General Awareness · Science General

Inventors and Scientific Discoveries

4,616 Questions

This hub provides questions related to great inventors and their scientific discoveries. It covers the inventors of the telephone, radio, and microchips, alongside Nobel Prize winners. These facts are crucial for the general awareness section of major competitive exams.

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Inventors and Scientific Discoveries Questions

Multiple choice blackman's principle of limiting factors photosynthesis in higher plants biology

Who proposed the theory of starch sugar inter conversion for opening and closing of the stomata?

  1. Steward

  2. Yin and Tung

  3. Sayre

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

Starch hydrolysis theory is the classical theory for stomatal opening and closing. It was originally proposed by Sayre, 1923. According to this theory, guard cells contain starch, which is hydrolysed to form glucose under high pH caused due to reduced carbon dioxide concentration. The carbon dioxide concentration is reduced due to the process of photosynthesis Glucose increases the osmotic concentration and hence, DPD of guard cells. The later absorb water from epidermal cells, swell up and open the stomatal pore. Major contributors to this theory were Lloyd, 1908, who proposed starch sugar interconversions; Sayre, proposed that starch hydrolysis occurs with rise of pH and Steward, suggested that closing movement requires ATP.

Multiple choice blackman's principle of limiting factors photosynthesis in higher plants biology

Who proposed that opening and closing of stomata is connected with the change in pH of guard cells?

  1. Lloyd

  2. Von Mohl

  3. Sayre

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

Botanist Sayre observed that stomatal opening is connected to change in ph of guard cells due to carbon dioxide. 

Stomata open in neutral and alkaline pH which is present in the daytime when carbon dioxide is constantly used.
In acidic condition, stomata remain closed which is present in night time when no photosynthesis occurs due to which accumulation of carbon dioxide occurs that results in the formation of carbonic acid. Thus guard cells movement is regulated by pH due to interconversion of starch and sugar.
So the correct answer is 'Sayre'.

Multiple choice blackman's principle of limiting factors photosynthesis in higher plants biology

Which of the following scientists is credited with the mechanism of opening and closing of stomata related to $K^+$ exchange?

  1. Levitt

  2. Sayre

  3. Scarth

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

  • Stomata are the structure present in the leaf which meant for exchange of gases and loss of water. 
  • Opening and closing of stomata are regulated by guard cells. 
  • Levitt found that in daytime starch gets converted into sugar which accumulates in guard cells.
  • Fujino found that in the presence of light there is the influx of potassium ion in guard cells which causes the opening of stomata.
  • High pH favours the closing of stomata.
So, the correct answer is 'Levitt'.

Multiple choice zoology aids to health immunity and the lines of immunity immune system of the body immunity and blood groups

Passive immunization was first developed by

  1. Robert Koch

  2. L. Pasteur

  3. Robert Hooke

  4. Emil von Behring and Kitasato
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Passive immunity is the transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another. Passive immunity can occur naturally when maternal antibodies are transferred to the fetus through the placenta or can be induced artificially, when high levels of human antibodies specific for a pathogen or toxin are transferred to non-immune individuals.
Emil Adolf von Behring and Kitasato Shibasaburo discovered the antitoxin-based immunity to diphtheria and tetanus and antitoxin became the first major success of modern therapeutic immunology.

So, the correct answer is option D.

Multiple choice zoology aids to health immunity and the lines of immunity immune system of the body immunity and blood groups

The method of passive immunity was discovered by

  1. Pasteur

  2. Von Behring

  3. Koch

  4. Jenner
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Passive immunity is the protection against disease through antibodies produced by another human being or animal.
  • Passive immunity doesn't last as long as active immunity.
  • Emil von Behring was awarded the first Nobel Prize in Physiology or Medicine in 1901 for his discovery of serum therapy for diphtheria. He showed that serum from rabbits immunized with tetanus toxin could prevent tetanus in rabbits because it contains antibodies against tetanus.
  • Hence the method of passive immunity was discovered by Von Behring.
  •  So, the correct answer is 'Von Behring'.
Multiple choice physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

Corpuscular theory of light was advanced by

  1. Huygen

  2. Newton

  3. Maxwell

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

$Answer:$ B

The corpuscular theory was largely developed by Sir Isaac newton. Newton's theory remained in force for more than 100 years and took precedence over Huygen's wave front theory, partly because of Newton’s great prestige. When the corpuscular theory failed to adequately explain the diffraction, interference and polarization of light it was abandoned in favour of Huygens' wave theory.

Multiple choice chemistry p- block elements-ii group 16 elements - general properties group 16 elements - trends in chemical properties group 16 elements

What was the observation made by Joseph Priestley during the experiment done for discovery of oxygen?

  1. A coloured gas is collected in the jar

  2. A colourless gas is collected in the jar

  3. No gas is collected in the jar

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

During the experiment performed by Joseph Priestley, the observation was that a colourless gas is collected in the jar i.e oxygen.

Multiple choice economics environmental economics acid rain air pollution - effects and control air pollution and its effects

The term acid rain was given by

  1. Fourier

  2. Angus

  3. Tyndall

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

The term acid rain was coined in 1872 by Robert Angus Smith. The acid rain is contains water having pH around 5.6. When the air pollutants like oxides of nitrogen and oxides of sulphur reach the troposphere, they react with the water or moisture and forms acids like nitric acid, nitrous acid or sulphuric acid. These acids then precipitate with the rain to form the acid rain. Hence, the correct answer is 'Angus'.

Multiple choice evs let's play with water law of constant proportion - i law of constant proportion law of definite proportions

The law of constant proportions was enunciated by: 

  1. Dalton

  2. Berthelot

  3. Avogadro

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

Proust defined law of constant proportions. It is also called as $\text{Proust's law}$. it states that a given chemical compound always contains its component elements in fixed ratio by mass and does not depend on the method of preparation of the compound. 
Hence, answer is option D.