All Free Biology MCQs with Answers

• A. Syphilis
• B. Genital herpes
• C. Gonorrhea
• D. HPV
• E. Both A and B

Explanation: Both syphilis and genital herpes can cause damage to the central nervous system of infants during birth.

• A. Gram-Negative bacteria
• B. Neisseria gonorrhoea
• C. Both A and B
• D. None of these

Explanation: Neiserria gonorrhoeae causes Gonorrhea. It has 3 stages and can be treated with antibiotics. It affects both, men and women.

• A. A person may contact syphilis by sharing milk with one already suffering from the disease
• B. Haemophilia is one of the STDs.
• C. Genital herpes and sickle cell anaemia are both STDs
• D. The chances of a 5 years old boy contracting an STD are very little

Explanation: Syphilis is caused by the bacterium Treponema pallidum. It is a sexually transmitted disease (STD) that is transferred through sexual…

• A. Offspring produced by asexual reproduction are called clones
• B. Microscopic and motile asexual reproductive structures are called zoospores
• C. In potatoes, bananas, and ginger, the plantlets arise from the internodes present in the modified stem
• D. Water hyacinth, growing in standing water, drains oxygen from water leading to the death of fishes

Explanation: Potato, banana, and ginger propagate vegetatively by their modified stems.

• A. A small non­-motile female gamete and a large motile male gamete
• B. A large non-­motile female gamete and a small motile male gamete
• C. A large non-­motile female gamete and a small non­motile male gamete
• D. A large motile female gamete and a small non­-motile male gemete

Explanation: Oogamy is the sexual reproduction involving the formation and subsequent fusion of a large, usually stationary, non-motile, female gamete…

• A. New genetic combination leading to variation
• B. Large biomass
• C. Longer viability of seeds
• D. Prolonged dormancy

Explanation: Sexual reproduction always involves meiosis (zygotic in case of haploid individuals and gametic in case of diploid individuals).

• A. Cleistogamous flowers are always autogamous
• B. Xenogamy occurs only by wind pollination
• C. Chasmogamous flowers do not open at all
• D. Geitonogamy involves the pollen and stigma of flowers of different plants

Explanation: In cleistogamy, as the flowers never open so there is no alternative of self pollination. It is invariably autogamous.

• A. Sporopollenin can be degraded by enzymes
• B. Sporopollenin is made up of inorganic materials
• C. Sporopollenin can withstand high temperatures as well as strong acids and alkalis
• D. Sporopollenin can withstand high temperatures but not strong acids

Explanation: Pollen grain is a haploid, unicellular body. It is cuticularised and the cutin is of special type called sporopollenin, which is resistant…

• A. When pollen is shed at the two-­celled stage, double fertilization does not take place
• B. Vegetative cell is larger than generative cell
• C. Pollen grains in some plants remain viable for months
• D. Intine is made up of cellulose and pectin

Explanation: In 60% of flowering plants, the pollen grains are shed at two­celled stage (tube cell + generative cell).

• A. It brings about the opening of the pollen tube
• B. It guides pollen tube from a synergid to egg
• C. It helps in the entry of the pollen tube into a synergid.
• D. It prevents the entry of more than one pollen tube into the embryo sac

Explanation: Within the embryo sac three cells are grouped together at the micropylar end and constitute the egg apparatus.

• A. Egg cell
• B. Persistant synergid
• C. Degenerated synergids
• D. Central cell

Explanation: The pollen tube enters into the embryo sac at the micropylar end. This entry may be between egg and one synergid or between wall of embryo…

• A. Two polar nuclei and one male gamete
• B. One polar nuclei and one male gamete
• C. Ovum and male gamete
• D. Two polar nuclei and two male gametes

Explanation: Double fertilization is the simultaneous occurrence of syngamy and triple fusion.

• A. The ovum and sperms are transported simultaneously to ampullary-isthmic junction of the cervix
• B. The sperms are transported into cervix within 48 hrs of release of ovum in uterus
• C. The sperms are transported into vagina just after the release of ovum in Fallopian tube
• D. The ovum and sperms are transported simultaneously to ampullary-isthmic junction of the Fallopian tube

Explanation: The fusion of a haploid male gamete (sperm) and a haploid female gamete (ovum) to form a diploid zygote is called fertilization.

• A. Release of secondary oocyte
• B. LH surge
• C. Decrease in estradiol
• D. Full development of Graafian follicle

Explanation: During ovulation, there is no decrease in estradiol. In fact, there is a surge in estradiol levels.

• A. One Y chromosome
• B. One X ­chromosome
• C. Two X­ chromosome
• D. One X ­chromosome and one Y­ chromosome

Explanation: A freshly released human egg, also known as an oocyte, contains half of the genetic material required for the formation of a new…

• A. Chikungunya virus
• B. Ebola virus
• C. Hepatitis B virus
• D. Human immunodeficiency virus

Explanation: Correct answer is a. Chikungunya virus Here's an explanation of each option: a.

• A. Follicles
• B. Corona radiata
• C. Corpus luteum
• D. Zona pellucida

Explanation: The follicle cells, after release of the egg, are modified to form a special structure called corpus luteum.

• A. Spermatogonia, Spermatocyte, Spermatid, Spermatozoa
• B. Spermatogonia, Spermatocyte, Spermatozoa, Spermatid
• C. Spermatocyte, Spermatogonia, Spermatozoa, Spermatid
• D. Spermatogonia, Spermatozoa, Spermatocyte, Spermatid

Explanation: Explanation for this question will be added soon.

• A. Uriniferous tubules
• B. Seminiferous tubules
• C. Seminal vesicles
• D. None of these

Explanation: Explanation for this question will be added soon.

• A. Nerve cells
• B. Muscles cells
• C. Fat cells
• D. Interstitial cells

Explanation: Explanation for this question will be added soon.