CBSE 12TH BIOLOGY - Online Test
Q1. In diploid organism, gametes are produced by meiosis division but in haploid organism gametes are produced by
Answer : Option B
Explaination / Solution:
During mitosis division two daughter cells are produced having same number of chromosome. In meiosis division four daughter cells having half the number of chromosomes are produced. So, haploid organisms follow mitosis division.
Q2. The enzyme ligase is used to
Answer : Option C
Explaination / Solution:
DNA ligase is a specific type of enzyme, a ligase, that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. It plays a role in repairing single-strand breaks in duplex DNA in living organisms.
The enzyme ligase is used to join vector and gene of interest to form hybrid genome that can be introduced into vectors.
Q3. Organic compounds first evolved in earth required for origin of life were
Answer : Option C
Explaination / Solution:
The organic compounds first evolved in earth required for origin of life were proteins and nucleic acids. Proteins are made of amino acids arranged in different order and DNA and RNA are nucleic acids.
Q4. First gene therapy was done for
Answer : Option A
Explaination / Solution:
A four-year old girl became the first gene therapy patient on September 14, 1990 at the NIH Clinical Center. She has adenosine deaminase (ADA) deficiency, a genetic disease which leaves her defenseless against infections.
Q5. Sexually transmitted disease can be transmitted through sharing of injection or from mother to foetus is
Answer : Option A
Explaination / Solution:
AIDS can be transmitted from infected partner to healthy partner during sexual intercourse. Beside this this syndrome can be transmitted from infected mother to their child and through sharing of injection and blood transfusion.
Q6. Adipose tissues in whales and dolphins help in
Answer : Option A
Explaination / Solution:
Adipose tissues in whales and dolphins help in thermoregulation. Adipose tissue stores fats that help maintaining temperature of the body. Fat acts as insulator that maintains constant temperature of the body.
Q7. The immunoglobulin abundant in colostrum is
Answer : Option C
Explaination / Solution:
Colostrum is the milk secreted by pregnant female after the delivery of baby. This milk contains immunoglobulin IgA that provide immunity to baby from several diseases.
Q8. A single strand of nucleic acid tagged with a radioactive molecule is called
Answer : Option C
Explaination / Solution:
A probe is a fragment of DNA or RNA of variable length (usually 100–1000 bases long) which can be radioactively labeled. It can then be used in DNA or RNA samples to detect the presence of nucleotide sequences (the DNA target) that are complementary to the sequence in the probe.
Q9. The concept of ecological pyramids was developed by :
Answer : Option B
Explaination / Solution:
The concept of ecological pyramid was developed by Charles Elton; these pyramids are also known as Eltonian pyramids. The pyramids are a graphical representation which depicts the number of organisms, biomass and productivity at each trophic level.
Q10. Inbreeding is necessary if you want to evolve a
Answer : Option B
Explaination / Solution:
Pure line is necessary for carrying out breeding programmers. Pure line is obtained by inbreeding plants followed by test crossing until we get homozygous plants for particular traits.
