Download genetics

INDIAN SCHOOL AL WADI AL KABIR
`Worksheet 3
Class XII
BIOLOGY
Date: 03/08/14
GENETICS
1 ABO blood group in humans is an example for dominance, co-dominance and multiple
alleles. Justify.
2. Mendel published his work on inheritance in 1865 but it remained unrecognized till
1900. Give any four reasons for this.
3. Explain the following terms:
(a) Alleles
(b) Pedigree analysis
4. Differentiate between:
(a) Deletion and Insertion
(b) XXY disorder and XO disorder
() Aneuploidy and Polyploidy
5. Write brief note on the sex determination in honey bees.
6. With the help of one example each explain male and female heterogamety.
7. Haemophilia is an example for a Mendelian disorder which is due to sex linked
recessive gene. Give brief description of any other two Mendelian disorders.
8. If a double stranded DNA has 30% of thymine, calculate the percent of guanine in the
DNA.
9. Briefly describe the following:
(a) VNTR
(b) SNPs
() Repetitive DNA
(d) Satellite DNA
Page 1 of 4
10. With the help of example explain negative regulation in the regulation of gene
expression.
11. Sickle cell anaemia is due frame shift mutation.Explain.
12. What are the different salient features of genetic code?
13. RNA splicing is an important step in the process of transcription in eukaryotes. What
is the role of this process?
14. During the process of DNA replication, synthesis in one strand is continuous while in
other strand is discontinuous. How the second strand become continuous?
15.With the help of a labeled diagram explain the structure of nucleosome.
PREVIOUS QUESTIONS
16. Name the enzyme and state its property that is responsible for continuous and
discontinuous replication of the two strands of a DNA molecule.
17. In a test cross progeny of pea plants, all were bearing violet flowers. Give the
genotypes of the parent pea plants.
18. A garden pea plant produced axial white flowers. Another of the same species
produced terminal violet flowers. Identify the dominant traits.
19. Name the respective pattern of inheritance where F1 phenotype
(a) Does not resemble either of the two parents and is in- between the two.
(b) Resembles only one of the two parents.
20. Name the source of the DNA polymerase used in PCR technique. Mention why it is
used.
21. In a typical monohybrid cross the F2 population ratio is written as 3:1 for phenotype
but expressed as 1:2:1 for genotype. Explain with the help of an example.
22. Differentiate between a cistron and an exon.
23. Mention the role of ribosomes in peptide bond formation. How does ATP facilitate it?
24. Explain the dual function of AUG codon. Give the sequence of bases it is
transcribed from and its anticodon.
Page 2 of 4
25. Draw a labeled schematic sketch of replication fork of DNA. Explain the role of the
enzymes involved in DNA replication.
26. Recently a girl baby has been reported to suffer from haemophilia. How is it
possible? Explain with the help of a cross.
27. (a) Draw a schematic representation of the structure of a transcription unit and
show the following in it:
(i) Direction in which the transcription occurs
(ii) Polarity of the two strands involved
(iii) Template strand
(iv) Terminator gene
(b) Mention the function of promoter gene in transcription
27. (a) In human genome which one of the chromosomes has the most genes and
which one has the fewest?
(b) Scientists have identified about 1.4 million single nucleotide polymorphs in
human genome. How is the information of their existence going to help the scientists?
29.In a maternity clinic , for some reasons the authorities are not able to hand over the
two new- borns to their respective real parents. Name and describe the technique that
you would suggest to sort out the matter.
30. Pea seeds with BB alleles have round seeds and large starch grains, while seeds
with bb alleles have wrinkled seeds with small starch grains. Work out the cross
between these two parents. Explain the phenotypic ratio of the progeny with respect to
seed shape and the starch grain size of the progeny produced.
31.(a) Work out a cross up to F2 generation between two pure breeding pea plants,
one bearing violet flowers and the other white flowers.
(b) (i) Name this type of cross.
(ii) State the different laws of Mendel that can be derived from such a cross.
Page 3 of 4
32. (a) Do you agree to the perception in our society that the woman is responsible for
the gender of the offspring? Substantiate your answer scientifically.
(b) How did Morgan explain linkage of genes?
33. (a) Mention the contributions of the following scientists:
(i) Maurice Wilkins and Rosalind Franklin
(ii) Erwin Chargaff
(b) Draw a double stranded dinucleotide chain with all the four nitrogen bases.
Label the polarity and the components of the dinucleotide.
34. (a) State the arrangement of different genes that in bacteria is referred to as operon.
(b) Draw a schematic labeled illustration of lac operon in a ‘switched on’ state.
(c) Describe the role of lactose in lac operon.
35. How did Alfred Hershey and Martha Chase arrive at the conclusion that DNA is the
genetic material?
Prepared by Ms. Rejitha
Page 4 of 4