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

Who discovered the Ozone layer?

  1. Henri Buisson and charles Fabry

  2. Carl sagan and Charles Fabry

  3. G.M.D Dobson

  4. Carl Sagan and G.M.D Dobson
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

French physicists Charles Fabry and Henri Buisson discovered the ozone layer in 1913 by analyzing the solar spectrum.

Multiple choice

Who really first predicted black holes?

  1. Albert Einstein

  2. John Mitchell

  3. tesla

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

John Michell, an English clergyman and natural philosopher, proposed the concept of 'dark stars' with gravity so strong that light could not escape in 1783.

Multiple choice

_________ was the first person to describe cells.

  1. Rudolf Virchow

  2. Ms. Louis

  3. Albert Einstein

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

Robert Hooke was the first to observe and describe cells using a primitive microscope in 1665, famously naming them 'cells' after the rooms in a monastery.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Terms apoplast and symplast were first used by

  1. Clark

  2. Munch

  3. Dixon

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

Apoplast refers to the non living component of plant like intercellular spaces and cell wall. Transportation through apoplast is fast. 

Symplast refers to living component of plant ie cell membrane and protoplasm. Transportation through symplast is slow process. 
E. Munch (1932), a German physiologist introduced the concept of apoplast and symplast, which is valuable in understanding the pathway of water movement through the root.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Pulsation theory was proposed by

  1. Godlewski

  2. Jagadish Chandra Bose

  3. Dixon and Joly

  4. Arthur
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Sir J.C. Bose proposed a theory of ascent of sap known as pulsation theory. The pulsation theory states that water is absorbed by the plants due to the metabolic activity of living cells which are in constant state of rythmatic pulsation. But it was not accepted as water can be passively absorbed by the roots even the cells were dead.
So, the correct answer is option B.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

First theory for ascent of sap was proposed by

  1. Westermeier

  2. Godlewski

  3. Bose

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

The first theories proposed to explain ascent of sap were Vital force theories. These theories believed that living cells are involved in the ascent of sap, e.g., relay pump theory by Godlewski, 1883 and Pulsation theory by Bose, 1923.  

Bose believed that the inner most cortical cells pump water into the interior that contains xylem channels. The vital force theories have been discarded because as proved by Boucherie in 1840 and Strasburger in 1891 water rises up the stem even when all the living cells are killed by poison or heat.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The first vital theory to explain ascent of sap was proposed by

  1. J. C. Bose

  2. Godlewski

  3. Blackmann

  4. Dixon and Jolly
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The first vital theory to explain ascent of sap was proposed by Godlewski who gave relay pump theory. According to him, there was a rhythmic change in the osmotic pressure of the living cells of xylem such as parenchyma and medullary rays which brought about a pumping action of water in an upward direction. Hence option B is correct.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Most accepted theory for ascent of sap given by

  1. Godlewski and Sachs

  2. J. C. Bose

  3. Stephan Hales

  4. Dixon and Jolly
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Most widely accepted theory of ascent of sap is the 'transpiration pull -cohesion-adhesion theory'. According to this theory water rises in plants due to the tension generated by loss of water through transpiration. The transpiration loss of water pulls the continuous water column in xylary elements which is maintained by cohesion and adhesion forces.

This theory was proposed by Dixon and Joly.

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Capillary force theory was given by 

  1. J.C Bose.

  2. Christian Wolf.

  3. Henry H. Dixon.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The capillary force theory was proposed by Christian Wolf. The theory was proposed in the year 1873. Water moves in the upward direction partially due to the capillary of xylem element and partially due to atmospheric pressure. This capillary acts as the tube which is responsible for the movement of water. 

Thus, the correct answer is option B. 

Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Transpirational pull theory was given by

  1. Henry H. Dixon.

  2. John H. Jolly.

  3. J.C. Bose.

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Most acceptable theory for the ascent of sap is the 'Physical force theory', called as 'Cohesion-Transpiration pull theory'. This theory was put forward by Dixon and Joly. According to this theory, the ascent of sap in plants is a physical process, the lifting force for which is provided by the pulling force generated by transpiration. The cohesion forces between the water molecules help in maintaining a continuous water column and the adhesion forces between water molecules and the tracheary elements help in sticking to water to the xylary elements. Both of these forces help in maintaining a continuous water column in the xylary elements.

Thus, the correct answer is option D.