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 Multiple Choice QuestionsMultiple Choice Questions

1.

The early stage human embryo distinctly possesses

  • gills

  • gill slits

  • external ear (pinna)

  • eye brows


B.

gill slits

Both chick and human embryos go through a stage where they have slits and arches in their necks like the gill slits and gill arches of fish. These structures are not gills and do not develop into gills in chicks and humans, but the fact that they are so similar to gill structures in fish at this point in development supports the idea that chicks and humans share a common ancestor with fish. Thus, developmental characters, along with other lines of evidence, can be used for constructing phylogenies.


2.

The first animal domesticated by primitive man was

  • dog

  • horse

  • cat

  • cow


A.

dog

Dog was the first animal to be domesticated by man.


3.

Assertion : Organochlorine pesticides are organic compounds that have been chlorinated.

Reason : Fenitrothion is one of the organochlorine pesticides. 

  • If both Assertion and Reason are true and the reason is the correct explanation of the assertion

  • If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


C.

If Assertion is true statement but Reason is false

Organochlorinc pesticides arc organic compounds or hydrocarbons to which are added several atoms of chlorine through the process called chlorination. Rate of degradation of organochlorines is very low. E.g. DDT, BHC.

Fenitrothion is an organophosphate pesticide which is the organic ester of phosphoric acid and its derivatives. These pesticides arc very toxic but are not persistant. It is an inhibitor used as an insecticide. It is cheap and used worldwide.


4.

Which of the following is an egg laying mammal ?

  • Kangaroo

  • Platypus

  • Penguin

  • Whale


B.

Platypus

Among all the 4 mammals, Platypus is the egg laying mammal.


5.

Assertion : All birds, except the ones like koel (cuckoo) build nests for retiring and taking rest during night time (day time for nocutrnal).

Reason : Koel lays its eggs in the nests of tailor bird.

  • If both Assertion and Reason are true and the reason is the correct explanation of the assertion

  • If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


C.

If Assertion is true statement but Reason is false

Koel or cuckoo need not build nests because they transfer their responsibilities to build nests, incubate eggs and nurture hatchlings to other birds specifically crows. Thus, they are called as brood parasites ie, they rely on others to raise their young ones. Being the brood parasite of the crow, the koel's breeding cycle synchronizes with that of crow. Both the koel's and crow's eggs are grey-green with rusty brown markings.

Tailor bird is a garden bird which makes its nest by sewing, it has no direct relation with koel and cuckoo. Also it is a songbird found across tropical Asia.


6.

Assertion : Bats and whales are classified as mammals.

Reason : Bats and whales have four-chambered heart.

  • If both Assertion and Reason are true and the reason is the correct explanation of the assertion

  • If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


B.

If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

Bats and whales are classified as mammals as they possess the essential mammalian characteristics like presence of milk gland or mammae, presence of pinnae, viviparous nature, hair on body, presence of diaphragm etc.

Though bats and whales have four chambered heart, it cannot be considered as the main characteristic of being mammals because it is also present in some reptiles (e.g. crocodile) and all birds.


7.

Genetic drift operates only in

  • island population

  • smaller population

  • larger population

  • none of these


B.

smaller population

Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms. It is more likely to occur in a small population.


8.

The cranial capacity was largest among the

  • Peking man

  • Java ape man

  • African man

  • Neanderthal man


D.

Neanderthal man

Neanderthal man was the first human fossil discovered, having a cranial capacity of 1400 cc.

African man (Australopithecus) was discovered, having a cranial capacity of 300-500 cc.

Java ape man (Pithecanthropus erectus) was discovered with cranial capacity 900 cc.

Peking man (Sinanthropus pekinensis) was discovered with  cranial capacity was 1100 cc. Therefore, Neanderthal man has the largest cranial capacity.


9.

Assertion : Holoblastic cleavage with almost equal-sized blastomeres is a characteristic of placental animals.

Reason : Eggs of most mammals, including humans, are of centrolecithal type.

  • If both Assertion and Reason are true and the reason is the correct explanation of the assertion

  • If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


C.

If Assertion is true statement but Reason is false

In holoblastic cleavage, the cleavage furrows bisect the entire egg ie, entire egg divides by each cleavage furrow. Placental mammals have isolecithal or microlecithal egg, the holoblastic cleavage produces blastomeres of equal or approximately equal size.

Centrolecithal eggs are found in insects and in some hydrozoa. In these yolk is concentrated at the centre of egg and the cytoplasm is present surrounding it. Meroblastic cleavage occurs in them.


10.

The correct sequence for the formation of chemicals on the primitive earth is

  • NH3, protein, carbohydrate and nucleic acid

  • NH3, water, nucleic acids and proteins

  • NH3, nucleic acids, protein and carbohydrate

  • protein, carbohydrate, water and nucleic acids


B.

NH3, water, nucleic acids and proteins

As the earth cooled, free atoms in the atmosphere formed inorganic molecules (including H2O and NH3) which interacted to form sugars and then proteins and nucleic acids.