Multiple Choice Questions

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The phase of menstrual cycle in humans that last for 7 - 8 days, is: 

  • follicular phase

  • ovulatory phase

  • luteal phase

  • menstruation


B.

ovulatory phase

The phase of menstrual cycle in humans that last for 7-8 days is ovulatory phase. During this phase, production of FSH decreases while that of LH increases which leads to ovulation on about the 14th day. But it may range from 9th to 16th day (approximately).

Follicular phase begins on the first day of menstruation and ends with ovulation.

Luteal phase is the second half of cycle. It lasts for about 14 days and ends just before a menstrual period.


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One of the genes present exclusively on the X-chromosome in humans is concerned with

  • baldness

  • red-green colour blindness

  • facial hair/moustaches in males

  • night blindness


Pollen grains are able to withstand extremes of temperature and dessication because their exine is composed of

  • cutin

  • suberin

  • sporopollenin

  • callose


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


Assertion : Use of fertilizers greatly enhances crop productivity.

Reason : Irrigation is very important in increasing crop productivity.

  • 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


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Which one of the following statements with regard to embryonic development in humans is correct?

  • Cleavage divisions bring about considerable increase in the mass of protoplasm

  • In the second cleavage division, one of the two blastomeres usually divides a little sooner than the second

  • With more cleavage divisions, the resultant blastomeres become larger and large

  • Cleavage division results in a hollow ball of cells called morula


Assertion : Mast cells in the human body release excessive amounts of inflammatory chemicals which cause allergic reactions.

Reason : Allergens in the environment on reaching human body stimulate mast cells in certain individuals.

  • 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


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


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


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The early stage human embryo distinctly possesses

  • gills

  • gill slits

  • external ear (pinna)

  • eye brows