.
  • Plants provide the bacteria with carbohydrates produced during photosynthesis, creating a mutually beneficial relationship.

The correct answer is Anti-transpirant

• Anti-transpirants are substances used to reduce the transpiration from plant surfaces.
• They reduce photosynthesis so it is used in limited conditions.
• It is mainly used in nurseries and Horticultural crops.
   

Additional Information

There are four types of Anti-transpirants

• Stomatal closing type: They reduce the water loss by closing the stomata.
• Examples: Phenyl mercuric acetate (PMA @ 10^-4), Atrazine, and CO₂
• Film-forming: Check transpirational loss due to the formation of thin-film which acts as a physical barrier.
• Examples: Mobileaf, Hexadecanol, Silicone, oils, and waxes.
• Reflecting type: These chemicals reflect the radiation and reduce the temperature.
• Examples: Kaolin @ 5%
• Growth retardants: These chemicals reduce the shoot growth and increases the root growth and enable to resist drought.
• Example: Cycocel (CCC)

The correct answer is IAA.

• Indole-3-acetic acid (IAA, 3-IAA) is the most common, naturally occurring, plant hormone of the auxin class.

• IAA is predominantly produced in the apical bud of and young leaves of plants and is known to be an inducer of cell division and elongation. 

• IAA, as well as most other auxins, are also known to act in concert with, or in opposition to, other plant hormones.

• Example: The ratio of auxin to cytokinin in certain plant tissues determines initiation of root versus shoot buds.

 The correct answer is the Directional growth of a plant.

Key Points

• Tropism is a biological phenomenon indicating the directional growth all turning movement of a plant towards or away from an external stimulus.
• Stimuli like light, gravity, water, touch, etc. influence the plant's growth and leads to tropism.
• It is a mechanism by which plants adapt to the environmental change in the presence of a stimulus.
• It results in differential growth.
• Plant hormones (Auxin) help to regulate the differential growth. 

The correct answer is Magnesium.

• Plants required about seventeen essential nutrients  to plant growth and health which can be grouped into two classes based on the amount required:

1. Macronutrient- Require in large amounts.
2. Micronutrient- Require in a Small amount.

 

Essential Macronutrient	Essential Micronutrient
carbon Hydrogen Oxygen Nitrogen Phosphorus Potassium Sulfur Magnesium Calcium	Iron Molybdenum Boron Chlorine Copper Zinc Nickel Manganese

 

 The correct answer is the Directional growth of a plant.

Key Points

• Tropism is a biological phenomenon indicating the directional growth all turning movement of a plant towards or away from an external stimulus.
• Stimuli like light, gravity, water, touch, etc. influence the plant's growth and leads to tropism.
• It is a mechanism by which plants adapt to the environmental change in the presence of a stimulus.
• It results in differential growth.
• Plant hormones (Auxin) help to regulate the differential growth. 

The correct answer is Magnesium.

• Plants required about seventeen essential nutrients  to plant growth and health which can be grouped into two classes based on the amount required:

1. Macronutrient- Require in large amounts.
2. Micronutrient- Require in a Small amount.

 

Essential Macronutrient	Essential Micronutrient
carbon Hydrogen Oxygen Nitrogen Phosphorus Potassium Sulfur Magnesium Calcium	Iron Molybdenum Boron Chlorine Copper Zinc Nickel Manganese

 

The correct answer is IAA.

• Indole-3-acetic acid (IAA, 3-IAA) is the most common, naturally occurring, plant hormone of the auxin class.

• IAA is predominantly produced in the apical bud of and young leaves of plants and is known to be an inducer of cell division and elongation. 

• IAA, as well as most other auxins, are also known to act in concert with, or in opposition to, other plant hormones.

• Example: The ratio of auxin to cytokinin in certain plant tissues determines initiation of root versus shoot buds.

The correct answer is Anti-transpirant

• Anti-transpirants are substances used to reduce the transpiration from plant surfaces.
• They reduce photosynthesis so it is used in limited conditions.
• It is mainly used in nurseries and Horticultural crops.
   

Additional Information

There are four types of Anti-transpirants

• Stomatal closing type: They reduce the water loss by closing the stomata.
• Examples: Phenyl mercuric acetate (PMA @ 10^-4), Atrazine, and CO₂
• Film-forming: Check transpirational loss due to the formation of thin-film which acts as a physical barrier.
• Examples: Mobileaf, Hexadecanol, Silicone, oils, and waxes.
• Reflecting type: These chemicals reflect the radiation and reduce the temperature.
• Examples: Kaolin @ 5%
• Growth retardants: These chemicals reduce the shoot growth and increases the root growth and enable to resist drought.
• Example: Cycocel (CCC)

Serine - is a non essential amino acid synthesized in plants during its Metabolism. It is synthesized during photo respiratory cycle of the plant.

Alanine - is a non-essential amino acid which means that it can be manufactured by the human body. It is most commonly produced by reductive amination of pyruvate.

Tryptophan - is an essential amino acid, meaning it cannot be produced by the human body. It is usually present in peptides, enzymes, and structural proteins.

Glutamic acid - is a non-essential amino acid and is highly involved in metabolism. It plays an important role in DNA synthesis. Biosynthesis of glutamic acid involves various schemes. The most common scheme is the conversion of glutamine to glutamic acid by adding water molecules with glutaminase as a helper enzyme.

The correct answer is Nitrogen.

Key Points

• Rhizobium is a symbiotic bacterium that forms nodules on the roots of leguminous plants and helps in the fixation of atmospheric nitrogen into ammonia.
• Blue-green algae (cyanobacteria) such as Anabaena and Nostoc also play a crucial role in nitrogen fixation, especially in aquatic ecosystems and rice paddies.
• Nitrogen fixation is the process of converting inert atmospheric nitrogen (N₂) into bioavailable forms such as ammonia (NH₃), which plants can absorb and use for growth.
• The process of biological nitrogen fixation contributes significantly to the nitrogen cycle, which is essential for maintaining soil fertility and agricultural productivity.
• These microorganisms form a mutualistic relationship with plants, where they provide nitrogen in exchange for carbohydrates and shelter.

Additional Information

• Nitrogen Cycle:
  • The nitrogen cycle is a biogeochemical cycle that describes the transformation and movement of nitrogen through the atmosphere, biosphere, and lithosphere.
  • Key processes include nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.
• Biological Nitrogen Fixation:
  • It is carried out by prokaryotic organisms, including free-living bacteria (e.g., Azotobacter) and symbiotic bacteria (e.g., Rhizobium).
  • The enzyme nitrogenase is key to this process, as it catalyzes the conversion of atmospheric nitrogen to ammonia.
• Importance of Nitrogen for Plants:
  • Nitrogen is a critical component of chlorophyll, which is essential for photosynthesis.
  • It is also a part of amino acids, nucleic acids (DNA and RNA), and ATP, all of which are fundamental to plant growth and development.
• Symbiotic Relationships:
  • In the case of Rhizobium, the bacteria infect the plant roots and form nodules, where nitrogen fixation occurs in an oxygen-free environment.
  • Plants provide the bacteria with carbohydrates produced during photosynthesis, creating a mutually beneficial relationship.

In second stage of aerobic oxidation, pyruvic acid formed in glycolysis is transported to mitochondria, where it is oxidized to carbon dioxide and water. 34 out of 36 ATPs are also released in this process, giving mitochondria the name, ‘Power House of the Cell’.

Golgi apparatus package proteins into membrane bound vesicles inside the cell before they are sent to their destination.

Ribosomes are responsible for protein synthesis.

Chloroplast is responsible for conducting photosynthesis.

 The correct answer is the Directional growth of a plant.

Key Points

• Tropism is a biological phenomenon indicating the directional growth all turning movement of a plant towards or away from an external stimulus.
• Stimuli like light, gravity, water, touch, etc. influence the plant's growth and leads to tropism.
• It is a mechanism by which plants adapt to the environmental change in the presence of a stimulus.
• It results in differential growth.
• Plant hormones (Auxin) help to regulate the differential growth. 

The correct answer is Magnesium.

• Plants required about seventeen essential nutrients  to plant growth and health which can be grouped into two classes based on the amount required:

1. Macronutrient- Require in large amounts.
2. Micronutrient- Require in a Small amount.

 

Essential Macronutrient	Essential Micronutrient
carbon Hydrogen Oxygen Nitrogen Phosphorus Potassium Sulfur Magnesium Calcium	Iron Molybdenum Boron Chlorine Copper Zinc Nickel Manganese

 

The correct answer is A-4, B-3, C-2, D-1.

Plant growth regulators	Possible precursors
Abscisis acid (ABA)	Farnesyl pyrophosphate or Zeaxanthin
Ethylene	Methionine
Gibberellin	Ispentenyl pyrophosphate
Indole Acetic Acid (IAA)	Tryptophan
Cytokinins	Adenosine monophosphate