Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “The Male Accessory Ducts and Glands”.

1. Which of the following is not included in accessory ducts?
a) Vas deferens
b) Prostate
c) Rete testis
d) Epididymis
Answer: b
Clarification: Prostate is a gland. The male sex accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens. The seminiferous tubules of the testes open into the vasa efferentia through rete testis.

2. Label the part marked 1.

a) Rete testes
b) Epididymis
c) Vas deferens
d) Vasa efferentia
Answer: b
Clarification: The epididymis is a comma shaped mass of 6m long narrow closely coiled tubule which lies along the upper, lower and inner side of each testis. The epididymis by its peristaltic and segmenting contractions pushes the sperms into the vas deferens.

3. What is the middle part of the epididymis is known as?
a) Cauda epididymis
b) Caput epididymis
c) Corset epididymis
d) Corpus epididymis
Answer: b
Clarification: At the anterior end of the testis it is called caput epididymis(head), in which the vasa efferentia open. The middle part of the epididymis is known as corpus epididymis(body). The posterior end of the epididymis is called as cauda epididymis(tail).

4. Epididymis stores sperm prior to ejaculation.
a) True
b) False
Answer: a
Clarification: Stores sperm prior to ejaculation. Storage in the epididymis makes the sperm motile and mature. If not ejaculated they are reabsorbed. Spermatozoa are produced continuously whether ejaculation takes place or not.

5. Label the part marked as 2.

a) Epididymis
b) Corpus epididymis
c) Vas deferens
d) Vasa efferentia
Answer: c
Clarification: A 40cm long vas deferens emerges from the cauda epididymis on each side and leaves the scrotal sac and enters the abdominal cavity through the inguinal canal.

6. The vas deferens is lined with ________ epithelium.
a) pseudostratified columnar
b) stratified columnar
c) stereocilia
d) smooth
Answer: a
Clarification: The vas deferens is lined with pseudostratified columnar epithelium. The free end of its cells also bears stereocilia. The muscular wall of the vas deferens is formed of smooth muscles, and the latter’s peristaltic contractions propel the sperms through the vas deferens.

7. Vas deferens, testicular artery, testicular vein and nerves that innervate the testes are together called as _________
a) Accessory ducts
b) Spermatozoa
c) Spermatic cord
d) Foramen
Answer: c
Clarification: The vas deferens ascends the pelvic cavity through the inguinal canal along with the testicular artery, testicular vein and nerves that innervate the testes these structures together constitute the spermatic cord.

8. Which gland produces a milky secretion with a pH 6.5?
a) Prostate
b) Cowper’s
c) Bulbourethral
d) Seminal vesicles
Answer: a
Clarification: The prostate gland is a single large chestnut-shaped, spongy and lobulated gland gland that surrounds the urethra. It produces a milky secretion with pH 6.5 which forms 25% of the volume of semen. Secretion of the prostate gland nourish and activates the spermatozoa to swim.

9. The secretion of _______ helps in lubrication of the penis.
a) seminal vesicles
b) prostate glands
c) bulbourethral glands
d) urethra
Answer: c
Clarification: Bulbourethral glands secrete an alkaline fluid. They also secrete mucus that lubricates the end of the penis and lining of the urethra. This decreases the number of sperms damaged during ejaculation.

10. The secretions of the accessory glands are rich in ______
a) magnesium
b) glucose
c) potassium
d) fructose
Answer: d
Clarification: Secretions of the accessory glands constitute the seminal plasma which is rich in fructose, calcium and certain enzymes (acid phosphatase, amylase, pepsinogen).

Biology Questions and Answers for Entrance exams on “Inheritance of One Gene-2”.

1. Self-pollination of F1 progeny will result in a new filial generation called _______
a) F1
b) F0
c) F2
d) F1.1
Answer: c
Clarification: The filial generations are numbered in relation to the parental generations. The self-pollination of F1 progeny will produce a generation that is two-step distant from the parental generation. Hence it will be F2 generation.

2. What are the possible phenotypes that can be observed after self-crossing violet flowered pea plants?
a) All violet
b) All white
c) 25% violet and 75% white
d) 25% white and 75% violet
Answer: d
Clarification: Violet is dominant over white. Self-crossing of violet flowered plants will produce 25% recessive plants, which will have white-flowers.

3. In Mendelian crosses, the F2 progeny exhibits a recessive phenotype and a blended phenotype.
a) True
b) False
Answer: b
Clarification: Mendelian crosses do not exhibit blending of phenotypes. These are performed on true-breeding parents, and the locus encoding the traits does not show any crossover. The phenotypes of F are dominant and recessive.

4. Which of the following was not observed in F2 progeny of true-breeding tall and dwarf plants?
a) Homozygous tall plants
b) Heterozygous tall plants
c) Homozygous dwarf plants
d) Heterozygous dwarf plants
Answer: d
Clarification: The F2 progeny has both dwarf and tall plants. 25% of them are homozygous tall, 50% are heterozygous tall, and 25% are homozygous dwarf. Dwarfness is a recessive trait and thus cannot be expressed in the heterozygous state.

5. Based on his experiments on pea plants, what were the things that he suspected of being transferred across generations?
a) Genes
b) Factors
c) Chromosomes
d) DNA
Answer: b
Clarification: Mendel studied pea plant inheritance of traits. He observed a pattern in the way traits were passed from parents to offsprings. Based on these, he suspected the existence of “factors” that need to be transferred through gametes from parents to offsprings.

6. What exactly are Mendel’s factors?
a) Genes
b) Proteins
c) Chromosomes
d) RNA
Answer: a
Clarification: The factors that Mendel observed were forgotten for decades to come. Later experiments, independent of these studies of Mendel, led to the discovery of genes as the source of transfer of information that codes for traits. Later it was found that Mendel’s factors were indeed genes.

7. What are the copies of genes that code for different phenotypes called?
a) Alleles
b) Gametes
c) Chromatin
d) DNA
Answer: a
Clarification: Alleles are the copies of genes that code for contrasting traits. They are different forms of the same gene. For an allele to express, it should have a fitness benefit over its counterpart allele.

8. To represent a genotype, the dominant allele is represented by a capital letter and the recessive allele by a small letter.
a) True
b) False
Answer: a
Clarification: The convention used to write the genotype uses a single letter to represent an allele. Capital letters symbolize dominant alleles. The corresponding small letters are used to represent recessive alleles.

9. Which zygosity has the same allelic pair of genes?
a) Homozygosity
b) Heterozygosity
c) Hemizygosity
d) Nullizygosity
Answer: a
Clarification: Homozygosity refers to the state of genes that have both copies of genes or alleles as the same alleles. Heterozygous condition has two different alleles.

10. VV, Vv and vv are _______, while violet and white are _________
a) genotypes, phenotypes
b) phenotypes, genotypes
c) genotypes, genotypes
d) phenotypes, phenotypes
Answer: a
Clarification: The genotypes refer to the allelic composition of a particular gene. Thus VV, Vv, and vv are the genotypes. Violet and white are the phenotypes. These refer to the expressed trait.

11. The factor expressed only in homozygous state is called _________
a) dominant
b) recessive
c) gene
d) allele
Answer: b
Clarification: A recessive factor cannot express itself when a dominant factor is present. It can only express when the organism has two copies of it. Thus, it requires homozygous state to express itself.

12. What is the cross between VV and vv called?
a) Monohybrid cross
b) Dihybrid cross
c) Monogamous cross
d) Digamous cross
Answer: a
Clarification: The offsprings produced from this cross are heterozygous for only one gene, which encodes for tallness. Thus, the cross is called a monohybrid cross.

13. What kind of a process is the segregation of alleles during meiosis?
a) Uniform
b) Gaussian
c) Stochastic
d) Poisson
Answer: c
Clarification: Segregation of alleles leads to each gamete having only a single allele at the end of meiosis. This process is purely random or stochastic. Thus, the probability of a gamete having either alleles is 50%.

14. If the F1 generation produced by a cross between axial and terminal flower-bearing plants produces only axial flowers, the F2 progeny produced by the self-crossing of F1 will also produce only axial flowers.
a) True
b) False
Answer: b
Clarification: The F1 progeny has only axial flowers, which imply that axial trait is dominant over the terminal trait. However, the F1 progeny are heterozygous. Upon self-crossing, 25% of the F2 progeny will be homozygous for the recessive trait, resulting in the formation of 3:1 ratio of axial flower-bearing to terminal flower-bearing plants.

Biology for Entrance exams,

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

1. Which of the following is incorrect with respect to mutation?
a) Sudden
b) Continuous
c) Change in chromosomes and genes
d) Leads to variation in DNA
Answer: b
Clarification: Mutations are not continuous. Instead, mutations are discontinuous variations in the genotype and phenotype of an organism. This is due to the changes in chromosomes and DNA. Mutations are sudden and they are a cause of the variation in DNA.

2. Which of the following is not a type of mutation?
a) Gene mutation
b) Chromosomal aberrations
c) Genomatic mutations
d) Colourful mutations
Answer: d
Clarification: Mutations are of three different types depending upon their cause and environment. The three types are:
i. Gene mutation
ii. Chromosomal aberrations
iii. Genomatic mutations

3. Which of the following is a classic example of point mutation?
a) Phenylketonuria
b) Sickle cell anaemia
c) Haemophilia
d) Thalassemia
Answer: b
Clarification: Sickle cell anaemia is a classic example of point mutation. Point mutation generally means that when a single base pair of DNA changes, a gene mutation occurs that causes the alternation of DNA.

4. Which of the following is also known as the removal of one or more bases from the nucleotide chain?
a) Deletion
b) Insertion
c) Transition
d) Transversion
Answer: a
Clarification: The removal of one or more bases from the nucleotide chain is also known as deletion. Deletion is a type of frame-shift mutation. If we add one or more bases in a nucleotide chain, then it is called insertion.

5. What is the substitution of a purine base with a pyrimidine base known as?
a) Deletion
b) Transition
c) Addition
d) Transversion
Answer: d
Clarification: The substitution of a purine base with a pyrimidine base or vice versa is known as transversion. This refers to the substitution mutation which is the replacement of one base by another.

6. Change in more than one nucleotide pair is known as a spontaneous mutation.
a) True
b) False
Answer: b
Clarification: No, change in more than one nucleotide pair is not called a spontaneous mutation, instead it is known as gross mutation. When gene mutations occur naturally and automatically due to any internal reasons, then it is called as spontaneous mutations.

7. Which of the following is not responsible for the formation of chromosomes?
a) DNA
b) Proteins
c) RNA
d) Endoplasmic reticulum
Answer: d
Clarification: The endoplasmic reticulum is not responsible for the formation of chromosomes. Chromosomes are made up of proteins, DNA, and RNA. The loss or gain of a segment of DNA often causes the alternation of chromosomes.

8. Intercalary aberrations are a part of which of the following?
a) Deletion
b) Addition
c) Inversion
d) Translocation
Answer: a
Clarification: Intercalary aberrations are a type of deletions where there is a loss of an intercalary segment of a chromosome due to its double break. Deletions result in the loss of some segments of chromosomes which further leads to mutation.

9. What does the given type of aberrations in the figure represent?

a) Deletions
b) Duplications
c) Translocation
d) Inversion
Answer: b
Clarification: The given figure represents the duplication aberrations where a part of the chromosome gets added so that a gene or a set of genes is duplicated or is represented twice.

10. How does deletion occur?
a) When a part of a chromosome is duplicated
b) When a part of a chromosome is left out
c) When a part of a chromosome is lost
d) When a part of a chromosome is translocated
Answer: c
Clarification: Deletions are a type of chromosomal aberrations where a part of a chromosome is lost. It is of two types-terminal and intercalary deletions. When the terminal segment of the chromosome is lost then it is known as terminal deletions and when an intercalary segment is lost then it is known as intercalary deletions.

11. What is translocation?
a) Shifting of part of chromosomes to the outside wall of nucleus
b) Shifting of a chromosome to another chromosome
c) Shifting of a part of a chromosome to another homologous chromosome
d) Shifting of a part of a chromosome to another non-homologous chromosome
Answer: d
Clarification: Translocation is the shifting of a part of a chromosome to another non-homologous chromosome. It results in the formation of new recombinant chromosomes as this induces faulty pairing of chromosomes during meiosis.

12. What is the full form of CML?
a) Chronic myopia lens
b) Chronic myelogenous leukaemia
c) Chronic muscle leukaemia
d) Cystic muscle leukaemia
Answer: b
Clarification: CML stands for Chronic myelogenous leukaemia. CML occurs due to the translocation of a segment of the long arm from chromosome 22 to chromosome 9. Chromosome 22 is also known as the Philadelphia chromosome.

13. Paracentric is a type of inversion involving centromere.
a) True
b) False
Answer: b
Clarification: Paracentric is not a type of inversion involving centromere. Instead, it is an inversion without involving centromere. Pericentric is a type of inversion which involves centromere.

14. Segmental changes of chromosome having an evolutionary significance, is of which of the following?
a) Deletion
b) Translocation
c) Inversion
d) Addition
Answer: b
Clarification: An important class of translocation having evolutionary significance is known as segmental changes or reciprocal translocation. It involves the mutual exchange of chromosome segments between two non-homologous chromosomes.

15. In which of the following organisms, an inversion occurs frequently?
a) Drosophila
b) Moth
c) Honey bees
d) Butterflies
Answer: a
Clarification: Inversion occurs frequently in Drosophila as a result of X-ray radiation. Inversion is technically a type of chromosomal aberration where the linear order of genes changes by 180° through the rotation.

16. Genomatic mutation is of how many types?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: Genomatic mutations are of two types-
i. Aneuploidy
ii. Euploidy
This kind of mutation involves the change in chromosome number that bring about visible threats on the phenotype.

Biology Multiple Choice Questions on “Biological Evolution – 1”.

1. _________ is the evolution from coacervates to simple cell structure.
a) Chemical evolution
b) Biological evolution
c) Organic evolution
d) Inorganic evolution
Answer: b
Clarification: The evolution starting from coacervates to the formation of a simple cell structure is known as Biological evolution. It is also called as Biogemy. This shows how cells originated during evolution.

2. Which of the following is related to protobionts?
a) Large colloidal drop like structures
b) Formed from micro molecules
c) Do not absorb molecules from the atmosphere
d) Does not contain proteins, nucleic acids, etc.
Answer: a
Clarification: Macromolecules synthesized in primitive oceans came together to form large colloidal drop like structures called protobionts. They grew up by absorbing molecules from the atmosphere. They also contained proteins, nucleic acids, lipids, etc.

3. Protobiont was formed by a cluster of ______
a) micro molecules
b) nucleic acids
c) lipids
d) macro molecules
Answer: d
Clarification: Each and every protobiont was formed by a cluster of macromolecules. The basic building blocks of protobionts is macromolecules. These molecules were synthesized abiotically in the primitive ocean.

4. Protobionts were unable to reproduce.
a) True
b) False
Answer: a
Clarification: It is true that protobionts were unable to reproduce. It is because many chemical reactions such as decomposition of glucose took place inside the protobionts. This totally disallowed them to reproduce which was one of the drawbacks.

5. What were the first sole living molecules according to Oparin?
a) Diploid
b) Coacervates
c) Mycoplasma
d) Bacteria
Answer: b
Clarification: The first sole living organisms were Coacervates. According to Oparin, these coacervates gave rise to a cell. Oparin’s coacervates had the ability to grow and exhibit a simple form of metabolism. But a lipid membrane and reproduction were absent.

6. Who discovered proteinoid microspheres with a primitive membrane?
a) Oparin
b) Haldane
c) Fox
d) Thomas
Answer: c
Clarification: A scientist named Fox in 1957 discovered proteinoid microspheres which had a primitive membrane. In his research, he heated a mixture of amino acids at temperature 130 – 180°C and poured it into cold water with lipids. He found out that the microsphere got separated.

7. Who among the scientist did not prove that RNA molecules have enzymatic activity?
a) Zaug
b) Thomas Cech
c) Altman
d) Oparin
Answer: d
Clarification: Zaug, Thomas Cech and Altman proved that RNA molecules have enzymatic activity. Ribozymes also called as RNA enzymes were able to replicate or produce primordial RNA. It was also believed that earth was an ‘RNA world’ about 4 billion years ago.

8. Life originated millions of years ago as ________
a) protobionts
b) eobionts
c) coacervates
d) bacteria
Answer: b
Clarification: It was estimated about 3.9 billion years ago that, life originated as Eobionts (protocell). They evolved during the Precambrian era. They were anaerobic as well as heterotrophic in nature.

9. What was the mode of respiration for the prokaryotes during biological evolution?
a) Aerobic
b) Anaerobic
c) Cellular
d) External
Answer: b
Clarification: These prokaryotes were single-celled and consisted of naked DNA. They were chemoheterotrophs. Dependent on surrounding materials for food and energy.

10. The organisms that perform chemosynthesis for survival are called _____
a) Chemoautotrophs
b) Chemoheterotrophs
c) Chemical organisms
d) Photoautotrophs
Answer: a
Clarification: Chemoautotrophs are the organisms that perform chemosynthesis for food and survival. They produce organic molecules from inorganic molecules. They are anaerobic in nature.

11. What was utilized by photoautotrophs during photosynthesis when H₂O was absent?
a) HF
b) HCl
c) H₂S
d) H₂N₂
Answer: c
Clarification: Photoautotrophs were anaerobic and utilized hydrogen from sources other than H₂O like H₂S. So, no oxygen was produced and the atmosphere was kept reducing. This type of photosynthesis was mainly done by planktonic sulfur bacteria.

Biology Multiple Choice Questions on “Viral Diseases in Humans-1”.

1. Which virus causes Small Pox disease?
a) Variola virus
b) Varicella zoster
c) Rubeola virus
d) Rhabdo virus
Answer: a
Clarification: Variola virus causes Small Pox disease. Varicella zoster, Rubeola and Rhabdo viruses cause Chicken Pox, Measles and Rabies respectively.

2. Variola virus has ________ as genetic material.
a) Single stranded RNA
b) Double stranded RNA
c) Single stranded DNA
d) Double stranded DNA
Answer: d
Clarification: Variola virus has double stranded DNA as genetic material. Plant viruses generally have Single stranded RNA as a genetic material. Animal viruses have Single stranded or Double stranded RNA or Double stranded DNA as genetic material. Bacteriophages have Double stranded DNA as genetic material.

3. Small Pox vaccine is which kind of vaccine?
a) Attenuated Vaccine
b) Inactivated Vaccine
c) Second Generation Vaccine
d) Third Generation Vaccine
Answer: a
Clarification: Small Pox vaccine is an Attenuated Vaccine. Attenuated Vaccines are made by weakening the virulent properties of the pathogen. These vaccines provide Artificial Active Immunity and vaccination is the best preventive remedy for Small Pox.

4. Who is known as the Father of Immunology?
a) Dmitry Ivanovsky
b) Edward Jenner
c) Erik Acharius
d) Francesco Redi
Answer: b
Clarification: Edward Jenner is the Father of Immunology. He discovered the Small Pox vaccine in 1796. Dmitry Ivanovsky is known as the Father of Virology. Erik Acharius is the Father of Lichenology. Francesco Redi is the Father of Parasitology.

5. When was Small Pox eradicated from the world?
a) 1971
b) 1977
c) 1967
d) 1980
Answer: d
Clarification: The last known case of Small Pox was in 1977. However, the world was declared Small Pox free in 1980 by the World Health Organisation.

6. In Chicken Pox, rashes first appear on the body and then on the face.
a) True
b) False
Answer: a
Clarification: Rashes first appear on the body and then on the face in Chicken Pox disease. The rash comes out in crop and with each fresh crop, there may be slight fever again. Rashes change into Papules-vesicles without fluid and then into pustules and finally into a dark brown scab which falls off leaving no scar.

7. Which of the following is the most common late complication of Chicken Pox?
a) Fever
b) Shingles
c) Small Pox
d) Mumps
Answer: b
Clarification: The most common late complication of Chicken Pox is Shingles which is caused by the reactivation of Varicella zoster virus. Shingles cause the appearance of painful rashes which appear as a stripe of blisters on the trunk or the back.

8. What is the full form of MMR vaccine?
a) Mumps Measles Rabies
b) Malignant Melanoma Rheumatism
c) Measles Mumps Rubella
d) Malignant-Malaria Rheumatoid
Answer: c
Clarification: MMR Vaccine is a combined vaccine given to babies within 12-15 months of their birth for the protection against Measles, Mumps and Rubella viruses.

9. What is the incubation period of Rhabdo virus?
a) 1 day-2 weeks
b) 10-20 days
c) 2-4 weeks
d) 10 days-1 year
Answer: d
Clarification: Rhabdo virus is introduced in the body by the bite of rabid or mad dogs usually. It can also be injected by the bite of cats, wolves etc. The incubation period of this virus is from 10 days to one year.

10. Which is the most important characteristic symptom of Rabies?
a) Fear of Height
b) Fear of Water
c) Fear of Cats
d) Fear of Fire
Answer: b
Clarification: Rabies is commonly called as hydrophobia which means Fear of Water. Therefore, Fear of Water is the most important characteristic symptom of Rabies. Other symptoms include excess salivation, severe headache, alternating phases of excitement and depression.

11. What is the mortality rate of humans if they contract rabies?
a) 50% fatal
b) 100% fatal
c) No effects
d) 33% fatal
Answer: b
Clarification: Rabies is 100% fatal if neurological symptoms have developed like violent movements, uncontrolled excitement, inability to move the parts of the body, confusion and loss of consciousness. Once these symptoms appear, the result is always death.

12. What is the earliest sign of contracting Polio?
a) Paralysis
b) Inflammation of the body
c) Inability to bend the head forward
d) Inability to walk
Answer: c
Clarification: The earliest sign of Polio is the inability to bend the head forward. However, the attack of paralysis begins with high fever, headache, chills, vomiting and pain all over the body. Within 2-3 days the paralysis reaches its maximum.

13. Which of the following options is incorrect regarding the contraction of Polio?
a) It spreads through intestinal discharges
b) It spreads through contaminated food and water
c) It spreads by flies
d) It spreads through mosquito bites
Answer: d
Clarification: Polio disease mainly spreads through intestinal discharges like the faeces. It may also spread through contaminated food or water and by flies or other insects which contaminate food or drink. Poliovirus usually enters the body through the alimentary canal where it multiplies and then reaches the nervous system via bloodstream.

14. What is the full form of OPV?
a) Oral Polio Vaccine
b) Oesophagus Polio Vaccine
c) Oral Plague Vaccine
d) Oesophagus Plague Vaccine
Answer: a
Clarification: The full form of OPV is the Oral Polio Vaccine. The Oral Polio Vaccine was developed by Albert Sabin and came into commercial use in 1961.