CBSE 12TH BIOLOGY - Online Test
Q1. Chromosome theory of inheritance was proposed by
Answer : Option B
Explaination / Solution:
Walter Sutton and Theodor Boveri are credited with developing the Chromosomal Theory of Inheritance, which states that chromosomes carry the unit of heredity (genes) in 1902.
Q2. The chemical substances produced by some microbes and can kill or retard the growth of disease causing microbes are called
Answer : Option A
Explaination / Solution:
Antibiotics, also called antibacterials, are a type of antimicrobial drug used in the treatment and prevention of bacterial infections.They may either kill or inhibit the growth of bacteria.
Q3. All are biofuels except
Answer : Option D
Explaination / Solution:
Biopetrol is fuel having characteristic similar to petrol but is produced from palmitic acid. So, it is not a biofuel. Biodiesel, marsh gas and ethanol are biofuels produced by action of microbes.
Q4. The first step of recombinant DNA technology involves
Answer : Option D
Explaination / Solution:
The first step of recombinant DNA technology involves isolation of genetic material. This is performed by using enzymes that hydrolyzes the outer covering of cell as cellulase, chitinases pectinase etc.
Q5. Which of the following is an example of divergent evolution?
Answer : Option A
Explaination / Solution:
In divergent evolution, same structure developed along different directions due to adaptation to different needs. Homologous organs are those organs that have common origin but performing different functions.
Q6. Non-motile spores produced exogenously by constriction at the tips of special hyphae are called as
Answer : Option C
Explaination / Solution:
The plant body of fungi is called mycelium. A small portion of mycelium is called hyphae. Asexual reproduction in fungi occurs by development of constriction at the tips of hyphae called conidiophores.
Q7. Humus will never be
Answer : Option B
Explaination / Solution:
Humification leads to accumulation of dark coloured amorphous substance called humus that is highly resistance to microbial action and decompose at very slow rate.
Q8. The animals that have had their DNA manipulated to possess and express an extra gene are known as
Answer : Option D
Explaination / Solution:
Transgenic animals are animals (most commonly mice) that have had a foreign gene deliberately inserted into their genome. Such animals are most commonly created by the micro-injection of DNA into the pronuclei of a fertilised egg which is subsequently implanted into the oviduct of a pseudopregnant surrogate mother. Transgenic cow, rat, rabbits and fish have been produced.
Q9. Greatest biological problems faced by human being is
Answer : Option B
Explaination / Solution:
The population is growing very fastly all over the world. Increased population demands more and more natural resources. Population explosion is the greatest biological problem faced by human beings world over.
Q10. Embryonal axis has the radicle and root cap enclosed in an undifferentiated sheath is known as
Answer : Option B
Explaination / Solution:
In monocotyledonous seeds embryonal axis has undifferentiated sheath that covers radicle and root cap is called coleorhiza.
