CBSE 12TH BIOLOGY - Online Test
Q1. Plasmid is a
Answer : Option D
Explaination / Solution:
Plasmid is a small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independently. Plasmid is most commonly found in bacteria as small circular, double stranded DNA molecule.
Q2. The first photo-autotroph organisms were
Answer : Option C
Explaination / Solution:
The first photo-autotroph organisms were bacteria. They are still present on earth in different form ranging from chemoautotrophs, autotrophs and heterotrophs.
Q3. Cry genes can be transferred as they are present in a bacteria in
Answer : Option A
Explaination / Solution:
Cry gene is present in plasmid of bacterium. This gene can be easily separated from plasmid and included into another crops to provide resistance against pests and insects.
Q4. Fruit softening is promoted by polygalacturonase which degrades
Answer : Option C
Explaination / Solution:
Pectin present in cell wall of plant cell is responsible for hardness of fruit coat. Polygalacturonase is induced into the fruit that degrade the pectin and soften the fruit.
Q5. Action plans and programmes to attain total reproductive health called family planning were initiated in India in.
Answer : Option D
Explaination / Solution:
The first action plan to attain total reproductive health called family planning was initiated in 1951 in India after independence.
Q6. Interactions between different species living within a particular area may be:
Answer : Option B
Explaination / Solution:
Interactions between different species living within a particular area may be useful as in case of mutualism, fatal as in case of parasitism or neutral in which no one is harmed.
Q7. Goitre can occur as a consequence of all the following except
Answer : Option B
Explaination / Solution:
Goitre is a deficiency disease that occurs due to less secretion of hormone thyroxin. Less or no secretion of this hormone may occurs due to iodine deficiency, pituitary adenoma and Grave’s disease.
Q8. The term gene was coined by
Answer : Option D
Explaination / Solution:
The term gene was coined by Johannsen in 1909. He defined gene to be elementary unit of inheritance that specifies the expression of a particular trait.
Q9. Amount of biomass produced per unit area by green plants is called:
Answer : Option C
Explaination / Solution:
Primary productivity refers to the degree to which autotrophic organisms (primarily plants and algae) convert energy into organic substances through photosynthesis or chemosynthesis. Since the process of photosynthesis consumes carbon dioxide and produces oxygen, it is of great importance to the environment. Primary productivity refers to the amount of carbon-fixing biomass produced.
Q10. The method of producing thousands of plants through tissue culture is called
Answer : Option A
Explaination / Solution:
The method of producing thousands of plants through tissue culture is called micro propagation. In this method, small part of plant is kept in nutrient medium along with plant hormones.
