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INDIAN SCHOOL AL WADI AL KABIR
`Work sheet 2
Class XII
BIOLOGY
Date: 20/05/15
GENETICS
1. Explain the law proposed by Mendel after dihybrid cross experiments.
2. With the help of two examples explain pleiotropy.
3. ABO blood group in humans is an example for dominance, co-dominance and multiple
alleles. Justify.
4. Mendel published his work on inheritance in 1865 but it remained unrecognized till 1900.
Give any four reasons for this.
5. Explain the following terms:
(a) Alleles
(b) Pedigree analysis
6. Differentiate between:
(a) Deletion and Insertion
(b) XXY disorder and XO disorder
(c) Aneuploidy and Polyploidy
7. Write brief notes on the sex determination in honey bees.
8. With the help of one example each explain male and female heterogamety.
9. Hemophilia is an example for a Mendelian disorder which is due to sex linked recessive gene.
Give brief description of any other two Mendelian disorders.
10. If a double stranded DNA has 30% of thymine, calculate the percent of guanine in the DNA.
11. Briefly describe the following:
(a) VNTR
(b) SNPs
(c) Repetitive DNA
(d) Satellite DNA
12. With the help of example explain negative regulation in the regulation of gene expression.
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13. Sickle cell anemia is due to frame shift mutation. Explain.
14. What are the different salient features of genetic code?
15. RNA splicing is an important step in the process of transcription in eukaryotes. What is the
role of this process?
16. During the process of DNA replication, synthesis in one strand is continuous while in other
strand is discontinuous. How the second strand become continuous?
17. With the help of a labeled diagram explain the structure of nucleosome.
PREVIOUS QUESTIONS
18. A tall and smooth seeded (both in heterozygous condition) plant is crossed with a dwarf and
wrinkled seeded plant (both recessive). Work out a cross to find out the phenotypic and
genotypic ratios of the progeny.
19. Name the enzyme and state its property that is responsible for continuous and discontinuous
replication of the two strands of a DNA molecule.
20. In a test cross progeny of pea plants, all were bearing violet flowers. Give the genotypes of
the parent pea plants.
21. A garden pea plant produced axial white flowers. Another of the same species produced
terminal violet flowers. Identify the dominant traits.
22. 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.
23. A normal visioned woman whose father is colour blind marries a man with normal vision.
Represent through a cross the probability of her sons and daughters to be colour blind.
24. 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.
25. Differentiate between a cistron and an exon.
26. Mention the role of ribosomes in peptide bond formation. How does ATP facilitate it?
27. Explain the dual function of AUG codon. Give the sequence of bases it is transcribed from
and its anticodon.
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28. Draw a labeled schematic sketch of replication fork of DNA. Explain the role of the enzymes
involved in DNA replication.
29. (a) Name the inheritance pattern where many genes influence a single phenotypic
expression? Give one example from human genetics.
(b)The following figure represents an operon model in bacteria.
(i) Name the inducer compound mentioned here.
(ii) Write the three types of enzymes coded by the mRNA
30. Recently a girl baby has been reported to suffer from hemophilia. How is it possible? Explain
with the help of a cross.
31. (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
32. (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?
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33. In a maternity clinic, for some reasons the authorities are not able to hand over the two newborn babies to their respective real parents. Name and describe the technique that you would
suggest to sort out the matter.
34. 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.
35. (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.
36. (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?
37. (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.
38. (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.
39. How did Alfred Hershey and Martha Chase arrive at the conclusion that DNA is the genetic
material?
40. In a court of law, two couples A and B claim a child X of blood group O as theirs. Couple A
has a man with blood group O and woman with blood group AB. Couple B has a man with blood
group A and woman with blood group B. The geneticists have helped in solving the problem but
the judge ordered for more recent and advanced techniques and the child was handed over
ultimately to couple B.
(a) Is it a correct judgment regarding the true/biological parents of the child? Justify with
your knowledge of genetics.
(b) Name the other technique that the judge has ordered in solving this problem.
(c) Indicate the value(s) exhibited by the judge.
Prepared by Ms. Agnes A
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