Science (English Medium)
Academic Year: 2019-2020
Date & Time: 14th March 2020, 10:30 am
Duration: 3h
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General Instructions:
Read the following instructions very carefully and strictly follow them:
- Question paper comprises five sections – A, B, C, D and E.
- There are 27 questions in the question paper. All questions are compulsory.
- Section A – Questions no. 1 to 5 are multiple choice questions, carrying 1 mark each.
- Section B – Questions no. 6 to 12 are short-answer questions type-I, carrying 2 marks each.
- Section C – Questions no. 13 to 21 are short-answer questions type-II, carrying 3 marks each.
- Section D – Questions no. 22 to 24 are short-answer questions type-III, carrying 3 marks each.
- Section E – Questions no. 25 to 27 are long-answer questions, carrying 5 marks each.
- Answers should be brief and to the point.
- There is no overall choice in the question paper. However, an internal choice has been provided in two questions of 1 mark, one question of 2 marks, two questions of 3 marks and three questions of 5 marks. Only one of the choices in such questions have to be attempted.
- The diagrams drawn should be neat, proportionate and properly labelled, wherever necessary.
- In addition to this, separate instructions are given with each section and question, wherever necessary.
Hormones released in human females only during pregnancy are ______.
hCG, hPL, Progesterone
Relaxin, hCG, hPL
hCG, hPL, Oxytocin
hCG, hPL, Oxytocin
Chapter:
Nematode specific genes were introduced into the tobacco host plant by using the vector ______.
Plasmid
Bacteriophage
pBR 322
Agrobacterium
Chapter:
The principle of vaccination is based on the property of ______.
Specificity
Diversity
Memory
Discrimination between ‘self’ and ‘non-self’
Chapter:
Opioids act as ______.
Depressants
Pain killers
Euphoria providers
Stimulants
Chapter:
One of the ex situ conservation methods for endangered species is ______.
Biosphere reserves
National parks
Cryopreservation
Wildlife sanctuaries
Chapter:
Ozone gas is continuously formed in the stratosphere by ______.
Action of UV rays on nascent oxygen
Reaction of oxygen with water vapour
Action of UV rays on molecular oxygen
Action of UV rays on water vapour
Chapter:
Introduction of an alien DNA into a plant host cell is achieved by making them ______.
Competent with bivalent ions
Using microinjections
Using gene gun
Using lysozymes and chitinase
Chapter:
Why are humming birds not found in the Polar region?
Chapter:
Spirulina is a rich source of proteins. Mention the two ways by which large scale culturing of these microbes is possible.
Chapter:
How does EcoRI specifically act on DNA molecule? Explain.
Chapter:
Name and explain the technique that can be used in developing improved crop varieties in plants bearing female flowers only.
Chapter:
When are the non-flowering plants said to be homothallic and monoecious; and heterothallic and dioecious? Give an example of each.
Chapter:
Explain the cause responsible in a human to have sex chromosomes as ‘XXY’ instead of ‘XX’ or ‘XY’.
Chapter:
List any two ways such individuals are different from the normal being.
Chapter:
How is the mechanism of evolution explained by de Vries?
Chapter:
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Write the scientific name of methanogen bacteria. Where are these bacteria generally found? Explain their role in biogas production.
Chapter:
Majority of angiosperms have hermaphrodite flowers, but self-pollination is discouraged by them. Explain any three outbreeding devices that they have developed to achieve this.
Chapter:
Differentiate between the pattern of inheritance in humans of the blood diseases, haemophilia and thalassemia.
Chapter:
‘‘Cotton bollworms enjoy feeding on cotton plants, but get killed when feed on Bt cotton plant.’’ Justify the statement.
Chapter:
How is gene therapy carried out to treat the patients suffering from ADA deficiency disease?
Chapter:
State the possibility of a permanent cure of ADA deficiency disease.
Chapter:
Compare the mechanism of sex determination in humans with that of honey bees, with respect to chromosome number.
How is the gamete formation comparable in the above two cases?
Chapter:
You are asked to find the genotype of a pea plant bearing violet flowers, growing in your school garden. Give your explanation to get the solution.
Chapter:
Mention the chemical nature of an antibody and name the type of cells they are produced by.
Chapter:
Write the difference between active and passive immune responses on the basis of antibodies.
Chapter:
Name the cells that act as HIV factory in humans when infected by HIV. Explain the events that occur in these infected cells.
Chapter:
Explain the solutions found by Ahmed Khan, a Bengaluru based plastic sack manufacturer, after realising the problems created by plastic wastes.
Chapter:
Name the process that makes the detritus become part of the soil in the nutrient cycle.
Chapter:
Write the factors responsible for controlling the rate of this process.
Chapter:
Mention the condition when the rate would be faster.
Chapter:
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Study the transverse section of human ovary given below and answer the questions that follow:
- Name the hormone that helps in the growth of A → B → C.
- Name the hormone secreted by A and B.
- State the role of the hormone produced by D.
Chapter:
Indiscriminate use of chemicals, pesticides and weedicides by humans are polluting our water bodies, which in turn are harming the living organisms. Study the flow chart and answer the questions based on it.
- Why does the concentration of DDT seem to be considerably high in the top consumer?
- How would the organisms at the highest level be affected?
- Name the phenomenon observed.
Chapter:
Given below is the diagram representing the observations made for separating DNA fragments by Gel electrophoresis technique. Observe the illustration and answer the questions that follow:
- Why are the DNA fragments seen to be moving in the direction A → B?
- Write the medium used on which DNA fragments separate.
- Mention how the separated DNA fragments can be visualised for further technical use.
Chapter:
When does the process of spermatogenesis begin in human males?
Chapter:
Briefly describe the process of spermatogenesis.
Chapter:
Explain the role of gonadotropin in spermatogenesis process.
Chapter:
Where does megasporogenesis occur in the ovule of an angiosperm? Describe the process up to the development of a mature embryo sac.
Chapter:
According to ecologists, tropical regions in the world account for greater biological diversity. Justify.
Chapter:
Why is habitat loss considered as the cause of biodiversity loss? Explain with the help of an example.
Chapter:
Why is alien species invasion considered as the cause of biodiversity loss? Explain with the help of an example.
Chapter:
Differentiate between primary and secondary succession.
Chapter:
Give an example of a pioneer species in Xerarch succession respectively.
Chapter:
Give an example of a pioneer species in Hydrarch succession respectively.
Chapter:
Name and write two characteristics of the type of DNA that forms the basis of DNA fingerprinting technique.
Chapter:
Explain different steps involved in DNA Fingerprinting.
Chapter:
Write a note on applications of DNA fingerprinting.
Chapter:
Explain the role of different genes in a lac operon, when in a ‘Switched On’ state.
Chapter:
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