List of practice Questions

(a) What are transgenic animals?
State why plant breeders are interested in artificial hybridisation programme. How do they carry out this process?
How does latitude influence the species richness of an ecosystem?
Tropical regions harbour more species than the temperate regions. How have biologists tried to explain this in their own ways? Explain.
(b) What is a ‘vaccine’? Explain the principle on which it works.
(a) “Mother’s milk is considered very essential for the new born infant.” Justify.
Explain the processing of heterogeneous nuclear RNA (hnRNA) into a fully functional mRNA in eukaryotes. Where does this processing occur in the cell?
(b) Mention one advantage and one disadvantage of amniocentesis.
(a) “Farmers prefer apomictic seeds to hybrid seeds.” Justify giving two reasons.
List the events that reduce the Biochemical Oxygen Demand (BOD) of a primary effluent during sewage treatment.
(b) What are the arrows in the given figure indicating? Write the result obtained thereafter.
The given DNA sequence:
5’ – G$\uparrow$A A T T C – 3’
3’ – C T T A A$\uparrow$G – 5’
(a) Name the restriction enzyme that recognises the given specific sequence of bases. What are such sequences of bases referred to as?
(b) Mention what does ‘K’ in the graph represent.

Observe the population growth curve and answer the questions given below: 
 


(a) State the conditions under which growth curve ‘A’ and growth curve ‘B’ plotted in the graph are possible. 
 

If the base adenine constitutes 31% of an isolated DNA fragment, then what will be the expected percentage of the base cytosine in it? Explain how you arrived at the answer.
Assertion (A): In molecular diagnosis, single stranded DNA or RNA tagged with radioactive molecule is called a probe.
Reason (R): A probe always searches and hybridises with its complementary DNA in a clone of cells.
Assertion (A): AIDS is a syndrome caused by HIV.
Reason (R): HIV is a virus that damages the immune system with DNA as its genetic material.
Assertion (A): “Biodiversity hotspots” are the regions which possess high levels of species richness, high degree of endemism.
Reason (R): Total number of biodiversity hotspots in the world is 22 with two of these hotspots found in India.
Assertion (A): In birds, the sex of the offspring is determined by males.
Reason (R): Males are homogametic while females are heterogametic.
The human chromosome with the highest and least number of genes in them are respectively:
Match the following genes of the lac operon listed in column ‘A’ with their respective products listed in column ‘B’:
\[ \begin{array}{|c|c|} \hline \textbf{A: Gene} & \textbf{B: Products} \\ \hline \text{a. ‘i’ gene} & \text{(i) β-galactosidase} \\ \text{b. ‘z’ gene} & \text{(ii) lac permease} \\ \text{c. ‘a’ gene} & \text{(iii) repressor} \\ \text{d. ‘y’ gene} & \text{(iv) transacetylase} \\ \hline \end{array} \] Select the correct option:
If the sequence of nitrogen bases of the coding strand in a transcription unit is 5’ – ATGAATG – 3’, the sequence of bases in its RNA transcript would be:
The first antibiotic was discovered accidentally by A while working on B. ‘A’ and ‘B’ are:
The source of ‘Smack’ is:

Observe the schematic representation of assisted reproductive technology given below: 
 


Identify the most appropriate technique depicted in the above diagram.