Practice free Zoology NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
Under unfavorable conditions, many zooplankton species in lakes and ponds are known to enter a stage of suspended development called as:
4. Read page 225, XII NCERT.
Very small animals are rarely found in polar region mainly because:
Answer 2. Read page 224, XII NCERT
Reptiles and birds are:
Fact. Page no.16
A cloning vector has two antibiotic resistance genes- for tetracycline and ampicillin. A foreign DNA
was inserted into the tetracycline gene. Non-recombinants would survive on the medium containing :
Both genes are functional in non-recombinants. In recombinants the gene for tetracycline resistance would be insertionally inactivated.
Elution is:
Answer 3. Read page 198, XII NCERT
A host cell normally does not take up a foreign DNA until it has been made competent to do so. This is because:
Cell membrane is made of a phospholipid bilayer and allows only lipid soluble substances to diffuse across it.
The first type II restriction endonuclease discovered that could cut dsDNA specific site was:
Answer 3. read page 195, XII NCERT
A gene, whose expression helps to identify transformed cells is known as
(a) A gene whose expression helps to identify transformed cell is known as selectable marker. Usually, the genes encoding resistance to antibiotics, such as tetracycline, ampicillin, etc. are useful selectable markers for e.g E.Coli.
Concept Enhancer Plasmid pBR322 has two resistance genes; amphicillin resistance (ampR) and tetracyclin resistance (tetR). These are considered as useful selectable markers.
The DNA fragments separated on an agarose gel can be visualised after staining with
(d) The DNA fragments separated on an agarose gel can be visualised after staining with ethidium
bromide. It is intercalating agent and a fluorescent agent. The stained DNA fragments are seen
bright orange coloured band under UV-light.
Thinking process Intercalation is the insertion of molecules between the planar bases of DNA. This
process is used as a method for analysing DNA. Intercalation occurs, when ligands of an appropriate
size and chemical nature fit themselves in between base pairs of DNA. These ligands are mostly
polycyclic, aromatic and planar and therefore often make good nucleic acid stains. Intensively
studied DNA intercalator include ethidium bromide, proflavine, etc.
A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant plasmid using
(d) DNA ligases (genetic gum) are used in recombinant DNA technology to join two individual fragments of double-stranded DNA by forming phosphodiester bonds between them to produce a recombinant DNA (plasmid).
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