All Free Biology MCQs with Answers

1611. The molecules of living matter that provide building blocks are mostly based on:

• A. Carbon
• B. Nitrogen
• C. Hydrogen
• D. Ammonia

Explanation: Carbon forms four covalent bonds and can make stable chains, rings, and complex structures, allowing it to serve as the backbone of carbohydrates, lipids, proteins, and nucleic acids. Nitrogen and hydrogen are important elements but do not provide the same versatile framework for most biological molecules. Students may choose nitrogen because it is present in proteins and nucleic acids, but carbon is the principal structural basis.

1612. Earthworm is included in_____________?

• A. Kingdom Plantae
• B. Kingdom Protoctista
• C. Kingdom Monera
• D. Kingdom Animalia

Explanation: An earthworm is a multicellular, heterotrophic animal belonging to the phylum Annelida, so it is placed in Kingdom Animalia. It cannot make its own food and has specialized animal tissues and organs, unlike plants. Students may choose Plantae because earthworms live in soil, but habitat does not determine kingdom.

1613. The number of naturally accusing chemical elements involved in bio chemical reaction is

• A. 126
• B. 86
• C. 92
• D. 206

Explanation: There are 92 naturally occurring chemical elements traditionally recognised in the periodic table, although only a smaller subset is essential for living organisms. Students may choose 126 by confusing naturally occurring elements with the total number of known or predicted elements, but 92 is the standard count of naturally occurring elements.

1614. Nuclein is in its nature?

• A. Basic
• B. Acidic
• C. Both
• D. None of these

Explanation: Nuclein was the original name given to the acidic nuclear material now understood to contain nucleic acid, whose phosphate groups give it an acidic nature. Students may choose “both” because nuclein is associated with basic proteins, but its defining chemical character is acidic.

1615. How many of the bio elements constituent 99% of the total human body?

• A. 8
• B. 4
• C. 6
• D. None of These

Explanation: Six elements, carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur, make up about 99% of the human body's mass and form the main biological molecules. Students may choose four by remembering only carbon, hydrogen, oxygen and nitrogen, which are the most abundant elements in organic compounds.

1616. Fresh Yeast cells are good source of :___________?

• A. Vitamin-B
• B. Nicotine
• C. Morphine
• D. None of the above

Explanation: Fresh yeast is a useful source of B-complex vitamins, which act mainly as coenzymes in metabolic reactions. Students may choose “none of the above” if they confuse yeast with tobacco or opium plants, which are associated with nicotine or morphine, respectively.

1617. Carrot is a source of_________?

• A. Vitamin A
• B. Vitamin B
• C. Vitamin C
• D. Vitamin D

Explanation: Carrots contain beta-carotene, which the body converts into vitamin A, supporting vision and epithelial health. Students may choose vitamin C because carrots are vegetables, but vitamin C is not the characteristic nutrient associated with carrots in this MCQ.

1618. Cotton, wool, silk are examples of ____________ ?

• A. Plant Fibres
• B. Animal Fibres
• C. Natural Fibres
• D. Synthetic Fibres

Explanation: Cotton, wool and silk are all natural fibres because they are obtained from living organisms or their products rather than manufactured chemically. Students may choose animal fibres because wool and silk are animal-derived, but cotton is a plant fibre, so natural fibres is the shared category.

1619. Who is the father of biology?

• A. Albert Einstein
• B. Aristotle
• C. Ronald Fisher
• D. None of above

Explanation: Aristotle is traditionally called the father of biology because he made systematic observations and classifications of living organisms. Students may choose Einstein because he is a famous scientist, but his major contributions were in physics, not the founding development of biology.

1620. Bio means: ___________?

• A. Life
• B. Community
• C. Cycle
• D. None of These

Explanation: The prefix bio comes from the Greek word bios, meaning life. Students may choose community because biology studies communities, but the prefix itself means life, not one level of ecological organization.