BIO 102 | Study Mode

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Question 11
A
Trypanosoma cruzi
B
T. rhodesiense
C
T. tangela
D
T. gambiense.
Explanation
Trypanosoma gambiense was first observed by Forde in 1901. It causes African sleeping sickness. The disease, also called trypanosomiasis, is found in western and central parts of Africa. The parasite is transmitted by blood sucking tse-tse fly, Glossina palpalis. Mouth and contractile vacuole are absent. Food is absorbed through the body surface.

The parasite multiplies by fission. In human beings the parasite lives in the blood plasma. It causes trypanosoma fever. It is accompanied by glandular swelling. Later the parasite enters cerebrospinal fluid and damages the brain. It makes the patient lethargic and unconscious. Because of it, the disease is called sleeping sickness. If untreated, the disease leads to death.


Correct option: D
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Question 12
A
housefly
B
tsetse fly
C
sandfly
D
fruit fly.
Explanation
Trypanosoma gambiense was first observed by Forde in 1901. It causes African sleeping sickness. The disease, also called trypanosomiasis, is found in western and central parts of Africa. The parasite is transmitted by blood sucking tse-tse fly, Glossina palpalis. Mouth and contractile vacuole are absent. Food is absorbed through the body surface.

The parasite multiplies by fission. In human beings the parasite lives in the blood plasma. It causes trypanosoma fever. It is accompanied by glandular swelling. Later the parasite enters cerebrospinal fluid and damages the brain. It makes the patient lethargic and unconscious. Because of it, the disease is called sleeping sickness. If untreated, the disease leads to death.


Correct option: B
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Question 13
A
cryptomerozoties
B
metacryptomerozoites
C
merozoites
D
trophozoites.
Explanation
Symptoms of malaria first appear several days after the infection of the malaria parasite in man. This interval of time or the incubation period is utilized by the parasites to increase their progeny. To establish malarial symptoms, it is necessary that a large number of organisms must continue erythrocytic cycle at a time.

A healthy person acquires infection when a female Anopheles mosquito, containing infective stages of parasite (sporozoites) in its salivary glands, bites him for sucking his blood. Once within the numan blood, the sporozoites get into liverto invade the hepatic cells. Here they multiply asexually by schizogony.

Liver schizogony has two phases, pre-erythrocytic and exo-erythrocytic: Pre-crythrocytic phase: After penetrating a hepatic cell each sporozoite becomes a cryptozoite. It grows for a number of days and becomes a spherical and non- pigmented schizont.

It divides by schizogony (multiple fission) and forms a large number of uninucleate cells, the cryptomerozoites. During pre-erythrocytic schi7ogony, blood remains sterile and its inoculation does not produce infection.

Exo-erythrocvic phase: Cryptomerozoites enter fresh liver cells to become metacryptozoites. They undergo schizogony similar to the previous one producing enormous number of metacrypto-merozoites. Metacryptonierozoites, after escaping into blood stream, invade the erythrocytes or red blood corpuscles. This starts the erythrocytic schizogony. With erythrocytic schizogony, the symptom of malaria starts appearing.


Correct option: B
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Question 14
A
Plasmodium falciparum
B
P. vivax
C
P. ovale
D
P. malariae.
Explanation
Plasmodium falciparum is the greatest killer of human beings over most parts of Africa and elsewhere in tropics. It causes malignant (or pernicious or cerebral or tropical) tertian malaria.

This malaria is most harmful. Plasmodium vivax causes benign tertian malaria. Plasmodium malariae causes quartan malaria. Plasmodium ovale is the rarest of the four species which infect man and it causes mild tertian malaria.


Correct option: A
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Question 15
A
sexual cycle
B
pre-crythrocytic schizogony
C
exoerythrocytic schizogony
D
post-erythrocytic schizogony.
Explanation
Plasmodium has two hosts.

(i) Female Anopheles mosquito: Here the sexual phase of the malaria parasite occurs and it is considered the definitive host of material parasite, (ii) Human beings: Here the asexual phase of malaria parasite occurs. It is considered as the intermediate host. Options b, c and d are the stages of the asexual phase of Plasmodium.


Correct option: A
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Question 16
A
polymorphic
B
monogenetic
C
facultative parasite
D
non-pathogenic.
Explanation
Trypanosoma is polymorphic i.e. it has more than one form. It has at least four forms that are recognized on the basis of the positions of kinetoplast and blepharoplast and the course taken by the tlagellum. Two or more such forms occur either in one or both the hosts in the life cycles of various species of Trypanosoma. These i forms are

(i) Leishmanial (amastigote): Round or oval form with a nucleus, blepharoplast and kinetoplast. Flagellum reduced and fibril-like embedded in cytoplasm.

(ii) Leptomonad (promastigote): Body elongate, nucleus large and anteriorly located blepharoplast and kinetoplast. Flagellum short and unattached.

(iii) Crithidial (epimastigote): Body elongate. Blepharoplast and kinetoplast placed immediately anterior to nucleus. Undulating membrane inconspicuous.

(iv) Trypanosomid (trypomastigote): Body elongate and slender. Blepharoplast and kinetoplast situated at or near posterior end. Undulating membrane conspicuous.

Tiypanosoma is digenetic i.e. it completes its life cycle in two hosts. It is an obligate parasite and is pathogenic.


Correct option: A
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Question 17
A
cuvier
B
haeckel
C
theophrastus
D
linnaeus.
Explanation
The term phylum was given by Cuvier.

Correct option: A
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Question 18
A
class-phylum-tribe-order family- genus species
B
di vision-class-family-tribe-order-genus- species
C
division-class-order-family-tribe-genus- species
D
phylum-order-class-tribe-family-genus- species
Explanation
To construct the hierarchy of classification, one or more species are grouped into a genus, one or more of genera into a family, families are clubbed into order, order into class, classes into phylum and various phyla into kingdom.

Correct option: C
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Question 19
A
Leishniania
B
Trypanosoma
C
A scar is
D
Plasmodium.
Explanation
Plasmodium is digenetic i.e. it completes its life cycle in two hosts, asexual cycle in man and sexual cycle in Anophelesmosquito. The breeding place of this mosquito is ponds, marshes, swampy areas etc. So, if all the ponds and puddles are destroyed, Anopheles will not be able to survive leading to destruction of its parasite, Plasmodium.

Correct option: D
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Question 20
A
erythrocytes
B
liver cells
C
erythrocytes and liver cells
D
erythrocytes, liver cells and spleen cells.
Explanation
Schizont stage of Plasmodium occurs in human erythrocytes and liver cells. Within the human blood the sporozoites, circulates about half an hour and enters into the liver cell. The kupffer cells of the liver clear the sporozoites from the blood stream and kill many of the organisms. A fraction of sporozoites escape destruction, however, and penetrate the hepatocytes where they take up the residence. Here they multiply by schizogony.

Correct option: C

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