CBSE 12TH BIOLOGY - Online Test
Q1. If vital index is >100 then the population will
Answer : Option A
Explaination / Solution:
Vital index is the ratio of births to deaths within a population during given time. If vital index is greater than hundred then the population will decreasing showing negative growth.
Q2. Marijuana, hashish, charas and ganga are group of drugs collectively called
Answer : Option C
Explaination / Solution:
A cannabinoid is one of a class of diverse chemical compounds that acts on cannabinoid receptors in cells that alter neurotransmitter release in the brain.
Marijuana, hashish, charas and ganga contain chemicals called cannabinoids. They are generally, taken as inhalation or oral ingestion to effects cardiovascular system of the body.
Q3. A DNA segment which serves as a kind of “ON-OFF switch” for transcription is a/an
Answer : Option A
Explaination / Solution:
An operator is a segment of DNA to which a transcription factor binds to regulate gene expression by repressing it. The protein that does this is called a repressor. Repressors bind to operators to prevent transcription.
The main operator (O2) in the classically defined lac operon is located slightly downstream of the promoter. Two additional operators, O1 and O3 are located at -82 and +412, respectively. Operator attach with template strand to initiate transcription process.
Q4. A group of animals related by descent and similar characters like appearance, size and configuration are known as
Answer : Option B
Explaination / Solution:
Breed is a group of animals related by descent and similar characters like appearance, size and configuration. All the animals falling to same breed are capable to breed in between.
Q5. In which of the following protected areas land patches will be permitted for grazing, plantation and cultivation?
Answer : Option C
Explaination / Solution:
Biosphere reserve is generally a vast protected area of land patches divided into three zone, core, buffer and transition zone. A transition zone May contain a variety of agricultural activities, grazing, plantation cultivation And settlements and other uses and in which local communities, management agencies, scientists, non-governmental organizations, cultural groups, economic interests and other stakeholders work together to manage and sustainably.
Q6. The middle layer of uterus is thick muscular myometrium that help in
Answer : Option D
Explaination / Solution:
The middle layer of uterus is thick and muscular structure called myometrium that help in exhibiting strong contraction during delivery of the baby.
Q7. When chromosome sets are present in multiple of ‘n’ the condition is called
Answer : Option B
Explaination / Solution:
Most of the organisms are diploid, contain two set of chromosome (2n) but a number of organisms contains multiple of chromosome set like 3n,4n, 6n etc. This condition of having multiple sets chromosome is called Euploidy.
Q8. One of the free-living anaerobic nitrogen-fixer is
Answer : Option B
Explaination / Solution:
Rhodospirillum is a free living anaerobic nitrogen-fixer. Rhizobium lives as symbiotic with leguminous plants and Azotobacter and Beijerinckia are symbiotic nitrogen fixer.
Q9. Fertilizers will not
Answer : Option A
Explaination / Solution:
Fertilizers will increase the fertility of soil and higher production of crop. When reaches to water bodies it causes eutrophication. The chemicals present in it also pollute the water. Fertilizer never acts as biological control against harmful organisms.
Q10. DNA fragments move at different distances in Gel Electrophoresis because
Answer : Option C
Explaination / Solution:
Gel electrophoresis is a technique used to separate DNA fragments (or other macromolecules, such as RNA and proteins) based on their size and charge. Electrophoresis involves running a current through a gel containing the molecules of interest. Based on their size and charge, the molecules will travel through the gel in different directions or at different speeds, allowing them to be separated from one another.
During gel electrophoresis different fragments move at different distances due to difference in their molecular weight of the fragments. Smaller fragments move more towards anode.
