Most Important 5 Marks Questions for Biology Class 12th CBSE Board Exam 2018




Most Important 5 Marks Questions for Biology Class 12th CBSE Board Exam 2018

Most Important 5 Marks Questions for Biology Class 12th CBSE Board Exam 2018

Most Important 5 Marks Questions for Biology Class 12th CBSE Board Exam 2018 are given below:

Question1:

(a) Mention the role of vectors in recombinant DNA technology. Give any two examples.

(b) With the help of diagrammatic representation only, show the steps of recombinant DNA technology.

Question2:

(a) What is plasmid?

(b) What is meant by ADA deficiency? How is gene therapy a solution to this problem? Why is not a permanent cure?

Question3:

Explain Hershey-Chase experiment. What was proved by this experiment?




Question4:

(a) A true-breeding pea plant, homozygous for inflated green pods is crossed with another pea plant with constricted yellow pods (Figg). What would be the phenotype and genotype of F1 and F2 generations? Give the phenotype ratio of F2 generation.

(b) State the generalization proposed by Mendel on the basis of the above-mentioned cross

CBSE Solved Papers for 2018 board exams

Question5:

Explain the steps involved in the production of genetically engineered insulin.

Question6:

(a) Name the nematode that infects and damages tobacco roots.

(b) How are transgenic tobacco plants produced to solve this problem?




Question7:

Explain the steps involved in the production of genetically engineered insulin.

Question8:

(a) Name the nematode that infects and damages tobacco roots.

(b) How are transgenic tobacco plants produced to solve this problem?

Question9:

Explain the steps involved in the production of genetically engineered insulin. Why is insulin thus produced preferred to the one produced from non-human sources?




Question10:

(a) Why is Bacillus thuringiensis considered suitable for developing GM plants?

(b) Explain how it has been used to develop GM crops.

Question: What is a semiconservative replication of DNA? Explain how it was experimentally proved.

Question11:

(a) A true-breeding pea plant homozygous for axial violet flowers is crossed with another pea plant with terminal white flowers (aavv). Work out the cross to show the phenotypes and genotypes of F1 and F2 generations along with the ratios.

(b) State the law that Mendel proposed on the basis of such a cross.

Question12:

What are transgenic animals? Explain any four ways in which such animals can be beneficial to humans.




Question13:

(a) What is a plasmid?

(b) What is meant by ADA deficiency? How is gene therapy a solution to this problem? Why is it not a permanent cure?

Question14:

Explain with the help of a diagram the development of a mature embryo sac from a megaspore mother cell in angiosperm.

Question15:

(a) Explain the experiment performed by Griffith on Streptococcus pneumoniae. What did he conclude from this experiment?

(b) Name the three scientists who followed up Griffith’s experiments.

(c) What did they conclude and how?




Question16:

Two blood samples A and B picked up from the crime scene were handed over to the forensic department for genetic fingerprinting. Describe how the technique of genetic fingerprinting is carried out. How will it be confirmed whether the samples belonged to the same individual or to two different individuals?

Question17:

One of the main objectives of biotechnology is to minimize the use of insecticides on cultivated crops. Explain with the help of a suitable example how insect-resistant crops have been developed using techniques of biotechnology.

Question18:

(a) How is mature insulin different from proinsulin secreted by the pancreas in humans?

(b) Explain how was human functional insulin produced using rDNA technology.

(c) Why is the functional insulin thus produced considered better than the ones used earlier by diabetic patients?




Question19:

(a) How did Griffith explain the transformation of R strain (non-virulent) bacteria into S strain (virulent)?

(b) Explain how MacLeod, McCarty, and Avery determined the biochemical nature of the molecule responsible for transforming R strain bacteria into S strain bacteria.

Question20:

You are given tall pea plants with yellow seeds whose genotypes are unknown. How would you find the genotype of these plants? Explain with the help of cross.

Question21:

(a) When and how does placenta develop into a human female?

(b) How is the placenta connected to the embryo?

(c) The placenta acts as an endocrine gland. Explain.




Question22:

(a) How does a Chromosomal disorder differ from a Mendelian disorder?

(b) Name any two chromosomal aberration associated disorders.

(c) List the characteristics of the disorders mentioned above that help in their diagnosis.

Question23:

Fitness is the end result of the ability to adapt and get selected by nature. Explain with suitable example.

Question24:

When and where are primary oocytes formed in a human female? Trace the development of these oocytes till ovulation (in menstrual cycle). How do gonadotropins influence this developmental process?




Question25:

(a) Explain the events taking place at the time of fertilization of an ovum in a human female.

(b) Trace the development of the zygote up to its implantation in the uterus.

(c) Name and draw a labeled sectional view of the embryonic stage that gets implanted.

Question26:

Describe the process of decomposition of detritus under the following heads: Fragmentation; leaching; catabolism; humification and mineralization.

Question27:

Describe in sequence the events that lead to the development of a 3-celled pollen grain from microspore mother cell in angiosperms.




Question28:

(a) Give a schematic representation showing the events of spermatogenesis in a human male.

(b) Describe the structure of a human sperm.

Question29:

(a) State the law of independent assortment.

(b) Using Punnett Square demonstrate the law of independent assortment in a dihybrid cross involving two heterozygous parents.

Question30:

How did Alfred Hershey and Martha Chase arrive at the conclusion that DNA is the genetic material?




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