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Biology in Human Welfare

Questions - Answers

Eight Marks Questions

1. Describe the life cycle of Plasmodium vivax in mosquito?

A: Mosquito phase/ Ross cycle: When a female Anopheles mosquito bites and sucks the blood of a malaria patient, the gametocytes along with the other stages of the erythrocytic cycle reach the crop of mosquito. Here all the stages are digested except the gametocytes. Further part of the life cycle consists of :

1. Gametogony: The formation of male and female gametes from the gametocytes is called gametogony. It occurs in the human of the crop of mosquito.

Formation of Male gamets: During this process, the nucleus of microgametocyte divides into eight daughter nuclei called pronuclei which reach the periphery. The cytoplasm is pushed out in the form of eight flagella like process. Into each flagellum like process, one pronucleus enters and forms a micro gamete/male gamete. These male gametes shows lashing movements

like those of flagella and get separated from the cytoplasm of microgametocytes, this process is called exflagellation.

Formation of female gamete: The female gametocyt undergoes a few changes and transforms into a female gamete. This process is called "maturation". The female gamete moves towards the pheriphery and the cytoplasm at that point forms a projection. This projection region is called the "fertilization cone"

2. Fertilization: The fusion of male and female gamets is called fertilization. It also occurs in the lumen of the crop of the mosquito. The pronuclei and cytoplasm of these two gamets fuse with each other, resulting in the formation of a synkaryon. Since the two gamets are dissmilar in size, this process is known as "anisogamy". The female gamete that bears the synkaryon is called the zygote, which is round and nonmotile.

3. Formation of Ookinite and Oocysts: The zygote remains inactive for some time and then tranforms into a long, slender, motile, vermiform Ookinite/Vermicule within 18 to 24 hours. It pierces the wall of the crop and settles beneath the basement membrane. It becomes round and secretes a cyst around its body. This encysted Ookinite in now called Oocyst. About 50 to 500 Oocysts are formed on the wall of the crop and appear in the form of small nodules. (Sir Ronald Ross identified these Oocysts for the first time.)

4. Sporogony: The formation of sporozoites in the Oocytes/ Oocysts is called "Sporogony". According to "Bano", the nucleus of the Oocyst first undergoes reduction division followed by repeated mitotic divisions resulting in the formation sporoblasts. Each nucleus of the sporoblast surrounded by a little bit of the cytoplasm and transforms into a sickle shaped sporozoite. Oocyst with such sporozoites is called "Sporocyst". When sporocyst ruptures, about 10,000 sporozoites are liberated into the haemocoel of the mosquito. From there, they travel into the salivary glands and ready to infection. it is completed in about 10-24 days.

2. Describe the life cycle of Ascaris lumbricoides with the help of a neat and labelled diagram.

A: Structure

Male: Curved posterior end which is considered the tail it is having a pair of equal sized chitinous 'Pineal spicules/Pineal setae', which serve to transfer the sperms during copulation.

Female: It has a straight posterior end, the tail. The female genital pore or vulva is present mid ventrally at about 1/3 the length from mouth.

Life history: Copulation takes place in the small intestine of man. After copulation, the female releases approximately two lakh eggs for day. Each egg is surrounded by a 'protein coat' with rippled surface. This is called 'mammillated eggs'. The protein coat followed by a chitinous shell and a lipid layer, internally. These eggs are passed out along with faecal matter. In the moist soil, development takes place inside the egg leading to the formation of the 1st stage 'rhabditiform larva' is produced. It under goes the 1st moulting and becomes the 2nd stage 'rhabditiform larva' which is the stage of infective to man. They reach the alimentary canal of man through contaminated food and water.

In the small intestine, the shell gets dissolved and the 2nd stage larva released. Now it undergoes extra intestinal migration. First it reaches the liver through the hepatic portal vein. From there it reaches the heart through the post caval vein.

It goes to the lungs through the pulmonary arteries. In the alveoli of the lungs it undergoes the 2nd moulting to produce the 3rd stage of larva. It undergoes the 3rd moulting so that the 4th stage larva is produced in the alveoli only. It leaves the alveoli and reaches the small intestine again, through the bronchi, trachea, larynx, glotis, pharynx, oesophagus and stomach. In the small intestine, it undergoes the 4th moulting (final moulting) to become a young one which attains sexual maturity with in 8 to 10 weeks.

Four Marks Question

1. Prevention is better than cure. Justify with regard to TDA abuse?

A: The age-old adage of 'prevention is better than cure', holds true here also.

Avoid undue parental pressure: Every child has his/ her own choice, capacity and personality. The parents should not force their childern to perform beyond their capacity by comparing them with others in studies, games.

Responsibility of parents and teachers: They should look for the danger signs and counsel such students who are likely to get into the 'trap'.

Seeking helps from peers: If peers find some one abusing drugs or alcohol immediately it should be brought to the notice of their parents or teachers. So that they can guide them appropriately.

Education and counselling: Educating and counselling the children to face problems, stress and failures as a part of life.

Seeking professional and medical help: A lot of help is available in the form of highly qualified psychologists, psychiatrists and de-addiction and rehabilitation programmers.

2. Explain the pathogenesity of wuchereria bancrafti.

A: Filarial fever: Characterised by headache, mental depression and increase in the body temperature.

Lymphangitis: Inflammation of the lymph vessels.

Lymphadenitis: Inflammation of he lymph glands.

Lymphoedema: Immense swelling of the lymph vessels and lymph glands.

e.g.: Limbs, scrotum of males, mammary glands in females.

Elephantiasis: The sweat glands of the skin in the affected regions disintegrate and the skin becomes rough. This terminal condition is referred to as elephantiasis.

Two Marks Questions

1. What is a hyper parasite.

A: It is a parasite which lives in/ on the body of another parasite.

e.g.: Nosema notabilis (a cindosporan parasite) lives in Sphaerospora polymorpha (also a cindosporan parasite) which lives in the urinary bladder of toad fish.

2. What do you mean by parasitic castration? Give one example?

A: Degeneration of gonads of the host, making it steirle. This effect is called parasitic castration.

e.g.: Sacculina (root headed barnacle, a crustacean) causes the degeneration of gonads in the crab carcnus maenas.

3. Define prepatent period. What is its duration in the life cycle of Plasmodium?

A: The interval between the first entry of Plasmodium into the blood in the form of sporozoites and the second entry of plasmodium into the blood in the form of cryptozoites is called prepatent period. It lasts approximately 8 days.

4. the eggs of Ascaris ar called mammillated egg. Justify?

A: Egg is surrounded by a protein coat with rippled surface is called mammillated eggs.

Posted Date : 01-12-2021

గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.

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