What is the main cause for the extinction of some species in tropical forest?
Deforestation
Afforestation
Pollution
Soil erosion
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
L- shaped chromosomes are also called
acrocentric
telocentric
sub- metacentric
None of these
C.
sub- metacentric
The shape of chromosome is determined by the position of centromere on the chromosomes. They may be of following five types:
(i) Acentric- centromere is absent.
(ii) Telocentric- centromere present at one end of chromosome.
(iii) Acrocentric- when chromosome is divided into a very small segment at one end and a very large segment on the other end.
(iv)Submetacentric- when chromosome has two unequal segments and forms V- shaped structure.
(v) Metacentric- two equal segments of chromosomes
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