Home
Class 12
BIOLOGY
Assertion : Tropical regions have got a ...

Assertion : Tropical regions have got a long evolutionary time for species diversification as compared to temperate regions.
Reason : Temperate regions have undergone frequent glaciations in the past whereas tropical regions have remained relatively undisturbed for millions of years.

A

a) If both assertion and reason are true and reason is the correct explanation of assertion.

B

b) If both assertion and reason are true but reason is not the correct explanation of assertion.

C

c) If assertion is true but reason is false.

D

d) If both assertion and reason are false.

Text Solution

Verified by Experts

The correct Answer is:
A
Speciation is a function of time. Temperate regions have undergone frequent glaciations in the past, due to which many species had been killed. However, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.
Promotional Banner

Similar Questions

Explore conceptually related problems

Assertion : PCR primers must not have self complementary regions. Reason : Self complementary regions result in hairpin structures adversely affecting the PCR.

Tropics ( 23.5^(@)N to 23.5^(@)S ) have________species as compared to temperature or polar regions. (a) less (b) equal (c) more (d) none of these

Assertion : A piece of DNA inserted into an alien organism generally does not replicate if not inserted into a chromosome. Reason : Chromosomes have specific sequences called ori region where DNA replication is initiated.

In temperate regions, cambium is less active during winter season and forms fewer xylary elemetns that have narrow vessels, this wood is called as

Assertion : Small sized animals are rarely found in polar regions. Reason : Small sized animals have larger surface area relative to their volume and they have to spend much energy to generate body heat through metabolism.

In temperate regions, during spring season, cambium is very active and produces a large number of xylary elements having vessel with wider cavities wood formed in this way is called as

In the tropical rainforest, the majority of trees have showy animal-pollinated flowers. In temperate forests the majority of trees are wind pollinated. Which factors best explain these contrasting patterns ? (i) Wind is rare in tropical forests. (ii) Because of high species diversity in the tropics, individuals of trees species are often widely separated making wind an inefficient means of pollen dispersal. (iii) More opportunities for coevolved mutualisms exist in tropical forests because of the high diversity of animal species. (iv) Trees in tropical forests are mostly evergreen and year-round leaf canopies impede pollen dispersal by wind. (v) Flowering in tropical forests occurs over a short period of time when wind is absent. (a) (i) , (ii) and (v) (b) (i),(iii) and (v) (c) (ii), (iii) and (iv) (d) (ii) and (iv)

Assertion : E.coli having pBR322 with DNA insert at BamHI site cannot grow in medium containing tetracyline. Reason : Recoginition site for BamHI is present in ter^(R) region of pBR22.

Answer the following questions . a. The earth's magnetic field varies from point is space. Does it also change with time ? It so , on what time scate does it change appreciably ? b. The earth's core is known to contain iron. Yet geologists do not regard this as a source of the earth's magnetism why ? c. The charged currents in the outer conducting regions of the earth's core are thought to be responsible for earth's magnetism . What might be the ' battery ' (i.e., the source of energy) to sustain these currents ? d. The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. How can geologists know about the earth's field in such distant past ? e. The earth's field departs from its dipole substantially at large distances (greater than about 30,000 km) what agencies may be responsible for this distortion ? f. Interstellar space has an extremely weak magnetic field of the order of 10^(-12) T, Can such a weak field be of any significant consequence ? Explain. [Note : Exercise 2 is meant mainly to arouse your curiosity . Answers to some question above are tentative or unknown . Brief answers wherever possible are given at the end . For details , you should consult a good text on geomagnetism.]