CBSE 12TH BIOLOGY - Online Test
Q1. In most mammals, the testes are located in scrotal sac for
Answer : Option B
Explaination / Solution:
Testis is located in scrotal sac out of the abdominal cavity. Sperm formation require 1-2 degree less temperature than normal body temperature. The process of sperm formation is called spermatogenesis.
Q2. In blood group typing in human, if an allele contributed by one parent is IA and an allele contributed by the other parent is i, the resulting blood group of the offspring will be
Answer : Option D
Explaination / Solution:
Blood group alleles IA and i is A. As allele A is dominant over the allele i. O blood group appear only when both the alleles are i.
Q3. Treatment of waste water is done by
Answer : Option C
Explaination / Solution:
Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage. This treatment is carried out in two stages: primary treatment and secondary treatment.
Q4. The neurotoxic form of Mercury which can be directly absorbed by fishes :
Answer : Option A
Explaination / Solution:
Mercury discharged into rivers and lakes is changed by bacteria to the neurotoxic form called methyl mercury. The latter is highly poisonous and may be directly absorbed by fish.
From fishes they enter into food chain and to human by bio-magnification.
Q5. The degenerative and irreversible changes in the organism is known as
Answer : Option A
Explaination / Solution:
life cycle of organism’s starts from growth and development followed by reproductive phase. After that senescence phase starts in which degenerative changes starts which is generally irreversible and leads to death of organisms.
Q6. In Genetic Engineering, to cut DNA at a specific site, the enzyme used is
Answer : Option C
Explaination / Solution:
In genetic engineering, restriction enzymes (or restriction endonucleases) are used to cut DNA into smaller fragments. The cuts are always made at specific nucleotide sequences. Different restriction enzymes recognise and cut different DNA sequences. These fragments are joined together using another enzyme called ligase.
Q7. Jurassic period of the Mesozoic era characterized by
Answer : Option D
Explaination / Solution:
Jurassic period of Mesozoic era characterized presence of Gymnosperms as dominant plant and first birds evolved from reptiles. Dianasours are also a kind of reptiles.
Q8. Insulin earlier was extracted from
Answer : Option C
Explaination / Solution:
insulin is taken from the pancreases of animals, usually pigs (porcine or pork insulin) and cows (bovine or beef insulin).
The insulin is purified which reduces the chance of the insulin user developing a reaction to the insulin.This insulin caused allergy in diabetic patients.
Q9. Acquired Immuno Deficiency Syndrome is
Answer : Option B
Explaination / Solution:
AIDS is mainly caused due to reduction of Helper-T cells that provide immunity against the different kinds of infection. It is located in WBCs.
Q10. The statistical study of human population is called
Answer : Option B
Explaination / Solution:
The statistical study of human population in a particular area that changes over time or space is called demography. It includes size, growth, density, distribution and vital statistics.
