Skip to content
GK24
Prime
General ScienceEasyAsked in: NDA · NDA-I 2024, GAT

Which of the following is not a part of compound microscope?

  1. A.Mirror
  2. B.Stage
  3. C.Clip
  4. D.Retina

Correct answer

D. Retina

Explanation

The correct answer is D, Retina. The retina is the light-sensitive layer at the back of the human eye; it is not a part of any microscope.

A compound microscope uses two lenses, the objective near the specimen and the eyepiece near the eye, to give a much larger image than a single lens. Its other parts hold the slide and light it: the base and arm support it, the stage carries the glass slide, clips keep the slide in place, and a mirror or a lamp below the stage reflects light up through the specimen. Coarse and fine adjustment knobs bring the image into focus.

A is wrong because a concave or plane mirror under the stage is used to direct light through the slide.

B is wrong because the stage is the flat platform on which the slide is placed.

C is wrong because the stage clips hold the slide firmly on the stage.

Exam tip: compound microscope – objective and eyepiece lenses; stage, clips and mirror hold and light the slide.

Practice Questions

View all
Q1.General ScienceAsked in: UPSC Civil Services · CSE Prelims 2022, GS Paper IMedium

Which of the following are nitrogen-fixing plants?

1. Alfalfa

2. Amaranth

3. Chickpea

4. Clover

5. Purslane (Kulfa)

6. Spinach

Select the correct answer using the code given below:

  1. A.1, 3 and 4 only
  2. B.1, 3, 5 and 6 only
  3. C.2, 4, 5 and 6 only
  4. D.1, 2, 4, 5 and 6
Show answer
Correct answer: A. 1, 3 and 4 only

Alfalfa, chickpea and clover are legumes, and legumes fix nitrogen. Plants of the legume family (Fabaceae) carry root nodules that house Rhizobium bacteria.

Q2.General ScienceAsked in: UPSC CAPF · CAPF 2017, Paper IMedium

The mass number of an element is NOT changed when it emits

  1. A.Alpha and Beta radiations only
  2. B.Alpha and Gamma radiations only
  3. C.Beta and Gamma radiations only
  4. D.Alpha, Beta and Gamma radiations
Show answer
Correct answer: C. Beta and Gamma radiations only

Neither beta nor gamma emission changes the total number of protons and neutrons in a nucleus, so the mass number stays the same.

Q3.General ScienceAsked in: UPSC CAPF · CAPF 2025, Paper IMedium

Which one among the following statements about facilitated transport in plants is correct?

  1. A.All passive transports are types of facilitated transport.
  2. B.Facilitated transport is an example of active transport.
  3. C.Water moves across plasma membrane by active transport.
  4. D.Facilitated transport requires assistance of carrier proteins.
Show answer
Correct answer: D. Facilitated transport requires assistance of carrier proteins.

In facilitated transport, molecules cross the membrane with the help of membrane proteins, while still moving down their concentration gradient.

Q4.General ScienceAsked in: UPSC CAPF · CAPF 2017, Paper IMedium

Who among the following has coined the term 'Quark', the fundamental particles that make up protons and neutrons in an atomic nucleus ?

  1. A.Richard Feynman
  2. B.Murray Gell-Mann
  3. C.Albert Einstein
  4. D.Niels Bohr
Show answer
Correct answer: B. Murray Gell-Mann

The American physicist Murray Gell-Mann proposed quarks in 1964 and gave them their name. Gell-Mann, and independently George Zweig, suggested that protons, neutrons and other such particles are built from smaller units.