Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “The Female Reproductive System”.

1. The primary sex organ of female reproductive system is ______
a) fallopian tubes
b) ovaries
c) uterus
d) cervix
Answer: b
Clarification: Ovaries are the primary female sex organs that produce the female gamete (ovum) and several steroid hormones (ovarian hormones). Each ovary is almond shaped, solid, greyish-pink in color.

2. The ovaries are suspended by _______
a) fallopian tubes
b) ovarian walls
c) ligaments
d) mesovarium
Answer: d
Clarification: The ovaries are located one on each side of the lower abdomen, near the kidney of its side. It is suspended from the dorsal body wall by a mesentery, called mesovarium.

3. Outermost layer of ovary is made up of ________
a) simple cuboidal cells
b) stereocilia
c) stroma
d) cilia
Answer: a
Clarification: Ovarian or germinal epithelium is the outermost layer of ovary formed of simple cuboidal cells. It is actually modified visceral peritoneum.

4. Stroma consists of an outer ovarian ________ and inner ovarian ________
a) medulla, cortex
b) cortex, medulla
c) tunica albuginea, stroma
d) stroma, stroma
Answer: b
Clarification: Each ovary is a solid structure consisting of ovarian epithelium, tunica albuginea, ovarian cortex and stroma. Stroma consists of an outer ovarian cortex and inner ovarian medulla.

5. The ovarian ______ has a white body or corpus albicans.
a) cortex
b) medulla
c) antrum
d) luteum
Answer: a
Clarification: The ovarian cortex has a white body or corpus albicans. It represents the degenerating corpus luteum. Corpus Luteum secretes the hormone. Progesterone during pregnancy, and the hormone relaxin towards the end of pregnancy.

6. Ovarian Medulla contains many rounded or oval bodies, called _______
a) corpus luteum
b) ovarian follicles
c) corpus albicans
d) antrum
Answer: b
Clarification: Ovarian Medulla contains many rounded or oval bodies, called ovarian follicles in various stages of development. Each follicle contains a large ovum surrounded by many layers of follicle cells. The follicle cells of a maturing follicle secret oestrogens into the blood.

7. Fallopian tubes are also called as _______
a) oviducts
b) follicles
c) fimbriae
d) luteum
Answer: a
Clarification: Fallopian tubes are also called as oviducts. Each fallopian tube is about 10-12 cm long and extends from the periphery of each ovary to the uterus the part closer to the ovary is the funnel-shaped infundibulum.

8. The opening of the infundibulum into the body cavity is called ______
a) isthmus
b) ampulla
c) ostium
d) thalamus
Answer: c
Clarification: The opening of the infundibulum into the body cavity is called ostium. The edges of the infundibulum possess motile, finger-like projections called fimbriae, which help in collection of the ovum after ovulation.

9. The last part of oviduct is called _________
a) isthmus
b) ampulla
c) ostium
d) thalamus
Answer: a
Clarification: The infundibulum leads to a long, wider, thin walled part of the oviduct called ampulla. The last part of the oviduct, isthmus has a narrow lumen, short and thick walled and it joins the uterus.

10. Fertilization occurs in the oviduct.
a) False
b) True
Answer: b
Clarification: Fertilization of the ovum takes place in the upper portion of the fallopian tube. The fallopian tubes convey the ovum from the ovary to the uterus.

Biology Multiple Choice Questions on “Reproductive Health – Natural Birth Control Methods”.

1. A contraceptive should be user-friendly, easily-available, and with least side-effects.
a) True
b) False
Answer: a
Clarification: A contraceptive is used as a method to ensure healthy population control. Hence it should be user-friendly, easily available, effective, and have no or least side-effects.

2. A contraceptive is meant to hinder the sexual desire and drive of the user.
a) True
b) False
Answer: b
Clarification: Contraceptives are designed to be user-friendly. They do not interfere with sexual desire and the act.

3. What is the principle of natural contraceptive methods?
a) Avoiding sperm and ovum to meet
b) Avoiding release of egg
c) Avoiding release of sperm
d) Abortion when pregnant
Answer: a
Clarification: Contraceptive methods are not harmful. Natural methods of contraception aim to prevent the meeting of ovum and sperm in the fallopian tube.

4. What contraceptive method prevents coitus during the ovulation period?
a) Periodic abstinence
b) Permanent abstinence
c) Periodic absence
d) Permanent absence
Answer: a
Clarification: One of the natural methods of contraception called periodic abstinence is used to prevent coitus during the 10th to 17th day of the menstrual cycle. This avoids the presence of sperm in the oviduct during the release of an egg.

5. What is the period 5 days prior, and post-ovulation called?
a) Fertile period
b) Infertile period
c) Abstinent period
d) Maternity period
Answer: a
Clarification: The period from 5 days before ovulation to 5 days after ovulation is called the fertile period. During the period, there are high chances that if coitus occurs, the sperm can fertilize the released egg.

6. What is the scientific term for the withdrawal of penis from vagina before ejaculation?
a) Periodic abstinence
b) Lactational amenorrhea
c) Coitus interruptus
d) Coitus pluralis
Answer: c
Clarification: Withdrawal of the penis from the vagina before ejaculation is an example of a natural method of birth control. It prevents sperm from entering the genital tract. Since this, in principle, prevents coitus, it is called “coitus interruptus.”

7. What method is used to prevent the ejaculated semen from entering the vagina during intercourse?
a) Periodic abstinence
b) Lactational amenorrhea
c) Coitus interruptus
d) Coitus pluralis
Answer: c
Clarification: Withdrawal, also called coitus interruptus, is a method used to prevent the ejaculation of semen into the female genital tract. This is one of the most effective natural methods as it prevents semen, which is rich in sperms from entering the female genital tract and hence avoids pregnancy.

8. What is coitus interruptus?
a) Rejection of sperms by female
b) Rejection of egg my male
c) Withdrawal of the penis from the vagina before ejaculation
d)Withdrawal of the penis from the vagina after ejaculation
Answer: c
Clarification: Coitus interruptus is basically a natural contraceptive method. Its purpose is to prevent pregnancy. It works by avoiding the insemination of the female genital tract. During coitus interruptus, the male partner withdraws the penis from the vagina before ejaculation.

9. What is the absence of menstruation called?
a) Periodic abstinence
b) Lactational amenorrhea
c) Coitus interruptus
d) Coitus pluralis
Answer: b
Clarification: The absence of menstruation occurs after the baby has been delivered, and the mother is lactating to nourish the baby. During this period, the mother cannot get pregnant. This lack of menstruation is called lactational amenorrhea.

10. What is lactational amenorrhea?
a) Inability of female to lactate
b) Inability of female to conceive
c) Inability of male to conceive
d) Inability of female to menstruate
Answer: d
Clarification: Lactational amenorrhea is the inability of a female to menstruate after parturition. This is the time when the female lactates extensively to support the growth and nourishment of the baby. Lack of menstruation removes the burden of blood loss and weakness and also acts as a measure to prevent another pregnancy before the baby is grown sufficiently to feed himself/herself.

11. Which of the following is not a natural contraceptive method?
a) Periodic abstinence
b) Condoms
c) Lactational amenorrhea
d) Coitus interruptus
Answer: b
Clarification: Condom is an example of a barrier method. Periodic abstinence, coitus interruptus, and lactational amenorrhea are natural methods.

12. Natural methods have ______ side-effects and have _____ rate of failure.
a) many, high
b) less, high
c) many, low
d) less, low
Answer: b
Clarification: Natural methods do not interfere with the normal functioning of the human system in any way. They do not rely on external devices or medications. Hence, they have least or no side-effects. However, they come up with high chances of failure.

Biology online test on “Inheritance Principles – Punnett Square-2”.

1. What filial generation exhibits a genotypic ratio of 1:2:1?
a) F0
b) F1
c) F2
d) F3
Answer: b
Clarification: The genotypic ratio refers to the ratio of different genotypes observed in a population. In the F2 generation of a Mendelian cross, the proportion of homozygous dominant: heterozygous: homozygous recessive is 1:2:1.

2. Which mathematical expression can be used to obtain the genotypic ratio of F2 offsprings from the gametes of the F1 progeny?
a) Monomial expression
b) Binomial expression
c) Trinomial expression
d) Algebraic expression
Answer: b
Clarification: The binomial expression (ax+by)² can be used to model the Mendelian genetics of F2 progeny. The x and y refer to the dominant and the recessive gametes obtained from the F1 heterozygous progeny.

3. Self-crossing of dwarf plants from F2 generation will produce _____
a) 100% tall and 0% dwarf plants
b) 0% tall and 100% dwarf plants
c) 50% tall and 50% dwarf plants
d) 25% tall and 75% dwarf plants
Answer: b
Clarification: The F2 dwarf plants are homozygous recessive. Therefore, the self-crossing will only produce dwarf plants as no copy of the dominant allele is present.

4. What method can be used to check the genotypic composition experimentally of the F2 tall plant?
a) Test cross
b) Self cross
c) Check cross
d) Exam cross
Answer: a
Clarification: To determine the genotype of a tall plant amongst the F2 progeny, Mendel employed test crossing. Here he crossed the tall plant with a recessive dwarf plant. If the genotype of the tall plant were TT, the offspring will all be tall. However, if the genotype is Tt, there will be 50% tall and 50% dwarf plants.

5. What is the genotype of a plant showing a dominant phenotype of violet flowers if it is test crossed and produces only violet-flowered plants?
a) VV
b) Vv
c) vv
d) v
Answer: a
Clarification: Test cross involves a cross between the plant whose genotype is to be determined with the homozygous recessive plants. If a violet-flowered plant is crossed with white-flowered plant, the offsprings will have one v allele. Thus, to exhibit a phenotype of violet-flowering, the genotype will be Vv. Hence the parent will have a genotype of VV.

6. What is the genotype of a plant showing a dominant phenotype of violet flowers if it is test crossed and produces both violet-flowered and white-flowered plants?
a) VV
b) Vv
c) vv
d) v
Answer: b
Clarification: If a cross occurs between violet-flowered and white-flowered plants, the offsprings will have an allele v. To have both violet and white flowers, the violet-flowered parent should be able to produce both V and v containing gametes. Thus, the genotype of the unknown parent will be Vv.

7. Mendel proposed three laws of inheritance based on his studies involving monohybrid crosses in pea plants.
a) True
b) False
Answer: b
Clarification: Based on his studies of monohybrid crosses, Mendel proposed two laws of inheritance. The third law came from his studies of dihybrid crosses.

8. What are the rules postulated by Mendel based on his studies of inheritance in pea plants called?
a) Principles of Inheritance
b) Rules of Inheritance
c) Principles of Heredity
d) Rules of Heredity
Answer: a
Clarification: Mendel formulated specific rules that he observed based on his studies in pea plants. These rules were later found to be universal and, in fact, the central pillars of genetics. These are now known as the principles or laws of inheritance.

9. What is the first law of Mendel termed as?
a) Law of Recessivity
b) Law of Dominance
c) Law of Segregation
d) Law of Independent Assortment
Answer: b
Clarification: The laws of inheritance were proposed by Mendel. These were verified by his experiments on pea plants and many others that followed him. The first of these laws is termed as the law of dominance.

10. What is the second law of Mendel called?
a) Law of Recessivity
b) Law of Dominance
c) Law of Segregation
d) Law of Independent Assortment
Answer: c
Clarification: The second law of Mendel is called the law of segregation. It gives the rule or pattern followed by the gametes during meiosis.

11. Which of the following is not a law postulated by Mendel?
a) Law of Recessivity
b) Law of Dominance
c) Law of Segregation
d) Law of Independent Assortment
Answer: a
Clarification: Mendel stated three laws of inheritance. These are the law of dominance, the law of segregation, and the law of independent assortment. The law of recessivity is not the law proposed by Mendel.

12. Which law explains the expression of the dominant phenotype in the F1 progeny?
a) Law of Recessivity
b) Law of Dominance
c) Law of Segregation
d) Law of Independent Assortment
Answer: b
Clarification: The first law of Mendel, also known as the law of dominance, explains the outcome of a monohybrid cross. It explains the reason for all progeny to have dominant phenotype as all progeny contain one copy of each allele obtained from parents, one of which is dominant over the other.

13. Which law explains the expression of the dominant phenotype in the F2 progeny?
a) Law of Recessivity
b) Law of Dominance
c) Law of Segregation
d) Law of Independent Assortment
Answer: b
Clarification: According to the law of dominance, the factors occur in pairs. One factor is dominant over the other. This leads to suppression of the expression of the recessive allele. Thus, the recessive allele can express only when both copies of the gene are recessive. This can give the F2 progeny the observed phenotype of 75% dominant and 25% recessive.

14. What does the second law of Mendel state?
a) Factors occur in pairs
b) The alleles separate during meiosis and pair up during fertilization
c) One factor is dominant over the other
d) Factors determine the characters of the offsprings
Answer: b
Clarification: The second law of Mendel is the law of segregation. It states that the alleles are segregated during the process of meiosis and these pair again after fertilization to restore the genetic composition. This explains the loss of recessive phenotype in F1 and reappearance of it in F2 generation.

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Biology Multiple Choice Questions on “Inheritance and Variation Principles – Mendelian Disorders”.

1. People suffering from colour blindness fail to distinguish which of the two colours?
a) Red and Green
b) Blue and Green
c) Red and Blue
d) Red and Yellow
Answer: a
Clarification: People who are colour blind fail to distinguish between red and green colours. Colour blindness is a sex-linked recessive trait in which the normal gene and its recessive allele are carried by X-chromosome.

2. When can a female be colour blind?
a) Father has normal vision and the mother is a carrier
b) Father has normal vision and mother is colour blind
c) Father is colour blind and the mother has a normal vision
d) Father is colour blind and mother is a carrier
Answer: d
Clarification: A female can be a colour blind only in two conditions:
i. When her father is colour blind and her mother is the carrier of this disease
ii. When both her father and her mother are colour blind
Therefore, for a female to be colour blind, her father must also have colour blindness.

3. Which of the following type of inheritance is shown by colour blindness?
a) Chromosomal inheritance
b) Criss-cross inheritance
c) Zig-zag inheritance
d) Up-down inheritance
Answer: b
Clarification: Colour-blindness is a sex-linked trait which shows criss-cross inheritance which means male transmits his trait to his grandson through his daughter, while a female transmits the traits to her granddaughter through her son.

4. What will be the percentage of sons having a normal vision if the father has normal vision and their mother is colour blind?
a) 0%
b) 25%
c) 50%
d) 100%
Answer: a
Clarification: The percentage of sons having normal vision, if the father has normal vision and mother is colour blind is 0% because as colour blindness is a sex-linked trait, it means that the trait only transmits through X-chromosome. As the mother is colour blind, both her gametes will carry the gene for colour blindness, so none of their sons will have a normal vision.

5. What percentage of children are colour blind if their father is colour blind and the mother is a carrier for Colour blindness?
a) 25%
b) 50%
c) 75%
d) 100%
Answer: b
Clarification: The percentage of children which are colour blind if their father is colour blind and the mother is a carrier for colour blindness is 50% because the father will produce Xc and Y chromosome and the mother will produce Xc and X chromosomes. Their children will have the genotypes- XcY, XY, XcXc and XcX. Therefore, 50% of children are colour blind, 25% have normal vision and 25% are the carriers of the disease.

6. Haemophilia is an autosomal recessive trait.
a) True
b) False
Answer: b
Clarification: No, haemophilia is not an autosomal recessive trait. It is X-linked recessive trait and shows transmission from normal carrier female to a male progeny. In this disease, the exposed blood of affected individuals cannot coagulate due to the presence of defective blood clotting factors.

7. How can a female be haemophilic?
a) Mother is haemophilic and father is normal
b) Mother is a carrier and father is haemophilic
c) Both mother and father are carriers
d) Both mother and father are haemophilic
Answer: b
Clarification: A female can only be haemophilic if her mother is at least a carrier of this disease and her father is haemophilic. But the possibility of a female becoming haemophilic is extremely rare because being haemophilic for the parents at the later stage of life is unviable.

8. What is the full form of AHG?
a) Anti haemophilic globulin
b) Anti haemoglobin
c) Allergic haemoglobin
d) Allergic haemophilic globulin
Answer: a
Clarification: AHG stands for Anti haemophilic globulin. It is a type of blood protein which is required for normal blood clotting. The person suffering from haemophilia A cannot synthesise this protein and even a small cut may lead to continuous bleeding for a long time.

9. What is the percentage of children being a carrier of haemophilia if their mother is a carrier and their father is a normal man?
a) 25%
b) 50%
c) 75%
d) 100%
Answer: a
Clarification: The percentage of children being a carrier of haemophilia if their mother is a carrier and their father is a normal man is 25% because the gametes formed by mother are X and X^h while the gametes formed by father are X and Y. The genotype of the offspring obtained would be XY, XX, XX^h and X^hY. Thus 50% of children are normal, 25% are carriers of haemophilia and 25% are haemophilic (only son).

10. How many genotypes of sickle cell anaemia are possible in a population?
a) One
b) Two
c) Three
d) Four
Answer: c
Clarification: Three types of genotypes of sickle cell anaemia are possible in a population. These are:
i. Hb^A Hb^A: Normal individuals
ii. Hb^A Hb^S: Normal individuals but act as a carrier in spreading the disease
iii. Hb^S Hb^S: Diseased individuals and they die before attaining maturity

11. Heterozygous individuals of sickle cell anaemia are severely affected by the disease.
a) False
b) True
Answer: a
Clarification: No, heterozygous individuals of sickle cell anaemia are not severely affected by the disease. Apparently, they appear to be unaffected by the disease. But, there is a 50% probability of transmission of the mutant gene to the progeny.

12. Which of the following statements are correct with respect to the figures given?

a) 1 represents normal WBCs
b) 1 represents normal RBCs
c) 2 represents abnormal RBCs
d) 2 represents normal RBCs
Answer: b
Clarification: 1^st figure represents the micrograph of RBCs from a normal individual while the 2^nd figure represents the micrograph of RBCs from an individual affected with sickle-cell anaemia. The RBCs of a normal individual are biconcave shaped while that of sickle cell anaemia are elongated sickle-like structure.

13. In which of the following places thalassemia is not common?
a) Indian subcontinent
b) South-east Africa
c) Mediterranean
d) North America
Answer: d
Clarification: Thalassemia is not common in North America. It is common in the Middle East, Indian subcontinent, Mediterranean and South-east Africa. It originated in the Mediterranean region and is caused by the deletion or mutation of the chromosomes.

14. By which of the following defects, thalassemia is caused?
a) Defects in RBCs
b) Defects in WBCs
c) Defects in platelets
d) Defects in lymphocytes
Answer: a
Clarification: The defect in the synthesis of globin polypeptide in RBC causes a group of disorders known as thalassemia. Absence or reduced synthesis of one of the globin chains leads to the excess of other chains which accumulate in our body to causes different diseases.

15. Which of the following statements is incorrect with respect to alpha-thalassemia?
a) Involves the genes HBA1 and HBA2
b) Inherited in a Mendelian dominant fashion
c) Connected to the deletion of the 16p chromosome
d) Result in decreased α-globin production
Answer: b
Clarification: Alpha-thalassemia is not inherited in a Mendelian dominant fashion. Instead, it is inherited in a Mendelian recessive fashion. It involves the genes HBA1 and HBA2 and it is also connected to the deletion of the 16p chromosome.

16. Which of the chromosome mutation leads to Beta-thalassemia?
a) 21
b) 10
c) 11
d) 13
Answer: c
Clarification: The mutation in the HBB gene on chromosome number 11 leads to the disorder beta-thalassemia. It is inherited as an autosomal recessive trait. The severity of beta-thalassemia depends upon the nature of the mutation.

Biology Multiple Choice Questions on “Mechanism of Evolution”.

1. Hugo de Vries did an experiment on which plant to prove mutation theory?
a) Evening primrose
b) Morning primrose
c) Night primrose
d) Pea pant
Answer: a
Clarification: Hugo de Vries proved mutation theory by doing experiments on Oenothera lamarckian, also known as evening primrose. It was from this plant; he came up with the observations. It is a complex heterozygous plant with a chromosomal aberration.

2. Which of the following does not belong to Mutation theory?
a) It can appear in all direction
b) It is the raw material of evolution
c) It appears suddenly
d) It is a continuous process
Answer: d
Clarification: Mutation is a jerky and discontinuous process. Otherwise, it can appear in all direction and are inheritable. Also, it can appear suddenly and produce their effect immediately.

3. _______ is termed as single-step large mutation.
a) Separation
b) Saltation
c) Anti mutation
d) Infinite mutation
Answer: b
Clarification: Single-step that causes large mutation is called saltation. It is called as such because the mutation occurs suddenly and abruptly that leads to evolution in large scale. Hugo de Vries used this term against Darwin’s theory of evolution.

4. Mutations are small and directional whereas Darwinism variations are random and directionless.
a) True
b) False
Answer: b
Clarification: It is a wrong statement. The statement should be in opposite manner i.e. mutations are random and directionless, whereas Darwinism variations are small and directional.

5. Which of the following point favor mutation theory?
a) Mutations are not very common
b) Mutations are mostly recessive
c) Mutation give rise to new varieties
d) Evening primrose is not a normal plant
Answer: c
Clarification: A number of mutations appear in nature and some mutations are also induced which have given rise to variations. This theory could explain both progressive and retrogressive evolution. The remaining options are against mutation theory.

6. Mutation theory couldn’t explain _______
a) development of mimicry
b) saltation
c) variations
d) chromosomes of flowers
Answer: a
Clarification: One of the drawbacks of mutation theory was that it couldn’t explain the development of mimicry, the relationship between the position of nectars in flower and also length of proboscis in their insect pollinators. The problem was that these cannot be imagined to have developed all of a sudden.

7. Who proposed the Evolutionary species concept?
a) Hugo de Vries
b) Charles Robert Darwin
c) George Gaylord Simpson
d) Gregor Johann Mendel
Answer: c
Clarification: Evolutionary species concept was given by George Gaylord Simpson. According to this concept, a species is an ancestor sequence of the population that evolved separately from other species and has its own evolutionary role and tendencies. This concept also includes evolution.

8. Which is the most accepted concept of species?
a) Biological species concept
b) Evolutionary species concept
c) Polytypic species concept
d) Typological species concept
Answer: d
Clarification: Typological species concept is the most accepted concept of species. According to this concept, a fixed pattern of characters is visible in the species of every living organism. All the members of that species show maximum resemblance with this pattern.

9. The process of formation of one or more new species from an existing species is called ______
a) Speciation
b) Saltation
c) Mutation
d) Radiation
Answer: a
Clarification: The process of formation of one or more species from an existing species is called Speciation. It is of two types, mainly: Divergent speciation and Transformation speciation. Speciation was one of the main theories of Darwin.

10. The local population of a particular area is known by a term called ______
a) Locals
b) Race
c) Villagers
d) Demes
Answer: d
Clarification: Local population of a particular area is called demes. The members of two different demes of the same species can interbreed. Races are small groups of species which are geographically isolated and have some genetic difference, which is controlled by genes.

Biology Multiple Choice Questions on “Protozoan Diseases in Humans”.

1. Entamoeba histolytica causes _________
a) dysentery
b) elephantiasis
c) small Pox
d) mumps
Answer: a
Clarification: Entamoeba histolytica is a pathogen which causes Amoebic Dysentery. Wuchereria bancrofti, Variola virus and Paramyxo virus cause Elephantiasis, Small Pox and Mumps respectively.

2. Entamoeba histolytica is found in _________
a) Stomach
b) Brain
c) Small Intestine
d) Large Intestine
Answer: d
Clarification: Entamoeba histolytica causes Amoebic Dysentery or Amoebiasis in the large intestine of humans. Its symptoms include constipation, abdominal pain, cramps and stools with excess mucus and blood clots.

3. The pathogen causing Amoebiasis is transmitted through which of the following?
a) By touch
b) Insect bite
c) Food or water contaminated with cysts
d) Droplet Infection
Answer: c
Clarification: Pathogen which causes Amoebiasis is Entamoeba histolytica. Certain carriers and vectors serve to transmit the parasite from faeces of the infected person to food and food products, thereby contaminating them. So the intake of contaminated food and water are the main source of infection.

4. Which of the following act as mechanical carriers to transmit Entamoeba histolytica?
a) Housefly
b) Caterpillar
c) Birds
d) Butterfly
Answer: a
Clarification: Houseflies act as mechanical carriers to transmit Entamoeba histolytica. Cysts of Entamoeba histolytica present in the stool of infected person are the source of infection.

5. Which of the following species of Plasmodium don’t cause Malaria?
a) Plasmodium piper
b) Plasmodium vivax
c) Plasmodium falciparum
d) Plasmodium malariae
Answer: a
Clarification: There are five species of Plasmodium which cause Malaria. These are Plasmodium vivax, Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale and Plasmodium knowlesi.

6. Out of 5 species of Plasmodium, which one is the most virulent?
a) Plasmodium vivax
b) Plasmodium falciparum
c) Plasmodium malariae
d) Plasmodium knowlesi
Answer: b
Clarification: Plasmodium falciparum is the deadliest species of Plasmodium that cause malaria in humans. It is responsible for causing roughly 50 % of all malaria cases.

7. Where do the sexual stages of Plasmodium develop in its life cycle?
a) Gut of mosquito
b) Brain of human
c) Red Blood Corpuscles of human
d) Liver of human
Answer: c
Clarification: The sexual stages or the gametocytes of Plasmodium develops in Red Blood Corpuscles of the human. The female gametocytes or megagametocytes are round with food-laden cytoplasm and a small excentric nucleus. Male gametocytes or Microgametocytes have a clear cytoplasm and a large central nucleus. Both contain a large amount of haemozoin.

8. In which form Plasmodium enters the human body?
a) Phanerozoites
b) Cryptozoites
c) Gametocytes
d) Sporozoites
Answer: d
Clarification: Plasmodium enters the human body as sporozoites through the bite of infected female Anopheles. Malarial Parasite requires two hosts to complete its life cycle-Human and Anopheles mosquito which also acts as a vector or a transmitting agent.

9. Shuffner’s dots are related to _________
a) Entamoeba histolytica
b) Mosquito
c) Red Blood Corpuscles
d) Liver
Answer: c
Clarification: Shuffner’s dots are related to the Red Blood Corpuscles of humans. They are present in the cytoplasm of RBCs. Presence of these granules indicates that RBCs are infected with Plasmodium.

10. When can malarial parasite be obtained in RBCs of a patient?
a) When there is a sudden increase in pulse rate
b) When the temperature rises with rigour
c) When the temperature of a patient suddenly drops
d) When a patient experiences shortness of breath
Answer: b
Clarification: Malarial Parasite can be obtained in the RBCs of the patient when the temperature of the patient rises with rigour. The high temperature of the patient signifies that the RBCs have ruptured and have released Haemozoin toxin in the blood which is responsible for high temperature after every 48 hours with chills and shivering, followed by profuse sweating.

11. Which of the following fish is introduced in a pond to control or eliminate the vector responsible for the transmission of malaria and elephantiasis?
a) Chimaera
b) Scoliodon
c) Gambusia
d) Trygon
Answer: c
Clarification: For diseases such as Malaria and Elephantiasis that are transmitted through vectors, the most important measure is to control or eliminate the vectors and their breeding places. Therefore, fishes like Gambusia are introduced in ponds which feed on mosquito larvae.

12. Where does the sexual stage of Plasmodium gets completed?
a) In the RBCs of human
b) In the liver of human
c) In the salivary glands of the mosquito
d) In mosquito’s gut
Answer: d
Clarification: When the Anopheles mosquito sucks the blood of an individual infected with Plasmodium pathogen then all the stages of Plasmodium are digested except that of Macrogametocytes and Microgametocytes. Further, fertilisation and development take place inside mosquito’s gut.

13. Malignant tertian/subtertian fever is produced by _________
a) Plasmodium ovale
b) Plasmodium falciparum
c) Plasmodium vivax
d) Plasmodium knowlesi
Answer: b
Clarification: Malignant tertian/subtertian fever is produced by Plasmodium falciparum. This pathogen is the deadliest of all the Plasmodium species. It also causes cerebral malaria and persistent subclinical malaria.

14. Sporozoite stage of Plasmodium is the infective stage to the mosquito.
a) True
b) False
Answer: b
Clarification: Gametocyte stage of Plasmodium is infective to the mosquito. Sporozoite stage of Plasmodium is infective to Humans.

15. Chloroquine is given to treat which disease?
a) Malaria
b) Tetanus
c) Tuberculosis
d) AIDS
Answer: a
Clarification: Chloroquine is mainly given to treat malaria. Some other drugs like Quinine (from the bark of Cinchona), camaquine, primaquine and daraprim are also administered to control malaria.