SAMPLE QUESTION PAPER (2021-22)
BIOLOGY (044)
TERM II
CLASS 12
Time: 2 Hrs Max. Marks: 40
GENERAL INSTRUCTIONS
i. All questions are compulsory.
ii. The question paper has three sections and 13 questions. All questions are compulsory.
iii. Mark distribution:
a. Section–A has 6 questions of 2 marks each
b. Section–B has 6 questions of 3 marks each
c. Section–C has a case-based question of 5 marks.
iv. There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
v. Wherever necessary, neat and properly labelled diagrams should be drawn.
SECTION A
Attempt all questions: –
Q.1 Sometimes red coloured itchy spots appear on the skin. What are these spots called in general terms? Under what conditions a person can get such an infection?
Ring worm infection (Fungus)
Hot and humid conditions are required for the growth of fungus, contact spread.
Q.2. Increase in human population and motorization have its own issues of resource utilization. At the end of the day, a lot of environmental issues crop up. How the figure given below help to sort out the problem?
Sewage treatment plant.
Anthropogenic activities generate lot of wastes (solid / liquid / gaseous).
STP are used to reduce the wastes in the liquid form as sewage. It includes domestic (kitchen/bathroom/toilet) wastes and may also include some industrial wastes. Basically it reduces organic load of sewage (BOD).
OR
The introduction of lady bird beetle is a beneficial methodology for agriculture / horticulture. Mention two points to justify the statement.
Lady bird beetle is a natural predator of other insects particularly pests.
By feeding on pests, it saves crop plants, also help in reducing the pesticide load.
Q.3. How vaccination does save us from possible infections during pandemic?
Vaccination preconditions our defense system against a specific pathogen.
It sensitizes the defense system to recognize the pathogen/antigen in advance.
It helps prepare the memory of the pathogen in advance.
So if pathogen comes now, body is preconditioned to fight it.
Q.4. Species area relationship is a good indicator of diversity of an ecosystem. If the value of Z is 0.7 for area A, and 0.15 for area B, which area has higher species richness and a steeper slope?
The area with the value of Z=0.7 has steeper slope, indicates more rich in species per unit area.
Q.5. An ecologist study an area with species A, thriving on unlimited resources and showing exponential growth, introduced species B and C to the same area. Consider two situations:
a. Species B depends on the same resources as that of A, but population C do not.
Competition between both A & B for the same resources, so A will not follow J-shaped curve. C remains unaffected.
b. Species B with status as that of population C (Status of C remains unchanged) but both do not share same time of the day.
No competition between any. Species A maintains follow J-shaped curve, Both B & C also remains unaffected as they depend on different resources.
What will be the effect on the growth pattern of the species A, B and C when living together in the same habitat?
Q.6. How Connell did explain the change in species composition of an area?
Connell observations: Competition exclusion – On the inter-tidal zone of rocky sea coast of Scotland, the larger and the superior barnacles (Balanus) dominate whereas the smaller barnacles (Chthamalus) has been eliminated from that zone.
OR
Over the past few decades, with the increase in warming at the global level, out of the regulators and the conformers, which of the two will have better chances of survival? Give two adaptations that support them to survive in the ambient environment? Give one suitable example.
a. Regulators
b. Regulating body temperature (thermo-regulation) & osmolarity of body fluids (osmo-regulation)
c. Birds / mammals
SECTION B
Q.7. The cases of cancerous growth are more prevalent in the society these days. How do normal cells get transformed into cancerous cells? Give three examples of non-food items that are considered as contributing factors.
Normal cells can change into cancer cells due to external (physical, chemical and biological factors) and internal (genetic):
a. Ionizing radiations like X-rays, gamma rays.
b. Non-ionizing radiations like UV radiations.
c. Chemicals like tobacco.
d. Cellular onco-genes if gets activated
OR
A patient reported for persistent fever and loose motions, although no specific reason could be pin pointed by the doctor. What did the doctor finally suspected? Which test helped the doctor to reach conclusion? Give two other symptoms that could also be visible.
a. HIV infection.
b. ELISA test.
c. Persistent systems (weakness/fever/diarrhea/white patches on skin) etc.
Q.8. How the mother provides protection against infections to a new born baby. Under which category of protective mechanisms it does come. If the mother does not follow this process after delivery, how could this affect the health of baby during first few years?
Mother’s milk
It comes under acquired immunity.
If the mother does not follow it, the infant will have reduced defences after birth, may get infected and affected badly. Future growth is also hampered.
Q. 9. What are Transformants? What procedure is applied to identify the transformants in the culture medium?
The plasmid that have the specific gene of interest inserted in it is called transformant.
Procedure to identify: –
In case insertion was planned for palindrome site in tetracycline gene.
a. Culturing the experimental bacteria with the plasmid (expected to have the gene of interest). Make a replica plate of the master copy (culture plate).
b. Culturing the experimental organism in the antibiotic ampicillin rich medium.
c. If they are able to grow, it denotes that they have the plasmid.
d. Now culturing it in tetracycline rich medium.
e. If able to grow then it is non-transformant.
f. If not able to grow, then it indicates that it has the plasmid tetracycline gene inactivated due to insertion of gene of interest.
Q.10 ‘The Evil Quartet’ is a well-established term in the field of ecology. Explain how the population of organisms is affected by it.
Evil quartet is a combination of 04 factors that affect the ecosystem badly.
a. Fragmentation: Splits habitat of animals that need migration to different pastures. Limited movement, limited pastures, population reduced.
b. Over-exploitation: undue interference in the autonomy of species, reduced freedom, reduced rate of reproduction, reduced population.
c. Alien species invasion: Species from other areas may compete with indigenous species and eliminate them.
d. Co-extinction: Two interdependent species. Reduction to one may lead to damage to other automatically.
Q.11 In the following figure three points A, B, C have been demarcated with A denoting Delhi, B denoting Faridabad and C denoting Agra. Water samples were collected from the three locations. The BOD levels of samples A, B and C were 400 mg/L, 480 mg/L and 20 mg/L respectively.
a. What is this indicative of?
Untreated sewage in the river water at Delhi and Faridabad.
b. Why the BOD level gets reduced considerably at the collection point at the start of Agra?
At point C, the level of BOD is reduced as the sewage is treated at STP.
c. Do you expect any variation in the values while on course through Agra.
While traversing through Agra, it is expected that sewage will be added so BOD will increase.
d. What effect will it have on Taj Mahal in Agra?
Q.12 The image below depicts the result of gel electrophoresis. The loading of sample is indicated at the top.
a. The top portion of the gel corresponds to which electrode?
Anode
b. What inference can you draw from the sample III & IV?
Sample III- largest in size as it travelled the least.
Sample IV- smallest in size as it travelled maximum.
c. DNA is invisible to naked eye, then how it becomes visible here?
Autoradiography after using DNA specific dye.
SECTION C
Q.13 Some of the diseases are inborn and practically there is no medicine to cure them.
The advancement in science & technology has provided some possible approaches that could be adopted in order to either reduce the morbidity or to prevent mortality. This approach came into lime light during the year 1990, when it was successfully applied on a 4-year girl.
a. The above paragraph pertains to which technique?
Gene therapy
b. The reported case was of which disease?
ADA deficiency
c. What intervention was planned by this technique?
R-DNA technology to transform lymphocytes, then introducing these into the blood of recipient. Such lymphocytes worked normally.
d. Why it was felt that repeated procedures will be required for the girl?
Since lymphocytes are mature, differentiated cells, they have limited life span. So repeated intervention is required.
e. What was thought to make it just one-time procedure for permanent cure?
Transformed stem cells from bone marrow to be infused in the recipient.
OR
GM crops especially Bt crops are known to have higher resistance to pest attacks. To substantiate this, experimental study was conducted in 4 different farmlands growing Bt and non Bt-Cotton crops. The farm lands had the same dimensions, fertility and were under similar climatic conditions. The histogram
below shows the usage of pesticides on Bt crops and non-Bt crops in these farm lands.
a. Which of the above farm lands have used the concepts of biotechnology in a better way?
Farm – II
b. Which of the above farm lands has depicts poor management practices?
Farm – III
c. As a farmer, which crop (GM / non GM) would you prefer and why?
GM crop, reduced demand of pesticides/fertilizers or increased tolerance to odd environment conditions.
d. In a separate experimental study, cotton bollworms were deliberately introduced in two farm lands where no pesticide was used. Explain what effect would a Bt and Non Bt crop have on the pest.
Cotton bollworm in Bt-cotton farm – Less damage to crop.
Cotton bollworm in non-Bt-cotton farm – More damage to crop.