Biology:2018:CBSE: (Outside Delhi): Set III
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How do cytokine barriers provide innate immunity in humans?Marks:1
Cytokines are the small proteins that are released by some cells of the immune system. These cells activate the cellular components of innate and specific immunity like macrophage, B and T lymphocytes, mast cell etc. Some cytokines like interferons that are released by virus infected cells protect non-infected cells from further viral infection.
Write the dual purpose served by Deoxyribonucleoside triphosphates in polymerization.Marks:1
The dual purpose served by Deoxyribonucleoside triphosphates in polymerization are:
i. It acts as substrate
ii. It also provides energy to drive DNA polymerization by breaking phosphoanhydride bond
Write the names of the following:
(a) A 15mya primate that was ape-like
(b) A 2mya primate that lived in East African grasslandsMarks:1
(a) Ramapithecus and Dryopithecus
Mention the chemical change that proinsulin undergoes, to be able to act as mature insulin.Marks:1
A proinsulin consists of three chains polypeptide A, polypeptide B and polypeptide C. The polypeptide chain A and B are linked together by disulphide bond. During maturation, polypeptide C chain is removed this converts the proinsulin into mature insulin.
Name two diseases whose spread can be controlled by the eradication of Aedes mosquitoes.Marks:1
Dengue and Chikunguniya are the disease whose spread can be controlled by the eradication of Aedes mosquitoes.
How did a citizen group called friends of Arcata Marsh, Arcata California, USA help to improve water quality of the marshland using Integrated Waste Water Treatment? Explain in four steps.Marks:2
The treatment is done in four stages:
- At first stage, physical impurities are removed by the process of sedimentation and filterationby using bar screens and grit separators.
- From the primary clarifier water is then pumped to the oxidation ponds, where microorganisms naturally remove up to 50% of the biochemical oxygen demand (BOD).
- After secondary treatment, water is then chlorinated and dechlorinated before going to enhancement marshes.
- In enhancement marshes, appropriate plants, algae, fungi and bacteria help in neutralizing, absorbing and assimilating the pollutants.
- The water is then either discharged into Humboldt Bay or used in the enhancement marshes to continue the cycle.
You are advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop.
(a) Recommend two microbes that can enrich the soil with nitrogen.
(b) Why do leguminous crops not require such enrichment of the soil?Marks:2
(a) Nostocand Anabaena are the two microbes that can enrich the soil with nitrogen.
(b) Leguminous plants have nodules on their roots. These nodules contain nitrogen fixing bacteria Rhizobium. These bacteria fix the atmospheric nitrogen directly into the soil. Since these plants contain all the necessary components required for nitrogen fixation these crops do not require any enrichment of the soil.
You have obtained a high yielding variety of tomato. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop.Marks:2
The procedures that ensure retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop are micropropagation and inbreeding.
Micropropagation is a technique in which plant cell is multiplied in in-vitro condition to regenerate a whole plant.
In this technique, the part of plant that is used to generate whole plant is called an explant. The explant is grown in laboratory conditions using special nutrient media. The progenies obtained by this process are genetically identical to the parent. Thus with the help of micropropagation, thousands of plants identical to parent plant can be produced in short period of time.
In inbreeding process, closely related species are mated. In this method also, the genetic composition of progenies remain similar to parent plant.
(a) Name the source plants of heroin drug. How is it obtained from the plant?
(b) Write the effects of heroin on the human body.Marks:2
(a) Heroin drug is obtained from Papaversomniferum, commonly known as poppy plant.
(b) The effects of heroin on the human body are:
i. It leads to slow heartbeat and cause vomiting, nausea etc.
ii. It also affects the functioning of the brain.
With the help of an algebraic equation, how did Hardy-Weinberg explain that in a given population the frequency of occurrence of alleles of a gene is supposed to remain the same through generations?Marks:2
Hardy-Weinberg states that in the absence of disturbances like mutation, the frequency of occurrence of alleles of a gene in a population remain constant.
This principle can be understood by a mathematical equation called Hardy-Weinberg equation.
For example a gene has two alleles A and a in a population. If p is the frequency of occurrence of dominant allele A and q is the frequency of occurrence of dominant allele a. Then the genotype frequency in the offsprings can be represented as:
(p+q)2= p2 +2pq+ q2 =1