CBSE Class 12 Biology Quiz | CBSE Class 12 Biology Objective Type Questions & Answers

Questions
21 External fertilisation occurs in majority of
A algae
B mosses
C fungi
D liverworts

Answer: algae
22 In animals, juvenile phase is followed by,
A reproductive phase
B senescent phase
C old age
D vegetative phase.

Answer: reproductive phase
23 The most significant feature of vegetative propagation is that
A it is a method of producing a large number of individuals genetically identical to the parent.
B it is a method of producing a large number of individuals genetically different from the parent.
C it ensures that the progeny individuals are resistant to diseases and pests.
D it is an age old practice.

Answer: it is a method of producing a large number of individuals genetically identical to the parent.
24 The terms homothallic and monoecious are used to denote
A unisexual condition
B bisexual condition
C staminate flowers
D pistillate flowers.

Answer: bisexual condition
25 Which one of the following impurities is easiest to remove from wastewater? [NCERT Exemplar]
A Suspended solids
B Dissolved solids
C Bacteria
D Colloids

Answer: Suspended solids
26 Nuisance growth of aquatic plants and bloom-forming algae in natural waters is generally due to high concentrations of [NCERT Exemplar]
A phosphorus
B calcium
C carbon
D sulphur

Answer: phosphorus
27 Catalytic converters are fitted into automobiles to reduce emission of harmful gases. Catalytic converters change unbumt hydrocarbons into [NCERT Exemplar]
A carbon dioxide and water
B methane
C carbon mono oxide
D carbon dioxide and methane.

Answer: carbon dioxide and water
28 Phosphate pollution in a waterbody is brought about by
A fertilizers and sewage.
B phosphate rocks and sewage
C phosphate rock weathering
D fertilizers

Answer: fertilizers and sewage.
29 Ozone hole is the largest over
A Antarctica
B Europe
C Africa
D America

Answer: Antarctica
30 Increase in the concentration of pollutants/chemicals in higher trophic levels, is known as
A biomagnification
B greenhouse effect
C biodegradation
D eutrophication

Answer: biomagnification
31 Increase in cases of skin cancer and high mutation rate are the result of
A ozone depletion
B CO pollution
C acid rain ,
D CO2 pollution

Answer: ozone depletion
32 Eutrophication causes a/an
A decrease in organic matter
B increase in inorganic nutrients
C decrease in dissolved oxygen
D increase in dissolved oxygen.

Answer: decrease in dissolved oxygen
33 Good ozone is found in the
A ionosphere.
B stratosphere
C troposphere
D mesosphere

Answer: stratosphere
34 Polyblend was first developed by
A Ahmed Khan
B Indian Institute of Biology.
C Ramesh Chandra Dagar
D KhadiandVillagelndustriesCommission

Answer: Ahmed Khan
35 The thickness of ozone is measured as
A parts per billion
B Dobson units
C parts per million
D decibel.

Answer: Dobson units
36 The extinction of passenger pigeon was due to [NCERT Exemplar]
A increased number of predatory birds.
B over exploitation by humans.
C non-availability of the food.
D bird flu virus infection.

Answer: over exploitation by humans.
37 Which of the following is not a cause for loss of biodiversity? [NCERT Exemplar]
A Keeping animals in zoological parks
B Over-exploitation of natural resources
C Destruction of habitat
D Invasion by alien species

Answer: Keeping animals in zoological parks
38 The enormous number of varieties of mango in India represents
A genetic diversity
B species diversity 1
C ecological diversity
D hybridisation programmes

Answer: genetic diversity
39 The World Summit on Sustainable Development (2002) was held in
A Brazil
B South Africa
C Sweden
D Argentina

Answer: South Africa
40 Which among the following is not a method of in-situ conservation?
A Botanical garden
B Ramsar sites
C National Park
D None of these

Answer: Botanical garden
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