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Free download in PDF CBSE Class 12 Biology Objective Type Questions & Answers. Here Gkseries provide Biology Solve Questions and Answers for CBSE Class 12 Students.
(21)
External fertilisation occurs in majority of
[A]
algae
[B]
mosses
[C]
fungi
[D]
liverworts
(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
(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
(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
(30)
Increase in the concentration of pollutants/chemicals in higher trophic levels, is known as
[A]
biomagnification
[B]
greenhouse effect
[C]
biodegradation
[D]
eutrophication
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
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
34
Polyblend was first developed by
[A]
Ahmed Khan
[B]
Indian Institute of Biology.
[C]
Ramesh Chandra Dagar
[D]
KhadiandVillagelndustriesCommission
35
The thickness of ozone is measured as
[A]
parts per billion
[B]
Dobson units
[C]
parts per million
[D]
decibel.
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
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
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