Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

41.

One greenhouse gas contributes 14% to total global warming and another contributes 6%. These are respectively identified as

  • N2O and CO2

  • CFCs and N2O

  • methane and CO2

  • methane and CFCs


B.

CFCs and N2O

Greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range. It is responsible for greenhouse effect. Primary greenhouse gases includes water vapor, carbon dioxide, methane, nitrous oxide and ozone.


42.

The following is the diagram of T.S. of anther. Identify the parts labelled A, B and C.

  • A- Connective tissue, B- Pollen grain, C- Endothecium

  • A- Endothecium, B- Connective tissue, C- Pollen grains

  • A- Pollen grains, B- Connective tissue, C- Endothecium

  • A- Endothecium, B- Pollen grains, C- Connective tissue


A.

A- Connective tissue, B- Pollen grain, C- Endothecium

Anther consists of two lobes, each with two elongated microsporangia or pollen sacs. The anther lobes are fused together by the connective tissue.

  1. Connective tissue- It joins anther thecae together and connects anther to filament.
  2. Endothecium- Structure and support. Dehiscence


43.

Tetradynamous condition is found in

  • Hibiscus rosa-sinesis

  • Ocimum sanctum

  • Helianthus annuus

  • Brassica campestris


D.

Brassica campestris

In tetradynamous condition there is 4 + 2 arrangement of stamens i.e., out of six stamens, 4 are long and 2 are short. It is a characterstic feature of members of family Brassicaceae.


44.

Which of the following represents the action of insulin?

  • Increases blood glucose level by stimulating glucagon production

  • Decreases blood glucose level by forming glycogen

  • Increases blood glucose level by promoting cellular uptake of glucose

  • Increases blood glucose level by hydrolysis of glycogen


B.

Decreases blood glucose level by forming glycogen

Insulin decreases the level of glucose in the blood. It acts by stimulating liver cells and muscle cells to take up glucose from the blood and convert it into glycogen. When the blood sugar level drops, the secretion of insulin is suppressed. When the blood sugar level increases, the secretion of insulin is stimulated.


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45.

If the sequence of bases in the coding strand of a double stranded DNA is 5'-GTTCGAGTC-3', the sequence of bases in its transcript will be

  • 5'-GACUCGAAC-3'

  • 5'-CAAGCUCAG-3'

  • 5'-GUUCGAGUC-3'

  • 5'-CUGAGCUUG-3'


C.

5'-GUUCGAGUC-3'

During transcription, one of the two DNA strands functions as template strand and the other functions as coding strand. Template strand serves as template for transcription whereas coding strand does not take part in transcription. Hence, the mRNA produced has base sequence complementary to template strand while similar to coding strand except that thymine (T) is replaced by uracil (U). Here,
Coding strand    5' GTTCGAGTC 3'
Template strand 5' CAAGCTCAG 3'
Transcript          5' GUUCGAGUC 3'


46.

Match column I with column II and select the correct option from codes given below.

Column I Column II
Brassica Himgiri
Okra Pusa Komal
Wheat Pusa Gaurav
Cowpea Pusa Sawani

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

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

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

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


A.

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

Hybridisation is used to develop new genotypes, evaluate their performance or exploit hybrid vigor.

The above mentioned crop varities bred by hybridisation and selection, for disease resistance to fungi, bacteria and viral diseases.

Crop Variety Resistance to diseases
Wheat Himgiri Leaf rust
Brassica Pusa swarnim White rust
Cowpea Pusa Komal Bacterial blight
Okra Pusa Swani Vein mosaic disease


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47.

Most animals that live in deep oceanic waters are

  • tertiary consumers

  • detritivores

  • primary consumers

  • secondary consumers


B.

detritivores

Benthos is the community of organisms which live on, in, or near the sea bed, also known as the benthic zone. As no light is available in this zone of sea, the energy source for deep benthic ecosystem is often organic matter from higher water column which drifts down to the depths. This dead and decaying matter sustains the benthic organisms, and therefore, most organisms in benthic zone i.e., in deep oceanic waters, are scavengers or detritivores.


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48.

In a 3.2 Kbp long piece of DNA, 820 adenine bases were found. What would be the number of cytosine bases?

  • 780

  • 1560

  • 740

  • 1480


A.

780

Total DNA = 3.2 Kbp = 3200 bp

Adenine = 820

According to Chargaff's rule

[A] = [T]; [G] = [C]

So, Thymine = 820

Therefore, total A + T content = 820 + 820 = 1640

Also, A + T = 3200 - (G + C)

So, G + C content = 3200 - 1640 = 1560

So, Cytosine = 15602 = 780


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49.

Some of the steps of DNA fingerprinting are given below. Identify their correct sequence from the options given.

A. Electrophoresis of DNA fragments
B. Hybridisation with DNA probe
C. Digestion of DNA by restriction endonucleases
D. Autoradiography
E. Blotting of DNA fragmentsto nitrocellulose membrane

  • C - A - B - E - D

  • C - A - E - B - D

  • A - E - C - B - D

  • A - C - E - D - B


B.

C - A - E - B - D

The technique of DNA fingerprinting involves following steps:

(i) Isolation of DNA from sample cell

(ii) Amplification of DNA using Polymerase Chain Reaction (PCR), (if DNA is less in amount).

(iii) Digestion of this DNA by restriction endonucleases (C)

(iv) These DNA fragments are electrophoresed in agarose gel. These fragments can be visualised using EtBr - UV system (A)

(v) Separated DNA fragments are transferred to nitrocellulose membrane using Southern Blotting (E).

(vi) Probing for VNTRs is done using labelled DNA probes (B).

(vii) The hybridised fragment can be detected by autoradiography (D).


50.

One of the following statements is incorrect with reference to biodiversity. Identify it.

  • The areas with very few plant and animal species (low species richness) with no threatened species are called biodiversity hotspots.

  • Biodiversity increases from higher altitudes to lower altitudes

  • Biodiversity decreases from the equator to polar regions

  • Depletion in genetic diversity of crop plants is mainly due to the introduction of better varieties with high yield, disease resistance, etc.


A.

The areas with very few plant and animal species (low species richness) with no threatened species are called biodiversity hotspots.

Biodiversity hotspots are areas of high endemism and high level of species richness. They are determined mainly by three factors:
(i) Number ofspecies/species diversity
(ii) Degree of endemism
(iii) Degree of threat


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