What is the main cause for the extinction of some species in tropical forest?
Deforestation
Afforestation
Pollution
Soil erosion
A.
Deforestation
Deforestation is the depletion of forest resources. Its main cause is the explosion of human and livestock populationwith the increased demand of the basic needs.
The major cause of deforestation is the loss of wildlife, rare speies of flora and fauna.
Afforestation or reforestation is the only way to conserve our natural resources and the rare species of flora and fauna.
The presence of diversity at the junction of territories of two different habitats is known as
bottleneck effect
edge effect
junction effect
Pasteur effect
In Cycas, pollination takes place in
3- celled stage
4- celled stage
2- celled stage
1- celled stage
A eukaryotic gene contains two kinds of base sequences. Which of these plays an important role in protein synthesis?
Introns
Exons
Both (a) and (b)
None of these
A bacterium divides after every 35 min, if a culture containing 105 cells per mL is grown, then cell concentration per mL after 175 mins will be
175105
125105
48105
32105
Biological concept of species is mainly based on
reproductive isolation
morphological features only
methods of reproduction only
morphology and methods of reproduction
In the treatment of waste water discharge, which treatment stage involves biological treatment?
Primary treatment
Secondary treatment
Tertiary treatment
Reverse osmosis stage
If root of a flowering plant has 24 chromosomes, then its gamete has how many chromosomes?
24
12
4
8