NEET 2020 Phase 1 question paper with solutions

180 questions · 180 min

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Sample questions with solutions

Q1

Which of the following is put into Anaerobic sludge digester for further sewage treatment?

  • A.

    Effluents of primary treatment

  • B.

    Primary sludge

  • C.

    Floating debris

  • D.

    Activated sludge

Answer: D

  1. Understand the flow of sewage treatment — after primary treatment, the wastewater passes into an aeration tank where microbes grow and form flocs, then it moves to a settling tank.

  2. The sediment that settles down in this settling tank is called activated sludge.

Settling tank sediment→Activated sludge\text{Settling tank sediment} \rightarrow \text{Activated sludge}
  1. A small part of this activated sludge is pumped back into the aeration tank to maintain the microbial population there, but the major remaining part is pumped into large tanks called anaerobic sludge digesters.

Therefore

Activated sludge (major part)→Anaerobic sludge digester\text{Activated sludge (major part)} \rightarrow \text{Anaerobic sludge digester}
  1. Eliminate the other options — effluents of primary treatment go to the aeration tank, and floating debris/primary sludge are removed earlier in the primary treatment stage, not sent to the anaerobic digester.

Hence, the answer is D (Activated sludge).

Q2

In gel electrophoresis, separated DNA fragments can be visualized with the help of

  • A.

    Ethidium bromide in infrared radiation

  • B.

    Ethidium bromide in UV radiation

  • C.

    Acetocarmine in bright blue light

  • D.

    Acetocarmine in UV radiation

Answer: B

  1. Why staining is needed — DNA fragments are colourless and cannot be seen directly, so a dye is needed to make them visible.

  2. Which dye is used — Given that ethidium bromide binds to DNA by intercalating between its bases, this dye is used to stain the separated fragments.

  3. How the stained DNA is seen — So, once stained, the DNA fragments are exposed to UV radiation, which makes the ethidium bromide fluoresce, revealing the bands.

Hence, the answer is Option B: Ethidium bromide in UV radiation.

Q3

Match the following columns and select the correct option :

Column-IColumn-II
(a) Gregarious, polyphagous pest(i) Asterias
(b) Adult with radial symmetry and larva with bilateral symmetry(ii) Scorpion
(c) Book lungs(iii) Ctenoplana
(d) Bioluminescence(iv) Locusta
  • A.

    (A)-(iv), (B)-(i), (C)-(ii), (D)-(iii)

  • B.

    (A)-(iii), (B)-(ii), (C)-(i), (D)-(iv)

  • C.

    (A)-(ii), (B)-(i), (C)-(iii), (D)-(iv)

  • D.

    (A)-(i), (B)-(iii), (C)-(ii), (D)-(iv)

Answer: A

  1. Matching gregarious, polyphagous pest (a): "Gregarious" means living in swarms, and "polyphagous" means feeding on many types of plants — this describes Locusta (locust), a well-known crop pest that swarms and damages many crop species. So, (a) matches with (iv).

  2. Matching radial adult, bilateral larva (b): An organism whose adult stage shows radial symmetry but whose larval stage shows bilateral symmetry belongs to phylum Echinodermata, exemplified by Asterias (starfish). So, (b) matches with (i).

  3. Matching book lungs (c): Book lungs are thin, stacked respiratory structures used for gas exchange, found characteristically in arachnids such as the scorpion. So, (c) matches with (ii).

  4. Matching bioluminescence (d): The ability to produce light is a well-marked feature of ctenophores (comb jellies), such as Ctenoplana. So, (d) matches with (iii).

  5. Conclusion: Combining these gives (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii). Hence, the answer is option A.

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