CBSE 12TH BIOLOGY - Online Test
Q1. The cultivation of a single cash crop in plantations or estates (large areas of land) on a large scale(in the whole year)is called plantational farming and example is/are
Answer : Option B
Explaination / Solution:
Plantation agriculture is a form of commercial farming where crops are grown for sale. Some crops are sold as raw materials to manufacturing industries or partially processed and value added before selling the products to large companies for further processing. Example of plantational farming is rubber plantation, tea plantation etc.
Q2. EtbR fluoresces in UV light because
Answer : Option A
Explaination / Solution:
Ethidium bromide is a molecule commonly used to visualize DNA in agarose gel electrophoresis experiments. It both binds to DNA and fluoresces under the proper conditions. Ethidium bromide is known as an intercalating agent. The flat structure of ethidium bromide allows it to intercalate, or insert, between nitrogenous bases of a DNA molecule. This interaction is especially useful because of ethidium bromide's second characteristic. When it is exposed to ultraviolet light, ethidium bromide fluoresces. Thus, this chemical provides both a means of tagging DNA molecules and a means of visualizing them.
Q3. Big bang theory try to explain
Answer : Option A
Explaination / Solution:
The Big Bang is a scientific theory about how the universe started, and then made the stars and galaxies we see today.
It tries to explain the origin of universe. It told us about the singular large explosion unimaginable in physical term.
Q4. Asexual reproduction is common in
Answer : Option B
Explaination / Solution:
Asexual reproduction is common in Protists and Monera. Both these kinds include organisms having single celled body. Binary and multiple fissions are generally followed for asexual mode of reproduction.
Q5. In which of the following places, succession will occur in short time
Answer : Option B
Explaination / Solution:
Succession will occur in short time in heavily overgrazed pasture. If organic compound are already available in the place new organisms will develops faster as compare to bare land without organic matter.
Q6. Some ethical standards are required to
Answer : Option D
Explaination / Solution:
The manipulation of living organisms by the human race cannot go on any further, without regulation. Some ethical standards are required to evaluate the morality of all human activities that might help or harm living organisms.
Going beyond the morality of such issues, the biological significance of such things is also important. Genetic modification of organisms can have unpredicatable results when such organisms are introduced into the ecosystem.
Q7. The most important step to overcome the problem of population explosion is to
Answer : Option D
Explaination / Solution:
The problem of population explosion can be overcome by motivating smaller families by using contraceptive methods.
Q8. The correct order of stages of embryogeny in dicotyledonous embryo is
Answer : Option C
Explaination / Solution:
Embryogeny in dicotyledonous plants involves mitotic division of zygote to form proembryo, further division in proembryo results into globular embryo followed by heart-shaped embryo to mature embryo.
Q9. A statement 933 females per 1000 males depict
Answer : Option C
Explaination / Solution:
Sex ration is the no of female available per thousands of male in a population. Sex ratio is decline due to female feticides alarmingly in some part of India.
Q10. Suddenly any person gets rid of Alcohol or drug then which kind of deficiency occurs in that person?
Answer : Option D
Explaination / Solution:
When a person suddenly stops taking alcohol or drug than he may develop deficiency syndrome called visual syndrome in person accommodating power decrease suddenly. Cry-du-chat syndrome is a genetic disease.
