CBSE 12TH BIOLOGY - Online Test
Q1. Haploid chromosome number is 12. What is the number in monosomic?
Answer : Option D
Explaination / Solution:
Monosomic is an aneuploidy in which a chromosome is deficient of its homologous causing genetic imbalance resulting in weaker than normal form. In normal form(2n) 24 chromosome should be present but 1 homologous pair is absent so, only 23 chromosome will be present in monosomic individual.
Q2. Which one of the following plant is commonly used as green manure?
Answer : Option A
Explaination / Solution:
Green manure is organic substance that increases the fertility of soil. Crotalaria juncea is grown into and ploughed to soil that decompose and increase the fertility.
Q3. The possible drawback of bioremediation method for oil spill containment is :
Answer : Option C
Explaination / Solution:
Bioremediation is a waste management technique that involves the use of organisms to neutralize pollutants from a contaminated site.
In this method large number of bacteria outcompete other organisms for oxygen creating a dead zone.Dead zones are low- oxygen, or hypoxic, areas in the world's oceans and lakes.
Q4. Technique associated with DNA amplification is
Answer : Option C
Explaination / Solution:
DNA amplification is done by using the technique of polymerase chain reaction in which millions of copies of DNA segments are produced.
Q5. Assertion: Organic evolution explains that new species originated from pre-existing life forms and there is gradual variation in trait to adjust in particular habitats.
Reason: existing living forms share similarities to various degrees among themselves and also with life forms that existed millions of years ago.
Reason: existing living forms share similarities to various degrees among themselves and also with life forms that existed millions of years ago.
Answer : Option C
Explaination / Solution:
Organic evolution are the events involved in the evolutionary development of a species. It means that all life descended from other life, although features may have changed dramatically along the way.
Charles Robert Darwin collected the observations on animal distribution and the relationship between living and extinct animals. He found that existing living forms share similarities to varying degrees not only among themselves but also with the life forms that existed millions of years ago, some of which have become extinct.
Q6. In grafting, scion forms
Answer : Option D
Explaination / Solution:
In grafting, scion forms the upper shoot system and stock forms the lower root system. Grafting is an artificial mode of vegetative propagation in which two plants are cut and same height and joined together.
Q7. An ecological succession on bare land proceeds towards
Answer : Option B
Explaination / Solution:
An ecological succession on bare land proceeds towards increasing wetness. Availability of water help in faster growth of organism including plants.
Q8. Bio-weapons are conventionally used by terrorists as they are
Answer : Option B
Explaination / Solution:
Bio-weapons are conventionally used by terrorists as they are invisible and extremely difficult to detect. It includes addition of microbes in water, food etc. that can cause disease in large number of people.
Q9. Contraceptive pills are taken for _______ days starting from 5th day menstruation
Answer : Option C
Explaination / Solution:
Contraceptive pills are taken for 21days starting from 5th day of menstruation. They increase the female hormone levels to obstruct in ovulation process.
Q10. Statement I: Embryos of monocotyledons possesses only one cotyledon.
Statement II: In grass family cotyledon is called as scutellum.
Statement III: In monocotyledonous embryo radicle and root cap is covered by coleoptile.
Statement II: In grass family cotyledon is called as scutellum.
Statement III: In monocotyledonous embryo radicle and root cap is covered by coleoptile.
Answer : Option A
Explaination / Solution:
monocotyledonous embryo contain only one cotyledon. In grass family, cotyledon is called as scutellum. In monocotyledonous embryo radicle and root cap is covered by coleorhiza.
