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6. Depending upon the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesised from it (DNA or RNA), list the types of nucleic acid polymerases.

Depending upon the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesised from it (DNA or RNA), two types of nucleic acid polymerases are found 1. DNA dependent DNA polymerase- It uses a DNA as a template to synthesise new strand of DNA.  2. DNA dependent RNA polymerase- It uses DNA as a template to synthesise RNA. 

5. Which property of DNA double helix led Watson and Crick to hypothesise semi-conservative mode of DNA replication? Explain.

The property of DNA double helix which led Watson and Crick to hypothesise semi-conservative mode of DNA replication is that the two strands of DNA are antiparallel and complementary to each other in terms of their base sequences. This arrangement suggests that DNA replication is semiconservative. During replication, the two strands unwind and each strand acts as a template for the synthesis of...

    If the sequence of the coding strand in a transcription unit is written as follows:
           Write down the sequence of mRNA.

The sequence of mRNA is the same as the coding strand of DNA except that thymine is replaced by uracil. Thus, the sequence of mRNA will be 5` - AUGCAUGCAUGCAUGCAUGCAUGCAUGC - 3`.

3. If the sequence of one strand of DNA is written as follows:

    Write down the sequence of complementary strand in 5'\rightarrow 3' direction.

With regard to base pairs the DNA strand are complementary to each other. So, if the sequence of DNA is   5'-ATGCATGCATGCATGCATGCATGCATGC-3' The sequence of the complementary strand will be  3`- TACGTACGTACGTACGTACGTACGTACG - 5`. In 5' - 3' strand, it can be written as 5'- GCATGCATGCATGCATGCATGCATGCAT-3'

2. If a double stranded DNA has 20 per cent of cytosine, calculate the per cent of adenine in the DNA.

By Chargaff's rule, we know that A=T and G=C. Since there are 20% cytosines, so guanines percentage will also be 20%. The G+C count is 20+20= 40%. Therefore, the remaining 60% will be contributed equally by adenine and thymine. Thus, the percentage of adenine and thymine are 30% each.     

1. Group the following as nitrogenous bases and nucleosides:
           Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine.

Nitrogenous bases- Adenine, thymine, uracil and cytosine Nucleosides- Cytidine and guanosine

10. Using various resources such as your school library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal, say horse.

The evolutionary stages of a horse are as follows:  Period Name of the evolutionary stage Features of the animal                                                      Eocene Eohippus It has 4 toes, all of them are functional. Head and neck are short Oligocene Mesohippus A slight increase in height with 3 toes on each foot Miocene Merychippus It was 100 cm tall with 3 toes on each foot....

9. Can we call human evolution as adaptive radiation?

No, human evolution cannot be called adaptive radiation because, in adaptive radiation, a single species diversifies into new different species, however, in case of human evolution, the gradual evolution of a single species occurred with time. 

8. Describe one example of adaptive radiation.

Adaptive radiation refers to the process in which the individuals belonging to a rapidly diversifying group, diverge from their lineage to form new species. Adaptive radiation works on the theory of natural selection. One example of adaptive radiation is Darwin's finches of Galapagos island. These finches were formed from a single diversifying species that came on this geographical region...

7. Practise drawing various animals and plants.

With the help of your teachers try drawing various plants and animals. While drawing, you can draw comparisons between different structures of animals and plants.  Note- The answer to this question varies according to the students. 

6. List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.

Some modern animals and fossils to which they can be linked are as follows:   Name of the animal Name of the fossils 1.  Man  Ramapithecus 2. Giraffe Palaeotragus 3. Tetrapods Ichthyostega 4. Fish Arandaspis 5. Dog Leptocyon 6. Horse Eohippus 7. Whale Protocetus 8. Bat Archaeonycteris 9. Elephant Moerithers 10. Camel Protylopus

5. Find out through internet and popular science articles whether animals other than man has self-consciousness.

Self-consciousness is the awareness of an animal towards its surroundings. Other than man, the animals which show self-consciousness are dolphins, orangutans, gorilla, chimps, elephants etc. Even dogs also show subtle consciousness.

4. Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)

The various components of human evolution involve the age of appearance, brain capacity, posture, locomotion, height, body hairs, dietary preferences, skeletal structure, cranium structure etc. A summary of human evolution based on these components is as follows:   Name of the Organisms Brain capacity in cm Posture                          Dietary preferences  Some other features   ...

3. Attempt giving a clear definition of the term species.

The term species refers to a group of individuals that are similar in their characters and can interbreed among themselves and produce viable and fertile progenies.

2. Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.

A recent study suggests Ledumahadi mafube is the fossil from South Africa, that marked the beginning of gigantic dinosaurs. This 200 million-year-old dinosaur weighed around 12 tons, making it the earliest dinosaur to pass beyond the 10-ton threshold. Later, dinosaurs would become even bigger. But in its time, Ledumahadi mafube was a giant among dwarfs (Source- Business standard).

Q 1.     Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.

Darwinian selection theory suggests that the environment selects organisms with useful variation over those which do not have useful variations. It is mainly because, in a dynamic environment, these organisms are better adapted to survive. A well-defined example for Darwin's theory is antibiotic resistance in bacteria. When bacteria were grown on penicillin containing agar medium, all the...

16. Mention any two autosomal genetic disorders with their symptoms.

The two autosomal genetic disorders are as follows 1. Sickle cell anaemia – It is an autosome linked recessive trait in which mutant haemoglobin molecules undergo polymerization under low oxygen tension causing a change in the shape of the RBC from biconvex disc to elongated sickle like structure. The defect is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth...

15. Who had proposed the chromosomal theory of the inheritance?

Sutton and Baveri in 1902 proposed the chromosomal theory of the inheritance.

14. What is point mutation? Give one example.

Point mutation- When a mutation occurs in a single base pair of DNA, it is termed as a point mutation.e.g. Sickle cell anaemia.

13. Explain the following terms with example

      (b) Incomplete dominance


Incomplete dominance-  Incomplete dominance is the phenomenon of neither of the two alleles being dominant so that expression in the hybrid is a fine mixture or intermediate between the expressions of two alleles. In snapdragon (Mirabilis jalapa), there are two types of pure breeding plants, red flowered and white flowered. On crossing the two, F1 plants possess pink flowers. On selfing them,...