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
B.
red-green colour blindness
The most common form of red-green colour blindness is an 'X chromosome linked recessive' disorder. The 'red' and 'green' genes are known to reside at the tip of the long arm of the X chromosome. Women have two copies of the X-chromosome, and so they may have normal colour vision, even if they carry one copy of the defective gene. Men have only one X-chromosome, and so will be colour blind.
The phase of menstrual cycle in humans that last for 7 - 8 days, is:
follicular phase
ovulatory phase
luteal phase
menstruation
Pollen grains are able to withstand extremes of temperature and dessication because their exine is composed of
cutin
suberin
sporopollenin
callose
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 : 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
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 : 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
