Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “Human Reproduction – Fertilisation”.

1. The population of vagina with semen during coitus is called as _______
a) Insemination
b) Outsemination
c) Copulation
d) Fertilization
Answer: a
Clarification: Coitus or copulation is the process that leads to the release of semen from the penis into the vagina. The sperms populate the vagina along with other contents of semen. This process is called insemination.

2. What is the correct order of travel of sperm through the female reproductive tract before it reaches the egg?
a) Vagina -> Fallopian tube -> Uterus -> Cervix
b) Vagina -> Cervix -> Uterus -> Oviduct
c) Vagina -> Uterus -> Cervix -> Oviduct
d) Vagina -> Fallopian tube -> Cervix -> Uterus
Answer: b
Clarification: Sperms are released into the vagina. From here, they travel through the cervix and uterus before reaching oviduct or fallopian tube, where they can encounter an egg.

3. The number of semen delivered by a male determines the number of babies the female can conceive.
a) True
b) False
Answer: b
Clarification: Males usually release millions of sperm at each coitus. However, the female tract prevents most of them from reaching the fallopian tube with only one sperm being able to fertilize the egg. However, in rare cases where female releases two eggs (one from each ovary), there’s a probability of conceiving twins. Thus it is the number of eggs and not the number of sperm that determines the number of babies that the female can conceive.

4. What part of the oviduct does the sperm encounter the egg?
a) Ampulla
b) Isthmus
c) Infundibulum
d) Fundus
Answer: a
Clarification: The egg is released and awaits in ampulla for the sperm. The sperms cross the reproductive tract barriers before reaching the ampulla to fertilize the egg.

5. During a menstrual cycle, copulation on which of the following phases has the least probability of fertilizing an egg?
a) Menstrual phase
b) Onset of follicular phase
c) End of the follicular phase
d) End of the luteal phase
Answer: c
Clarification: Fertilization occurs only when the egg and sperm are present in the ampulla at the same time. Hence the coitus should happen near the period of ovulation. Ovulation occurs at the end of the follicular phase or the onset of luteal phase.

6. What is fertilization?
a) Release of egg from ovary
b) Release of sperm from testis
c) Mixing of semen with vaginal fluid
d) Fusion of sperm with egg nuclei
Answer: d
Clarification: Ovulation is the release of egg from the ovary. Spermiation is the release of sperm from testis. Insemination is the release of semen into vagina. Fertilization is the process that leads to fusion of male and female gametes.

7. What layer of egg cell prevents entry of other sperms?
a) Corpus luteum
b) Zona pellucida
c) Endometrium
d) Corona radiata
Answer: b
Clarification: The sperm contacts the egg cell at zona pellucida. The zona pellucida then undergoes chemical changes which renders egg insusceptible to further encounters with another sperm. This is essential to ensure that only a single sperm fertilizes the egg.

8. What triggers the completion of meiosis of secondary oocyte?
a) Maturation of Graafian follicle
b) Entry of sperm into the egg cell
c) Release of estrogen
d) Coitus
Answer: b
Clarification: The secondary oocyte released from the ovary has finished first round of meiosis. The second round of meiosis occurs in ampulla after the egg encounters the sperm. This leads to formation of large ovum and a tiny second polar body.

9. The haploid ovum is also called as _____________
a) oogonium
b) oocyte
c) ootid
d) osteoid
Answer: c
Clarification: The haploid ovum is formed after the second round of meiosis is completed. This haploid ovum is also called as ootid. Oogonium is the egg mother cell that is diploid and undergoes meiosis to form egg.

10. The fusion of haploid sperm and egg nuclei during fertilization leads to formation of a __________
a) haploid zygote
b) diploid zygote
c) haploid embryo
d) diploid embryo
Answer: b
Clarification: The fusion of sperm and egg restores the chromosome number. The new cell is called zygote having the potential to develop into a new organism.

11. At what stage of development is the sex of the human baby determined?
a) Zygote
b) Embryo
c) Fetus
d) Puberty
Answer: a
Clarification: The sex, in humans, is determined by the chromosomes received by the zygote from the male and female nuclei. If it is XX, the zygote will develop into a female child. If it is XY, the zygote develops into a male baby.

12. Which of the following is the correct number of chromosomes based on the cell type?
a) Sperm: 23; Egg: 23; Zygote: 23
b) Sperm: 46; Egg: 46; Zygote: 46
c) Sperm: 23; Egg: 23; Zygote: 46
d) Sperm: 46; Egg: 46; Zygote: 23
Answer: c
Clarification: Sperm and egg are haploid cells hence have only one set of chromosomes. Zygote on the other hand is diploid thus has 46 chromosomes.

13. The sex of the human baby is male if ______
a) sperm has X chromosome
b) sperm has Y chromosome
c) ovum has X chromosome
d) ovum has Y chromosome
Answer: b
Clarification: The sex in humans is determined by the sex chromosome that the male gamete carries. The females are XX hence meiosis results in all ova having X chromosome. Males are XY and 50% sperms have X and 50% have Y. Thus the determining factor that makes a baby male is Y chromosome in the sperm.

14. The sex ratio is low owing to the inherent bias in the number of sperms that carry Y chromosome.
a) True
b) False
Answer: b
Clarification: The human males have XY as their sex chromosomes. Thus upon undergoing meiosis, the probability of sperm having an X chromosome is the same as that of having a Y chromosome. There is no natural bias here. The lower sex ratio hence cannot be accounted to such a biological phenomenon.

15. Which of the following is not a layer that the sperm has to encounter before reaching the egg nuclei?
a) Zona pellucida
b) Corona radiata
c) Perivitelline space
d) Zona radiata
Answer: d
Clarification: The egg nuclei and cytoplasm is enveloped by various layers which prevent desiccation and provides nourishment and suitable habitat for the development of the egg. The sperm has to break these barriers to reach the egg nuclei.

Biology Multiple Choice Questions on “Reproductive Health – Infertility”.

1. What is the inability to conceive a baby even after unprotected intercourse called?
a) Sterility
b) Infertility
c) Fertility
d) Reproductivity
Answer: b
Clarification: Infertility is the inability of an individual or a couple to achieve pregnancy even if unprotected sexual intercourse is carried out. Sterility is an inability to produce and release gametes. Sterility leads to infertility. However, all infertile individuals are not sterile.

2. Infertility can arise because of many factors, one of which can be psychological.
a) True
b) False
Answer: a
Clarification: The inability of an individual to have the potential to conceive a baby is called infertility. This can arise because of psychological reasons too. This is driven by many factors that can be personal or social.

3. What clinics can help in diagnosing and providing treatment for patients suffering infertility?
a) Fertility clinics
b) Infertility clinics
c) Psychology clinics
d) Philosophy clinics
Answer: b
Clarification: Infertility clinics are the health care units devised by the Government. They are aimed at providing appropriate treatment and care for infertile patients.

4. ART stands for _______
a) Assisted Reproductive Technologies
b) Assisted Reproductive Techniques
c) Assisted Respiratory Technologies
d) Assisted Respiratory Techniques
Answer: a
Clarification: ART stands for Assisted Reproductive Technologies. These help the infertile couple to achieve a baby by using various methods.

5. A significant source of infertility comes from males.
a) True
b) False
Answer: a
Clarification: In India, females are mostly blamed for being incapable of conceiving the baby. However, owing to the complex development of male reproductive organs, the chances of the male being infertile are higher than those of females being infertile.

Biology Multiple Choice Questions on “Inheritance Principles – Linkage and Recombination-1”.

1. What type of crosses were carried out by Morgan on Drosophila?
a) Monohybrid
b) Dihybrid
c) Bihybrid
d) Trihybrid
Answer: b
Clarification: Morgan was trying to observe the phenomenon reported by Mendel. Hence, he did dihybrid crosses on Drosophila. These dihybrid crosses allowed him to understand the process of meiosis. He also identified the phenomenon of linkage. This was used later by his student to create the first genetic map.

2. Which of the collect cross that was performed by Morgan?
a) Yellow-bodied, white-eyed females with brown-bodied, red-eyed males
b) Yellow-bodied, white-eyed males with brown-bodied, red-eyed females
c) Yellow-eyed, white-bodied females with brown-eyed, red-bodied males
d) Yellow-eyed, white-bodied males with brown-eyed, red-bodied females
Answer: a
Clarification: Morgan used Drosophila as a genetic model to visualize the changes in the chromosomal patterns and explain the observations of Mendel. For this, he performed a dihybrid cross of yellow-bodied, white-eyed females with brown-bodied, red-eyed males.

3. What was the observation made by Morgan based on his dihybrid crosses?
a) Genes segregate independently
b) Genes do not segregate independently
c) Genes disappear
d) New genes appear
Answer: b
Clarification: If the segregation law was to hold, the expected phenotypic ratio of F2 was 9:3:3:1. However, Morgan saw a deviation from this ratio. This implied that the genes do not segregate independently.

4. What chromosome were the genes located on that were used by Morgan in his dihybrid cross?
a) X chromosome
b) Y chromosome
c) W chromosome
d) Z chromosome
Answer: a
Clarification: The genes were located on X-chromosome. These are called sex-linked genes because their expression depends on the sex of the fly. The X chromosome is present in copies of two in females, but the males have only one copy of X. Thus, a recessive mutant might remain suppressed in females, but the males will always exhibit the phenotype.

5. For genes located on the same chromosome, the proportion of parental gene combinations are higher than the non-parental combinations.
a) True
b) False
Answer: a
Clarification: For genes that are located on the same chromosome, segregation is weak as they are linked. This leads to more chances of parental combinations than of the non-parental ones.

6. What is the physical association of genes located on a chromosome called?
a) Linkage
b) Recombination
c) Mutation
d) Replication
Answer: a
Clarification: Linkage is the phenomenon of the physical association of genes that are located on the same chromosome. This leads to fewer chances of genes undergoing independent segregation.

7. What is the process of the production of non-parental phenotypes called?
a) Linkage
b) Recombination
c) Mutation
d) Replication
Answer: b
Clarification: Recombination leads to combinations of genes. Hence leads to newer phenotypes. The parental phenotypes occur without recombination hence are more frequently observed in the progeny. Recombination events are rare and hence the non-parental phenotypes are rare.

8. Linkage and recombination frequencies have been used to generate ______
a) solutions for global warming
b) genetic maps
c) genetic networks
d) mutation maps
Answer: b
Clarification: Linkage and recombination frequencies give the relative distance of genes on the chromosome. Thus, it can be used to construct genetic maps.

9. Genes located on different chromosomes have a high probability of getting recombination than those present on the same chromosome.
a) True
b) False
Answer: a
Clarification: Genes located on different chromosomes are weakly linked. This allows them to recombine more frequently. Linkage is inversely related to recombination. Genes are located close to each other have low chances of recombination, and thus have high linkage. Genes on different chromosomes are far from each other, hence they have almost no linkage, hence having higher chances of undergoing recombination.

Biology Objective Questions & Answers on “Evolution – Origin of Life – 2”.

1. What is most important element for origin of life?
a) Water
b) Oxygen
c) Carbon
d) Nitrogen
Answer: a
Clarification: Water is essential for origin of life, since first life originated in the water of oceans. After a long time, the water of primitive oceans had rich mixtures of organic compounds. This produced a platform for origin of life.

2. The theory of spontaneous generation was rejected by which scientist?
a) Pasteur
b) Lavoisier
c) Kuhn
d) Lamarck
Answer: a
Clarification: Pasteur is very famous for his Germ Theory. This theory disproved spontaneous generation, as he had done an experiment to prove that life came from pre-existing cells.

3. Which among the compounds were formed during the origin of life?
a) Urea, amino acid
b) Urea, nucleic acid
c) Proteins, nucleic acid
d) Proteins, amino acid
Answer: c
Clarification: Proteins, nucleic acid were the main two compounds formed during origin of life. Experiments done by many scientists also resulted to creation of proteins and nucleic acid. This shows that these compounds existed during origin of life.

4. The name of the theory given by Louis Pasteur was called as _______
a) Cellular theory
b) Recapitulation theory
c) Germ theory of disease
d) Pasteurization
Answer: c
Clarification: Louis Pasteur found the Germ theory of diseases or Germ theory. He stated that life did not come from killed yeast in pre-sterilized flask. Whereas the flask opened to air, the new organisms arose from the killed yeast.

5. Life originated on earth about _____
a) 8 billion years ago
b) 5 billion years ago
c) 4 billion years ago
d) 3 billion years ago
Answer: c
Clarification: Life originated on earth about 4 billion years ago. That is life appeared 500 million years after the formation of earth. First non-cellular forms of life originated 3 billion years ago.

6. What did Stanley Miller synthesize in his evolution experiment?
a) Virus
b) Protein
c) Cell
d) Amino acid
Answer: d
Clarification: Miller created a closed flask containing an electric discharge along with gases maintained at 800°C. It resulted in the formation of amino acids. They had similarity with meteorite content which indicated that life came from outer space.

7. Nucleoproteins were the first substance to give sign of ______
a) Species
b) Evolution
c) Life
d) Genes
Answer: c
Clarification: Nucleoproteins are complex structured compounds which bonding between a nucleic acid and a protein. Nucleoproteins were the first compound to give sign of life. It had the property of self-duplication.

8. Life first originated in ______
a) Earth
b) Air
c) Water
d) Soil
Answer: c
Clarification: Life first originated in water. Whether cellular or acellular, life started in water environment only, millions of years ago. Water was formed from the reaction of active hydrogen and free oxygen atoms.

9. Miller and Urey had performed an experiment to prove the origin of life. They took gases H₂0 and CH₄ along with _______
a) N₂ and H₂O
b) NH₃ and H₂
c) CH₄ and N₂
d) CO₂ and NH₃
Answer: b
Clarification: Miller took a mixture of water, methane, ammonia and hydrogen in a closed flask at 800°C. It was done in a closed flask and using electric discharge tubes, and later observed the formation of amino acids.

10. It is due to the phenomenon Big bang; the origin of life took place.
a) True
b) False
Answer: b
Clarification: Universe was created due to Big bang theory and not life. Life originated about 4 billion years ago whereas the Big bang took place about 20 million years back.

11. At what temperature was the flask maintained in Miller’s experiment?
a) 900°C
b) 800°C
c) 700°C
d) 600°C
Answer: b
Clarification: It was at 800°C in which the flask was maintained along with electric discharge. A moderately high temperature was required to keep the flask sterilized. Thus, creating amino acids as the product.

To practice all objective questions on Biology,

Biology Written Test Questions for Pharmacy Entrance Exams on “Origin and Evolution of Man – 5”.

1. Which of the following does not belong to Peking man’s characteristics?
a) Origin and evolution before 6 lakh years
b) They lived in huts
c) Cranial capacity was 850-1300 c.c.
d) Complete erect posture
Answer: b
Clarification: Peking man lived in caves and not in huts. They were not civilized like modern man. The remaining options are the characteristics of Peking man.

2. Who discovered the fossil of Heidelberg man?
a) Ottoschotensack
b) Habbertensack
c) Fulhrott
d) Heidelinsack
Answer: a
Clarification: The fossil was discovered by Ottoschotensack. He found a fossil of the lower jaw from Heidelberg in Germany. They evolved during the Pleistocene epoch.

3. Which of the following does not belong to Homo sapiens?
a) Neanderthal man
b) Cromagnon man
c) Modern man
d) Peking man
Answer: d
Clarification: Peking man belongs to Homo erectus and not Homo sapiens. Homo sapiens consist of Neanderthal man, Cromagnon man, and Modern man. Modern man refers to Homo sapiens sapiens.

4. Who is known as the direct ancestor of modern man?
a) Cromagnon man
b) Java man
c) Heidelberg man
d) Neanderthal man
Answer: a
Clarification: Cromagnon man is known as the direct ancestor of modern man. Their scientific name is Homo sapiens fossilis. Fossils were discovered by Mac Gregor from Cromagnon rocks of France.

5. Ceremonial burial of dead body was started by _________
a) Neanderthal man
b) Modern man
c) Java man
d) Handy man
Answer: a
Clarification: The ceremonial burial of the dead body was started by Neanderthal man. The dead body was buried along with flowers and tools. They were the first ones believe in the immortality of the soul.

6. Which is the correct statement of Neanderthal man?
a) They lived in caves
b) Cranial capacity was 1000-1300 c.c.
c) They wore clothes of animal skin
d) High developed chin
Answer: c
Clarification: They lived in huts. They had a cranial capacity of 1300-1600 c.c. and a less developed chin. They had a complete erect posture. Also, they had a semicircular jaw and was orthognathous.

7. The scientific name of Cromagnon man is ______
a) homo sapiens sapiens
b) homo sapiens fossilis
c) homo sapiens neanderthalensis
d) homo sapiens pekinensis
Answer: b
Clarification: The scientific name of Cromagnon man is Homo sapiens fossilis. They evolved around 50,000 to 10,000 years ago and discovered from Cromagnon rocks. They were the direct ancestor of modern man.

8. Who started the domestication of animals?
a) Java man
b) Neanderthal man
c) Heidelberg man
d) Cromagnon man
Answer: d
Clarification: Homo sapiens fossilis also known as Cromagnon man started the domestication of animals. This man was a hunter and used domesticated dogs in hunting. Also, they used to wear cloth of animal skin. By nature, they were carnivorous.

9. Prehistoric cave art developed about 10,000 years ago.
a) True
b) False
Answer: b
Clarification: It is a wrong statement as prehistoric cave art developed about 18,000 years ago. It was one of the special features of the Cromagnon man. They painted beautiful paintings on cave walls.

10. The cranial capacity of Modern man was ______ c.c.
a) 1300-1600
b) 1000-1100
c) 850-1300
d) 1300
Answer: a
Clarification: The cranial capacity of Modern man is the same as that of Neanderthal man i.e. 1300-1600 c.c. They had a fully developed brain. Heidelberg man had a cranial capacity of only 1300 c.c. whereas Peking man had ranged from 850-1300 c.c.

11. Cromagnon man had higher cranial capacity than Modern man.
a) True
b) False
Answer: a
Clarification: Cromagnon man had maximum cranial capacity about 1650 whereas Modern man had only 1300-1600 c.c. This shows that the cranial capacity reduced after the evolution of Cromagnon man. The size of the skull also reduced to a more humanoid one.

To practice Biology Written Test Questions for Pharmacy Entrance Exams,

Biology Multiple Choice Questions on “Human Health and Disease – Cell Mediated Immunity”.

1. The full form of CMI is __________
a) cell Medium Immunoglobulin
b) cell-Mediated Immunity
c) cyst Marked Infection
d) cellular Medium Infection
Answer: b
Clarification: The full form of CMI is Cell-Mediated Immunity. The immune system comprises of T- lymphocytes that defend the body against pathogens, cancers and foreign structures like tissue transplants.

2. Which of the following mediate the CMI?
a) T-lymphocytes
b) Red blood corpuscles
c) White Blood cells
d) B-lymphocytes
Answer: a
Clarification: T-lymphocytes mediate CMI. T-cells/T-lymphocytes are long-lived small cells which have 100,000 receptor sites on their surface for binding antigens. T-cells themselves do not secrete antibodies but help B-cells to produce them.

3. Which of the following is called as Competent lymphocytes?
a) B-lymphocytes
b) T-lymphocytes
c) C- lymphocytes
d) S-lymphocytes
Answer: b
Clarification: T-lymphocytes are called as Competent lymphocytes. The cells develop antigen specificity through the previous contact. T-lymphocytes respond to specific antigen by forming a clone of cells.

4. Number of lymphocytes present in a healthy human is ___________
a) 1 trillion
b) 1 million
c) 1 billion
d) 10 trillion
Answer: a
Clarification: Number of lymphocytes present in a healthy human is 1 trillion. Unusually high or low lymphocyte counts can be a sign of disease.

5. A person without thymus would not be able to reject a tissue transplant.
a) True
b) False
Answer: a
Clarification: Thymus is a lobed organ located near the heart and beneath the breast bone. It is the site where T-lymphocytes mature. T-cells are the specialized white blood cells which help to defend the body.

6. What is the life of the effector cells of the immune system?
a) A few weeks
b) A few days
c) A few months
d) A few years
Answer: b
Clarification: The life span of effector cells of the immune system is a few days only. Our body releases two types of cells-effector cells and memory cells, of which, effector cells are short-lived and are responsible for the primary response of our body.

7. Which of the following sets include all the types of T-cells?
a) Killer cells and Helper cells
b) Suppressor and Cytotoxic cells
c) Depressor cells, Helper cells and Memory cells
d) Killer cells, Helper cells, Suppressor cells and Memory cells.
Answer: d
Clarification: T-cells of our immune system gets differentiated into Killer or cytotoxic cells, Helper cells, Suppressor cells and Memory cells. Killer, Helper and Suppressor T-cells are also called as Effector cells.

8. Life span of T-cells __________
a) 4-5 hours
b) 4-5 days
c) 4-5 weeks
d) 4-5 years
Answer: d
Clarification: Life span of T-cells is around 4-5 years. The T-cells produced are relatively long-lived to compensate the less number of T-cells produced by thymus in the later years.

9. B-cells produce antibodies in response to the instruction received from _________
a) Killer T-cells
b) Suppressor T-cells
c) Memory Cells
d) Helper T-cells
Answer: d
Clarification: B-cells produce antibodies in response to the instruction received from Helper T-cells. Along with this, Helper T-cells also attract macrophages to the site of infection.

10. How can Organ transplantation rejection be prevented?
a) Immunosuppressant drugs
b) Depressant drugs
c) Interferons
d) New T-cells
Answer: a
Clarification: Our body produces a certain type of antibodies in response to the antigens. When an organ is transplanted, the body recognises the ‘non-self’ cells and starts attacking them. Therefore, Organ Transplantation rejection can be prevented by giving Immunosuppressant drugs so that the immune system gets suppressed and do not attack the ‘non-self’ cells.

11. Which of the following cells of the immune system are responsible for causing pores in the plasma membrane of antigens?
a) Helper T-cells
b) Killer T-cells
c) Suppressor T-cells
d) Memory cells
Answer: b
Clarification: Killer T-cells are responsible for producing pores in the plasma membrane of the antigens. The interaction of Killer T-cells with antigens will produce perforins to kill the infected cells.

12. What does T stand for in T-lymphocytes?
a) Tonsils
b) Thymus
c) Tissue
d) Thyroid
Answer: b
Clarification: The letter T in T-lymphocytes stands for Thymus. The thymus is a primary lymphoid organ which is responsible for differentiating T-lymphocytes into antigen sensitive lymphocytes.

13. Helper T-cells can be distinguished from killer T-cells by the presence of _________
a) CD-2 receptor
b) CD-3 receptor
c) CD-8 receptor
d) CD-4 receptor
Answer: d
Clarification: Helper T-cells can be distinguished from Killer T-cells by the presence of CD-4 receptor. CD-8 receptors are present in both Killer T-cells and Suppressor T-cells.

14. Which of the following cell surfaces do not have Major Histocompatibility complex?
a) Red Blood Corpuscles
b) White Blood Cells
c) Helper T-cells
d) Killer T-cells
Answer: a
Clarification: The cell surface of Red Blood Corpuscle does not have Major Histocompatibility Complex. This complex is responsible for displaying the peptide fragments of antigens to the appropriate T-cells of our immune system.

15. What is meant by Apoptosis?
a) Accidental Cell Death
b) Programmed Cell death
c) Accidental Cell division
d) Programmed Cell division
Answer: b
Clarification: Apoptosis has been derived from an Ancient Greek word meaning “falling off”. In biology, Apoptosis refers to a form of programmed cell death that occurs in multicellular organisms. It is used by the immune system to get rid of the virus-infected cells.